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1. A plastic scintillator-based muon tomography system with an integrated muon spectrometer

Author: G. Jonkmans, Vinicius N.P. Anghel, Z. Liu, R. Hydomako, K. Boniface, D. Waller, K. Boudjemline, A. Erlandson, T. J. Stocki, V. V. Golovko, J. C. Armitage, A. Robichaud, J. Bueno, R. Gazit, E. Charles, P. L. Drouin, F. Baig, C. Jewett, C. Howard, D. Godin, M. Thompson, and G. Gallant
Subjects: Physics, Nuclear and High Energy Physics, Large-volume inspection, Muon, Muon tomography, Spectrometer, Physics::Instrumentation and Detectors, Scattering, Scintillator, Tracking (particle physics), Nuclear physics, Momentum, Scintillation detector, Cosmic-ray muon, Multiple Coulomb scattering, High Energy Physics::Experiment, Tomography, Instrumentation
Abstract: A muon scattering tomography system which uses extruded plastic scintillator bars for muon tracking and a dedicated muon spectrometer that measures scattering through steel slabs has been constructed and successfully tested. The atmospheric muon detection efficiency is measured to be 97% per plane on average and the average intrinsic hit resolution is 2.5 mm. In addition to creating a variety of three-dimensional images of objects of interest, a quantitative study has been carried out to investigate the impact of including muon momentum measurements when attempting to detect high-density, high-Z material. As expected, the addition of momentum information improves the performance of the system. For a fixed data-taking time of 60 s and a fixed false positive fraction, the probability to detect a target increases when momentum information is used. This is the first demonstration of the use of muon momentum information from dedicated spectrometer measurements in muon scattering tomography.
Published: 2015
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2. Development of gas microstrip detectors for digital X-ray imaging and radiation dosimetry

Author: J. Dubeau, A.J. Waker, D.G. Gobbi, M. S. Dixit, Paul C. Johns, J. C. Armitage, D. Karlen, and F.G. Oakham
Subjects: Physics, medicine.medical_specialty, Photon, business.industry, Image quality, X-ray detector, Radiation, Particle detector, Microstrip, Detective quantum efficiency, Optics, medicine, Dosimetry, Medical physics, Electrical and Electronic Engineering, business, Instrumentation
Abstract: Our recent work in the application of gas microstrip detector (GMD) technology to the fields of digital X-ray imaging and radiation dosimetry is described. The GMD can measure the position and the energy of individual photons at the high counting rates encountered in X-ray imaging. GMD based imaging systems have high detective quantum efficiency and permit improvement of image quality and contrast using display windowing and measured energy information. Results are presented on the performance of a prototype GMD imaging system operated with a xenon/methane 90/10 gas mixture at 1 atmosphere. Results are also presented on the performance of a GMD filled with tissue equivalent gases for applications in the field of radiation dosimetry in mixed neutron and /spl gamma/ fields. The results show that the GMD can be used for dosimetric discrimination between different types of radiation in mixed field environments.
Published: 1998
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3. Results for electrons from the 1995 ATLAS forward calorimeter prototype testbeam

Author: L. Shaver, G.G. Stairs, V.D. Khovansky, A. Savin, R. S. Orr, V. Jemanov, L. Austin, J. Steinberg, D. Tompkins, John Rutherfoord, Pavel Shatalov, Michael Shupe, K. A. Johns, A. Artamonov, V. Epchtein, R. Norton, J. Mayer, J. C. Armitage, M. Ryabinin, and Peter Loch
Subjects: Physics, Nuclear and High Energy Physics, Calorimeter (particle physics), Physics::Instrumentation and Detectors, business.industry, Resolution (electron density), Linearity, Electron, Signal, Atomic and Molecular Physics, and Optics, Optics, medicine.anatomical_structure, Atlas (anatomy), Electrode, medicine, business, Electron ionization
Abstract: The performance of the ATLAS electromagnetic liquid argon/brass forward calorimeter with its new readout geometry consisting of tube/rod electrodes with cylindrical shell gaps, has been evaluated with a full depth prototype in a testbeam experiment with electrons in 1995. The results for signal linearity of better than 1% and a constant term in the relative energy resolution of 3% meet and even exceed the original performance requirements very well. Space resolution in the order of 0.5 mm in the high energy limit, and an insignificant signal dependency on the electron impact angle have been found in addition.
Published: 1998
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4. Construction, commissioning and first data from the CRIPT muon tomography project

Author: Gerald Oakham, Z. Liu, Martin Magill, M. Thompson, D. Waller, G. Jonkmans, A. Erlandson, G. Gallant, K. Boudjemline, J. C. Armitage, V. V. Golovko, J. Bueno, Douglas Bryman, C. Jewett, T. J. Stocki, A. Robichaud, E. Charles, R. Gazit, J. Botte, R. Hydomako, T. Cousins, Vinicius N.P. Anghel, and S. Noel
Subjects: Nuclear physics, Physics, Muon tomography, Data acquisition, Muon, Volume of interest, Physics::Instrumentation and Detectors, Detector, Cosmic ray, Tomography, Scintillator, Remote sensing
Abstract: The Cosmic Ray Inspection and Passive Tomography (CRIPT) project is investigating muon scattering tomography (MST) for applications in border security, nuclear non-proliferation, and nuclear waste characterization. The construction of the full-scale prototype MST system began in the Summer of 2011 and was completed in September 2012. The CRIPT detector employs 12 layers of scintillator to track atmospheric muons before and after passage through a volume of interest, and to estimate each muon's momentum. The total height of the system is 5.5 m and its weight is 20 tonnes. Details of its construction are presented. After the integration of the custom data acquisition electronics, the commissioning of the CRIPT detector began. The first tomographic images were obtained in October 2012 and are presented here.
