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132 results on '"R. C. Walker"'

1. Pseudomonas Prosthetic Joint Infections: A Review of 102 Episodes

Author: N. B. Shah, D. R. Osmon, J. M. Steckelberg, R. J. Sierra, R. C. Walker, A. J. Tande, and E. F. Berbari
Subjects: Orthopedic surgery, RD701-811
Abstract: Background: The outcome of patients with Pseudomonas prosthetic joint infection (PS PJI) has not been well studied. The aim of this retrospective cohort study was to assess the outcome of patients with Pseudomonas PJI and to review risk factors associated with failure of therapy.Methods: Between 1/1969 and 12/2012, 102 episodes of PS PJI in 91 patients were identified.Results: The mean age at the time of diagnosis was 67.4 years; forty three percent had knee involvement. Over 40 percent had either diabetes mellitus or a history of gastrointestinal or genitourinary surgery. Nearly half (48 out of 102 episodes) received aminoglycoside monotherapy, while 25% received an anti-pseudomonal cephalosporin. The 2-year cumulative survival free from failure was 69% (95% CI, 56%-82%). Patients treated with resection arthroplasty, two-stage exchange, and debridement with implant retention had a 2-year cumulative survival free from failure of 80% (95% CI, 66%-95%), 83% (95% CI, 60%-100%), and 26% (95% CI, 23%-29%) respectively (P=0.0001).Conclusions: PS PJI's are associated with a high failure rate. Patients treated with debridement and implant retention had a worse outcome.
Published: 2016
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2. Linear polarization in the nucleus of M87 at 7 mm and 1.3 cm

Author: D. L. Meier, R. C. Walker, Jong-Ho Park, E. V. Kravchenko, Kazuhiro Hada, Masanori Nakamura, and Marcello Giroletti
Subjects: Radio galaxy, Polarimetry, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, symbols.namesake, Optics, 0103 physical sciences, Faraday effect, 010303 astronomy & astrophysics, Very Long Baseline Array, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Linear polarization, business.industry, Astronomy and Astrophysics, Polarization (waves), Astrophysics - Astrophysics of Galaxies, Wavelength, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), symbols, Millimeter, business, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on high angular resolution polarimetric observations of the nearby radio galaxy M87 using the Very Long Baseline Array at 24 GHz ($\lambda=$1.3 cm) and 43 GHz ($\lambda=$7 mm) in 2017-2018. New images of the linear polarization substructure in the nuclear region are presented, characterized by a two-component pattern of polarized intensity and smooth rotation of the polarization plane around the 43 GHz core. From a comparison with an analogous dataset from 2007, we find that this global polarization pattern remains stable on a time interval of 11 yr, while showing smaller month-scale variability. We discuss the possible Faraday rotation toward the M87 nucleus at centimeter to millimeter wavelengths. These results can be interpreted in a scenario where the observed polarimetric pattern is associated with the magnetic structure in the confining magnetohydrodynamic wind, which also serves as the source of the observed Faraday rotation., Comment: 9 pages, including 4 pages of Appendix; published in A&A Letters
Published: 2020
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3. Machine learning to predict early recurrence after oesophageal cancer surgery

Author: S A Rahman, R C Walker, M A Lloyd, B L Grace, G I van Boxel, B F Kingma, J P Ruurda, R van Hillegersberg, S Harris, S Parsons, S Mercer, E A Griffiths, J R O'Neill, R Turkington, R C Fitzgerald, T J Underwood, Ayesha Noorani, Rachael Fels Elliott, Paul A W Edwards, Nicola Grehan, Barbara Nutzinger, Jason Crawte, Hamza Chettouh, Gianmarco Contino, Xiaodun Li, Eleanor Gregson, Sebastian Zeki, Rachel de la Rue, Shalini Malhotra, Simon Tavaré, Andy G Lynch, Mike L Smith, Jim Davies, Charles Crichton, Nick Carroll, Peter Safranek, Andrew Hindmarsh, Vijayendran Sujendran, Stephen J Hayes, Yeng Ang, Shaun R Preston, Sarah Oakes, Izhar Bagwan, Vicki Save, Richard J E Skipworth, Ted R Hupp, J Robert O'Neill, Olga Tucker, Andrew Beggs, Philippe Taniere, Sonia Puig, Timothy J Underwood, Fergus Noble, James P Byrne, Jamie J Kelly, Jack Owsley, Hugh Barr, Neil Shepherd, Oliver Old, Jesper Lagergren, James Gossage, Andrew Davies Fuju Chang, Janine Zylstra, Vicky Goh, Francesca D Ciccarelli, Grant Sanders, Richard Berrisford, Catherine Harden, David Bunting, Mike Lewis, Ed Cheong, Bhaskar Kumar, Simon L Parsons, Irshad Soomro, Philip Kaye, John Saunders, Laurence Lovat, Rehan Haidry, Victor Eneh, Laszlo Igali, Michael Scott, Shamila Sothi, Sari Suortamo, Suzy Lishman, George B Hanna, Christopher J Peters, and Anna Grabowska
Subjects: Male, Esophageal Neoplasms, Lymphovascular invasion, medicine.medical_treatment, 030230 surgery, computer.software_genre, Machine Learning, 0302 clinical medicine, Upper GI, Neoadjuvant therapy, Aged, 80 and over, Incidence (epidemiology), General Medicine, Middle Aged, Esophageal cancer, Regression, Random forest, Oncology, Esophagectomy, Area Under Curve, 030220 oncology & carcinogenesis, Cohort, Adenocarcinoma, Female, Original Article, Elastic net regularization, Adult, medicine.medical_specialty, Early Recurrence, Machine learning, Risk Assessment, 03 medical and health sciences, SDG 3 - Good Health and Well-being, Clinical Decision Rules, medicine, Humans, Aged, Ensemble forecasting, Receiver operating characteristic, business.industry, General surgery, Original Articles, medicine.disease, ROC Curve, Surgery, Artificial intelligence, Neoplasm Recurrence, Local, business, computer, Cancer surgery
Abstract: Background Early cancer recurrence after oesophagectomy is a common problem, with an incidence of 20–30 per cent despite the widespread use of neoadjuvant treatment. Quantification of this risk is difficult and existing models perform poorly. This study aimed to develop a predictive model for early recurrence after surgery for oesophageal adenocarcinoma using a large multinational cohort and machine learning approaches. Methods Consecutive patients who underwent oesophagectomy for adenocarcinoma and had neoadjuvant treatment in one Dutch and six UK oesophagogastric units were analysed. Using clinical characteristics and postoperative histopathology, models were generated using elastic net regression (ELR) and the machine learning methods random forest (RF) and extreme gradient boosting (XGB). Finally, a combined (ensemble) model of these was generated. The relative importance of factors to outcome was calculated as a percentage contribution to the model. Results A total of 812 patients were included. The recurrence rate at less than 1 year was 29·1 per cent. All of the models demonstrated good discrimination. Internally validated areas under the receiver operating characteristic (ROC) curve (AUCs) were similar, with the ensemble model performing best (AUC 0·791 for ELR, 0·801 for RF, 0·804 for XGB, 0·805 for ensemble). Performance was similar when internal–external validation was used (validation across sites, AUC 0·804 for ensemble). In the final model, the most important variables were number of positive lymph nodes (25·7 per cent) and lymphovascular invasion (16·9 per cent). Conclusion The model derived using machine learning approaches and an international data set provided excellent performance in quantifying the risk of early recurrence after surgery, and will be useful in prognostication for clinicians and patients., Early recurrence after surgery for adenocarcinoma of the oesophagus is common. A risk prediction model was derived using modern machine learning methods that accurately predicts risk of early recurrence using postoperative pathology. Machine learning may help
Published: 2019
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4. Proximal Resection Margin in Ivor-Lewis Oesophagectomy for Cancer

Author: R. C. Walker, S. F. Hughes, Shah-Jalal Sarker, and Y. A. Qureshi
Subjects: Male, medicine.medical_specialty, Esophageal Neoplasms, medicine.medical_treatment, Adenocarcinoma, 030230 surgery, 03 medical and health sciences, 0302 clinical medicine, Margin (machine learning), medicine, Carcinoma, Humans, Prospective Studies, Carcinoma, Small Cell, Prospective cohort study, Survival rate, Aged, business.industry, Margins of Excision, Cancer, Middle Aged, Prognosis, medicine.disease, Surgery, Esophagectomy, Survival Rate, Oncology, 030220 oncology & carcinogenesis, Carcinoma, Squamous Cell, Resection margin, Female, business, Follow-Up Studies
Abstract: The purpose of this study was to investigate whether a long proximal oesophageal resection margin (PRM) is associated with improved survival after oesophagectomy for cancer and to identify the optimal margin to aim for in this patient group.A prospectively maintained database identified 174 patients who underwent Ivor-Lewis oesophagectomy for cancer. Demographic, clinical, and pathological data were collected. X-tile software was used to identify the optimal resection point. Two models were analysed: single point resection with comparison of two groups (short and long), and two resection points with three groups (short, medium, and long) to provide a range.The median PRM was 4.0 cm (interquartile range: 2.5-6.0 cm). After adjustment for significant confounders, multivariable Cox PH analysis demonstrated that the optimal resection margin was 1.7 cm, and in the three-group analysis the optimum PRM was between 1.7 and 3 cm. In the two-group analysis, the long margin had no effect on DFS (p = 0.37), but carried a significantly improved overall survival (hazard ratio [HR] = 0.46, 95 % confidence interval [CI] 0.25-0.87, p = 0.02). In the three-group analysis, the medium and long groups had improved OS compared with the short group (on average 54 %, HR ≥ 0.45, p ≤ 0.04). The 5-year disease-free and overall survival rates were highest in the medium PRM group (48 and 57 % respectively).Optimal survival following oesophagectomy for cancer is achieved with a PRM 1.7 cm, but a PRM 3 cm does not yield a further survival advantage. Thus, the optimal PRM is likely to be between 1.7 and 3 cm.
Published: 2016

5. Endemic fungal infections in solid organ and hematopoietic cell transplant recipients enrolled in the Transplant-Associated Infection Surveillance Network (TRANSNET)

Author: Carol A. Kauffman, Kaitlin Benedict, Elias Anaissie, Mindy G. Schuster, Benjamin Park, Kieren A. Marr, Alison G. Freifeld, Vicki A. Morrison, Tom Chiller, Loreen A. Herwaldt, Peter G. Pappas, John W. Baddley, Barbara D. Alexander, R. C. Walker, Thomas F. Patterson, Katherine M. Knapp, David R. Andes, G. M. Lyon, and James I. Ito
Subjects: Adult, Male, medicine.medical_specialty, Antifungal Agents, Time Factors, Adolescent, Endemic Diseases, medicine.medical_treatment, Comorbidity, Hematopoietic stem cell transplantation, Blastomycosis, Article, Organ transplantation, Histoplasmosis, Young Adult, Amphotericin B, Internal medicine, medicine, Humans, Cumulative incidence, Prospective Studies, Child, Respiratory Tract Infections, Aged, Transplantation, Coccidioidomycosis, Respiratory tract infections, Coinfection, business.industry, Incidence, Hematopoietic Stem Cell Transplantation, Organ Transplantation, Middle Aged, medicine.disease, United States, surgical procedures, operative, Infectious Diseases, Immunology, Female, Itraconazole, business
Abstract: Background Invasive fungal infections are a major cause of morbidity and mortality among solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients, but few data have been reported on the epidemiology of endemic fungal infections in these populations. Methods Fifteen institutions belonging to the Transplant-Associated Infection Surveillance Network prospectively enrolled SOT and HCT recipients with histoplasmosis, blastomycosis, or coccidioidomycosis occurring between March 2001 and March 2006. Results A total of 70 patients (64 SOT recipients and 6 HCT recipients) had infection with an endemic mycosis, including 52 with histoplasmosis, 9 with blastomycosis, and 9 with coccidioidomycosis. The 12-month cumulative incidence rate among SOT recipients for histoplasmosis was 0.102%. Occurrence of infection was bimodal; 28 (40%) infections occurred in the first 6 months post transplantation, and 24 (34%) occurred between 2 and 11 years post transplantation. Three patients were documented to have acquired infection from the donor organ. Seven SOT recipients with histoplasmosis and 3 with coccidioidomycosis died (16%); no HCT recipient died. Conclusions This 5-year multicenter prospective surveillance study found that endemic mycoses occur uncommonly in SOT and HCT recipients, and that the period at risk extends for years after transplantation.
Published: 2014

6. Kinematics of the jet in M87 on scales of 100 -- 1000 Schwarzschild radii

Author: R. C. Walker, A. P. Lobanov, P. Hardee, Florent Mertens, and Astronomy
Subjects: Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, FOS: Physical sciences, Angular velocity, Kinetic energy, 01 natural sciences, magnetohydrodynamics (MHD), galaxies: individual: M 87, symbols.namesake, 0103 physical sciences, 010303 astronomy & astrophysics, Very Long Baseline Array, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Astronomy and Astrophysics, galaxies: jets, Computational physics, Lorentz factor, Flow velocity, Space and Planetary Science, Poynting vector, symbols, Magnetohydrodynamics, Astrophysics - High Energy Astrophysical Phenomena, Schwarzschild radius
Abstract: Very long baseline interferometry (VLBI) imaging of radio emission from extragalactic jets provides a unique probe of physical mechanisms governing the launching, acceleration, and collimation of relativistic outflows. The two-dimensional structure and kinematics of the jet in M\,87 (NGC\,4486) have been studied by applying the Wavelet-based Image Segmentation and Evaluation (WISE) method to 11 images obtained from multi-epoch Very Long Baseline Array (VLBA) observations made in January-August 2007 at 43 GHz ($\lambda = 7$ mm). The WISE analysis recovers a detailed two-dimensional velocity field in the jet in M\,87 at sub-parsec scales. The observed evolution of the flow velocity with distance from the jet base can be explained in the framework of MHD jet acceleration and Poynting flux conversion. A linear acceleration regime is observed up to $z_{obs} \sim 2$\,mas. The acceleration is reduced at larger scales, which is consistent with saturation of Poynting flux conversion. Stacked cross correlation analysis of the images reveals a pronounced stratification of the flow. The flow consists of a slow, mildly relativistic layer (moving at $\beta \sim 0.5\,c$), associated either with instability pattern speed or an outer wind, and a fast, accelerating stream line (with $\beta \sim 0.92$, corresponding to a bulk Lorentz factor $\gamma \sim 2.5$). A systematic difference of the apparent speeds in the northern and southern limbs of the jet is detected, providing evidence for jet rotation. The angular velocity of the magnetic field line associated with this rotation suggests that the jet in M87 is launched in the inner part of the disk, at a distance $r_0 \sim 5\, R_\mathrm{s}$ from the central engine. The combined results of the analysis imply that MHD acceleration and conversion of Poynting flux to kinetic energy play the dominant roles in collimation and acceleration of the flow in M\,87., Comment: 20 pages, accepted in A&A
Published: 2016
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7. THE 2010 M 87 VHE FLARE AND ITS ORIGIN: THE MULTI-WAVELENGTH PICTURE

Author: D. E. Harris, M. Giroletti, R. C. Walker, L. Stawarz, W. McConville, P. Colin, C. M. Hui, D. Mazin, I. A. Steele, M. Beilicke, and Martin Raue
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), European VLBI Network, Active galactic nucleus, 010504 meteorology & atmospheric sciences, Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, jets [galaxies], FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 7. Clean energy, 01 natural sciences, law.invention, Astrophysical jet, law, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Very Long Baseline Array, 0105 earth and related environmental sciences, Physics, Supermassive black hole, observations [gamma rays], individual (M 87) [galaxies], non-thermal [radiation mechanisms], Black hole, 13. Climate action, active [galaxies], nuclei, Astrophysics - Cosmology and Nongalactic Astrophysics, Flare
Abstract: The giant radio galaxy M 87, with its proximity (16 Mpc) and its very massive black hole ((3 - 6) \times 10^9 M_solar), provides a unique laboratory to investigate very high energy (E>100 GeV; VHE) gamma-ray emission from active galactic nuclei and, thereby, probe particle acceleration to relativistic energies near supermassive black holes (SMBH) and in relativistic jets. M 87 has been established as a VHE gamma-ray emitter since 2005. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In 2008, a rise in the 43 GHz Very Long Baseline Array (VLBA) radio emission of the innermost region (core; extension of < 100 Rs ; Schwarzschild radii) was found to coincide with a flaring activity at VHE. This had been interpreted as a strong indication that the VHE emission is produced in the direct vicinity of the SMBH. In 2010 a flare at VHE was again detected triggering further multi-wavelength (MWL) observations with the VLBA, Chandra, and other instruments. At the same time, M 87 was also observed with the Fermi-LAT telescope at MeV/GeV energies, the European VLBI Network (EVN), and the Liverpool Telescope (LT). Here, preliminary results from the 2010 campaign will be reported., 6 pages, 2 figures; Procceedings of the workshop "High Energy Phenomena in Relativistic Outflows III" (HEPRO III), Barcelona, June 27 - July 1, 2011
Published: 2012

8. False-positiveAspergillusgalactomannan assay in solid organ transplant recipients with histoplasmosis

Author: Carol A. Kauffman, Paschalis Vergidis, L. J. Wheat, Alison G. Freifeld, R. C. Walker, Daniel R. Kaul, D. C. Slagle, and A. K. Kressel
Subjects: Adult, Antigens, Fungal, Histoplasma, Enzyme-Linked Immunosorbent Assay, Aspergillosis, Histoplasmosis, Microbiology, Mannans, Galactomannan, chemistry.chemical_compound, Antigen, medicine, Humans, False Positive Reactions, Transplantation, Aspergillus, biology, Inhalation, medicine.diagnostic_test, business.industry, Galactose, Organ Transplantation, Middle Aged, biology.organism_classification, medicine.disease, Infectious Diseases, Bronchoalveolar lavage, chemistry, Immunology, Female, business
Abstract: Post-transplantation histoplasmosis may be acquired via inhalation, may result from endogenous reactivation, or may be derived from the allograft. The Histoplasma and Aspergillus enzyme-linked immunoassays are increasingly being relied upon for rapid diagnosis of fungal infections, especially in immunocompromised patients. We describe 4 cases of solid organ transplant recipients who had histoplasmosis and a falsely positive Aspergillus galactomannan (GM) obtained from the serum or bronchoalveolar lavage (BAL) fluid. We also report our experience, testing for Histoplasma antigen (Ag) in specimens positive for Aspergillus GM. From January 2007 through December 2010, of 2432 unique patients who had positive Aspergillus GM tests, 514 (21%) were tested for Histoplasma Ag, and 27 were found to be positive. Most specimens that tested positive for both Aspergillus and Histoplasma were obtained by BAL. False-positive tests for Aspergillus GM can occur in immunosuppressed patients who have histoplasmosis, and may obscure the correct diagnosis.
Published: 2011