Published: 2012
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5. Machine learning for the cosmic ray inspection and passive tomography project (CRIPT)

Author: C. Jewett, A. Robichaud, G. Jonkmans, Douglas Bryman, Christopher Warren, A. Erlandson, B. E. Morgan, T. J. Stockil, Martin Magill, R. Hydomako, J. T. Smith, V. V. Golovko, Gerald Oakham, J. Botte, Vinicius N.P. Anghel, E. Charles, S. NoeI, D. Waller, D. Ong, T. Cousins, G. GalIant, M. Thompson, M. McCaIl, R. Gazit, Z. Liu, J. Bueno, K. Boudjemline, and J. C. Armitage
Subjects: Physics, Artificial neural network, business.industry, Detector, Decision tree, Cosmic ray, Machine learning, computer.software_genre, Expert system, Physical information, Robustness (computer science), Artificial intelligence, Tomography, business, computer
Abstract: Muons, which are produced naturally in the upper atmosphere, can be used to scan cargo for special nuclear materials (SNM). Preliminary simulated results show that detecting the presence of these materials can be accomplished by measuring the scattering of cosmic ray muons. Machine learning tools have been used on these data to classify it as SNM or not. The muon exists long enough, and is penetrating enough, that it can be used to passively scan cargo to detect SNM. By measuring the deflection angles of muons after they exit a container, one can determine whether or not SNM are present. Different detector approaches have been evaluated by considering the performance, cost, and robustness of several technologies. Simulations have been performed to help design the detectors and to determine the effectiveness of the proposed techniques. Realistic cargo containers have been simulated. Two types of techniques can be used to determine whether the cargo containers contain SNM. More traditional methods use an expert system which uses knowledge of physics to compute physical information about the cargo. The other approach is to use Machine Learning classifiers, which can be used to determine if the cargo contains SNM. These techniques include the following algorithms: decision trees, neural networks, special vector machines, and k nearest neighbours. Preliminary results from the two approaches to classification have been obtained and will be discussed in the paper.
Published: 2012
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6. Passivation of gas microstrip detectors and stability of long-term operation

Author: G. Chapman, M. Salomon, J. Dubeau, W. Faszer, M. S. Dixit, J. C. Armitage, Louis-Andre Hamel, and G. Oakham
Subjects: Physics, Nuclear and High Energy Physics, Passivation, business.industry, Nickel oxide, Detector, Stability (probability), Term (time), chemistry.chemical_compound, chemistry, UPILEX, Isobutane, Optoelectronics, business, Instrumentation, Layer (electronics)
Abstract: We have studied the long-term operation of gas microstrip detectors which have been passivated with a layer of nickel oxide. We have used as the active gas CF4/isobutane (80:20) and three different types of substrates: Tedlar, glass and Upilex. In all three cases we found that the detectors are stable after passivation and can operate for a month without changes in gain at rates of MHz. The total accumulated charge was approximately 100 mC.
Published: 1994
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7. Gas microstrip detectors on resistive plastic substrates

Author: D. Karlen, A. Greenwald, S.C. Taylor, Ian Shipsey, F.G. Oakham, Erik A. Johnson, J. Dubeau, J. C. Armitage, M. S. Dixit, and G.C. Stuart
Subjects: Physics, Nuclear and High Energy Physics, Resistive touchscreen, business.industry, Amplifier, Insulator (electricity), Radiation length, Anode, UPILEX, Shielding effect, Optoelectronics, business, Instrumentation, Electrical conductor
Abstract: Plastics are desirable as substrates for gas microstrip detectors (GMDs) because of their flexibility, low density and long radiation length. GMDs have been fabricated on white Tedlar which has bulk electrical conductivity and on ion-implanted Upilex which has a thin electrically conductive layer on the surface of an insulator. The shielding effect of the thin conductive surface layer on the GMD gains has been investigated. High X-ray rate measurements show no charging or loss of gain for ion-implanted Upilex GMDs. Three such GMDs were recently tested in a high intensity beam at CERN. The anode signals were read out using fast, low noise, high gain amplifiers. Preliminary results of the test are presented.
Published: 1994
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8. Cosmic ray muon tomography system using drift chambers for the detection of Special Nuclear Materials

Author: D. Waller, Douglas Bryman, Gerald Oakham, E. Charles, T. J. Stocki, Vinicius N.P. Anghel, Martin Thompson, G. Jonkmans, G. Gallant, S. Noel, A. Erlandson, K. Boudjemline, J. C. Armitage, Z. Liu, T. Cousins, J. Botte, and C. Jewett
Subjects: Nuclear physics, Physics, Muon tomography, Muon, Physics::Instrumentation and Detectors, Scattering, Detector, High Energy Physics::Experiment, Cosmic ray, Tomography, Tracking (particle physics), Particle detector
Abstract: The smuggling of illicit Special Nuclear Materials (SNM) and Radiological Materials (RM) is a major security concern. Current radiation detection systems for cargo are not sensitive to well-shielded nuclear materials. The Muon Scattering Tomography (MST) method that we are developing might be a solution to this problem. It is based on the measurement of multiple scattering of cosmic ray-induced muons, traversing high-Z materials such as uranium and plutonium. This is possible due to the muons' highly penetrating nature. The technique involves measuring the angular deflections of these muons with charged particle tracking detectors placed around the object to be probed. One candidate detector is the single wire drift chamber. It can measure the 2-D impact position of a muon. The CRIPT (Cosmic Ray Inspection and Passive Tomography) collaboration has performed computer simulations of detectors designed to detect SNM via MST. We have also worked on the development of image reconstruction algorithms, and simulated the performances of different muon spectrometer designs and the response of the drift chambers. In addition to these efforts, the collaboration has built three prototypes which are being tested.