9. Risk factor analysis ofHistoplasma capsulatumfungemia

Author: Maha Assi, Glenn D. Roberts, R. C. Walker, Mohamad S. Sandid, and Larry M. Baddour
Subjects: Male, medicine.medical_specialty, Minnesota, Histoplasma, Gastroenterology, Histoplasma capsulatum, Histoplasmosis, Immunocompromised Host, fluids and secretions, Risk Factors, Disseminated histoplasmosis, Internal medicine, Humans, Medicine, Blood culture, Risk factor, Fungemia, Aged, Retrospective Studies, Aged, 80 and over, Univariate analysis, medicine.diagnostic_test, biology, business.industry, Mean age, General Medicine, Middle Aged, bacterial infections and mycoses, biology.organism_classification, medicine.disease, Infectious Diseases, Case-Control Studies, Immunology, Female, business
Abstract: The primary objective of the study was to investigate the risk factors for Histoplasma capsulatum fungemia. We conducted a retrospective case-control study among patients with histoplasmosis seen at Mayo Clinic in Rochester from 1 January 1991 through 31 December 2005. Blood cultures were prepared from specimens obtained from 111 patients with a diagnosis of histoplasmosis of which 55 had demonstrated H. capsulatum fungemia whereas the cultures of the remaining 56 patients were negative. The mean age of the patients was 56 years, of which 70% men and 95% were white. In univariate analysis, immunocompromised status (OR 2.9, P=0.008), peripheral leukocyte count (WBC)3000 cells/mm(3) (OR 7.3, P0.001), albumin3.5 g/ dl (OR 3.1, P=0.018), and Charlson score of4 (OR 2.9, P=0.022) were associated with H. capsulatum fungemia, but age55 years was not (OR 1.4, P=0.38). In multivariable analysis, immunocompromised status (OR 2.4, P=0.043) and WBC3000 cells/mm(3) (OR 6.5, P=0.001) remained significant factors associated with H. capsulatum fungemia. Immunocompromised status and WBC3000 cells/ mm(3) are independent risk factors for the development of H. capsulatum fungemia.
Published: 2010

10. A Statistical Description of AGN Jet Evolution from the VLBA Imaging and Polarimetry Survey (VIPS)

Author: J. F. Helmboldt, G. B. Taylor, R. D. Blanford, and R. C. Walker
Subjects: Physics, Jet (fluid), Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Polarimetry, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Position angle, Core (optical fiber), Space and Planetary Science, Astrophysics::Galaxy Astrophysics
Abstract: A detailed analysis of the evolution of the properties of core-jet systems within the VLBA Imaging and Polarimetry Survey (VIPS) is presented. We find a power-law relationship between jet intensity and width that suggests for the typical jet, little if any energy is lost as it moves away from its core. Using VLA images at 1.5 GHz, we have found evidence that parsec-scale jets tend to be aligned with the the direction of emission on kiloparsec scales. We also found that this alignment improves as the jets move farther from their cores on projected scales as small as ~50-100 pc. This suggests that realignment of jets on these projected scales is relatively common. We typically find a modest amount of bending (a change in jet position angle of ~5 deg.) on these scales, suggesting that this realignment may typically occur relatively gradually., Comment: Accepted to ApJ, 20 pages, 8 figures
Published: 2008

11. Minimal residual disease testing after stem cell transplantation for multiple myeloma

Author: Parameswaran Hari, Robert F. Cornell, A M Sherrod, R C Walker, and Claudio A. Mosse
Subjects: Oncology, medicine.medical_specialty, Neoplasm, Residual, 03 medical and health sciences, 0302 clinical medicine, Autologous stem-cell transplantation, Internal medicine, medicine, Animals, Humans, Progenitor cell, Autografts, Multiple myeloma, Transplantation, business.industry, High-Throughput Nucleotide Sequencing, Hematology, medicine.disease, Minimal residual disease, Surgery, Graft-versus-host disease, medicine.anatomical_structure, 030220 oncology & carcinogenesis, Bone marrow, Stem cell, business, Multiple Myeloma, Multiplex Polymerase Chain Reaction, 030215 immunology, Stem Cell Transplantation
Abstract: Increased use of novel agents and autologous stem cell transplantation has led to a significant improvement in PFS and overall survival in patients with multiple myeloma. Despite improved treatment strategies, most patients eventually relapse due to persistent low levels of disease in the bone marrow. Increasingly sensitive methods to measure or detect such disease have been evaluated, including multi-parametric flow cytometry, PCR, next-generation sequencing and imaging modalities. The following literature review examines current methods for detecting and monitoring minimal or measurable residual disease (MRD) in the post-transplant setting. Improved methods for detecting MRD will refine the current definitions of remission and could guide treatment approaches.
Published: 2015

12. Modeling the 3C 120 Radio Jet from 1 to 30 Milliarcseconds

Author: R. C. Walker, José L. Gómez, and P. E. Hardee
Subjects: Physics, Jet (fluid), Leading edge, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Electron, Astrophysics, Viewing angle, Computational physics, Lorentz factor, symbols.namesake, Space and Planetary Science, Speed of sound, symbols, Twist, Adiabatic process
Abstract: The predicted spatial development of helical structures along an expanding jet are used to model observed structures and motions in the 3C 120 jet. Proper motions of helical components associated with the pattern and of other components that move through the pattern provide estimates of flow and helical pattern speeds. Theoretical modeling allows determination of sound speeds as a function of jet viewing angle. Jet morphology argues against viewing angles larger than 12 deg. At a 12 deg viewing angle the most likely scenario involves a decline in jet sound speed from c/3 < a_j < c/1.7 at ~0.5 mas from the core to 0.1c < a_j < 0.25c at ~25 mas from the core accompanied by some acceleration in the jet flow from Lorentz factor < 5 to Lorentz factor > 7. At smaller viewing angles the jet sound speed is lower and at a 6 deg viewing angle the jet sound speed is about a factor 2 less but the flow Lorentz factor is comparable. The decline in radio intensity is on the order of what would be associated with isothermal jet expansion. Knot interknot intensity variations are greater than would be expected from adiabatic compressions associated with the helical twist and we infer the presence of a shock along the leading edge of the helical twist. Our results imply that the macroscopic heating of the expanding jet fluid is less than the microscopic energization of the synchrotron radiating relativistic electrons., 26 pages, 15 figures, in press Astrophysical Journal
Published: 2005

13. An Attempt to Probe the Radio Jet Collimation Regions in NGC 4278, NGC 4374 (M84), and NGC 6166

Author: J. M. Wrobel, R. C. Walker, and Chun Ly
Subjects: Time delay and integration, Physics, Jet (fluid), Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Black hole, Space and Planetary Science, Angular diameter, NGC 6166, Very-long-baseline interferometry, Schwarzschild radius, Very Long Baseline Array
Abstract: NRAO Very Long Baseline Array (VLBA) observations of NGC 4278, NGC 4374 (M84), NGC 6166, and M87 (NGC 4486) have been made at 43 GHz in an effort to image the jet collimation region. This is the first attempt to image the first three sources at 43 GHz using Very Long Baseline Interferometry (VLBI) techniques. These three sources were chosen because their estimated black hole mass and distance implied a Schwarzschild radius with large angular size, giving hope that the jet collimation regions could be studied. Phase referencing was utilize for the three sources because of their expected low flux densities. M87 was chosen as the calibrator for NGC 4374 because it satisfied the phase referencing requirements: nearby to the source and sufficiently strong. Having observed M87 for a long integration time, we have detected its sub-parsec jet, allowing us to confirm previous high resolution observations made by Junor, Biretta & Livio, who have indicated that a wide opening angle was seen near the base of the jet. Phase referencing successfully improved our image sensitivity, yielding detections and providing accurate positions for NGC 4278, NGC 4374 and NGC 6166. These sources are point dominated, but show suggestions of extended structure in the direction of the large-scale jets. However, higher sensitivity will be required to study their sub-parsec jet structure.
Published: 2004

14. A VLBA Search for a Stimulated Recombination Line from the Accretion Region in NGC 1275

Author: K. R. Anantharamaiah and R. C. Walker
Subjects: Physics, Hydrogen, Spatial discrimination, Radiation field, Astrophysics (astro-ph), FOS: Physical sciences, High density, chemistry.chemical_element, Astronomy and Astrophysics, Astrophysics, Plasma, Radiation, Radiation damping, chemistry, Space and Planetary Science, Recombination
Abstract: The radio source 3C84, in NGC1275, has a two sided structure on parsec scales. The northern feature, presumed to be associated with a jet moving away from the Earth, shows strong evidence for free-free absorption. The ionized gas responsible for that absorption would be a source of detectable stimulated recombination line emission for a wide range of physical conditions. The VLBA has been used to search for the H65$\alpha$ hydrogen recombination line. The line is only expected to be seen against the northern feature which contains a small fraction of the total radio flux density. This spatial discrimination significantly aids the search for a weak line. No line was seen, with upper limits of roughly 15% of the continuum over a velocity range of 1486 km/s with resolutions up to 6.6 km/s. In the absence of a strong radiation field, this would imply that the free-free absorbing gas has a wide velocity width, is moving rapidly relative to the systemic velocity, or is concentrated in a thin, high density structure. All of these possibilities are reasonably likely close to an AGN. However, in the intense radiation environment of the AGN, even considering only the radiation we actually observe passing through the free-free absorbing gas, the non-detection is probably assured by a combination of saturation and radiation damping., Comment: 14 pages with 4 postscript figures. Accepted for publication in the April 2003 Astronomical Journal
Published: 2003

15. Submission Guidelines

Author: R. C. Walker and M. Knight
Subjects: Economics, Econometrics and Finance (miscellaneous), Business, Management and Accounting (miscellaneous)
Published: 2009

16. Movement and remediation of trichloroethylene in a saturated, heterogeneous porous medium

Author: R C. Walker, Mart Oostrom, Jacob H. Dane, and C Hofstee
Subjects: geography, geography.geographical_feature_category, Groundwater flow, Trichloroethylene, Chemistry, Environmental remediation, Environmental engineering, Mineralogy, Aquifer, Plume, Permeability (earth sciences), Infiltration (hydrology), chemistry.chemical_compound, Environmental chemistry, Environmental Chemistry, Geotechnical engineering, Water treatment, Saturation (chemistry), Porous medium, Injection well, Dissolution, Groundwater, Water Science and Technology
Abstract: An intermediate-scale flow cell experiment was conducted to remove a liquid trichloroethylene (TCE) spill from a saturated, heterogeneous porous medium using pump-and-treat (P&T) as well as surfactant flushing (SF) techniques. Dissolved TCE concentrations were measured at 20 locations, while fluid saturations were obtained with a dual-energy gamma scanner. The behavior of the TCE spill has been described by Oostrom et al. (1998b) [Oostrom, M., Hofstee, C., Walker, R.C., Dane, J.H., 1998b. Movement and remediation of TCE in a saturated heterogeneous porous medium: 1. Spill behavior and initial dissolution, this issue.]. A total of six alternating P&T and SF periods were used to remediate the flow cell. A two-well system, consisting of an injection and an extraction well, was used during the first five remediation periods. For the last SF period, a three-well system was employed with two injection wells and one extraction well. During the first P&T period, most entrapped TCE was removed, but TCE saturations in a substantial pool on top of a fine-grained sand layer were largely unaffected. During the first SF period, a dense plume was formed containing solubilized TCE which partially sank into the fine-grained sand. In addition, unstable fingers developed below the liquid TCE in the pool. In several samples, small TCE droplets were found, indicating mobilization of TCE. Most of the samples with concentrations larger than 5000 ppm had a milky, emulsion-like appearance. The SF considerably reduced the amount of TCE in the pool on top of the fine-grained sand. During the second P&T period, plume sinking and instabilities were not observed. After starting the second SF period, some unstable fingering and plume sinking resumed, starting at the upstream end of the TCE in the pool. The saturation distribution obtained after the second SF period was quite similar to the one obtained after the first SF period, indicating that additional removal of TCE through SF was difficult as a result of the limited accessibility of the TCE in the pool. A gamma scan, obtained after three weeks of pumping using the three-well configuration, shows that all the liquid TCE had been removed from the coarse-grained sand. Computations based on extraction rates and measured TCE concentrations show that only about 60% of the injected TCE was removed from the cell during the experiment. Part of the missing 40% might have moved downwards into the fine-grained sand as a result of pure phase mobilization. The experimental results suggest that besides the positive effects of solubilization, possible detrimental processes such as pure phase mobilization and dense aqueous-phase plume behavior should be considered during SF.
Published: 1999

17. Infiltration and redistribution of perchloroethylene in partially saturated, stratified porous media

Author: Jacob H. Dane, Mart Oostrom, R C. Walker, and C. Hofstee
Subjects: geography, Capillary pressure, geography.geographical_feature_category, Soil science, Aquifer, Partially saturated, Infiltration (hydrology), Fully automated, Vadose zone, Environmental Chemistry, Geotechnical engineering, Porous medium, Groundwater, Geology, Water Science and Technology
Abstract: Contamination of the subsurface by nonaqueous phase liquids (NAPLs) is a widespread problem. To investigate the behavior of a nonspreading, dense NAPL (DNAPL) in the vadose zone, we conducted perchloroethylene (PCE) infiltration experiments in nominally 1- and 2-dimensional (D), stratified porous media. In addition, the usefulness and limitations of a multifluid flow simulator to describe PCE infiltration and redistribution under the experimental conditions were tested. The physical simulations were conducted in a column (1-D) and a flow container (2-D) which were packed with two distinct layers of coarse-grained sand and a fine-grained sand layer in between. Volumetric water and PCE contents were determined with a fully automated dual-energy gamma radiation system. While migrating through the drier parts of the coarse-grained sand layers, PCE appeared to wet the water–air interface rather than displacing any water. In the wetter parts of the porous medium, PCE displaced water and behaved as a true nonwetting fluid. PCE showed a limited response to gradients in capillary pressure and rather high values for the volumetric PCE content were measured in the fine-grained sand layers. This was attributed to the nonspreading nature of PCE. The multifluid flow simulator appeared to predict the initial PCE movement in the vadose zone reasonably well. However, the model was not capable of predicting the final amounts of PCE retained in either the unsaturated or saturated part of the flow domain, mainly because the simulator does not consider the nonspreading flow behavior of NAPLs.
Published: 1998

18. Surfactant enhanced removal of PCE in a nominally two-dimensional, saturated, stratified porous medium

Author: Jacob H. Dane, C. Hofstee, W.E Hill, and R C. Walker
Subjects: Chromatography, Environmental remediation, Human decontamination, Micelle, Permeability (earth sciences), chemistry.chemical_compound, Pulmonary surfactant, chemistry, Chemical engineering, Triton X-100, Environmental Chemistry, Saturation (chemistry), Porous medium, Water Science and Technology
Abstract: Although surfactant enhanced remediation of nonaqueous phase liquids (NAPLs) by pump-and-treat technology has been studied extensively in the laboratory with one-dimensional columns, very few multi-dimensional investigations have been reported. In this study we focus on the removal of perchloroethylene (PCE) from a two-dimensional, saturated porous medium containing a low permeability sand layer situated in an otherwise high permeability sand. A PCE spill was applied at the surface of the porous medium and allowed to redistribute until static equilibrium was achieved. The porous medium was then flushed with various surfactant and co-solvent formulations injected at the PCE source location and extracted at the bottom of the porous medium using a configuration similar to that of Abdul and Ang [Abdul, S.A., Ang, C.C., 1994. In situ surfactant washing of polychlorinated biphenyls and oils from a contaminated field site: Phase II. Pilot study. Ground Water 32, 727–734]. Effluent samples were analyzed for dissolved PCE concentrations. Volumetric water and PCE content values were determined at a number of locations by means of dual-energy gamma radiation measurements. Once surfactant flushing had started, PCE moved as a distinct separate phase ahead of the surfactant front. Most of this downward moving PCE accumulated on top of the low permeability sand layer. Some PCE, however, passed quickly through this layer and subsequently through the high permeability sand below it. Movement of some of the PCE into and through the low permeability sand layer was attributed to local heterogeneities combined with reduced interfacial tensions associated with the surfactant formulation. Clean-up of PCE in most of the high permeability sand was considered to be effective. PCE accumulated on top of the fine layer, however, posed a significant challenge to remediation and required several pumping configurations and surfactant/co-solvent formulations before most of it was removed.
Published: 1998

19. Surfactant enhanced removal of PCE in a partially saturated, stratified porous medium

Author: R C. Walker, Jacob H. Dane, W.E Hill, and C. Hofstee
Subjects: geography, geography.geographical_feature_category, Chemistry, Mineralogy, Aquifer, Permeability (earth sciences), Pulmonary surfactant, Vadose zone, Environmental Chemistry, Saturation (chemistry), Porous medium, Water content, Groundwater, Water Science and Technology
Abstract: Dense nonaqueous phase liquids (DNAPLs), such as perchloroethylene (PCE), pose a significant threat to the environment, specifically to our drinking water present in aquifers. In many instances, a DNAPL will become trapped and form pools on top of confining layers while migrating through the vadose zone. Residual DNAPL and DNAPL pools form sources of long term contamination, which are difficult to remove by classical pump-and-treat remediation. A physically simulated PCE spill into a large, two-dimensional flow container, packed with a fine sand layer surrounded by coarse sand, was therefore studied in this work. A water table was maintained near the bottom of the flow container, such that the coarse sand just below the fine layer was unsaturated, but the bottom of the fine sand layer was at or near saturation. A PCE spill was applied at the center of the porous medium's surface and allowed to redistribute until static equilibrium was reached. The porous medium was then flushed with a surfactant solution (Triton X-100, 4.0% by volume), using the same application configuration as for the spill, while simultaneously extracting solution at one or more locations at the bottom of the porous medium. Effluent samples were analyzed for PCE concentrations. Volumetric water and PCE content values were determined several times at a number of locations by means of dual-energy gamma radiation measurements. The coarse sand in the upper portion of the porous medium was cleaned rapidly by the surfactant flushing. Removal of PCE from the fine sand layer, however, proved to be more difficult because most of the surfactant solution bypassed the PCE. Lateral spreading of the surfactant plume occurred near the saturated/nearly saturated zones in the fine and coarse sand. This lateral spreading, unfortunately, allowed for solubilized PCE, the concentration of which was enhanced by micelle formation, to move into regions previously uncontaminated. The pumping configuration was subsequently changed in an attempt to force the surfactant solution through the entire fine layer, i.e., to hydraulically control the surfactant flushing, while simultaneously increasing the amount of solubilized PCE.
Published: 1998

20. Respiratory syncytial virus pneumonitis-induced diffuse alveolar damage in an autologous bone marrow transplant recipient

Author: S N Markovic, A Adlakha, T F Smith, and R C Walker
Subjects: General Medicine
Published: 1998