Published: 2010
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9. Measurement of three-jet distributions sensitive to the gluon spin ine + e − annihilations at $$\sqrt s = 91$$ GeV

Author: Phillip Allport, P. W. Jeffreys, A. M. Lee, B. C. Shen, J. D. Hobbs, H. E. Stier, D. A. Hinshaw, G. G. Hanson, P. Tarras, H. Mes, P. G. Estabrooks, R. K. Keeler, A. Simon, J. D. Gillies, I. P. Duerdoth, G. Giacomelli, Gideon Alexander, H. Przysiezniak, C. Y. Chang, N. C. Wood, E.J. Prebys, Otmar Biebel, D. G. Charlton, W. G. Scott, Paolo Capiluppi, P. Schenk, R. J. Barlow, O. Runolfsson, T. Mouthuy, L. Lessard, F. S. Merritt, Mitsuaki Nozaki, P. M. Watkins, M. Couch, D. J. Miller, Claudio Grandi, R. Humbert, M. S. Dixit, Frans Meijers, R. Kowalewski, Margret Fincke-Keeler, M. Jimack, John Allison, N. Wermes, M. A. Whalley, G. A. Snow, C. P. Ward, J. T.M. Chrin, L. Janissen, C. Milstene, Ehud Duchovni, R. Shypit, M. J. Losty, P. Singh, S. Schreiber, B. B. Brabson, J. G. Layter, A. M. Rossi, D. G. Fong, T. Kawamoto, J. Gascon, Kiyotomo Kawagoe, I. Wingerter, B. P. O'Neill, F. Lamarche, G. Beaudoin, A. Buijs, A. P. Wagner, T. J. McMahon, R. G. Kellogg, P. Pfister, T. Tsukamoto, J. Hagemann, H. Ihssen, S. W. Gensler, R. W. L. Jones, S. Levegrün, H. M. Fischer, S. Orito, John H. Schwarz, H. von der Schmitt, W. R. Gibson, G. Duckeck, R. Mir, R. J. Hemingway, Silvia Arcelli, A. Michelini, J. M. Roney, D. Hochman, N. J. Thackray, T. J. Smith, C. Ho, D. Strom, G. T. Zorn, Stefano Marcellini, R. F. McGowan, T. Kobayashi, H. Oh, Shlomo Dado, S. Sanghera, R. K. Carnegie, K. Stephens, C. Fukunaga, P. Jovanovic, J. Goldberg, J. C. Armitage, P. Mättig, H. O. Ogren, J. A. Wilson, Christoph Geich-Gimbel, P. Igo-Kemenes, G. Maringer, F. Odorici, S. A. Robins, J. R. McNutt, Austin Ball, D. Menszner, Alessandro Montanari, H. M. Bosch, D. C. Imrie, Tohru Takeshita, M. M. Deninno, M. J. Oreglia, W. Schappert, H. Jeremie, P. Le Du, H. Kreutzmann, A. Beck, J. Mildenberger, Harold Nguyen, Marcello Mannelli, M. Jobes, U. Binder, E. Heflin, R. M. Brown, Wolfram Dietrich Zeuner, E. K. U. Gross, A. Gaidot, M. Kuwano, P. Scharff-Hansen, Lorne Levinson, C. M. Hawkes, M. Cooper, Daniel Lellouch, G. P. Siroli, B. Nellen, P. Leblanc, M. J. Goodrick, M. Sproston, B. Panzer-Steindel, R. E. Hughes-Jones, U. Maur, I. Cohen, J. Hart, V. Gibson, Y. Yang, P. F. Harrison, J. L. Pinfold, G. Eckerlin, Michael Dittmar, W. J. Larson, D. Axen, A. Jawahery, John Baines, B. W. Kennedy, Georges Azuelos, G. Tysarczyk-Niemeyer, J. Kroll, O. Schaile, F. X. Gentit, J. E. Conboy, S. W. O'Neale, Peter R Hobson, M. Ogg, M. Hansroul, J. R. Carter, K. W. Bell, G. N. Patrick, G. Yekutieli, Gideon Bella, Stephen Lloyd, J. W. Gary, Takehiko Mori, A. D. Schaile, Peter Sherwood, S. Wotton, H. Takeda, Max Weber, K. J. Anderson, J. C. Hill, R. W. Springer, M. Weymann, A. Pouladdej, H. J. Burckhart, D. E. Klem, A. A. Carter, Misao Sasaki, A. M. Smith, Jacqueline Batley, N. I. Geddes, J. Ludwig, K. Runge, G. Vasseur, P. Routenburg, D. R. Ward, F. G. Oakham, P. Bock, Erez Etzion, M. W. Moss, Paul Kyberd, F. K. Loebinger, B. Lorazo, V. H. Winterer, A. Dieckmann, P. M. Hattersley, S. Bougerolle, Andris Skuja, B. Poli, J. Banks, M. W. Redmond, S. R. Hou, Claude Leroy, Gareth J. Barker, Tetsuro Mashimo, J. P. Martin, R. J. Homer, A. Rollnik, S. De Jong, M. F. Turner, P. Poffenberger, J. P. Pansart, N. K. Watson, J. von Krogh, I. J. Bloodworth, P. A. Elcombe, Shlomit Tarem, C. Wahl, W. J. Collins, Sachio Komamiya, A. T. Watson, S. Weisz, P. Ashton, Dave Robinson, Randall Sobie, G. D. Lafferty, C. P. Howarth, W. Gorn, D. E. Plane, T. P. Kokott, Rene Brun, J. E. Pilcher, M. Settles, G. A. Bahan, Stephen Hillier, R. D. Heuer, C. Moisan, J. P. Walker, C. K. Hargrove, T. W. Pritchard, Fabrizio Fabbri, G. M. Dallavalle, P. Teixeira-Dias, S. Rossberg, P. S. Wells, M. Hauschild, C. J. Oram, D. J.P. Dumas, C. J. Virtue, P. Paschievici, Terry Richard Wyatt, D. Van den plas, G. W. Wilson, D. Karlen, M. Coupland, D. L. Rees, P. Debu, J. Becker, D. R. Rust, R. P. Middleton, G. J. VanDalen, P. Lennert, M. H. Letho, R. Van Kooten, J. M. Lorah, W. Mohr, S. J. Pawley, Claus Kleinwort, L. Köpke, X. C. Lou, P. G. Murphy, Giora Mikenberg, P. E.L. Clarke, T. Behnke, B. Holl, I. Zacharov, Horst Breuker, R. Yaari, S. Bethke, Marco Cuffiani, Gunter Quast, A. Astbury, O. Ganel, A. J. Martin, and K. Riles
Subjects: Physics, Particle physics, Physics and Astronomy (miscellaneous), Electron–positron annihilation, High Energy Physics::Phenomenology, Scalar (mathematics), Elementary particle, Jet (particle physics), Gluon, Nuclear physics, High Energy Physics::Experiment, Field theory (psychology), Quantum field theory, Engineering (miscellaneous), Spin-½
Abstract: Three-jet variables constructed from multi-hadronic events produced byZ0 decays are compared to theoretical calculations assuming a vector gluon or a hypothetical scalar gluon. The data yield conclusive direct evidence for the former case. The distributions of the reduced energy of the second-most energetic jet and of the cosine of the Ellis-Karliner angle are chosen to demonstrate this effect.