21. Limits onWWZandWWγCouplings frompp¯→eνjjXEvents ats}=1.8TeV

Author: B. Flaugher, J. P. Berge, P. Yeh, S. Vejcik, J. Huth, M. Dickson, A. Titov, S. Cihangir, J. Strait, F. Ptohos, R. Ely, T. J. Phillips, H. Grassmann, A. B. Wicklund, J. I. Lamoureux, G. Punzi, B. L. Winer, E. Engels, O. Schneider, A. Stefanini, W. Carithers, D. Bisello, E. Kovacs, E. E. Schmidt, T. Takahashi, D. A. Kardelis, T. Baumann, C. Bromberg, S. Belforte, S. Moulding, M. Cordelli, R. J. Miller, S. Leone, R. G. Wagner, S. Segler, G. Brandenburg, J. Wolinski, A. Maghakian, L. Keeble, C. Haber, M. Turcotte, A. T. Goshaw, H. Mitsushio, F. Azfar, Y. Teramoto, J. Hauser, G. Houk, D. W. Gerdes, N. Wainer, M. Mishina, A. Sgolacchia, R. P. Thun, J. Steele, S. Funaki, M. Paulini, K. Yasuoka, S. Donati, S. Eno, M. Roach-Bellino, Y. Morita, T. Chikamatsu, S. Bertolucci, Weiya Zhang, H. Jensen, Mosè Mariotti, S. Dell'Agnello, D. A. Smith, C. Boswell, B. Farhat, K. Strahl, M. P. Schmidt, D. Neuberger, P. Lukens, G. Pauletta, G. Wang, P. Musgrave, N. Produit, S. Miscetti, G. Watts, G. Piacentino, Umesh Joshi, K. E. Ohl, C. Hawk, M.-T. Cheng, D. Carlsmith, M. J. Wang, R. M. Hans, R. Oishi, W. Koska, J. Skarha, H. Frisch, T. A. Fuess, T. Muller, Andrea Castro, K. Maeshima, M. Campbell, P. Giannetti, R. M. Keup, B. A. Barnett, A. Sansoni, S. Zucchelli, R. E. Blair, P. Melese, F. D. Snider, F. Rimondi, S. Geer, M. Gold, S. H. Kim, V. Scarpine, J. Lys, J. Kroll, P. Limon, K. L. Byrum, J. Patrick, T. L. Watts, Y. K. Kim, Marina Cobal, C. Grosso-Pilcher, Jakita O. Thomas, A. Fry, F. Bird, R. C. Walker, L. Stanco, R. Wilkinson, P. Giromini, S. van den Brink, J. Tonnison, C. Wei, Andrew Beretvas, J. D. Cunningham, J. R. Dittmann, M. J. Shochet, P. Hu, E. Kuns, J. C. Yun, L. Nodulman, L. Pondrom, E. Wicklund, G. Bellettini, L. Pescara, C. P. Jessop, K. Hara, A. Zanetti, G. Unal, Alan Sill, Michele Gallinaro, W. Bokhari, D. Bortoletto, S. R. Amendolia, T. Rodrigo, K. Tollefson, H. Wenzel, S. H. Oh, J. D. Lewis, J. Incandela, H. Iso, M. Incagli, L. Demortier, N. S. Lockyer, W-M. Yao, I. Yu, A. Dunn, H. Kasha, C. Couyoumtzelis, C. N. Chiou, E. Meschi, Sung Keun Park, J. E. Elias, Q. F. Wang, C. Pagliarone, J. Konigsberg, N. Giokaris, M. Krasberg, A. G. Clark, S. Seidel, F. Keyvan, T. Devlin, J. Conway, A. F. Garfinkel, P. Kesten, P. Koehn, P. K. Teng, F. Bedeschi, F. DeJongh, R. Hollebeek, Hyun-Chul Kim, M. G. Albrow, V. Bolognesi, J. Wang, W. J. Robertson, J. Mueller, R. D. Kennedy, J. Spalding, J. Lu, D. Lucchesi, P. F. Shepard, M. Binkley, Mark Kruse, Kiminori Kondo, Paul Tipton, I. Fiori, K. Biery, R. Hamilton, M. Pillai, G. Bauer, M. Vondracek, J. Bellinger, C. Anway-Wiese, G. P. Yeh, C. Yosef, H. Y. Chao, J. A. J. Matthews, F. Ukegawa, J. Freeman, P. de Barbaro, E. Kajfasz, C. B. Luchini, R. L. Swartz, S. Miyashita, C. H. Wang, M. Contreras, J. Mansour, N. M. Shaw, James Proudfoot, M. Franklin, J. W. Chapman, G. Sganos, S. Behrends, B. Denby, B. T. Huffman, J. Siegrist, R. L. Wagner, A. Caner, W. Badgett, N. Labanca, K. Ragan, H. H. Williams, R. Vidal, L. Gladney, Fumio Abe, W. Kowald, A. Mukherjee, S. Mikamo, A. Hölscher, J. Yoh, M. Atac, E. H. Low, R. E. Hughes, J. Antos, G. Sullivan, H. S. Budd, H. Areti, L. Song, T. L. Thomas, L. F. Nakae, Konstanty Sumorok, P. Azzi, R. Plunkett, A. Barbaro-Galtieri, W. C. Wester, Sacha E Kopp, S. R. Hahn, K. Sliwa, N. Turini, D. Crane, J.I. Friedman, K. Goulianos, Giorgio Apollinari, L. Groer, N. Uemura, M. D. Peters, Y. Cen, C. Wendt, S. Tether, Teruki Kamon, M. Frautschi, Y. Seiya, P. Maksimovic, Leonard Spiegel, A. Scribano, C. Campagnari, Daniel P Cronin-Hennessy, P. McIntyre, P. Hurst, M. Timko, James Bensinger, G. Michail, Y. Ye, P. Sinervo, R. B. Drucker, Kevin Burkett, W. K. Sakumoto, P. F. Derwent, P. Wilson, H. Keutelian, T. Yoshida, G. Gagliardi, J. Hylen, M. Yin, D. H. Kim, G. W. Foster, V. Papadimitriou, M. Mangano, J. Cooper, D. Saltzberg, M. Miller, S. Delchamps, A. Schindler, T. M. Liss, G. Busetto, M. Loreti, T. Song, A. Yagil, T. Daniels, D. Y. Wu, A. T. Laasanen, P. Maas, R. W. Kadel, Yasuo Fukui, T. Okusawa, Le Zhang, J. Huston, A. Spies, D. Yovanovitch, T. Westhusing, S. Ogawa, R. M. Harris, D. Glenzinski, R. Kephart, Steve Kuhlmann, D. Amidei, C. Loomis, R. Mattingly, A. Bodek, J. Wyss, G. Chiarelli, M. M. Deninno, O. Long, Andreas Warburton, S. Errede, M. W. Bailey, A. Grewal, J. Tseng, D. Errede, Q. Shen, A. Menzione, T. Kaneko, Y. Kato, S. Zhang, F. Cervelli, M. Shimojima, Catherine Newman-Holmes, P. Auchincloss, P. Schlabach, K. Takikawa, D. Vucinic, C. Nelson, L. Ristori, K. Kordas, P. Bartalini, E. Buckley-Geer, D. Kestenbaum, S. B. Kim, Riccardo Paoletti, I. Nakano, J. Bao, J. P. Marriner, Q. Fan, Douglas Benjamin, J. Cammerata, A. Tollestrup, J. Romano, P. Singh, M. Shapiro, M. Dell'Orso, J. Heinrich, Jose M. Benlloch, G. F. Sciacca, L. Christofek, R. Handler, L. Rosenson, T. Mimashi, L. E. Kirsch, A. Byon-Wagner, F. Zetti, C. Blocker, A. Gordon, P. Sphicas, Hong Sj, S. A. Hauger, F. Tartarelli, Virgil E Barnes, W. Taylor, J. F. de Troconiz, S. Galeotti, T. Boulos, R. C. Webb, A. Martin, S. Lammel, T. LeCompte, M. Lindgren, D. Theriot, L. Holloway, D. Benton, Nicola Bacchetta, J. Gonzalez, B. Harral, X. Wu, K. Einsweiler, S. Tkaczyk, David Stuart, and A. Bhatti
Subjects: Physics, Coupling, Particle physics, Luminosity (scattering theory), High Energy Physics::Phenomenology, Tevatron, General Physics and Astronomy, Electron, Lambda, law.invention, Nuclear physics, law, Transverse momentum, High Energy Physics::Experiment, Fermilab, Neutrino, Collider
Abstract: We present limits on anomalous WWZ and WW-gamma couplings from a search for WW and WZ production in p-bar p collisions at sqrt(s)=1.8 TeV. We use p-bar p -> e-nu jjX events recorded with the D0 detector at the Fermilab Tevatron Collider during the 1992-1995 run. The data sample corresponds to an integrated luminosity of 96.0+-5.1 pb^(-1). Assuming identical WWZ and WW-gamma coupling parameters, the 95% CL limits on the CP-conserving couplings are -0.33
Published: 1997

22. Measurement of theB+andB0Lifetimes Using Topological Reconstruction of Inclusive and Semileptonic Decays

Author: G. Grieco, E. Engels, Sangjin Kim, R. W. Kadel, M. L. Miller, R. Kephart, R. E. Blair, E. H. Low, P. Lukens, D. W. Gerdes, M. W. Bailey, D. Bortoletto, Y. Morita, D. Crane, X. Wu, Y. Cen, A. Barbaro-Galtieri, L. Rosenson, W. Yao, D. Benton, A. Stefanini, D. Yovanovitch, C. Newman-Holmes, M. Timko, A. Sansoni, T. Kaneko, O. Schneider, A. Caner, A. Menzione, T. Kamon, J. Wyss, J. Freeman, A. Hölscher, S. Vejcik, D. Benjamin, H. Keutelian, S. Donati, D. A. Smith, B. Harral, J. Gonzalez, J. Bellinger, K. Ragan, K. Kordas, N. Turini, E. Kuns, R. L. Wagner, C. Campagnari, G. Unal, P. Auchincloss, S. Zhang, E. Buckley-Geer, P. Koehn, K. Goulianos, T. J. Phillips, T. Chikamatsu, S. Funaki, J. Hauser, L. Gladney, S. Zucchelli, J. Romano, W. Koska, J. F. de Troconiz, A. Schindler, S. Hong, G. W. Foster, T. Westhusing, S. Seidel, Q. Shen, L. Groer, L. Pescara, A. Grewal, F. Rimondi, S. Tether, P. Hurst, S. Eno, M. Mishina, L. Nodulman, A. Titov, B. Denby, Y. Teramoto, P. Melese, W. K. Sakumoto, O. Long, D. Errede, L. Holloway, S. Mikamo, R. C. Webb, R. M. Keup, K. Sliwa, A. B. Wicklund, A. Zanetti, C. Haber, W. J. Robertson, F. Abe, J. Heinrich, I. Fiori, R. Hollebeek, M. Campbell, D. A. Kardelis, G. Houk, A. Castro, G. Chiarelli, Y. K. Kim, G. Busetto, M. Shimojima, D. Saltzberg, A. Tollestrup, M. Shochet, J. P. Berge, R. Ely, C. Pagliarone, D. Bisello, M. Gold, V. Papadimitriou, K. Kondo, C. B. Luchini, E. Kovacs, A. F. Garfinkel, H. Kasha, A. Fry, P. Bartalini, F. Ptohos, J. Bao, S. Segler, N. Bacchetta, Marina Cobal, T. Lecompte, C. Boswell, W. Badgett, K. Strahl, H. S. Kim, C. Anway-Wiese, E. Meschi, D. Neuberger, H. H. Williams, I. Nakano, S. Dell'Agnello, F. Azfar, J. D. Cunningham, S. Behrends, G. Apollinari, T. Boulos, T. Takahashi, J. Spalding, S. Ogawa, S. E. Kuhlmann, C. Wendt, S. A. Hauger, H. Mitsushio, P. F. Shepard, L. Keeble, Richard Hughes, P. Sinervo, V. E. Barnes, J. Konigsberg, J. Tseng, J. P. Marriner, M. Frautschi, A. J. Martin, T. Okusawa, A. Maghakian, D. Glenzinski, R. Oishi, H. Frisch, J. Proudfoot, D. Carlsmith, K. Biery, T. Rodrigo, P. Giromini, R. B. Drucker, A. G. Clark, R. M. Hans, J. Yoh, M. Franklin, J. Siegrist, R. C. Walker, M. Shapiro, J. Strait, F. D. Snider, J. Wolinski, D. Theriot, P. Wilson, J. Kroll, L. F. Nakae, J. Friedman, A. Beretvas, G. P. Yeh, M. Contreras, G. F. Sciacca, John Wehrley Chapman, G. Bellettini, W. Zhang, R. Paoletti, A. Gordon, F. Bird, Tony Liss, H. S. Budd, R. Handler, P. Maas, F. Keyvan, Y. Fukui, D. Y. Wu, S. Cihangir, J. Incandela, Jose M. Benlloch, P. Musgrave, S. Park, P. F. Derwent, J. Huston, I. Yu, S. Miscetti, Peter McIntyre, G. Pauletta, D. Lucchesi, G. Watts, P. Limon, E. Wicklund, M. Binkley, T. Baumann, C. Hawk, A. Scribano, M. Incagli, S. Errede, G. Brandenburg, J. Skarha, M. D. Peters, S. Belforte, L. Pondrom, J. Patrick, R. Vidal, T. Yoshida, H. Areti, J. Tonnison, D. P. Coupal, S. Kopp, K. Burkett, K. Sumorok, T. Song, Y. Kato, M. Turcotte, S. Lammel, P. Schlabach, Mark Kruse, A. Bhatti, L. Ristori, R. M. Harris, R. Wilkinson, L. E. Kirsch, N. Lockyer, K. Takikawa, J. Mansour, M. G. Albrow, R. L. Swartz, J. D. Lewis, C. Grosso-Pilcher, J. I. Lamoureux, A. Yagil, R. Thun, K. L. Byrum, L. Song, M. P. Schmidt, R. Mattingly, A. T. Goshaw, K. Yasuoka, K. Einsweiler, S. Miyashita, H. Iso, T. Devlin, G. Gagliardi, Paul Tipton, M. Dell'Orso, R. G. Wagner, K. Hara, G. Michail, W. Carithers, E. E. Schmidt, J. Steele, N. Produit, E. Kajfasz, H. Wenzel, C. Nelson, M. Vondracek, B. Flaugher, A. Warburton, C. P. Jessop, H. Grassmann, F. Dejongh, S. H. Kim, U. Joshi, P. Sphicas, S. Geer, B. T. Huffman, D. Hennessy, N. M. Shaw, B. A. Barnett, K. Maeshima, L. Demortier, B. L. Winer, G. Piacentino, J. Huth, A. Etchegoyen, L. Stanco, J. Mueller, M. Krasberg, M. Yin, M. Mariotti, N. Wainer, M. Cordelli, F. Cervelli, D. Kestenbaum, D. Amidei, W. C. Wester, F. Tartarelli, D. H. Kim, P. Giannetti, T. Mimashi, J. R. Cooper, J. Hylen, J. E. Elias, G. Bauer, F. Bedeschi, N. Uemura, M. Lindgren, G. Punzi, F. Ukegawa, A. Mukherjee, C. Blocker, Qian Wang, S. Moulding, A. Sill, A. Spies, P. Singh, M. Roach-Bellino, V. Bolognesi, M. Mangano, J. C. Yun, G. Sganos, S. Leone, A. Dunn, J. A J Matthews, M. Pillai, Q. Fan, Y. Ye, H. Jensen, V. Scarpine, P. de Barbaro, M. Deninno, R. Plunkett, M. Gallinaro, T. Daniels, J. Wang, M. Dickson, G. Sullivan, F. Zetti, R. Hamilton, M. Loreti, P. Kesten, J. H. Thomas, P. Azzi, S. R. Hahn, B. Farhat, A. Bodek, A. Byon-Wagner, R. D. Kennedy, Y. Seiya, A. T. Laasanen, J. P. Done, T. Watts, S. Tkaczyk, S. Bertolucci, T. Muller, K. E. Ohl, P. Hu, T. A. Fuess, and N. Giokaris
Subjects: Physics, Semileptonic decay, Particle physics, Meson, Branching fraction, Electron–positron annihilation, Hadron, General Physics and Astronomy, Elementary particle, Nuclear physics, Particle decay, High Energy Physics::Experiment, B meson, Collider Detector at Fermilab, Boson
Abstract: The lifetimes of the ${\mathit{B}}^{+}$ and ${\mathit{B}}^{0}$ mesons have been measured using fully reconstructed decays. In a sample of \ensuremath{\sim}49 600J/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$ decays recorded with the Collider Detector at Fermilab, 148\ifmmode\pm\else\textpm\fi{}16 ${\mathit{B}}^{+}$ and 121\ifmmode\pm\else\textpm\fi{}16${\mathit{B}}^{0}$ mesons have been reconstructed using the silicon vertex detector. Unbinned likelihood fits to the proper lifetime distributions of these B mesons give ${\mathrm{\ensuremath{\tau}}}^{+}$=1.61\ifmmode\pm\else\textpm\fi{}0.16 (stat)\ifmmode\pm\else\textpm\fi{}0.05 (syst) ps, ${\mathrm{\ensuremath{\tau}}}^{0}$=1.57\ifmmode\pm\else\textpm\fi{}0.18 (stat) \ifmmode\pm\else\textpm\fi{}0.08 (syst) ps, and ${\mathrm{\ensuremath{\tau}}}^{+}$/${\mathrm{\ensuremath{\tau}}}^{0}$=1.02\ifmmode\pm\else\textpm\fi{}0.16 (stat) \ifmmode\pm\else\textpm\fi{}0.05 (syst).
Published: 1997

23. Parameters of Disks from VLBI Observations

Author: R. C. Walker
Subjects: Physics, Very-long-baseline interferometry, Astronomy
Abstract: VLBI provides the only direct imaging technique currently available that is able to resolve even the outer parts of accretion disks. Recent observations of water masers in NGC 4258 and of free-free absorption of counterjet radiation in NGC 1275 are the best examples of where VLBI has provided important data on the parameters of disks. Other observations are now being made of similar sources. In addition, recent VLBI observations of HI absorption promise to add yet more constraints on the outer disk regions.
Published: 1997