Published: 1991
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10. Measurement of branching ratios and τ polarization from τ→eνν−,τ→μνν−,andτ→π(K)ν decays at LEP

Author: Gideon Bella, H. J. Burckhart, Jacqueline Batley, H. M. Fischer, A. Michelini, H. E. Stier, P. E.L. Clarke, J. Hart, Sachio Komamiya, P. G. Estabrooks, T. Behnke, Robin Middleton, C. Milstene, Erez Etzion, B. B. Brabson, S. A. Robins, Y. Yang, D. G. Fong, Andris Skuja, P. Schenk, A. D. Schaile, Tetsuro Mashimo, J. Gascon, W. Gorn, H. von der Schmitt, G. A. Bahan, T. P. Kokott, Rene Brun, Richard Keeler, Marcello Mannelli, Gareth J. Barker, M. Jobes, U. Binder, Shlomit Tarem, P. Scharff-Hansen, W. J. Larson, J. W. Gary, T. Kobayashi, F. Odorici, A. M. Smith, H. Takeda, G. N. Patrick, G. Vasseur, P. F. Harrison, J. R. Carter, B. Lorazo, P. M. Watkins, F. G. Oakham, M. F. Turner, A. M. Lee, J. D. Hobbs, Robert M Brown, F. L. Fabbri, S. Rossberg, K. Stephens, G. G. Hanson, Kiyotomo Kawagoe, N. C. Wood, R. Yaari, Paul Kyberd, S. Bethke, F. K. Loebinger, P. Singh, J. R. McNutt, Claude Leroy, J. P. Pansart, A. P. Wagner, N. Wermes, P. Igo-Kemenes, Marco Cuffiani, J. D. Gillies, B. Poli, V. H. Winterer, G. Giacomelli, I. Wingerter, M. W. Redmond, Ehud Duchovni, M. A. Whalley, R. W. L. Jones, H. Mes, I. P. Duerdoth, J. M. Roney, G. Maringer, F. S. Merritt, J. Goldberg, Tohru Takeshita, P. Pfister, E. K. U. Gross, G. A. Snow, E.J. Prebys, Silvia Arcelli, A. Rollnik, C. P. Ward, H. Ihssen, P. Le Du, A. Gaidot, D. R. Rust, S. W. O'Neale, Peter R Hobson, H. Jeremie, B. Nellen, R. E. Hughes-Jones, M. Kuwano, H. Kreutzmann, M. S. Dixit, B. Panzer-Steindel, S. W. Gensler, G. Mikenberg, A. Buijs, Georges Azuelos, J. C. Armitage, Frans Meijers, S. R. Hou, L. Janissen, T. Mouthuy, D. E. Klem, U. Maur, P. Leblanc, D. J. Miller, Ken W Bell, John Baines, M. Sasaki, P. Lennert, V. Gibson, P. Routenburg, Max Weber, J. G. Layter, C. Moisan, R. J. Barlow, H. Przysiezniak, J. Mildenberger, J. P. Walker, D. E. Plane, M. J. Goodrick, I. Cohen, J. C. Hill, P. Teixeira-Dias, R. F. McGowan, N. K. Watson, A. Dieckmann, Harold Nguyen, B. C. Shen, Stephen Hillier, F. Lamarche, Gunter Quast, G. M. Dallavalle, R. J. Hemingway, N. I. Geddes, Shlomo Dado, D. R. Ward, Phillip Allport, S. Wotton, S. Bougerolle, W. J. Collins, H. O. Ogren, Christoph Geich-Gimbel, G. J. VanDalen, B. P. O'Neill, D. J.P. Dumas, R. Van Kooten, M. H. Lehto, S. Sanghera, O. Runolfsson, M. Weymann, M. W. Moss, M. Sproston, P. S. Wells, M. M. Deninno, J. Kroll, G. Eckerlin, R. Sobie, P. Jovanovic, W. G. Scott, C. J. Virtue, A. M. Rossi, T. Tsukamoto, S. L. Lloyd, C. J. Oram, F. X. Gentit, Austin Ball, P. W. Jeffreys, R. Kowalewski, M. Jimack, G. D. Lafferty, X. C. Lou, W. R. Gibson, Terry Richard Wyatt, A. T. Watson, J. Hagemann, P. M. Hattersley, M. Coupland, J. E. Conboy, D. Menszner, J. P. Martin, M. Ogg, C. Ho, S. J. Pawley, C. Wahl, J. M. Lorah, Gideon Alexander, K. J. Anderson, Alessandro Montanari, T. J. Smith, S. De Jong, A. Beck, E. Heflin, Paolo Capiluppi, T. W. Pritchard, Claus Kleinwort, Claudio Grandi, L. Köpke, A. Pouladdej, R. G. Kellogg, Lorne Levinson, O. Schaile, D. C. Imrie, B. Holl, W. Mohr, M. Hansroul, C. P. Howarth, M. J. Losty, L. Lessard, C. Y. Chang, B. W. Kennedy, Gilles Beaudoin, Stefano Marcellini, P. Debu, J. E. Pilcher, G. P. Siroli, J. Banks, P. Taras, Mitsuaki Nozaki, P. A. Elcombe, I. Zacharov, S. Weisz, R. D. Heuer, D. Van den plas, Horst Breuker, C. Fukunaga, D. Hochman, N. J. Thackray, D. L. Rees, J. Becker, M. Hauschild, R. J. Homer, P. Paschievici, A. Astbury, J. L. Pinfold, O. Ganel, A. J. Martin, K. Riles, P R Poffenberger, C. K. Hargrove, S. Levegrün, S. Schreiber, R. Mir, H. Oh, T. J. McMahon, J. Allison, G. Duckeck, D. Strom, G. T. Zorn, H. M. Bosch, R. K. Carnegie, Wolfram Dietrich Zeuner, J. A. Wilson, D. Axen, A. Jawahery, G. Tysarczyk-Niemeyer, M. Fincke-Keeler, P. G. Murphy, M. J. Oreglia, Peter Sherwood, R. W. Springer, J. Ludwig, K. Runge, P. Bock, W. Schappert, D. A. Hinshaw, A. Simon, Otmar Biebel, D. G. Charlton, M. Couch, R. Humbert, J. T.M. Chrin, T. Kawamoto, S. Orito, John H. Schwarz, Michael Dittmar, G. Yekutieli, A. A. Carter, P. Mättig, I. J. Bloodworth, M. Settles, J. von Krogh, G. W. Wilson, P. Ashton, Dave Robinson, D. Karlen, C. M. Hawkes, M. Cooper, Daniel Lellouch, R. Shypit, and Takehiko Mori
Subjects: Nuclear physics, Physics, Coupling constant, Nuclear and High Energy Physics, Pion, Muon, Electron–positron annihilation, Weinberg angle, Electron, Pseudovector, Lepton
Abstract: From a sample of 3308 e + e − → τ + τ − events with an estimated background of 1.9%, we find 964 τ → e ν ν , 903 τ → μν ν , and 309 τ → π( K )ν candidates. Efficiency and background estimates determined from both Monte Carlo and control sample studies yield the following branching ratios: B(τ → e ν ν ) = 17.4 ± 0.5 ( stat ) ± 0.4 ( sys )% , B(τ → μν ν ) = 16.8 ± 0.5 ± 0.4%, and B(τ → π( K )ν) = 12.1 ± 0.7 ± 0.5% . These values are in good agreement with previous measurements. The measured lepton branching ratios, when combined with the world-average measured value for the τ lifetime, yield a ratio of the τ Fermi coupling constant to that of the lighter leptons given by G τ / G e, μ = 0.92 ± 0.04, where it is assumed G e = G μ ≡ G e , μ . The average τ polarization at the Z° resonance is measured to be −0.01±0.09 from an analysis of the momentum spectra of the electron, muon, and pion candidates, implying that the ratio of vector to axial vector couplings of the τ to the Z° is ν τ / α τ = 0.01 ± 0.04. The measurements of the average polarizations in the forward and backward hemispheres lead to the efficiency-corrected, forward-backward polarization asymmetry A FB pol = −0.22 ± 0.10, implying for the electron couplings to the Z° the ratio ν e / α e = 0.15±0.07. Since these values for the tau and electron couplings are consistent with one another, we assume lepton universality to derive ν / α = 0.05 ± 0.04 and a value for the weak mixing angle of sin 2 θ W = 0.237 ± 0.009 , with no ambiguity introduced by the relative signs of ν and α.
Published: 1991
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11. A search for scalar leptoquarks in Z0 decays

Author: H. E. Stier, P. G. Estabrooks, Erez Etzion, Gareth J. Barker, N. I. Geddes, P. Schenk, A. D. Schaile, Shlomit Tarem, P. M. Watkins, H. Mes, Kiyotomo Kawagoe, S. Rossberg, I. P. Duerdoth, V. H. Winterer, Tohru Takeshita, I. Wingerter, O. Schaile, A. P. Wagner, R. P. Middleton, B. Poli, S. R. Hou, J. M. Roney, Georges Azuelos, G. Beaudoin, L. Janissen, D. J. Miller, K. W. Bell, Max Weber, Misao Sasaki, H. O. Ogren, J. Goldberg, B. C. Shen, Shlomo Dado, H. Takeda, M. Hansroul, Christoph Geich-Gimbel, B. Nellen, N. Wermes, C. Milstene, P. Leblanc, F. Odorici, W. G. Scott, P. S. Wells, F. G. Oakham, C. J. Virtue, O. Runolfsson, X. C. Lou, P. G. Murphy, M. M. Deninno, Terry Richard Wyatt, B. Holl, J. Kroll, R. J. Homer, R. Kowalewski, L. Lessard, Andris Skuja, S. W. O'Neale, Ehud Duchovni, M. Coupland, T. J. Smith, F. X. Gentit, J. E. Conboy, J. D. Gillies, M. Ogg, M. J. Losty, Peter R Hobson, Giora Mikenberg, Silvia Arcelli, Claudio Grandi, P. Igo-Kemenes, D. C. Imrie, Richard Keeler, P. Mättig, I. Zacharov, C. Y. Chang, M. J. Goodrick, A. Pouladdej, I. Cohen, Tetsuro Mashimo, P. Singh, T. Mouthuy, C. Moisan, J. P. Walker, Horst Breuker, R. J. Barlow, G. Maringer, H. Ihssen, H. Jeremie, K. Stephens, C. Fukunaga, C. M. Hawkes, M. Cooper, Daniel Lellouch, R. Shypit, Takehiko Mori, G. K. VanDalen, P. W. Jeffreys, R. Van Kooten, F. S. Merritt, J. R. McNutt, G. P. Siroli, J. D. Hobbs, Claude