24. Measurement ofσB(W→eν)andσB(Z0→e+e−)inpp¯Collisions at√s=1.8TeV

Author: Andrea Sansoni, S. Donati, K. Yasuoka, W. Koska, R. J. Miller, J. D. Lewis, B. A. Barnett, Giorgio Apollinari, A. Mukherjee, F. Ptohos, Andrew Beretvas, Kostantinos Kordas, E. H. Low, W. J. Robertson, R. E. Hughes, Teruki Kamon, Petar Maksimovic, F. DeJongh, Craig Blocker, Mosè Mariotti, J. Proudfoot, Y. Cen, Kaori Maeshima, M. Campbell, M. D. Peters, D. A. Smith, P. Giannetti, K. E. Ohl, T. Song, G. Houk, D. A. Kardelis, V. Scarpine, W. K. Sakumoto, D. Glenzinski, Q. Fan, J. Cammerata, A. Tollestrup, S. Geer, G. Piacentino, S. B. Kim, R. C. Walker, N. Produit, Y. Teramoto, T. Baumann, R. Handler, C. Grosso-Pilcher, R. Vidal, S. Dell'Agnello, P. F. Shepard, S. H. Oh, P. Sphicas, H. Keutelian, F. Tartarelli, Virgil E Barnes, A. Schindler, C. Hawk, M. Cordelli, G. Busetto, L. Song, M. Krasberg, W. Carithers, Robert M Harris, L. Pondrom, E. Wicklund, P. Hurst, T. Devlin, S. R. Hahn, P. Wilson, Jose M. Benlloch, G. Michail, J. Wolinski, L. Nodulman, T. Kaneko, A. Caner, S. Vejcik, J. R. Bensinger, L. Groer, Alan Garfinkel, T. Chikamatsu, R. G. Wagner, G. Sganos, P. McIntyre, R. Wilkinson, J. Bao, H. Y. Chao, P. Melese, J. Mansour, R. Mattingly, M. Gold, I. Yu, J. E. Elias, F. Keyvan, B. Flaugher, S. Lammel, Jay Hauser, M. Mishina, A. Menzione, Sijing Zhang, J. Incandela, A. Bodek, T. Takahashi, G. Bauer, J. W. Chapman, J. Conway, F. D. Snider, M. J. Shochet, D. D. Yovanovitch, J. Wyss, J. Antos, Luca Stanco, Sacha E Kopp, F. Cervelli, C. Yosef, T. L. Watts, P. Kesten, S. Behrends, Konstanty Sumorok, C. Haber, R. L. Swartz, Marjorie Shapiro, G. Chiarelli, A. Titov, M. Turcotte, L. Demortier, V. Bolognesi, J. Spalding, O. Schneider, Kiminori Kondo, T. LeCompte, A. Zanetti, M. M. Deninno, O. Long, C. Pagliarone, S. Galeotti, A. B. Wicklund, J. Tseng, D. W. Gerdes, P. Schlabach, F. Bird, P. F. Derwent, Kazuhiko Hara, P. Musgrave, Andrea Castro, M. Mangano, A. Dunn, S. Bertolucci, W. C. Wester, J. Lys, C. H. Wang, D. Errede, E. E. Schmidt, A. Hölscher, S. Zucchelli, R. E. Blair, S. Delchamps, F. Rimondi, C. Nelson, Weiya Zhang, E. Buckley-Geer, Riccardo Paoletti, D. Lucchesi, P. Maas, J. P. Berge, D. Y. Wu, R. Kephart, C. Boswell, P. K. Teng, M. Lindgren, E. Kuns, J.I. Friedman, M. Timko, J. Tonnison, S. Miyashita, R. Ely, H. Areti, L. Christofek, R. B. Drucker, S. Eno, A. Grewal, Yasuo Fukui, Y. Kato, P. Sinervo, Nicola Labanca, T. Okusawa, K. Biery, Le Zhang, R. L. Wagner, Alan Sill, P. Limon, John Huth, L. Holloway, J. N. Bellinger, J. Skarha, K. Goulianos, P. Auchincloss, Daniel P Cronin-Hennessy, G. W. Brandenburg, L. Keeble, Catherine Newman-Holmes, P. Hu, G. Unal, S. Tkaczyk, David Stuart, D. Neuberger, Jun Lu, Mark Kruse, J. Patrick, C. Anway-Wiese, R. Hamilton, M. Pillai, Kevin Einsweiler, J. Huston, H. H. Williams, S. C. van den Brink, A. Spies, T. A. Fuess, W. Kowald, M. Vondracek, C. Loomis, P. de Barbaro, S. Ogawa, S. Leone, Jing Wang, A. Stefanini, G. P. Yeh, S. A. Hauger, Daniela Bortoletto, E. Kajfasz, M. Franklin, H. Grassmann, Umesh Joshi, W-M. Yao, J. Cooper, R. M. Keup, S. H. Kim, R. D. Kennedy, M. Atac, K. Ragan, D. Benton, R. W. Kadel, S. Cihangir, Henry J. Frisch, Tony Liss, G. Pauletta, H. S. Budd, C. Couyoumtzelis, S. Funaki, J. F. de Troconiz, Kevin Burkett, Wendy Taylor, J. A.J. Matthews, S. Mikamo, M. Incagli, J. C. Freeman, M. Yin, S. Segler, M. Contreras, T. Boulos, E. Meschi, Sung Keun Park, Sally Seidel, T. Mimashi, M. Dickson, R. Oishi, B. T. Huffman, G. Gagliardi, Manfred Paulini, M. J. Wang, D. Theriot, B. Farhat, Allan G Clark, M. Miller, Patrizia Azzi, R. C. Webb, A. Martin, S. Moulding, Fumio Abe, R. M. Hans, Douglas Benjamin, T. J. Phillips, Doyeong Kim, Paul Tipton, A. Fry, N. Uemura, C. B. Luchini, M. Frautschi, J. Kroll, James Strait, J. Konigsberg, D. Saltzberg, M. Roach-Bellino, S. R. Amendolia, X. Wu, K. Sliwa, K. Takikawa, W. Bokhari, C. P. Jessop, Duncan Carlsmith, Y. Seiya, C. Campagnari, G. Wang, D. Crane, N. S. Lockyer, M. W. Bailey, D. Amidei, T. L. Thomas, P. Bartalini, P. Lukens, Jakita O. Thomas, F. Zetti, J. C. Yun, Avraham Yagil, G. Sullivan, V. Papadimitriou, K. Strahl, C. N. Chiou, Y. Morita, C. Wei, J. Siegrist, M. Loreti, A. Byon-Wagner, M. P. Schmidt, M. T. Cheng, H. Iso, T. Westhusing, P. Koehn, I. Nakano, R. K. Plunkett, T. Daniels, R. J. Hollebeek, Yongsun Kim, A. Gordon, A. T. Goshaw, Nikos Giokaris, J. I. Lamoureux, C. Bromberg, M. Shimojima, A. Maghakian, Stefano Belforte, L. Pescara, Nicola Turini, A. T. Laasanen, Henrik Jeldtoft Jensen, S. Tether, H. Mitsushio, F. Azfar, L. Ristori, Hong Sj, K. Tollefson, L. F. Nakae, S. Miscetti, Andreas Warburton, P. Singh, Leonard Spiegel, Jochen Jens Heinrich, D. Kestenbaum, M. Dell'Orso, Nicola Bacchetta, J. Romano, J. Gonzalez, F. Bedeschi, B. Harral, Tomoko Yoshida, A. Scribano, G. F. Sciacca, H. Wenzel, F. Ukegawa, A. Barbaro-Galtieri, L. Gladney, W. Badgett, L. Rosenson, D. Vucinic, L. E. Kirsch, T. Rodrigo, Marina Cobal, I. Fiori, S. Errede, Y. Ye, J. D. Cunningham, G. Bellettini, M. Binkley, Q. Shen, M. G. Albrow, J. Hylen, Hyun-Chul Kim, T. Muller, G. W. Foster, C. Wendt, Gordon Watts, Jay Dittmann, Michele Gallinaro, K. L. Byrum, P. Giromini, H. Kasha, Dario Bisello, A. Bhatti, G. Punzi, B. L. Winer, E. Engels, J. P. Marriner, P. Yeh, E. Kovacs, N. Wainer, A. Sgolacchia, R. P. Thun, Q. F. Wang, J. Steele, S. E. Kuhlmann, J. Mueller, N. M. Shaw, B. Denby, and J. Yoh
Subjects: Nuclear physics, Physics, Luminosity (scattering theory), Proton, Antiproton, law, Physics::Accelerator Physics, General Physics and Astronomy, Sigma, High Energy Physics::Experiment, Collider, Collider Detector at Fermilab, law.invention
Abstract: We present a measurement of $\sigma \cdot B(W \to e \nu)$ and $\sigma \cdot B(Z^0 \to e^+e^-)$ in proton - antiproton collisions at $\sqrt{s} =1.8$ TeV using a significantly improved understanding of the integrated luminosity. The data represent an integrated luminosity of 19.7 pb$^{-1}$ from the 1992-1993 run with the Collider Detector at Fermilab (CDF). We find $\sigma \cdot B(W \to e \nu) = 2.49 \pm 0.12$~nb and $\sigma \cdot B(Z^0 \to e^+e^-) = 0.231 \pm 0.012$~nb.
Published: 1996

25. Measurement of the mass of theBs0meson

Author: Jay Hauser, M. Timko, D. A. Kardelis, J. Skarha, T. Yoshida, S. B. Kim, S. Tkaczyk, Sacha E Kopp, R. Ely, Jun Lu, Mark Kruse, N. Produit, Daniela Bortoletto, C. H. Wang, M. Lindgren, Paul Tipton, James Bensinger, P. F. Derwent, M. Krasberg, Kazuhiko Hara, P. Maas, H. Areti, B. Farhat, J. Wolinski, David Stuart, J. N. Bellinger, Yasuo Fukui, Nicola Labanca, T. Okusawa, T. Chikamatsu, J. D. Lewis, Daniel P Cronin-Hennessy, Robert M Harris, Fumio Abe, Y. Morita, J. Huston, L. Holloway, K. Takikawa, P. Melese, M. Gold, T. L. Watts, J. Siegrist, J. Patrick, E. H. Low, R. E. Hughes, G. Bauer, F. Bird, L. Song, F. D. Snider, Andrea Castro, C. Pagliarone, S. Galeotti, Petar Maksimovic, Kevin Burkett, A. Gordon, Jay Dittmann, M. P. Schmidt, D. Lucchesi, H. Y. Chao, F. Keyvan, Mosè Mariotti, S. Vejcik, P. Hu, M. J. Shochet, I. Nakano, G. Unal, T. Kaneko, A. Zanetti, M. Mishina, P. K. Teng, Umesh Joshi, J. Cooper, Y. Teramoto, R. D. Kennedy, Michele Gallinaro, E. Kovacs, A. Hölscher, Jochen Jens Heinrich, R. L. Swartz, Marjorie Shapiro, Alan Sill, R. M. Keup, T. Baumann, G. P. Yeh, T. Song, D. Errede, S. H. Kim, P. Sphicas, F. Tartarelli, D. W. Gerdes, Virgil E Barnes, Tony Liss, E. Buckley-Geer, T. Takahashi, James Mueller, Riccardo Paoletti, Chris Wendt, B. Flaugher, P. Sinervo, J. Incandela, T. Boulos, M. Cordelli, H. Wenzel, F. Ukegawa, W. Carithers, C. Bromberg, Luca Stanco, G. Busetto, Y. Kato, L. Demortier, K. E. Ohl, V. Bolognesi, S. Segler, A. Caner, S. C. van den Brink, A. Scribano, T. A. Fuess, B. T. Huffman, T. Mimashi, M. Dickson, R. G. Wagner, K. Ragan, R. K. Plunkett, Sally Seidel, D. Amidei, Stefano Belforte, A. T. Goshaw, H. Mitsushio, F. Azfar, Henrik Jeldtoft Jensen, J. Spalding, W. K. Sakumoto, O. Schneider, J. Bao, S. P. Pappas, S. Leone, S. Lammel, S. Geer, A. Menzione, C. Haber, M. Turcotte, S. Behrends, Henry J. Frisch, R. Oishi, A. B. Wicklund, W. C. Wester, P. Yeh, L. Ristori, Catherine Newman-Holmes, M. W. Bailey, L. Pondrom, E. Wicklund, P. Limon, A. Dunn, John Huth, S. R. Amendolia, J. W. Chapman, Jakita O. Thomas, I. Yu, J. E. Elias, T. J. Phillips, A. Fry, C. Grosso-Pilcher, C. P. Jessop, E. E. Schmidt, S. Delchamps, H. S. Budd, R. J. Miller, X. Wu, K. Sliwa, D. Crane, D. Y. Wu, T. LeCompte, C. Wei, M. Binkley, Lawrence Nodulman, Q. Shen, S. Errede, M. G. Albrow, S. E. Kuhlmann, D. Glenzinski, A. Mukherjee, H. Keutelian, T. L. Thomas, Nicola Bacchetta, J. Romano, M. Roach-Bellino, A. Grewal, Le Zhang, R. Vidal, J. Hylen, R. L. Wagner, G. W. Brandenburg, G. Sganos, J. Gonzalez, F. Bedeschi, P. Bartalini, A. Byon-Wagner, H. Iso, B. Harral, P. Lukens, Andrea Sansoni, S. Donati, K. Strahl, K. Goulianos, J. Tseng, T. Muller, S. Ogawa, Jing Wang, P. Kesten, A. Titov, Kiminori Kondo, G. W. Foster, P. F. Shepard, S. H. Oh, Doyeong Kim, J. Mansour, J. Lys, R. Mattingly, K. Yasuoka, R. Hamilton, M. Pillai, S. Zhang, A. Schindler, M. Incagli, A. Bodek, P. Hurst, G. Sullivan, V. Papadimitriou, R. C. Walker, A. Barbaro-Galtieri, L. Gladney, R. J. Hollebeek, T. Westhusing, W. Koska, M. Vondracek, C. Loomis, P. de Barbaro, S. Zucchelli, M. T. Cheng, D. Theriot, J. I. Lamoureux, N. M. Shaw, R. E. Blair, B. Denby, E. Kajfasz, C. Yosef, D. Vucinic, P. Koehn, G. Piacentino, G. Michail, F. Rimondi, L. Groer, Alan Garfinkel, S. Tether, S. R. Hahn, J.I. Friedman, P. McIntyre, R. Wilkinson, F. Zetti, C. Hawk, Duncan Carlsmith, J. Yoh, S. Bertolucci, S. Miscetti, Andrew Beretvas, K. Tollefson, M. Shimojima, S. Eno, D. D. Yovanovitch, J. Wyss, G. Chiarelli, I. Fiori, G. Houk, G. Punzi, Weiya Zhang, J. P. Berge, C. Boswell, J. Antos, Andreas Warburton, Hong Sj, B. L. Winer, E. Engels, B. A. Barnett, L. Keeble, M. M. Deninno, Marina Cobal, O. Long, Giorgio Apollinari, J. P. Marriner, Konstanty Sumorok, L. Pescara, James Proudfoot, John Conway, D. Neuberger, M. J. Wang, R. M. Hans, L. Christofek, R. B. Drucker, F. Cervelli, K. Biery, J. D. Cunningham, Teruki Kamon, H. H. Williams, P. Musgrave, G. Bellettini, F. DeJongh, Craig Blocker, P. Schlabach, S. A. Hauger, E. Kuns, W. Kowald, A. Stefanini, W-M. Yao, N. S. Lockyer, P. Auchincloss, C. Nelson, Kaori Maeshima, C. N. Chiou, M. Yin, M. Atac, E. Meschi, Sung Keun Park, J. F. de Troconiz, Dario Bisello, A. Bhatti, M. Franklin, H. Grassmann, F. Ptohos, S. Funaki, W. J. Robertson, S. Miyashita, J. C. Freeman, R. W. Kadel, S. Moulding, N. Uemura, C. B. Luchini, R. C. Webb, A. Martin, M. Frautschi, P. Wilson, M. Campbell, M. D. Peters, D. A. Smith, P. Giannetti, G. Wang, V. Scarpine, R. Handler, S. Dell'Agnello, N. Wainer, A. Sgolacchia, R. P. Thun, Q. F. Wang, J. Steele, Douglas Benjamin, K. L. Byrum, P. Singh, D. Kestenbaum, M. Dell'Orso, Y. Ye, P. Giromini, G. F. Sciacca, W. Badgett, H. Kasha, L. Rosenson, T. Rodrigo, L. E. Kirsch, Hyun-Chul Kim, Gordon Watts, K. Kordas, M. Mangano, D. Benton, S. Cihangir, C. Couyoumtzelis, Manfred Paulini, W. Bokhari, J. C. Yun, Wendy Taylor, J. A.J. Matthews, G. Gagliardi, Yongsun Kim, Allan G Clark, D. Saltzberg, C. Campagnari, M. Loreti, Nikos Giokaris, R. Kephart, A. Maghakian, T. Daniels, Nicola Turini, A. T. Laasanen, J. Konigsberg, Avraham Yagil, L. F. Nakae, Leonard Spiegel, C. Anway-Wiese, G. Pauletta, M. Contreras, J. Kroll, James Strait, Y. Cen, Q. Fan, J. Cammerata, A. Tollestrup, T. Devlin, Jose M. Benlloch, J. Tonnison, Kevin Einsweiler, S. Mikamo, M. Miller, Patrizia Azzi, and Y. Seiya
Subjects: Physics, Statistics::Theory, Nuclear and High Energy Physics, Particle physics, Statistics::Applications, Meson, High Energy Physics::Experiment, Mass measurement, Collider Detector at Fermilab
Abstract: We measure the mass of the ${\mathit{B}}_{\mathit{s}}^{0}$ meson by reconstructing the decay chain ${\mathit{B}}_{\mathit{s}}^{0}$\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\varphi}, J/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$, and \ensuremath{\varphi}\ensuremath{\rightarrow}${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{\ensuremath{-}}}$. The data are obtained from 19.3 ${\mathrm{pb}}^{\mathrm{\ensuremath{-}}1}$ of integrated luminosity of p\ifmmode\bar\else\textasciimacron\fi{}p collisions at \ensuremath{\surd}s=1.8 TeV using the Collider Detector at Fermilab. A sample of 80 000 inclusive J/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$ events is used to study systematic biases in track reconstruction and to calibrate the momentum scale. We reconstruct the kinematically similar decays ${\mathit{B}}^{+}$\ensuremath{\rightarrow}J/\ensuremath{\psi}${\mathit{K}}^{+}$ and ${\mathit{B}}^{0}$\ensuremath{\rightarrow}J/\ensuremath{\psi}${\mathit{K}}^{\mathrm{*}0}$ to study the mass measurement technique used for the ${\mathit{B}}_{\mathit{s}}^{0}$ meson. Based on the observation of 32 \ifmmode\pm\else\textpm\fi{} 6 candidates, the mass of the ${\mathit{B}}_{\mathit{s}}^{0}$ meson is measured to be 5369.9 \ifmmode\pm\else\textpm\fi{} 2.3 \ifmmode\pm\else\textpm\fi{} 1.3 MeV/${\mathit{c}}^{2}$ and the mass difference between ${\mathit{B}}_{\mathit{s}}^{0}$ and the average mass of ${\mathit{B}}^{+}$ and ${\mathit{B}}^{0}$ is determined to be 89.7 \ifmmode\pm\else\textpm\fi{} 2.7 \ifmmode\pm\else\textpm\fi{} 1.2 MeV/${\mathit{c}}^{2}$. \textcopyright{} 1996 The American Physical Society.
Published: 1996

26. Structure and evolution of the compact radio source in NGC 1275

Author: Jonathan D. Romney, J. M. Benson, K. I. Kellermann, R. C. Vermeulen, R. C. Walker, and Vivek Dhawan
Subjects: Physics, Jet (fluid), Multidisciplinary, Accretion (meteorology), Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Parsec, Core (optical fiber), Interferometry, Feature (computer vision), New General Catalogue, Cutoff, Research Article
Abstract: Investigations of the fine-scale structure in the compact nucleus of the radio source 3C 84 in NGC 1275 (New General Catalogue number) are reported. Structural monitoring observations beginning as early as 1976, and continuing to the present, revealed subluminal motions in a jet-like relatively diffuse region extending away from a flat-spectrum core. A counterjet feature was discovered in 1993, and very recent nearly simultaneous studies have detected the same feature at five frequencies ranging from 5 to 43 GHz. The counterjet exhibits a strong low-frequency cutoff, giving this region of the source an inverted spectrum. The observations are consistent with a physical model in which the cutoff arises from free-free absorption in a volume that surrounds the core but obscures only the counterjet feature. If such a model is confirmed, very-long-baseline radio interferometry observations can then be used to probe the accretion region, outside the radio jet, on parsec scales.
Published: 1995