Leroy, C. Wahl, P. Taras, S. W. Gensler, J. P. Pansart, R. W. L. Jones, N. C. Wood, W. Gorn, R. E. Hughes-Jones, U. Maur, Mitsuaki Nozaki, A. M. Lee, G. G. Hanson, F. Lamarche, D. E. Plane, R. J. Hemingway, Stephen Hillier, P. Le Du, H. Kreutzmann, B. Panzer-Steindel, V. Gibson, M. H. Lehto, M. A. Whalley, G. A. Bahan, J. Mildenberger, Harold Nguyen, Gunter Quast, S. Wotton, T. Kobayashi, G. M. Dallavalle, John Baines, Margret Fincke-Keeler, I. J. Bloodworth, C. P. Howarth, P. Jovanovic, E. K. U. Gross, A. Gaidot, M. Kuwano, Gideon Bella, H. J. Burckhart, N. K. Watson, M. Sproston, G. A. Snow, C. P. Ward, B. B. Brabson, M. Weymann, A. Buijs, J. E. Pilcher, Austin Ball, G. Giacomelli, J. Hart, E.J. Prebys, A. M. Rossi, D. E. Klem, D. R. Ward, M. Settles, D. Menszner, R. F. McGowan, D. G. Fong, Sachio Komamiya, Jacqueline Batley, B. P. O'Neill, Alan Watson, D. J.P. Dumas, P. Pfister, J. L. Pinfold, A. Astbury, J. Gascon, T. Tsukamoto, H. von der Schmitt, Alessandro Montanari, M. W. Moss, O. Ganel, S. Levegrün, H. M. Fischer, A. J. Martin, M. F. Turner, Y. Yang, P. Routenburg, P. M. Hattersley, T. P. Kokott, Rene Brun, J. Hagemann, J. C. Armitage, G. W. Wilson, D. Karlen, K. Riles, G. Eckerlin, M. S. Dixit, Frans Meijers, C. J. Oram, W. R. Gibson, P. F. Harrison, S. Bougerolle, W. J. Collins, S. J. Pawley, C. Ho, Marcello Mannelli, A. Michelini, Paul Kyberd, F. K. Loebinger, C. K. Hargrove, Stephen Lloyd, M. Jobes, U. Binder, D. Hochman, N. J. Thackray, P. Scharff-Hansen, G. D. Lafferty, A. Dieckmann, Claus Kleinwort, P. A. Elcombe, L. Köpke, W. J. Larson, P. Teixeira-Diaz, H. Przysiezniak, D. R. Rust, M. W. Redmond, J. W. Gary, T. W. Pritchard, J. G. Layter, A. Beck, A. Rollnik, A. M. Smith, P. E.L. Clarke, T. Behnke, E. Heflin, G. Vasseur, B. Lorazo, P. Lennert, Phillip Allport, R. M. Brown, S. Sanghera, M. Hauschild, S. A. Robins, R. Sobie, M. Jimack, John Allison, J. P. Martin, Gideon Alexander, Lorne Levinson, Paolo Capiluppi, K. J. Anderson, John Hill, P. Paschievici, B. W. Kennedy, S. De Jong, R. G. Kellogg, J. Banks, D. L. Rees, J. Becker, R. Yaari, S. Weisz, R. D. Heuer, Fabrizio Fabbri, D. Van den plas, S. Bethke, Marco Cuffiani, Stefano Marcellini, P. Debu, P R Poffenberger, J. M. Lorah, W. Mohr, D. Axen, A. Jawahery, G. Tysarczyk-Niemeyer, Peter Sherwood, R. W. Springer, Michael Dittmar, G. Yekutieli, J. Ludwig, K. Runge, P. Bock, A. Simon, Otmar Biebel, D. G. Charlton, M. Couch, R. Humbert, G. Duckeck, A. A. Carter, J. T.M. Chrin, D. Strom, G. T. Zorn, H. M. Bosch, T. Kawamoto, Wolfram Dietrich Zeuner, S. Orito, John H. Schwarz, D. A. Hinshaw, R. Mir, H. Oh, M. J. Oreglia, J. R. Carter, G. N. Patrick, J. von Krogh, P. Ashton, Dave Robinson, S. Schreiber, T. J. McMahon, R. K. Carnegie, J. A. Wilson, and W. Schappert
Subjects: Quark, Physics, Nuclear and High Energy Physics, Particle physics, Branching fraction, Electron–positron annihilation, High Energy Physics::Phenomenology, Scalar (physics), Nuclear physics, High Energy Physics::Experiment, Leptoquark, Neutrino, Particle Physics - Experiment, Storage ring, Lepton
Abstract: A search for scalar leptoquarks has been performed with data from the OPAL detector at the e+e− storage ring LEP. In a data sample corresponding to an integrated luminosity of 6.3 pb−1 no evidence for leptoquark production was observed where the leptoquark decays into a quark and either a charged lepton (e, μ, τ) or a neutrino. An upper limit of 1.7 pb on the production cross section for leptoquarks is obtainedassuming a branching ratio of 50% for the decay of the leptoquark into the channels with a charged lepton. Lower limits on the leptoquark mass between 41.4 and 46.4 GeV/c2 at 95% CL are obtained, depending on the effecte SU(2) × U(1) invariant couplings assigned to the leptoquark.