27. Study oftt¯Production inpp¯Collisions Using Total Transverse Energy

Author: A. Barbaro-Galtieri, L. Gladney, D. Vucinic, I. Fiori, James Proudfoot, Stefano Belforte, Henrik Jeldtoft Jensen, L. Ristori, Nicola Bacchetta, J. Romano, J. Gonzalez, F. Bedeschi, B. Harral, M. P. Schmidt, I. Nakano, L. Santi, P. Azzi-Bacchetta, J. Konigsberg, C. Bromberg, Avraham Yagil, A. Akopian, P. Lukens, Maurice Garcia-Sciveres, M. Timko, J. Skarha, M. Okabe, R. J. Miller, T. Yoshida, G. Sullivan, V. Papadimitriou, D. D. Yovanovitch, J. Wyss, P. Koehn, G. Chiarelli, A. Mukherjee, M. M. Deninno, S. Segler, P. Sphicas, O. Long, M. Franklin, B. T. Huffman, Y. Iwata, N. M. Shaw, Leonard Spiegel, S. Funaki, S. Bagdasarov, R. K. Plunkett, Maria Spiropulu, N. Tamura, Daniela Bortoletto, C. Anway-Wiese, B. Denby, F. Tartarelli, Virgil E Barnes, M. Ninomiya, P. Singh, J. C. Freeman, C. Wei, J. Yoh, E. Kuns, D. Kestenbaum, T. Ohsugi, M. Dell'Orso, L. Pescara, A. Caner, Bj Kim, G. Pauletta, M. Contreras, B. A. Barnett, L. Keeble, Giorgio Apollinari, S. Tkaczyk, David Stuart, Teruki Kamon, S. Truitt, R. C. Walker, H. Grassmann, S. Miscetti, S. R. Hahn, A. Menzione, J. Iwai, J. Antos, Craig Blocker, Kaori Maeshima, G. F. Sciacca, W. Badgett, G. Piacentino, G. P. Yeh, Marina Cobal, Fumio Abe, Konstanty Sumorok, L. Demortier, V. Bolognesi, J. Kroll, James Strait, D. Cauz, Tony Liss, G. Wang, K. Takikawa, D. Errede, T. LeCompte, A. Hölscher, P. Wilson, L. Rosenson, J. D. Cunningham, G. Bellettini, M. Dickson, M. Mangano, T. J. Phillips, J. Lys, Y. Kato, G. Guillian, R. Roser, L. E. Kirsch, A. Sgolacchia, R. P. Thun, Q. F. Wang, J. Steele, A. Byon-Wagner, K. Strahl, S. Bertolucci, Jay Hauser, Y. Morita, F. Zetti, C. Hawk, Catherine Newman-Holmes, C. H. Wang, J. Tonnison, C. Pagliarone, S. Galeotti, Weiya Zhang, J. P. Berge, M. Lindgren, J.I. Friedman, N. Eddy, R. J. Hollebeek, D. Lucchesi, S. Aota, K. L. Byrum, P. Giromini, L. Christofek, R. B. Drucker, Sacha E Kopp, H. Minato, R. Ely, T. L. Thomas, P. Bartalini, P. Limon, J. I. Lamoureux, John Huth, J. W. Chapman, K. Biery, T. Takada, H. H. Williams, M. Gold, L. Breccia, H. Kasha, L. Holloway, W. Kowald, Scott D. Metzler, D. Neuberger, M. T. Cheng, T. L. Watts, J. N. Bellinger, Daniel P Cronin-Hennessy, Chris Wendt, A. Gordon, D. Benton, S. Cihangir, P. Auchincloss, C. Couyoumtzelis, Manfred Paulini, J. Patrick, T. Asakawa, Kevin Einsweiler, A. Stefanini, M. J. Shochet, H. Nakada, M. Atac, W. Bokhari, J. C. Yun, J. Siegrist, Hong Sj, F. Cervelli, S. Donati, Kevin Burkett, Wendy Taylor, J. A.J. Matthews, G. Gagliardi, Allan G Clark, D. Saltzberg, T. Ohmoto, L. Pondrom, E. Wicklund, Yongsun Kim, Nikos Giokaris, A. Maghakian, S. A. Hauger, C. Campagnari, S. R. Amendolia, P. Schlabach, S. Mikamo, C. Nelson, K. Yasuoka, K. T. Pitts, W. Ashmanskas, B. Flaugher, R. L. Wagner, M. Loreti, J. Incandela, R. Kephart, T. Daniels, Q. Fan, J. Cammerata, W. Koska, Jun Lu, I. Yu, Mark Kruse, J. E. Elias, T. Takano, N. Uemura, M. Frautschi, B. L. Winer, E. Engels, T. Rodrigo, T. Kaneko, J. F. de Troconiz, K. Goulianos, Alan Sill, J. Conway, Hiroshi Ikeda, P. Kesten, Nicola Turini, A. T. Laasanen, A. Tollestrup, Jochen Jens Heinrich, Paul Tipton, Douglas Benjamin, A. Titov, R. Hamilton, M. Pillai, R. C. Webb, A. Martin, Hyun-Chul Kim, M. Vondracek, C. Loomis, P. de Barbaro, D. Wolinski, Kiminori Kondo, K. Kelley, S. Leone, T. Devlin, H. Wenzel, F. Ukegawa, A. Ribon, Andrew Beretvas, Jose M. Benlloch, E. Kajfasz, K. Ragan, F. Ptohos, W. J. Robertson, Marjorie Shapiro, D. Toback, Y. Seiya, Gordon Watts, H. S. Budd, P. Melese, Rachel A. Oliver, J. P. Marriner, E. Buckley-Geer, Riccardo Paoletti, Sally Seidel, R. W. Kadel, M. Mishina, Jay Dittmann, R. Vidal, P. Sinervo, S. B. Kim, H. Y. Chao, P. Murat, M. Krasberg, M. Campbell, M. D. Peters, D. A. Smith, P. Giannetti, F. Keyvan, S. C. van den Brink, A. Spies, T. A. Fuess, J. Wolinski, Y. Teramoto, T. Chikamatsu, V. Scarpine, R. Handler, S. Behrends, Henry J. Frisch, Michele Gallinaro, A. B. Wicklund, G. Bauer, A. D. Hardman, S. Dell'Agnello, F. D. Snider, P. F. Shepard, James D. Olsen, D. Amidei, A. T. Goshaw, R. Oishi, H. Mitsushio, F. Azfar, S. H. Oh, J. Spalding, D. W. Gerdes, E. E. Schmidt, S. Delchamps, W. C. Wester, M. W. Bailey, S. Errede, K. D. Hoffman, Marcus Hohlmann, T. Muller, Le Zhang, G. Michail, L. Groer, Alan Garfinkel, J. Suzuki, P. McIntyre, R. Wilkinson, G. Houk, Jing Wang, E. Kovacs, T. Uchida, E. Hayashi, Mosè Mariotti, M. Incagli, K. E. Ohl, W. K. Sakumoto, S. Geer, Stephan Lammel, D. Theriot, P. Yeh, C. Grosso-Pilcher, Lawrence Nodulman, S. Tether, Duncan Carlsmith, K. Tollefson, T. Miyamoto, M. J. Wang, R. M. Hans, W. Carithers, N. S. Lockyer, Y. Cen, C. N. Chiou, J. Bao, C. Holck, J. D. Lewis, Kostantinos Kordas, R. E. Hughes, Petar Maksimovic, T. Song, Robert M Harris, H. Akimoto, Andrea Castro, P. Hu, K. Karr, G. Unal, R. D. Kennedy, Doyeong Kim, C. Miao, M. Shimojima, Andreas Warburton, A. Scribano, R. Stroehmer, M. Binkley, Q. Shen, M. G. Albrow, Umesh Joshi, J. Cooper, R. M. Keup, S. H. Kim, X. Wu, K. Sliwa, D. Crane, J. Boudreau, D. Glenzinski, H. Keutelian, A. Dunn, Steve Kuhlmann, R. Culbertson, R. S. Guo, G. Velev, H. Sato, T. Kuwabara, S. Vejcik, J. Mansour, R. Mattingly, Giovanni Punzi, James Mueller, Luca Stanco, C. Haber, A. Bodek, S. Lusin, Dario Bisello, A. Bhatti, Y. Ye, J. Hylen, C. Yosef, G. W. Foster, S. Miyashita, J. Wahl, James Bensinger, P. F. Derwent, Kazuhiko Hara, Yasuo Fukui, Nicola Labanca, T. Okusawa, T. Takahashi, J. Done, J. Huston, A. Zanetti, P. K. Teng, F. DeJongh, W-M. Yao, M. Yin, E. Meschi, Sung Keun Park, T. Baumann, M. Cordelli, G. Busetto, R. G. Wagner, G. Sganos, S. P. Pappas, A. Soumarokov, J. Tseng, S. Zucchelli, R. E. Blair, and F. Rimondi
Subjects: Physics, Transverse plane, Particle physics, Computer Science::Information Retrieval, Scalar (mathematics), General Physics and Astronomy, High Energy Physics::Experiment, Production (computer science), Neutrino, Collider Detector at Fermilab, Energy (signal processing), Boson, Lepton
Abstract: We analyze a sample of {ital W}+jet events collected with the Collider Detector at Fermilab (CDF) in {ital pp} collisions at {radical}{ital s}=1.8 TeV to study {ital tt} production. We employ a simple kinematical variable H, defined as the scalar sum of the transverse energies of the lepton, neutrino, and jets. For events with a {ital W} boson and four or more jets, the shape of the H distribution deviates by 3.8 standard deviations from that expected from known backgrounds to {ital tt} production. However, this distribution agrees well with a linear combination of background and {ital tt} events, the agreement being best for a top mass of 180 GeV/{ital c}{sup 2}. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.
Published: 1995

28. Measurement of theBMeson Differential Cross Sectiondσ/dpTinpp¯Collisions at√s=1.8TeV

Author: P. F. Shepard, S. H. Oh, A. Schindler, T. L. Watts, F. Bird, L. Demortier, V. Bolognesi, Y. Cen, S. Segler, Jay Hauser, G. Michail, L. Groer, S. Tkaczyk, David Stuart, Alan Garfinkel, P. McIntyre, H. Y. Chao, R. Wilkinson, F. Keyvan, P. Melese, Q. Fan, Alan Sill, Jay Dittmann, Y. Teramoto, Michele Gallinaro, J. Cammerata, A. Tollestrup, B. T. Huffman, J. Konigsberg, R. K. Plunkett, Sacha E Kopp, D. Amidei, T. Devlin, Jose M. Benlloch, R. Ely, J. D. Lewis, J. Tonnison, S. C. van den Brink, A. Spies, P. Limon, T. A. Fuess, Mosè Mariotti, Avraham Yagil, A. T. Goshaw, H. Mitsushio, F. Azfar, E. Kajfasz, S. Miyashita, S. Errede, T. Baumann, John Huth, J. W. Chapman, J. Spalding, O. Schneider, P. Singh, D. Kestenbaum, M. Mishina, N. Wainer, E. Kovacs, A. Hölscher, M. Dell'Orso, K. E. Ohl, A. Gordon, Jakita O. Thomas, T. Muller, S. Behrends, S. Miscetti, Doyeong Kim, S. Leone, Stefano Belforte, A. Sgolacchia, R. P. Thun, C. Wei, Q. F. Wang, J. Steele, H. Jensen, W. C. Wester, J. N. Bellinger, Daniel P Cronin-Hennessy, Jun Lu, Mark Kruse, A. B. Wicklund, R. Oishi, C. H. Wang, Paul Tipton, M. Lindgren, W. K. Sakumoto, M. Cordelli, G. Busetto, E. E. Schmidt, R. G. Wagner, T. Rodrigo, L. F. Nakae, K. Ragan, S. Geer, H. S. Budd, S. Delchamps, G. P. Yeh, C. Grosso-Pilcher, M. Roach-Bellino, Daniela Bortoletto, P. Lukens, Tony Liss, Kevin Einsweiler, T. Westhusing, Marina Cobal, Kevin Burkett, L. Holloway, J. D. Cunningham, Leonard Spiegel, Andrea Sansoni, S. Donati, G. Bellettini, E. H. Low, L. Ristori, D. Y. Wu, G. Houk, M. W. Bailey, R. J. Miller, A. Grewal, Le Zhang, R. E. Hughes, Jochen Jens Heinrich, J. Patrick, K. Yasuoka, G. Sullivan, V. Papadimitriou, M. Shimojima, P. Sphicas, F. Tartarelli, Virgil E Barnes, G. Punzi, B. L. Winer, E. Engels, B. Farhat, C. Anway-Wiese, W. Koska, S. Mikamo, J. P. Marriner, Andreas Warburton, Nicola Bacchetta, J. Romano, J. Gonzalez, F. Bedeschi, B. Harral, M. Timko, A. Caner, Andrew Beretvas, A. Mukherjee, Hyun-Chul Kim, G. F. Sciacca, P. Koehn, W. Badgett, S. Lammel, A. Menzione, H. Wenzel, F. Ukegawa, M. Miller, Patrizia Azzi, Gordon Watts, J. Skarha, T. Yoshida, T. LeCompte, T. Mimashi, M. Dickson, L. Pescara, T. J. Phillips, C. Pagliarone, S. Galeotti, K. Biery, Fumio Abe, L. Song, S. Zhang, A. Barbaro-Galtieri, L. Gladney, J. Tseng, Petar Maksimovic, T. Boulos, K. Takikawa, D. Vucinic, Y. Seiya, G. Pauletta, M. Contreras, J. Kroll, S. Tether, James Strait, S. Ogawa, Jing Wang, K. Tollefson, H. H. Williams, D. Lucchesi, D. Glenzinski, T. Kaneko, L. Rosenson, W. Kowald, Robert M Harris, A. Stefanini, Andrea Castro, D. A. Kardelis, N. M. Shaw, B. Denby, P. Yeh, Dario Bisello, A. Bhatti, Lawrence Nodulman, S. B. Kim, N. Produit, K. Kordas, Wendy Taylor, J. A.J. Matthews, R. C. Walker, R. L. Swartz, Marjorie Shapiro, G. Gagliardi, P. Hu, J. Yoh, G. Unal, Chris Wendt, M. J. Shochet, M. Krasberg, Allan G Clark, M. Atac, I. Fiori, H. Keutelian, M. Mangano, G. Piacentino, E. Buckley-Geer, Riccardo Paoletti, D. Saltzberg, L. E. Kirsch, J. Wolinski, T. Chikamatsu, Steve Kuhlmann, R. D. Kennedy, B. A. Barnett, L. Keeble, Giorgio Apollinari, A. Zanetti, James Proudfoot, T. Song, S. R. Hahn, P. Sinervo, G. Bauer, Teruki Kamon, P. Musgrave, C. Campagnari, F. D. Snider, P. K. Teng, A. Scribano, A. Byon-Wagner, H. Iso, W. Carithers, J. Antos, M. Incagli, D. Theriot, Craig Blocker, F. Zetti, C. Hawk, Kaori Maeshima, M. Loreti, Y. Ye, Konstanty Sumorok, P. Hurst, Y. Morita, S. Zucchelli, R. E. Blair, F. Rimondi, R. Kephart, D. W. Gerdes, J. Siegrist, T. Daniels, S. Moulding, R. J. Hollebeek, J. Mansour, R. Mattingly, M. P. Schmidt, N. Uemura, C. B. Luchini, Nicola Turini, A. T. Laasanen, P. Wilson, John Conway, S. Eno, J. Bao, I. Nakano, M. Frautschi, Chunjie Wang, G. Sganos, D. D. Yovanovitch, J. Wyss, J. I. Lamoureux, M. Binkley, Duncan Carlsmith, Q. Shen, J. Hylen, G. Chiarelli, C. Bromberg, M. G. Albrow, G. W. Foster, M. M. Deninno, O. Long, K. Strahl, K. L. Byrum, M. J. Wang, P. Giromini, R. M. Hans, E. Kuns, A. Bodek, S. Bertolucci, Weiya Zhang, H. Kasha, C. Yosef, J. P. Berge, D. Benton, N. S. Lockyer, C. Boswell, C. N. Chiou, F. DeJongh, L. Christofek, R. B. Drucker, S. Cihangir, C. Couyoumtzelis, Manfred Paulini, W-M. Yao, M. Yin, E. Meschi, Sung Keun Park, P. Auchincloss, W. Bokhari, J. C. Yun, Yongsun Kim, Nikos Giokaris, Hong Sj, Umesh Joshi, F. Cervelli, J. Cooper, R. M. Keup, P. Schlabach, A. Maghakian, C. Nelson, B. Flaugher, J. Incandela, Douglas Benjamin, S. H. Kim, P. Kesten, A. Titov, Kiminori Kondo, F. Ptohos, W. J. Robertson, R. W. Kadel, M. Campbell, M. D. Peters, D. A. Smith, P. Giannetti, V. Scarpine, R. Handler, S. Dell'Agnello, X. Wu, K. Sliwa, D. Crane, James Bensinger, P. F. Derwent, Kazuhiko Hara, P. Maas, H. Areti, Yasuo Fukui, Nicola Labanca, L. Pondrom, E. Wicklund, T. Okusawa, S. R. Amendolia, J. Huston, I. Yu, J. E. Elias, M. Franklin, H. Grassmann, S. Funaki, J. C. Freeman, G. Wang, J. Lys, J.I. Friedman, D. Neuberger, D. Errede, Y. Kato, Catherine Newman-Holmes, T. L. Thomas, P. Bartalini, M. T. Cheng, S. A. Hauger, J. F. de Troconiz, R. C. Webb, A. Martin, R. L. Wagner, K. Goulianos, R. Hamilton, M. Pillai, M. Vondracek, C. Loomis, P. de Barbaro, Sally Seidel, A. Fry, C. P. Jessop, M. Gold, A. Dunn, S. Vejcik, T. Takahashi, James Mueller, Luca Stanco, G. Brandenburg, C. Haber, M. Turcotte, and R. Vidal
Subjects: Physics, Particle physics, Meson, High Energy Physics::Phenomenology, Hadron, General Physics and Astronomy, Order (ring theory), Elementary particle, Quarkonium, Particle decay, Quantum mechanics, High Energy Physics::Experiment, B meson, Collider Detector at Fermilab
Abstract: This paper presents the first direct measurement of the $B$ meson differential cross section $d\ensuremath{\sigma}{/dp}_{T}$ in $p\overline{p}$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8$ TeV using a sample of $19.3\ifmmode\pm\else\textpm\fi{}0.7$ p${\mathrm{b}}^{--1}$ accumulated by the Collider Detector at Fermilab. The cross section is measured in the central rapidity region $|y|l1$ for ${p}_{T}\left(B\right)g6.0$ GeV $/c$ by fully reconstructing the $B$ meson decays ${B}^{+}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{+}$ and ${B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{*0}\left(892\right)$, where $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${K}^{*0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$. A comparison is made to the theoretical QCD prediction calculated at next-to-leading order.
Published: 1995

29. A measurement of Bose-Einstein correlations in e+e− annihilation at TRISTAN

Author: M. E. Mattson, H. Miyata, A. Murakami, Kazuo Abe, Hiroyuki Sagawa, K. Ueno, Y. Sugimoto, J. Rowe, A. Bodek, P. N. Kirk, Y. Yamashita, Tsunehiko Omori, Ryuki Tanaka, Y. Takaiwa, T. Nozaki, Bj Kim, S. Matsumoto, C. Rosenfeld, C. A. Fry, J. S. Kang, Stephen L. Olsen, F. Kajino, Yoshimasa Kurihara, F. Liu, M. Oyoshi, K. Gotow, N. Takashimizu, M. Shirai, R. C. Walker, S. S. Myung, T. Aso, Steve Schnetzer, S. Kanda, Richard Breedon, Seong Keun Kim, Saroj Kumar Sahu, Takashi Sasaki, S. Ebara, K. L. Sterner, M. Sato, J. Vinson, Suyong Choi, S. Behari, A. Maki, L. Y. Zheng, R. L. Lander, D. Y. Kim, Moo Hyun Lee, K. Ohkubo, L. E. Piilonen, Winston Ko, C. Velissaris, Kazumasa Miyano, Susumu Terada, N. Nakajima, S. Kobayashi, A. Abashian, Y. Fujii, and Y. Sakai
Subjects: Nuclear physics, Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, law, Track (disk drive), Detector, High Energy Physics::Experiment, Bose–Einstein correlations, Collider, law.invention
Abstract: Using e+e− annihilation events accumulated with the AMY detector at the TRISTAN collider, we have studied the Bose-Einstein correlations in the distributions of like-sign charged tracks. As reference samples we used the opposite-sign charged track pairs and mixed pairs, which are like-sign pairs synthesized from tracks belonging to different events. The results of the different reference samples give approximately 0.45 for the correlation strength and approximately 0.65 fm for the source size. Previous measurements of these parameters in e+e− annihilation at energies from CESR to LEP show remarkably flat dependence on s . Our results conform well with this picture.
Published: 1995