Published: 1991
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12. Measurement of theZ 0 line shape parameters and the electroweak couplings of charged leptons

Author: M. Jimack, John Allison, D. Axen, A. Jawahery, G. Tysarczyk-Niemeyer, Peter Sherwood, R. W. Springer, B. Holl, N. C. Wood, C. M. Hawkes, M. Cooper, Daniel Lellouch, J. Ludwig, G. J. Van Dalen, K. Runge, P. Bock, A. Simon, Otmar Biebel, D. G. Charlton, Takehiko Mori, I. Zacharov, Horst Breuker, G. A. Snow, C. P. Ward, M. Couch, A. D. Schaile, R. G. Kellogg, C. Y. Chang, P. Taras, Mitsuaki Nozaki, D. A. Hinshaw, R. Humbert, J. T.M. Chrin, Stefano Marcellini, V. H. Winterer, O. Runolfsson, T. Kawamoto, T. J. Smith, S. Orito, S. Bougerolle, P. Mättig, L. Lessard, John H. Schwarz, T. R. Wyatt, Claudio Grandi, S. R. Hou, Gunter Quast, P. Singh, T. Mouthuy, J. M. Lorah, W. Mohr, R. Mir, H. Oh, I. J. Bloodworth, J. G. Layter, S. Sanghera, F. S. Merritt, M. Settles, R. W. L. Jones, G. Beaudoin, M. J. Oreglia, W. J. Collins, G. D. Lafferty, P. Le Du, J. Hart, Y. Yangh, H. Kreutzmann, B. Panzer-Steindel, H. Przysiezniak, A. M. Rossi, K. J. Anderson, A. Astbury, G. Duckeck, D. Karlen, W. R. Gibson, Tohru Takeshita, D. Strom, P. E.L. Clarke, T. Behnke, Paul Kyberd, F. K. Loebinger, G. Giacomelli, T. Tsukamoto, Shlomo Dado, S. Levegrün, G. T. Zorn, T. W. Pritchard, Georges Azuelos, H. M. Bosch, Wolfram Dietrich Zeuner, C. Moisan, J. R. Carter, O. Ganel, P. W. Jeffreys, P. Igo-Kemenes, G. Maringer, G. N. Patrick, K. W. Bell, J. P. Walker, C. Ho, X. C. Lou, Gideon Bella, D. Hochman, N. J. Thackray, H. J. Burckhart, Jacqueline Batley, M. W. Redmond, A. M. Lee, P. G. Murphy, A. J. Martin, Max Weber, H. Jeremie, K. Stephens, A. Rollnik, D. E. Klem, Kiyotomo Kawagoe, R. F. McGowan, J. C. Hill, Giora Mikenberg, J. R. McNutt, B. C. Shen, C. Fukunaga, A. Beck, M. A. Whalley, K. Riles, R. E. Hughes-Jones, U. Maur, R. Van Kooten, E. K. U. Gross, P. Teixeira-Dias, E. Heflin, A. Gaidot, Erez Etzion, M. Kuwano, W. G. Scott, M. Sproston, G. Eckerlin, Gareth J. Barker, R. M. Brown, Lorne Levinson, A. P. Wagner, P. Routenburg, A. Dieckmann, V. Gibson, John Baines, R. Kowalewski, M. J. Losty, M. F. Turner, P. Poffenberger, N. I. Geddes, Shlomit Tarem, P. A. Elcombe, Silvia Arcelli, J. L. Pinfold, A. Buijs, M. H. Lehto, H. O. Ogren, Christoph Geich-Gimbel, J. P. Martin, M. Sasaki, S. De Jong, B. W. Kennedy, D. L. Rees, J. Becker, B. Poli, S. Rossberg, C. J. Oram, D. R. Ward, P. F. Harrison, Stephen Lloyd, J. M. Roney, R. Yaari, S. Bethke, C. K. Hargrove, M. M. Deninno, H. M. Fischer, P. Debu, J. Mildenberger, Harold Nguyen, R. P. Middleton, Marco Cuffiani, J. Kroll, A. Michelini, J. D. Hobbs, F. X. Gentit, N. Wermes, G. G. Hanson, J. E. Conboy, M. Ogg, Ehud Duchovni, R. Shypit, S. A. Robins, D. E. Plane, Stephen Hillier, Michael Dittmar, E.J. Prebys, G. M. Dallavalle, A. Pouladdej, H. Ihssen, B. P. O'Neill, G. Yekutieli, M. S. Dixit, Frans Meijers, Alan Watson, D. J.P. Dumas, J. Hagemann, S. W. Gensler, J. Goldberg, B. Nellen, P. Leblanc, O. Schaile, D. C. Imrie, A. A. Carter, M. J. Goodrick, T. Kobayashi, M. Hansroul, S. W. O'Neale, Peter R Hobson, I. Cohen, S. J. Pawley, Phillip Allport, Claus Kleinwort, L. Köpke, R. J. Homer, S. Wotton, Margret Fincke-Keeler, G. P. Siroli, G. W. Wilson, M. Hauschild, P. S. Wells, D. R. Rust, P. Paschievici, C. J. Virtue, P. Pfister, Gideon Alexander, J. C. Armitage, M. Coupland, Paolo Capiluppi, P. Schenk, P. Lennert, S. Schreiber, M. Weymann, T. J. McMahon, Richard Keeler, C. Wahl, C. P. Howarth, J. E. Pilcher, R. K. Carnegie, H. E. Stier, R. Sobie, N. K. Watson, Claude Leroy, M. W. Moss, J. A. Wilson, J. P. Pansart, P. M. Hattersley, Sachio Komamiya, P. G. Estabrooks, W. Schappert, T. P. Kokott, Rene Brun, J. Banks, P. M. Watkins, S. Weisz, R. D. Heuer, Fabrizio Fabbri, D. Van den plas, I. Wingerter, J. von Krogh, P. Ashton, Dave Robinson, H. Mes, I. P. Duerdoth, L. Janissen, C. Milstene, F. Odorici, Andris Skuja, Tetsuro Mashimo, W. Gorn, G. A. Bahan, M. Jobes, U. Binder, P. Scharff-Hansen, W. J. Larson, J. W. Gary, A. M. Smith, G. Vasseur, B. Lorazo, B. B. Brabson, D. G. Fong, J. Gascon, H. von der Schmitt, Marcello Mannelli, H. Takeda, F. G. Oakham, J. D. Gillies, R. J. Barlow, D. J. Miller, F. Lamarche, R. J. Hemingway, P. Jovanovic, Austin Ball, D. Menszner, and Alessandro Montanari
Subjects: Physics, Particle physics, Muon, Physics and Astronomy (miscellaneous), Electron–positron annihilation, Electroweak interaction, Weinberg angle, Standard Model, Nuclear physics, High Energy Physics::Experiment, Engineering (miscellaneous), Pseudovector, Boson, Lepton
Abstract: We report on an improved measurement of the mass of theZ0 boson, its total width and its partial decay widths into hadrons and leptons, as well as the effective axial vector and vector couplings to charged leptons. These measurements are based on a data set of approximately 160 000 hadronicZ0 decays and 18 000 decays into electrons, muons and taus, recorded by the OPAL experiment at centre of mass energies near the mass of theZ0. The total width and the partial widths to visible final states, derived from the measured cross sections, are used to extract the invisible width. The effective couplings of theZ0 to charged leptons are studied using measurements of the lepton pair cross sections and forward-backward asymmetries at the different centre of mass energy points of theZ0 scan. The implications of our results in the context of the Standard Model are discussed.