30. A determination of α in e+e− annihilation at GeV

Author: J. S. Kang, R. C. Walker, Steve Schnetzer, S. Ebara, N. Takashimizu, K. Gotow, Moo Hyun Lee, P. N. Kirk, Y. Fujii, M. H. Ye, F. Liu, Kazuo Abe, Y. Yamashita, T. Ishizuka, T. Aso, Tsunehiko Omori, David Stuart, Richard Breedon, Y. K. Li, C. A. Fry, S. Lusin, Dong-Chul Son, Ryuki Tanaka, Bj Kim, Takashi Sasaki, K. Ueno, J. Rowe, H. Miyata, Y. Takaiwa, J. Vinson, Y. Sakai, A. Bodek, M. E. Mattson, Robert Stone, A. Murakami, Seong Keun Kim, J. R. Smith, F. Kajino, W. G. Yan, W. X. Gao, D. Y. Kim, T. Thomas, S. S. Myung, C. Velisarris, Hiroyuki Sagawa, S. Matsumoto, T. Nozaki, C. Rosenfeld, A. Maki, L. Y. Zheng, K. L. Sterner, Stephen L. Olsen, M. Oyoshi, A. Abashian, Yoshimasa Kurihara, S. Kobayashi, S. Kanda, R. L. Lander, C. P. Cheng, S. Wilson, Suyong Choi, Kisoo Lee, Saroj Kumar Sahu, Kazumasa Miyano, Yasuhiro Sugimoto, Y. S. Chung, Susumu Terada, R. Poling, S. Behari, T. Kumita, K. W. Park, L. E. Piilonen, L. M. Chinitz, and Winston Ko
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, Logarithm, Electron–positron annihilation, High Energy Physics::Phenomenology, Monte Carlo method, Jet (particle physics), Nuclear physics, Strong coupling, High Energy Physics::Experiment, Matrix element
Abstract: We present a study of differential two jet ratios in multi-hadronic final states produced by e(+)e(-) annihilation in the AMY detector at TRISTAN. The data are compared to the predictions of the next-to-leading logarithm parton-shower (NLL PS) Monte Carlo and the O(alpha(s)(2)) matrix element QCD models. We determine the strong coupling strength alpha(s)(57.3 GeV) = 0.130 +/- 0.006.
Published: 1995

31. Observation of Top Quark Production inp¯pCollisions with the Collider Detector at Fermilab

Author: T. Ohsugi, M. Dell'Orso, G. F. Sciacca, P. Lukens, G. Sullivan, V. Papadimitriou, M. Franklin, R. C. Walker, W. Badgett, L. Rosenson, H. Y. Chao, F. Keyvan, T. Baumann, M. Cordelli, G. Busetto, R. G. Wagner, T. L. Thomas, P. Bartalini, P. Koehn, L. Pescara, T. Asakawa, T. L. Watts, G. Houk, H. Grassmann, S. R. Hahn, J. Iwai, J. Antos, Konstanty Sumorok, L. E. Kirsch, James D. Olsen, J. Spalding, S. Tkaczyk, David Stuart, G. Sganos, S. P. Pappas, Jochen Jens Heinrich, S. C. van den Brink, A. Spies, T. A. Fuess, S. Ogawa, Jing Wang, S. Segler, B. T. Huffman, S. Bagdasarov, R. K. Plunkett, A. Byon-Wagner, W. C. Wester, M. Ninomiya, C. Wei, G. P. Yeh, A. Soumarokov, J. Tseng, H. Wenzel, F. Ukegawa, Henry J. Frisch, N. Eddy, R. J. Hollebeek, J. I. Lamoureux, S. Zucchelli, R. E. Blair, F. Rimondi, A. Ribon, M. Mangano, M. Incagli, Andrea Sansoni, S. Donati, K. Yasuoka, W. Ashmanskas, Tony Liss, M. Dickson, N. Tamura, R. Oishi, S. Bertolucci, Weiya Zhang, J. P. Berge, James Bensinger, C. H. Wang, M. Lindgren, J. Siegrist, Hong Sj, W. Koska, T. J. Phillips, Y. Morita, F. DeJongh, Jay Hauser, Sacha E Kopp, H. Minato, C. Anway-Wiese, M. W. Bailey, L. Christofek, R. B. Drucker, P. Auchincloss, A. Akopian, Maurice Garcia-Sciveres, M. Timko, J. Skarha, P. F. Derwent, Kazuhiko Hara, Yasuo Fukui, L. Holloway, Scott D. Metzler, A. Dunn, R. S. Guo, D. Theriot, F. Cervelli, Andrew Beretvas, W-M. Yao, M. Yin, E. Meschi, R. Ely, J. N. Bellinger, Daniel P Cronin-Hennessy, G. Pauletta, M. Contreras, T. Yoshida, J. Patrick, P. Sphicas, F. Tartarelli, Virgil E Barnes, D. Amidei, A. T. Goshaw, H. Mitsushio, F. Azfar, P. Schlabach, C. Nelson, Sung Keun Park, J. Kroll, James Strait, B. Flaugher, J. Incandela, Nicola Labanca, T. Okusawa, T. Takahashi, J. Huston, Kevin Burkett, Wendy Taylor, J. Konigsberg, T. Takano, A. Caner, Bj Kim, S. Errede, J. A.J. Matthews, Allan G Clark, J. Conway, P. Kesten, Duncan Carlsmith, K. T. Pitts, T. Kaneko, D. Saltzberg, C. Campagnari, M. Loreti, Avraham Yagil, G. Cauz, A. Titov, Kiminori Kondo, D. Glenzinski, D. D. Yovanovitch, J. Wyss, G. Chiarelli, A. Menzione, G. Gagliardi, Douglas Benjamin, R. Kephart, T. Daniels, Nicola Turini, A. T. Laasanen, F. Ptohos, W. J. Robertson, M. M. Deninno, T. Muller, Marjorie Shapiro, R. W. Kadel, O. Long, M. Mishina, Leonard Spiegel, H. Keutelian, Steve Kuhlmann, R. Culbertson, E. Kuns, T. LeCompte, E. Buckley-Geer, Riccardo Paoletti, J. Boudreau, M. Campbell, M. D. Peters, J. Mansour, R. Mattingly, D. A. Smith, P. Giannetti, S. Behrends, V. Scarpine, A. B. Wicklund, R. Handler, A. Bodek, E. E. Schmidt, C. Yosef, S. Dell'Agnello, Jun Lu, Mark Kruse, S. Delchamps, Marcus Hohlmann, Le Zhang, Paul Tipton, Umesh Joshi, J. Cooper, R. M. Keup, S. H. Kim, G. W. Brandenburg, P. Melese, Rachel A. Oliver, S. Vejcik, Q. Fan, J. Cammerata, A. Tollestrup, Jay Dittmann, S. Funaki, J. C. Freeman, G. Punzi, B. L. Winer, E. Engels, J. P. Marriner, X. Wu, K. Sliwa, Alan Sill, D. Wolinski, K. Kelley, S. Leone, M. T. Cheng, Y. Teramoto, M. P. Schmidt, Michele Gallinaro, I. Nakano, T. Devlin, Jose M. Benlloch, D. Crane, S. Mikamo, H. H. Williams, H. S. Budd, W. Carithers, Y. Seiya, D. Benton, S. Cihangir, C. Couyoumtzelis, Manfred Paulini, A. Scribano, A. Sgolacchia, R. P. Thun, Q. F. Wang, J. Steele, W. Kowald, A. Stefanini, M. Atac, E. Kovacs, R. J. Miller, A. Mukherjee, G. Velev, H. Sato, S. B. Kim, R. Vidal, P. F. Shepard, S. H. Oh, M. Binkley, Q. Shen, M. G. Albrow, R. L. Wagner, C. Pagliarone, S. Galeotti, S. A. Hauger, L. Santi, G. Wang, P.K. Sinervo, T. Kuwabara, P. Murat, M. Krasberg, J. Wolinski, T. Chikamatsu, James Mueller, P. Azzi-Bacchetta, D. Lucchesi, K. Biery, J. F. de Troconiz, N. Uemura, M. Frautschi, G. Piacentino, K. Goulianos, F. Zetti, C. Hawk, G. Bauer, F. D. Snider, G. Michail, T. Takada, L. Breccia, Chris Wendt, Stephan Lammel, Robert M Harris, Hiroshi Ikeda, R. C. Webb, A. Martin, D. W. Gerdes, H. Nakada, W. Bokhari, C. Bromberg, L. Groer, J. C. Yun, Alan Garfinkel, J. Suzuki, P. McIntyre, R. Wilkinson, J. Bao, E. Hayashi, Mosè Mariotti, J. Tonnison, B. A. Barnett, L. Keeble, P. Yeh, J. Lys, Luca Stanco, L. Demortier, V. Bolognesi, Lawrence Nodulman, H. Akimoto, Giorgio Apollinari, Teruki Kamon, S. Truitt, R. Hamilton, M. Pillai, Andrea Castro, K. E. Ohl, M. Vondracek, C. Loomis, Craig Blocker, C. Haber, W. K. Sakumoto, Kevin Einsweiler, P. Limon, P. de Barbaro, John Huth, J. W. Chapman, Kaori Maeshima, P. Hu, K. Karr, S. Geer, G. Unal, A. Barbaro-Galtieri, L. Gladney, E. Kajfasz, D. Errede, R. Roser, J.I. Friedman, C. Grosso-Pilcher, Yongsun Kim, Nikos Giokaris, A. Maghakian, A. Hölscher, Y. Kato, G. Guillian, S. Miscetti, K. Ragan, D. Toback, D. Vucinic, R. D. Kennedy, P. Wilson, T. Rodrigo, Catherine Newman-Holmes, Doyeong Kim, C. Miao, Sally Seidel, Marina Cobal, J. D. Cunningham, G. Bellettini, M. Okabe, I. Fiori, D. Neuberger, N. M. Shaw, B. Denby, M. Shimojima, Andreas Warburton, James Proudfoot, J. Yoh, Stefano Belforte, J. D. Lewis, L. Pondrom, E. Wicklund, Hyun-Chul Kim, Gordon Watts, Henrik Jeldtoft Jensen, S. R. Amendolia, I. Yu, L. Ristori, J. E. Elias, Kostantinos Kordas, Nicola Bacchetta, J. Romano, R. E. Hughes, J. Gonzalez, F. Bedeschi, B. Harral, M. Gold, Petar Maksimovic, K. L. Byrum, P. Giromini, T. Song, H. Kasha, T. Ohmoto, C. Holck, T. Miyamoto, M. J. Wang, R. M. Hans, N. S. Lockyer, Y. Cen, C. N. Chiou, Y. Ye, S. Tether, J. Hylen, G. W. Foster, K. Tollefson, K. Strahl, S. Lusin, S. Aota, A. Gordon, Dario Bisello, A. Bhatti, Y. Iwata, Daniela Bortoletto, S. Miyashita, Fumio Abe, K. Takikawa, M. J. Shochet, A. Zanetti, P. K. Teng, J. Wahl, T. Uchida, P. Singh, and D. Kestenbaum
Subjects: Physics, Quark, Particle physics, Top quark, Mass distribution, 010308 nuclear & particles physics, High Energy Physics::Phenomenology, General Physics and Astronomy, 01 natural sciences, Nuclear physics, Particle decay, Pair production, 0103 physical sciences, Mass spectrum, High Energy Physics::Experiment, Production (computer science), 010306 general physics, Collider Detector at Fermilab
Abstract: We establish the existence of the top quark using a $67{\mathrm{pb}}^{\ensuremath{-}1}$ data sample of $\overline{p}p$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ collected with the Collider Detector at Fermilab (CDF). Employing techniques similar to those we previously published, we observe a signal consistent with $t\overline{t}$ decay to $\mathrm{WWb}\overline{b}$, but inconsistent with the background prediction by $4.8\ensuremath{\sigma}$. Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. We measure the top quark mass to be $176\ifmmode\pm\else\textpm\fi{}8(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}10(\mathrm{syst})\mathrm{GeV}{/c}^{2}$, and the $t\overline{t}$ production cross section to be ${6.8}_{\ensuremath{-}2.4}^{+3.6}\mathrm{pb}$.
Published: 1995

32. Charge Asymmetry inW-Boson Decays Produced inpp¯Collisions ats=1.8TeV

Author: T. Baumann, M. Cordelli, G. Busetto, R. G. Wagner, K. Strahl, G. Sganos, P. Hurst, J. Tonnison, M. Timko, J. Tseng, A. Byon-Wagner, H. Iso, K. L. Byrum, S. Zucchelli, R. E. Blair, P. Giromini, S. Zhang, F. Rimondi, A. Gordon, A. Barbaro-Galtieri, L. Gladney, J. Skarha, H. Kasha, James Bensinger, D. D. Yovanovitch, J. Wyss, P. F. Derwent, T. Yoshida, Kazuhiko Hara, W. Carithers, N. Bacchetta, M. M. Deninno, O. Long, I. Fiori, P. Maas, R. J. Hollebeek, F. Ptohos, James Proudfoot, H. Areti, Daniela Bortoletto, E. Kuns, S. Eno, Yasuo Fukui, Nicola Labanca, T. Okusawa, J. I. Lamoureux, J. Bao, B. Farhat, P. Melese, J. Huston, Fumio Abe, J. Siegrist, F. DeJongh, L. Ristori, W-M. Yao, M. Yin, E. Meschi, Sung Keun Park, J. Romano, J. Gonzalez, F. Bedeschi, B. Harral, M. P. Schmidt, W. J. Robertson, R. W. Kadel, K. Takikawa, M. J. Wang, I. Nakano, Andrea Sansoni, S. Donati, S. Tkaczyk, David Stuart, S. Segler, M. Franklin, R. M. Hans, B. T. Huffman, S. Miyashita, T. Rodrigo, Y. Teramoto, J. Mueller, H. Grassmann, J. D. Lewis, Michele Gallinaro, G. P. Yeh, R. J. Miller, Y. Cen, R. K. Plunkett, Tony Liss, S. C. van den Brink, T. Mimashi, M. Dickson, S. Funaki, Hyun-Chul Kim, K. Yasuoka, Kostantinos Kordas, A. Mukherjee, Gordon Watts, Kevin Einsweiler, D. Glenzinski, Q. Fan, J. Cammerata, A. Tollestrup, M. J. Shochet, W. Koska, G. Bellettini, A. Spies, T. A. Fuess, Jakita O. Thomas, H. Keutelian, N. S. Lockyer, E. H. Low, R. E. Hughes, Steve Kuhlmann, Petar Maksimovic, D. Amidei, Hong Sj, A. T. Goshaw, A. Zanetti, T. Devlin, M. Campbell, V. Papadimitriou, F. Tartarelli, T. J. Phillips, Y. Morita, N. M. Shaw, M. D. Peters, D. A. Smith, J. C. Freeman, B. Denby, P. Giannetti, Henry J. Frisch, M. Gold, H. Mitsushio, F. Azfar, S. Miscetti, S. Cihangir, Marina Cobal, Andrew Beretvas, Manfred Paulini, M. Mishina, T. Song, J. D. Cunningham, L. Demortier, V. Bolognesi, S. Errede, J. Mansour, R. Mattingly, G. Piacentino, F. Zetti, C. Hawk, A. Bodek, V. Scarpine, R. Handler, S. Dell'Agnello, S. Behrends, A. B. Wicklund, W. Bokhari, S. Belforte, J. C. Yun, J. Yoh, R. Oishi, G. Wang, T. L. Watts, C. Pagliarone, S. Galeotti, F. Bird, P. Singh, A. Dunn, D. Kestenbaum, Yongsun Kim, D. Lucchesi, M. Dell'Orso, R. C. Walker, Nikos Giokaris, A. Maghakian, Umesh Joshi, J. Cooper, R. M. Keup, S. H. Kim, P. Musgrave, E. E. Schmidt, S. Delchamps, D. Y. Wu, S. R. Hahn, A. Grewal, Le Zhang, G. W. Brandenburg, Giorgio Chiarelli, P. Limon, John Huth, F. Keyvan, K. Biery, Chris Wendt, D. Benjamin, P. Yeh, S. Bertolucci, Weiya Zhang, J. P. Berge, T. Muller, C. Boswell, Lawrence Nodulman, K. Tonnifson, S. Ogawa, M. W. Bailey, Jing Wang, J. W. Chapman, D. Benton, L. Song, J. Spalding, O. Schneider, N. Wainer, A. Sgolacchia, R. P. Thun, J. Steele, H. Jensen, J. Antos, Konstanty Sumorok, H. H. Williams, M. Incagli, G. F. Sciacca, W. Badgett, L. Rosenson, X. Wu, K. Sliwa, D. Theriot, W. Kowald, A. Stefanini, T. Kaneko, R. B. Drucker, S. Leone, D. A. Kardelis, M. Atac, P. Auchincloss, D. Crane, J.I. Friedman, T. Boulos, R. L. Swartz, Marjorie Shapiro, S. Tether, Dario Bisello, G. Punzi, H. S. Budd, L. E. Kirsch, B. L. Winer, S. B. Kim, N. Produit, Duncan Carlsmith, Jun Lu, Mark Kruse, A. Bhatti, S. Vejcik, E. Engels, R. L. Wagner, J. P. Marriner, E. Buckley-Geer, S. Moulding, N. Uemura, C. B. Luchini, Riccardo Paoletti, M. Frautschi, Paul Tipton, K. Goulianos, M. Krasberg, F. Cervelli, P. Sinervo, J. Benlloch, M. Roach-Bellino, P. Lukens, J. Bellinger, J. Wolinski, T. Chikamatsu, G. Sullivan, A. Sill, B. A. Barnett, L. Keeble, N. Turini, P. Schlabach, T. Takahashi, B. Flaugher, C. Nelson, G. M. Grieco, P. Koehn, Giorgio Apollinari, J. Incandela, Luca Stanco, D. Neuberger, G. Bauer, F. D. Snider, Teruki Kamon, R. Hamilton, Craig Blocker, C. Haber, M. Turcotte, J. Conway, L. Pescara, Kaori Maeshima, E. Kovacs, M. Pillai, P. Kesten, D. W. Gerdes, A. Titov, M. Vondracek, C. Loomis, P. Wilson, Kiminori Kondo, P. de Barbaro, S. Mikamo, E. Kajfasz, M. Miller, Patrizia Azzi, K. Ragan, Y. Ye, L. Pondrom, E. Wicklund, J. Hylen, G. W. Foster, Y. Seiya, I. Yu, J. E. Elias, Sally Seidel, A. Fry, A. Scribano, C. P. Jessop, M. Binkley, Q. Shen, M. G. Albrow, Doyeong Kim, T. Westhusing, M. Shimojima, Andreas Warburton, Robert M Harris, Andrea Castro, P. Hu, G. Unal, R. D. Kennedy, J. Konigsberg, Avraham Yagil, L. F. Nakae, Leonard Spiegel, C. Anway-Wiese, G. Pauletta, M. Contreras, Q. F. Wang, J. Kroll, James Strait, W. C. Wester, M. Mangano, D. Errede, A. Hölscher, Y. Kato, K. E. Ohl, Wendy Taylor, J. A.J. Matthews, W. K. Sakumoto, G. Gagliardi, S. Geer, Catherine Newman-Holmes, C. Grosso-Pilcher, Allan G Clark, G. Houk, D. Saltzberg, C. Campagnari, T. L. Thomas, P. Bartalini, M. Loreti, R. Vidal, P. F. Shepard, S. H. Oh, A. Schindler, R. Kephart, G. Michail, T. Daniels, L. Groer, Alan Garfinkel, P. McIntyre, R. Wilkinson, M. T. Cheng, A. T. Laasanen, Jay Hauser, Sacha E Kopp, R. Ely, S. A. Hauger, Daniel P Cronin-Hennessy, J. F. de Troconiz, Kevin Burkett, R. C. Webb, A. Martin, Jochen Jens Heinrich, H. Wenzel, F. Ukegawa, M. Lindgren, M. Mariotti, L. Holloway, J. Patrick, P. Sphicas, Virgil E Barnes, A. Caner, S. Lammel, A. Menzione, and T. LeCompte
Subjects: Quark, Nuclear physics, Physics, Particle decay, Particle physics, Tevatron, General Physics and Astronomy, Elementary particle, Charge (physics), Parton, Collider Detector at Fermilab, Boson
Abstract: Charge asymmetry has been measured using 19 039 [ital W] decays recorded by the Collider Detector at Fermilab during the 1992--93 run of the Tevatron Collider. The asymmetry is sensitive to the ratio of [ital d] and [ital u] quark distributions to [ital x][lt]0.01 at [ital Q][sup 2][approx][ital M][sup 2][sub [ital W]], where nonperturbative effects are minimal. It is found that of the two current sets of parton distributions, those of Martin, Roberts, and Stirling are favored over the sets most recently produced by the CTEQ Collaboration. The [ital W] asymmetry data provide stronger constraints on [ital d]/[ital u] ratio than the recent measurements of [ital F][sub 2][sup [mu][ital n]]/[ital F][sub 2][sup [mu][ital p]], which are limited by uncertainties originating from deuteron corrections.
Published: 1995

33. Probing the origin of VHE emission from M 87 with MWL observations in 2010

Author: P. Colin, Lat Collaborations, C. M. Hui, Lukasz Stawarz, D. Mazin, Matthias Beilicke, R. C. Walker, and Martin Raue
Subjects: History, Active galactic nucleus, European VLBI Network, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Radio galaxy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 010501 environmental sciences, 01 natural sciences, Education, law.invention, Telescope, law, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, Line-of-sight, Computer Science Applications, Particle acceleration, Fermi Gamma-ray Space Telescope, Flare, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The large majority of extragalactic very high energy (VHE; E>100 GeV) sources belongs to the class of active galactic nuclei (AGN), in particular the BL Lac sub-class. AGNs are characterized by an extremely bright and compact emission region, powered by a super-massive black hole (SMBH) and an accretion disk, and relativistic outflows (jets) detected all across the electro-magnetic spectrum. In BL Lac sources the jet axis is oriented close to the line of sight, giving rise to a relativistic boosting of the emission. In radio galaxies, on the other hand, the jet makes a larger angle to the line of sight allowing to resolve the central core and the jet in great details. The giant radio galaxy M 87 with its proximity (1 6Mpc) and its very massive black hole ((3-6) x 10^9 M_solar) provides a unique laboratory to investigate VHE emission in such objects and thereby probe particle acceleration to relativistic energies near SMBH and in jets. M 87 has been established as a VHE emitter since 2005. The VHE emission displays strong variability on time-scales as short as a day. It has been subject of a large joint VHE and multi-wavelength (MWL) monitoring campaign in 2008, where a rise in the 43 GHz VLBA radio emission of the innermost region (core) was found to coincide with a flaring activity at VHE. This had been interpreted as a strong indication that the VHE emission is produced in the direct vicinity of the SMBH black hole. In 2010 again a flare at VHE was detected triggering further MWL observations with the VLBA, Chandra, and other instruments. At the same time M 87 was also observed with the Fermi-LAT telescope at GeV energies and the European VLBI Network (EVN). In this contribution preliminary results from the campaign will be presented., 5 pages, 2 figures, in the proceedings of the "International Workshop on Beamed and Unbeamed Gamma-Rays from Galaxies" 11-15 April 2011, Lapland Hotel Olos, Muonio, Finland, Journal of Physics: Conference Series Volume 355, 2012
Published: 2012

34. Measurements of the proton elastic form factors for1≤Q2≤3(GeV/c)2at SLAC

Author: E. M. Riordan, B. Debebe, A. Para, M. W. Krasny, B. W. Filippone, R. G. Arnold, R. S. Hicks, R. Gearhart, Sridhara Dasu, J. Alster, F. Dietrich, L.W. Whitlow, G. deChambrier, J. Jourdan, J. Button-Shafer, D. Benton, P. de Barbaro, Karol Lang, L. Andivahis, R. D. McKeown, K. van Bibber, P. E. Bosted, D. H. Potterveld, A. Bodek, Ross Milner, S. E. Rock, Z. M. Szalata, A. Lung, H. Harada, and R. C. Walker
Subjects: Physics, Combinatorics, Scattering cross-section, Particle physics, Particle properties, Proton, Particle model, Theoretical models
Abstract: We report measurements of the proton form factors [ital G][sub [ital E]][sup [ital p]] and [ital G][sub [ital M]][sup [ital p]] extracted from elastic scattering in the range 1[le][ital Q][sup 2][le]3 (GeV/[ital c])[sup 2] with total uncertainties [lt] 15% in [ital G][sub [ital E]][sup [ital p]] and [lt] 3% in [ital G][sub [ital M]][sup [ital p]]. Comparisons are made to theoretical models, including those based on perturbative QCD, vector-meson dominance, QCD sum rules, and diquark constituents in the proton. The results for [ital G][sub [ital E]][sup [ital p]] are somewhat larger than indicated by most theoretical parametrizations, and the ratios of the Pauli and Dirac form factors [ital Q][sup 2]([ital F][sub 2][sup [ital p]]/[ital F][sub 1][sup [ital p]]) are lower in value and demonstrate a weaker [ital Q][sup 2] dependence than those predictions. A global extraction of the elastic form factors from several experiments in the range 0.1 [lt] [ital Q][sup 2] [lt] 10 (GeV/[ital c])[sup 2] is also presented.
Published: 1994

35. Measurement of kinematic and nuclear dependence ofR=σLσTin deep inelastic electron scattering

Author: M. W. Krasny, P. E. Bosted, B. W. Filippone, B. Debebe, D. Benton, J. Button-Shafer, A. Lung, R. S. Hicks, A. Bodek, G. deChambrier, S. E. Rock, R. A. Gearhart, F. S. Dietrich, Ross Milner, K. van Bibber, Sridhara Dasu, H. Harada, R. G. Arnold, J. Alster, D. H. Potterveld, R. D. McKeown, L.W. Whitlow, R. C. Walker, J. Jourdan, L. Andivahis, A. Para, Z. M. Szalata, P. de Barbaro, Karol Lang, and E. M. Riordan
Subjects: Nuclear physics, Physics, Quantum chromodynamics, Particle physics, Scattering, EMC effect, Elementary particle, Twist, Inelastic scattering, Nucleon, Deep inelastic scattering
Abstract: We report results on a precision measurement of the ratio R=σ_L/σ_T in deep inelastic electron-nucleon scattering in the kinematic range 0.2≤x≤0.5 and 1≤Q^2≤10 (GeV/c)^2. Our results show, for the first time, a clear falloff of R with increasing Q^2. Our R results are in agreement with QCD predictions only when corrections for target mass effects and some additional higher twist effects are included. At small x, the data on R favor structure functions with a large gluon contribution. We also report results on the differences R_A-R_D and the cross section ratio σ^A/σ^D between Fe and Au nuclei and the deuteron. Our results for R_A-R_D are consistent with zero for all x, Q^2 indicating that possible contributions to R from nuclear higher twist effects and spin-0 constituents in nuclei are not different from those in nucleons. The ratios σ^A/σ^D from all recent experiments, at all x, Q^2 values, are now in agreement.
Published: 1994

36. Measurements of cross section and charge asymmetry for e+e− → μ+μ− and e+e− → τ+τ− at = 57.8

Author: David Stuart, D. Haim, B. J. Kim, C. Rosenfeld, K. Ueno, Y. Sugimoto, J. R. Smith, Kazuo Abe, T. Thomas, Sun Kee Kim, Kisoo Lee, H. Miyata, J. Rowe, M. H. Ye, M. Shirai, A. Bodek, Robert Stone, S. Matsumoto, Yoshimasa Kurihara, Moo Hyun Lee, T. Nozaki, L. M. Chinitz, S. Kobayashi, S. Kanda, F. Kajino, C. A. Fry, Y. Sakai, A. Abashian, C. P. Cheng, Y. K. Li, S. S. Myung, R. C. Walker, Steve Schnetzer, C. Velissaris, Winston Ko, N. Takashimizu, A. Maki, L. Y. Zheng, Dong-Chul Son, K. L. Sterner, Y. Fujii, K. Gotow, S. Wilson, S. L. Olsen, T. Aso, Richard Breedon, T. Kumita, Ryuki Tanaka, Takashi Sasaki, Y. Takaiwa, J. Vinson, M. E. Mattson, T. Ishizuka, A. Murakami, J. S. Kang, F. Liu, T. J. Wang, S. Ebara, D. Y. Kim, Tsunehiko Omori, S. Lusin, P. N. Kirk, Y. Yamashita, K. Ohkubo, M. Oyoshi, R. L. Lander, Kazumasa Miyano, Susumu Terada, K. W. Park, D. K. Cho, L. E. Piilonen, Hiroyuki Sagawa, Suyong Choi, Y. S. Chung, Saroj Kumar Sahu, and S. Behari
Subjects: Physics, Coupling constant, Nuclear and High Energy Physics, Annihilation, Electron–positron annihilation, media_common.quotation_subject, Elementary particle, Charge (physics), Asymmetry, lcsh:QC1-999, Standard Model, Nuclear physics, Cross section (geometry), Atomic physics, lcsh:Physics, media_common
Abstract: With data corresponding to 142 pb−1 accumulated at s = 57.8 GeV by the AMY detector at TRISTAN we measure the cross section of the reactions e+e− → μ+μ− and e+e− → τ+τ− and the symmetry in the angular distributions. For the lowest order cross section we obtain σμμ = 27.54 ± 0.65 ± 0.95 pb and σττ = 28.27 ± 0.87 ± 0.69 pb, and for the forward-backward asymmetry, Aμμ = 0.303 ± 0.027 ± 0.008 and Aττ = −0.291 ± 0.040 ± 0.019. These measurements agree with the standard model. Assuming e−μ−τ univrsality we extract the vector and axial coupling constants | gν| = 0.00 ± 0.09 and |gA| = 0.476 ± 0.024. A fit of data to composite models places lower bounds (95% confidence level) on the compositeness scale of 2–4 TeV.
Published: 1994

37. Measurements of the inclusive jet cross section in photon-photon interactions at TRISTAN

Author: J. R. Smith, S. Lusin, Takashi Sasaki, Saroj Kumar Sahu, S. Behari, Dong-Chul Son, David Stuart, Bj Kim, Stephen L. Olsen, M. H. Lee, Yoshimasa Kurihara, N. Morgan, S. K. Choi, T. Nozaki, C. Velisarris, Sunghee Kim, Kisoo Lee, K. Ohkubo, T. Ishizuka, F. Kajino, A. Maki, L. Y. Zheng, A. Murakami, Robert Stone, M. Shirai, K. Gotow, M. H. Ye, Kazumasa Miyano, Y. Fujii, Kazuo Abe, S. S. Myung, A. Abashian, W. G. Yan, C. Rosenfeld, T. Aso, J. S. Kang, Richard Breedon, K. Ueno, F. Liu, S. Kobayashi, A. Bodek, P. N. Kirk, J. Vinson, M. Oyoshi, Susumu Terada, T. Kumita, W. X. Gao, F. Sannes, S. Ebara, C. P. Cheng, K. L. Sterner, D. Haim, T. Thomas, Winston Ko, Ryuki Tanaka, Y. Takaiwa, S. Kanda, D. Y. Kim, R. L. Lander, D. K. Cho, L. E. Piilonen, C. A. Fry, Y. K. Li, S. Wilson, Y. Yamashita, J. Rowe, S. Matsumoto, R. C. Walker, Steve Schnetzer, N. Takashimizu, K. W. Park, Yasuhiro Sugimoto, M. E. Mattson, Y. S. Chung, L. M. Chinitz, Hiroyuki Sagawa, Tsunehiko Omori, H. Miyata, and Y. Sakai
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, Photon, High Energy Physics::Phenomenology, Detector, Physics::Optics, Parton, Jet (particle physics), Photon structure function, Nuclear physics, Cross section (physics), High Energy Physics::Experiment, Perturbation theory (quantum mechanics)
Abstract: We present cross section measurements for inclusive jet production in almost-real photon-photon interactions at TRISTAN using the AMY detector. The results are compared with leading-order QCD calculations for different parameterizations of the parton density in the photon.
Published: 1994

38. Two-body disintegration of the deuteron with 0.8–1.8 GeV photons

Author: Douglas H Beck, R. C. Walker, R. D. McKeown, D. Collins, Jim Napolitano, C. Marchand, Z. E. Meziani, R.S. Kowalczyk, D. F. Geesaman, G. Boyd, Ronald Gilman, B. W. Filippone, E. R. Kinney, R. J. Holt, J. E. Nelson, B. Zeidman, M.C. Green, R. E. Segel, C. E. Jones, R. G. Milner, P. E. Bosted, J. Jourdan, H. E. Jackson, R. C. Minehart, S. J. Freedman, T. Y. Tung, and D. H. Potterveld
Subjects: Nuclear reaction, Physics, Nuclear and High Energy Physics, Photon, Proton, Hadron, Bremsstrahlung, Baryon, Nuclear physics, Neutron, Atomic physics, Nuclear Experiment, Nucleon, Caltech Library Services
Abstract: The differential cross section for the reaction 2H(γ,p)n has been measured at several center-of-mass angles ranging from 50° to 143° for photon energies between 0.8 and 1.8 GeV. The experiment was performed at the SLAC-NPAS facility with the use of the 1.6 GeV/c spectrometer to detect the high energy protons produced by a bremsstrahlung beam directed at a liquid deuterium target. Contributions from concurrent disintegration by the residual electron beam were determined by measuring the proton yield without the Cu photon radiator. At angles not very far from 90°, the energy dependence of the cross sections is consistent with predictions of scaling using counting rules for constituent quarks. At least one theoretical calculation based on a meson-baryon picture of the reaction is able to reproduce the magnitude and energy dependence of the 90° cross section. The angular distribution exhibits a large enhancement at backward angles at the higher energies.
Published: 1993

39. Measurement of α from the moment of particle momenta within jets from e+e- annihilation

Author: Robert Stone, David Stuart, Kisoo Lee, Kazuo Abe, A. Abashian, Sun Kee Kim, J. R. Smith, F. Sannes, T. Thomas, W. X. Gao, Kazumasa Miyano, B. J. Kim, S. Kanda, R. C. Walker, M. Oyoshi, Steve Schnetzer, Takashi Sasaki, Ko Winston, N. Takashimizu, J. Rowe, M. E. Mattson, Richard Breedon, Dong-Chul Son, L. E. Piilonen, C. Rosenfeld, A. Bodek, W. G. Yan, Yasuhiro Sugimoto, Y. S. Chung, M. H. Ye, Hiroyuki Sagawa, C. Velisarris, S. L. Olsen, R. L. Lander, S. K. Choi, K. Gotow, Y. Fujii, K. Ueno, J. Vinson, Y. K. Li, P. N. Kirk, Susumu Terada, T. Kumita, S. Wilson, D. Haim, N. Morgan, F. Liu, M. E. Zomorrodian, S. Kobayashi, Y. Yamashita, Tsunehiko Omori, Yoshimasa Kurihara, Saroj Kumar Sahu, L. M. Chinitz, C. P. Cheng, T. Nozaki, J. S. Kang, A. Murakami, T. Aso, H. Miyata, C. A. Fry, M. H. Lee, S. Ebara, Y. Sakai, K. W. Park, T. Ishizuka, R. Poling, Ryuki Tanaka, Y. Takaiwa, S. Matsumoto, A. Maki, L. Y. Zheng, F. Kajino, S. S. Myung, K. L. Sterner, and S. Lusin
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, Logarithm, Electron–positron annihilation, High Energy Physics::Phenomenology, Jet (particle physics), Nuclear physics, Momentum, Moment (mathematics), Particle, High Energy Physics::Experiment
Abstract: We present a study of the third moment of the inclusive momentum distribution of particles within jets produced by e+e- annihilation at TRISTAN. In this analysis, the QCD coupling strength alpha(s) is determined by fits to the prediction of the Next-to-Leading Logarithm Parton-Shower model. The measured value of alpha(s) (57.9 GeV) = 0.134(-0.005)+0.006.
Published: 1993

40. Evidence for hard scattering of hadronic constituents of photons in photon-photon collisions of TRISTAN

Author: Hiroyuki Sagawa, K. Gotow, R. L. Lander, C. Rosenfeld, S. Wilson, Richard Breedon, K. Tomioka, R. C. Walker, Steve Schnetzer, S. S. Myung, L. E. Piilonen, Y. Takaiwa, M. Frautschi, S. Matsumoto, J. Vinson, S. K. Choi, E. H. Low, A. Murakami, F. Sannes, David Stuart, S. Kanda, A. Bacala, K. P. Hu, E. Araki, A. T.M. Wang, T. Nozaki, Y. Oshi, T. Ishizuka, W. G. Yan, H. Kagan, C. P. Cheng, A. Z. Lai, Sun Kee Kim, S. L. Olsen, T. Kumita, Dong-Chul Son, Y. K. Li, C. Velisarris, J. S. Kang, P. N. Kirk, Kazuo Abe, J. Lim, Takashi Sasaki, J. R. Smith, T. Kojima, Yoshimasa Kurihara, Robert Stone, S. Lusin, Tsunehiko Omori, Y. Yamashita, K. Ueno, Yusuke Higashi, Kaori Maeshima, W. X. Gao, P. Gu, M. E. Mattson, H. Miyata, Kazumasa Miyano, C. A. Fry, R. L. Malchow, M. H. Ye, A. Sill, H. Yoshinaka, Yongsun Kim, B. J. Kim, A. Maki, R. D. Kass, Moo Hyun Lee, Winston Ko, S. Kobayashi, Susumu Terada, R. Poling, T. Thomas, D. Blanis, A. Abashian, K. L. Sterner, Rr Mcneil, F. Kajino, R. Tanaka, J. Rowe, A. Bodek, Y. Sakai, Yasuhiro Sugimoto, and Y. Fujii
Subjects: Physics, Nuclear physics, Quantum chromodynamics, Nuclear and High Energy Physics, Particle physics, Photon, Luminosity (scattering theory), Scattering, Nuclear Theory, High Energy Physics::Phenomenology, Hadron, High Energy Physics::Experiment, Nuclear Experiment
Abstract: We present results of an experimental study of e+e−+ hadrons in the kinematic regime for which the process is interpreted as hadron production in collisions of almost-real photons. The data sample corresponds to an integrated luminosity of 27.5 pb− and covers center-of-mass energies from 55 to 61.4 GeV. We observe more events than expected from the incoherent sum of quark-parton and vector-meson-dominance models, and we give a quantitative explanation of the excess by including the hard scattering of the hadronic constituents of the photons calculated with QCD.
Published: 1992

41. Longitudinal and transverse response functions inFe56(e,e’) at momentum transfer near 1 GeV/c

Author: R. C. Minehart, L. C. Dennis, L. M. Chinitz, B. W. Filippone, Wolfgang Lorenzon, R. M. Sealock, James McCarthy, G. Boyd, J. Morgenstern, Donal Day, J. Y. Mougey, Z. E. Meziani, K. L. Giovanetti, L. C. Smith, J. P. Chen, T. Koh, D. H. Potterveld, Ross Milner, K. W. Kemper, R. C. Walker, O. Rondon-Aramayo, C. E. Woodward, R. D. McKeown, J. Jourdan, G. E. Dodge, S.T. Thornton, and Douglas H Beck
Subjects: Physics, Nuclear reaction, Nuclear physics, Scattering, Electric field, Momentum transfer, Extrapolation, Coulomb, General Physics and Astronomy, Electron, Born approximation, Atomic physics, Nuclear Experiment
Abstract: Inclusive electron-scattering cross sections have been measured for ^(56)Fe in the quasielastic region at electron energies between 0.9 and 4.3 GeV, at scattering angles of 15° and 85°. Longitudinal and transverse response functions at a q of 1.14 GeV/c have been extracted using a Rosenbluth separation. The experimental Coulomb sum has been obtained with aid of an extrapolation. The longitudinal response function, after correction for Coulomb distortion, is lower than quasifree-scattering-model predictions at the quasielastic peak and on the high-ω side.
Published: 1991

42. Advances in Rosetta protein structure prediction on massively parallel systems

Author: Bin Qian, R. C. Walker, David Baker, and Srivatsan Raman
Subjects: Petascale computing, Theoretical computer science, Protein structure, General Computer Science, Process (engineering), Computer science, Rosetta Code, Key (cryptography), Parallel computing, Folding (DSP implementation), IBM, Protein structure prediction
Abstract: One of the key challenges in computational biology is prediction of three-dimensional protein structures from amino-acid sequences. For most proteins, the "native state" lies at the bottom of a free-energy landscape. Protein structure prediction involves varying the degrees of freedom of the protein in a constrained manner until it approaches its native state. In the Rosetta protein structure prediction protocols, a large number of independent folding trajectories are simulated, and several lowest-energy results are likely to be close to the native state. The availability of hundred-teraflop, and shortly, petaflop, computing resources is revolutionizing the approaches available for protein structure prediction. Here, we discuss issues involved in utilizing such machines efficiently with the Rosetta code, including an overview of recent results of the Critical Assessment of Techniques for Protein Structure Prediction 7 (CASP7) in which the computationally demanding structure-refinement process was run on 16 racks of the IBM Blue Gene/L (TM) system at the IBM T. J. Watson Research Center. We highlight recent advances in high-performance computing and discuss,future development paths that make use of the next-generation petascale (> 10(12) floating-point operations per second) machines.
Published: 2008

43. A measurement of the photon structure function F2

Author: J. Rowe, A. Bodek, Richard Breedon, T. Kumita, Y. Sugimoto, E. H. Low, Robert Stone, David Stuart, S. Kanda, M. E. Mattson, T. Nozaki, H. Kagan, J. S. Kang, Y. Ishi, C. Velisarris, E. J. Kim, Takashi Sasaki, Kazumasa Miyano, A. Murakami, Yusuke Higashi, K. Ueno, J. Vinson, L. E. Piilonen, J. R. Smith, P. N. Kirk, T. Kojima, T. Yasuda, Y. C. Zhu, Y. Yamashita, Kazuo Abe, S. L. Olsen, C. A. Fry, K. Gotow, S. K. Choi, M. H. Ye, N. M. Shaw, R. L. Malchow, H. Miyata, E. H. Thorndike, Hiroyuki Sagawa, C. P. Cheng, J. Lim, Kaori Maeshima, Yongsun Kim, A. T.M. Wang, M. Frautschi, W. Metcalf, Y. Yamagishi, H. Harada, R. D. Kass, B. J. Kim, Y. Takaiwa, Sarah Catherine Eno, P. Gu, Susumu Terada, A. Bacala, H. S. Budd, C. Rosenfeld, T. Ishizuka, A. Sill, R. L. Lander, Dong-Chul Son, Tsunehiko Omori, Yoshimasa Kurihara, S. Matsumoto, S. S. Myung, H. W. Zheng, Moo Hyun Lee, K. Ohta, S. Schenetzer, Winston Ko, P. Auchincloss, S. Kobayashi, F. Sannes, Y. H. Ho, Hyunyong Kim, K. P. Hu, D. H. Han, A. Maki, G. N. Kim, Y. K. Li, S. Lusin, S. Wilson, R. Poling, R. C. Walker, D. Blanis, R. Tanaka, K. L. Sterner, A. Z. Lai, Rr Mcneil, S. K. Kim, F. Kajino, Y. Fujii, Y. Sakai, T. Thomas, and A. Abashian
Subjects: Quantum chromodynamics, Nuclear physics, Physics, Nuclear and High Energy Physics, Particle physics, Structure function, Range (statistics), High Energy Physics::Experiment, Photon structure function
Abstract: The photon structure function F2 has been measured at average Q2 values of 73,160 and 390 ( GeV c ) 2 . We compare the x dependence of the Q2 = 73 ( GeV c ) 2 data with theoretical expectations based on QCD. In addition we present results on the Q2 evolution of the structure function for the intermediate x range (0.3⩽ x ⩽0.8). The results are consistent with QCD.
Published: 1990

44. Observation of anomalous production of muon pairs in e+e− annihilation into four-lepton final states

Author: S. S. Myung, H. W. Zheng, H. Kagan, M. H. Ye, Rr Mcneil, E. H. Thorndike, J. Lim, A. Maki, M. E. Mattson, A. Bodek, C. A. Fry, Gordon Watts, S. K. Kim, Y. Ishi, R. C. Walker, Steve Schnetzer, Tsunehiko Omori, D. H. Han, P. Gu, H. Ichinose, Hiroyuki Sagawa, F. Kajino, Y. Sakai, M. Dickson, S. Lusin, T. Thomas, Yoshimasa Kurihara, Kazuo Abe, J. Li, David Stuart, P. N. Kirk, T. Nozaki, R. L. Malchow, C. Velissaris, Yasuhiro Sugimoto, L. E. Piilonen, W. Metcalf, N. M. Shaw, Yongsun Kim, Kaori Maeshima, Y. Yamashita, E. J. Kim, H. S. Budd, Y. Yamagishi, C. P. Cheng, M. Frautschi, R. D. Kass, R. Tanaka, Y. Takaiwa, Takashi Sasaki, Y. C. Zhu, H. Miyata, S. L. Olsen, Hyunyong Kim, E. H. Low, G. N. Kim, A. Bacala, Dong-Chul Son, M. H. Lee, F. Sannes, A. Sill, A. Murakami, K. P. Hu, Y. Fujii, S. Wilson, D. Blanis, K. Ohta, A. Abashian, T. Kojima, J. R. Smith, Winston Ko, Yusuke Higashi, S. Matsumoto, T. Yasuda, S. Kobayashi, Y. H. Ho, R. Imlay, K. Gotow, K. L. Sterner, C. Rosenfeld, A. T.M. Wang, T. Mori, C. G. Trahern, T. Kumita, Kazumasa Miyano, Sarah Catherine Eno, Susumu Terada, B. J. Kim, Y. K. Li, R. Poling, R. L. Lander, Robert Stone, H. Harada, P. Auchincloss, Richard Breedon, J. Vinson, D. Perticone, J. S. Kang, K. Ueno, I. H. Park, J. Liu, and T. Ishizuka
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, Muon, Electron–positron annihilation, Bremsstrahlung, law.invention, Nuclear physics, Angular distribution, law, Beam direction, High Energy Physics::Experiment, Nuclear Experiment, Collider, Lepton
Abstract: We report results of a study of four-lepton final states produced in e+e− collisions at center-of-mass energies from 50 to 61.4 GeV using the AMY detector at the TRISTAN collider. For the cases where two or three charged tracks are produced at large angles relative to the beam direction, the cross sections agree with QED. However, we observe an excess of e+e−→e+e−μ+μ− events with four tracks at wide angles and with dimuon mass less than 1.0 GeV/c2.
Published: 1990

45. A search for leptoquark and colored lepton pair production in e+e− annihilations at TRISTAN

Author: E. H. Thorndike, Y. Sugimoto, P. Auchincloss, J. Lim, T. Nozaki, A. T.M. Wang, J. R. Smith, P. Gu, Hyunyong Kim, M. H. Lee, C. Rosenfeld, W. Metcalf, T. Kojima, I. H. Park, T. Yasuda, Y. Fujii, E. J. Kim, Dong-Chul Son, S. Wilson, David Stuart, J. Liu, F. Sannes, Takashi Sasaki, K. Gotow, K. P. Hu, T. Ishizuka, P. N. Kirk, R. Imlay, M. Frautschi, Tsunehiko Omori, Y. K. Li, A. Bacala, R. R. McNeill, S. K. Kim, Y. Yamashita, Yusuke Higashi, Y. C. Zhu, S. L. Olsen, D. H. Han, Richard Breedon, G. N. Kim, S. Matsumoto, A. Maki, N. M. Shaw, R. Poling, T. Mori, F. Kajino, C. A. Fry, D. Perticone, Y. Sakai, M. H. Ye, A. Abashian, J. S. Kang, M. E. Mattson, J. Vinson, J. Li, R. L. Lander, L. E. Piilonen, R. L. Malchow, Y. Ishi, R. Tanaka, K. Ueno, Y. Takaiwa, C. G. Trahern, E. H. Low, Robert Stone, S. Lusin, T. Kumita, R. D. Kass, T. Thomas, A. Murakami, C. P. Cheng, Hiroyuki Sagawa, A. Sill, R. C. Walker, Steve Schnetzer, Yk Kim, K. Ohta, D. Blanis, Winston Ko, H. Miyata, Kazuo Abe, S. Kobayashi, Kazumasa Miyano, Kaori Maeshima, Yoshimasa Kurihara, H. S. Budd, Y. Yamagishi, K. L. Sterner, Sarah Catherine Eno, Susumu Terada, H. Harada, H. Kagan, A. Bodek, S. S. Myung, and H. W. Zheng
Subjects: Nuclear physics, Physics, Nuclear and High Energy Physics, Particle physics, Pair production, Colored, Electron–positron annihilation, High Energy Physics::Phenomenology, High Energy Physics::Experiment, Leptoquark, Lepton
Abstract: We report on a search for the pair production of leptoquarks and colored leptons in e + e − annihilations t center-of-mass energies from 50 to 60.8 GeV, using the AMY detector at TRISTAN. No evidence for such particles is found and 95% CL mass limits are given.
Published: 1990

46. A search for SUSY particles in e +e − annihilations at s=50–60.8GeV

Author: K. Gotow, Y. Fujii, T. Mori, H. Kagan, H. Itoh, Yasuhiro Sugimoto, Y. T. Xu, A. Maki, E. H. Low, C. G. Trahern, T. Kumita, I. H. Park, Tsunehiko Omori, W. Metcalf, S. Matsumoto, Kazuo Abe, Z. P. Mao, S. Lusin, Y. K. Li, T. Ishizuka, J.S. Kang, A. Bacala, M. C.S. Williams, S. Kobayashi, R. C. Walker, M. Frautschi, H. Harada, Kaori Maeshima, Steve Schnetzer, A. T.M. Wang, A. Murakami, D. Perticone, P. Auchincloss, Y. Yamagishi, T. Kojima, S. Wilson, E.J. Kim, R. L. Lander, F. Sannes, G. N. Kim, T. Yasuda, P. N. Kirk, K. Ueno, J. Li, K. P. Hu, A. Bodek, M.H. Lee, Robert Stone, J. R. Smith, Hiroyuki Sagawa, Richard Breedon, Y. Yamashita, R. L. Malchow, Yusuke Higashi, R. L. Imlay, Yongsun Kim, C. P. Cheng, J. Vinson, R. D. Kass, D. Son, M. E. Mattson, N. M. Shaw, Y. Ishi, C. Rosenfeld, H. S. Budd, H. Miyata, Y. Sakai, Ryuki Tanaka, Y. Takaiwa, K. Toyoshima, T. Thomas, S. S. Myung, H. W. Zheng, R. Poling, A. Abashian, Yoshimasa Kurihara, Kazumasa Miyano, Sarah Catherine Eno, Susumu Terada, H. J. Kim, D. Blanis, K. L. Sterner, E. H. Thorndike, J. Lim, D.H. Han, P. Gu, H. Yokota, David Stuart, S. K. Kim, Y. C. Zhu, S. L. Olsen, F. Kajino, R. R. McNeil, A. Sill, C. A. Fry, K. Ohta, Y. H. Ho, L. E. Piilonen, M. H. Ye, KO Winston, T. Nozaki, and Takashi Sasaki
Subjects: Physics, Quark, Nuclear and High Energy Physics, Particle physics, Electron–positron annihilation, High Energy Physics::Phenomenology, Supersymmetry, lcsh:QC1-999, Nuclear physics, Pair production, Higgs boson, High Energy Physics::Experiment, lcsh:Physics, Lepton
Abstract: Searches for the pair production of the supersymmetric partner particles of leptons, quarks, and non-minimal Higgs have been made in e + e − annihilations at center-of-mass energies between 50 and 60.8 GeV using the AMY detector at TRISTAN. No evidence for their existence is observed and 95% CL mass limits are presented.
Published: 1990

47. Characteristics of EGRET Blazars in the VLBA Imaging and Polarimetry Survey (VIPS)

Author: S. E. Healey, G. B. Taylor, Peter F. Michelson, R. C. Walker, L. Weintraub, Christopher D. Fassnacht, Neil Gehrels, A. C. S. Readhead, Loránt O. Sjouwerman, Roger W. Romani, T. J. Pearson, Garret Cotter, Roger Blandford, S. E. Tremblay, and Joseph Helmboldt
Subjects: Physics, Brightness, biology, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Polarimetry, FOS: Physical sciences, Flux, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, biology.organism_classification, Polarization (waves), symbols.namesake, Space and Planetary Science, symbols, Egret, Radio frequency, Blazar, Doppler effect
Abstract: We examine the radio properties of EGRET-detected blazars observed as part of the VLBA Imaging and Polarimetry Survey (VIPS). VIPS has a flux limit roughly an order of magnitude below the MOJAVE survey and most other samples that have been used to study the properties of EGRET blazars. At lower flux levels, radio flux density does not directly correlate with gamma-ray flux density. We do find that the EGRET-detected blazars tend to have higher brightness temperatures, greater core fractions, and possibly larger than average jet opening angles. A weak correlation is also found with jet length and with polarization. All of the well-established trends can be explained by systematically larger Doppler factors in the gamma-ray loud blazars, consistent with the measurements of higher apparent velocities found in monitoring programs carried out at radio frequencies above 10 GHz., 20 pages, 7 figures, accepted to ApJ
Published: 2007

48. The VLBA Imaging and Polarimetry Survey at 5 GHz

Author: Roger W. Romani, T. J. Pearson, A. C. S. Readhead, Neil Gehrels, S. E. Healey, G. B. Taylor, Roger Blandford, Loránt O. Sjouwerman, Garret Cotter, Peter F. Michelson, R. C. Walker, Steven T. Myers, L. Weintraub, Christopher D. Fassnacht, S. E. Tremblay, and J. F. Helmboldt
Subjects: Physics, Jet (fluid), Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Polarimetry, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Spectral line, Automated data, symbols.namesake, Space and Planetary Science, Position (vector), Faraday effect, Very-long-baseline interferometry, Perpendicular, symbols, Astrophysics::Galaxy Astrophysics
Abstract: We present the first results of the VLBA Imaging and Polarimetry Survey (VIPS), a 5 GHz VLBI survey of 1,127 sources with flat radio spectra. Through automated data reduction and imaging routines, we have produced publicly available I, Q, and U images and have detected polarized flux density from 37% of the sources. We have also developed an algorithm to use each source's I image to automatically classify it as a point-like source, a core-jet, a compact symmetric object (CSO) candidate, or a complex source. The mean ratio of the polarized to total 5 GHz flux density for VIPS sources with detected polarized flux density ranges from 1% to 20% with a median value of about 5%. We have also found significant evidence that the directions of the jets in core-jet systems tend to be perpendicular to the electric vector position angles (EVPAs). The data is consistent with a scenario in which ~24% of the polarized core-jets have EVPAs that are anti-aligned with the directions of their jet components and which have a substantial amount of Faraday rotation. In addition to these initial results, plans for future follow-up observations are discussed., Comment: 36 pages, 3 tables, 13 figures; accepted for publication in ApJ
Published: 2006
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49. VLBA Imaging Polarimetry of Active Galactic Nuclei: An Automated Approach

Author: T. J. Pearson, Steven T. Myers, G. B. Taylor, Neil Gehrels, Christopher D. Fassnacht, James S. Ulvestad, Loránt O. Sjouwerman, Anthony C. S. Readhead, R. C. Walker, Peter F. Michelson, and Edward B. Fomalont
Subjects: Physics, Active galactic nucleus, Linear polarization, media_common.quotation_subject, Astrophysics (astro-ph), Polarimetry, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Polarization (waves), symbols.namesake, Space and Planetary Science, Sky, Very-long-baseline interferometry, Faraday effect, symbols, Very Long Baseline Array, media_common
Abstract: We present full polarization Very Long Baseline Array (VLBA) observations at 5 GHz and 15 GHz of 24 compact active galactic nuclei (AGN). These sources were observed as part of a pilot project to demonstrate the feasibility of conducting a large VLBI survey to further our understanding of the physical properties and temporal evolution of AGN jets. The sample is drawn from the Cosmic Lens All-Sky Survey (CLASS) where it overlaps with the Sloan Digital Sky Survey at declinations north of 15 degrees. There are 2100 CLASS sources brighter than 50 mJy at 8.4 GHz, of which we have chosen 24 for this pilot study. All 24 sources were detected and imaged at 5 GHz with a typical dynamic range of 500:1, and 21 of 24 sources were detected and imaged at 15 GHz. Linear polarization was detected in 8 sources at both 5 and 15 GHz, allowing for the creation of Faraday rotation measure (RM) images. The core RMs for the sample were found to have an average absolute value of 390 +/- 100 rad/m^2. We also present the discovery of a new Compact Symmetric Object, J08553+5751. All data were processed automatically using pipelines created or adapted for the survey., 25 pages, 3 figures, 4 tables, accepted to the Astrophysical Journal Supplement Series Full resolution figures and more available from http://www.aoc.nrao.edu/~gtaylor/VIPS
Published: 2005

50. VLBI observations of weak sources using fast frequency switching

Author: Alan L. Roy, Heino Falcke, R. C. Walker, and Enno Middelberg
Subjects: Physics, Radio galaxy, Astronomy, Astrophysics (astro-ph), Phase (waves), Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Space and Planetary Science, Very-long-baseline interferometry, Calibration, Limit (mathematics), Astrophysics::Galaxy Astrophysics
Abstract: We have developed a new phase referencing technique for high frequency VLBI observations. In conventional phase referencing, one interleaves short scans on a nearby phase calibrator between the target source observations. In fast frequency switching described here, one observes the target source continuously while switching rapidly between the target frequency and a lower reference frequency. We demonstrate that the technique allows phase calibration almost reaching the thermal noise limit and present the first detection of the AGN in the FR I radio galaxy NGC 4261 at 86 GHz. Although point-like, this is the weakest source ever detected with VLBI at this frequency., Comment: Accepted by A&A, 14 pages, 12 figures, needs aa.cls, aas_macros.sty and amsmath.sty, replaced due reformatting
Published: 2005

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