Published: 1991
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13. A study of - in Z0 decays

Author: Gideon Bella, H. J. Burckhart, Jacqueline Batley, M. Jobes, F. Odorici, R. Mir, U. Binder, H. Oh, H. O. Ogren, Michael Dittmar, C. M. Hawkes, M. Cooper, Daniel Lellouch, F. S. Merritt, G. Yekutieli, R. F. McGowan, Christoph Geich-Gimbel, Silvia Arcelli, M. M. Deninno, Tohru Takeshita, P. Scharff-Hansen, J. Kroll, F. X. Gentit, J. E. Conboy, Paul Kyberd, M. Ogg, R. Shypit, Takehiko Mori, T. Mouthuy, F. K. Loebinger, M. W. Moss, P. Igo-Kemenes, A. Pouladdej, G. Maringer, M. J. Oreglia, H. Jeremie, C. Moisan, J. P. Walker, F. Lamarche, R. E. Hughes-Jones, N. C. Wood, U. Maur, W. J. Larson, J. D. Hobbs, Georges Azuelos, P. M. Hattersley, H. Mes, M. W. Redmond, R. J. Hemingway, I. P. Duerdoth, R. Van Kooten, G. G. Hanson, P. Singh, J. W. Gary, A. Rollnik, K. W. Bell, P. Teixeira-Dias, G. A. Snow, C. P. Ward, A. A. Carter, G. Giacomelli, Max Weber, P. E.L. Clarke, M. Sprotson, J. R. Carter, A. M. Rossi, K. J. Anderson, Misao Sasaki, T. Behnke, R. W. L. Jones, M. H. Lehto, L. Janissen, B. C. Shen, P. Jovanovic, A. M. Smith, G. N. Patrick, E.J. Prebys, Austin Ball, Kiyotomo Kawagoe, T. Tsukamoto, D. E. Klem, S. Levegrün, D. Menszner, R. Sobie, G. Vasseur, B. Lorazo, S. Wotton, P. Le Du, W. G. Scott, M. S. Dixit, Frans Meijers, G. Beaudoin, M. Jimack, John Allison, H. Kreutzmann, B. Panzer-Steindel, D. Hochman, N. J. Thackray, I. J. Bloodworth, A. Simon, Otmar Biebel, E. K. U. Gross, A. P. Wagner, Alessandro Montanari, Gunter Quast, M. Weymann, K. Stephens, J. M. Roney, N. I. Geddes, R. Yaari, D. G. Charlton, J. R. McNutt, A. Gaidot, M. Couch, M. F. Turner, M. Kuwano, R. Kowalewski, M. Geerts, J. P. Martin, S. Bethke, B. B. Brabson, Shlomo Dado, C. Fukunaga, R. Humbert, Marco Cuffiani, M. Settles, H. E. Stier, John Hill, B. Poli, D. G. Fong, J. Gascon, X. C. Lou, S. De Jong, H. von der Schmitt, S. Schreiber, J. T.M. Chrin, M. J. Losty, G. Duckeck, T. J. McMahon, J. D. Gillies, P. G. Estabrooks, R. G. Kellogg, P. Routenburg, P. G. Murphy, D. Strom, V. Gibson, B. P. O'Neill, J. Hart, H. M. Fischer, T. Kawamoto, A. Michelini, Giora Mikenberg, G. T. Zorn, John Baines, R. J. Barlow, A. Astbury, P. M. Watkins, P. Debu, G. W. Wilson, Marcello Mannelli, R. K. Carnegie, Stefano Marcellini, A. Dieckmann, S. Orito, John H. Schwarz, J. Hagemann, D. Karlen, J. A. Wilson, D. C. Imrie, Y. Yang, C. Y. Chang, M. Fincke-Keeler, H. M. Bosch, Wolfram Dietrich Zeuner, Andris Skuja, S. A. Robins, I. Wingerter, J. L. Pinfold, O. Ganel, Tetsuro Mashimo, J. G. Layter, P. Taras, A. J. Martin, D. R. Ward, C. J. Oram, P. F. Harrison, Mitsuaki Nozaki, K. Riles, G. P. Siroli, W. Schappert, W. Gorn, J. Mildenberger, S. Bougerolle, G. A. Bahan, W. J. Collins, Harold Nguyen, S. Sanghera, Stephen Lloyd, J. M. Lorah, Erez Etzion, D. E. Plane, G. D. Lafferty, Gareth J. Barker, C. K. Hargrove, B. Holl, D. A. Hinshaw, Shlomit Tarem, W. Mohr, P. Pfister, Stephen Hillier, G. M. Dallavalle, G. Eckerlin, T. J. Smith, Phillip Allport, P. A. Elcombe, S. Rossberg, T. W. Pritchard, H. Takeda, I. Zacharov, J. C. Armitage, R. P. Middleton, F. G. Oakham, Alan Watson, D. L. Rees, D. J.P. Dumas, J. Becker, P. Mättig, S. J. Pawley, Horst Breuker, G. J. VanDalen, B. Nellen, P. Leblanc, M. Hansroul, W. R. Gibson, C. Ho, Claus Kleinwort, L. Köpke, R. J. Homer, D. Axen, P. Schenk, A. D. Schaile, A. Beck, A. Jawahery, Gideon Alexander, Paolo Capiluppi, G. Tysarczyk-Niemeyer, E. Heflin, M. J. Goodrick, I. Cohen, R. M. Brown, Lorne Levinson, N. Wermes, B. W. Kennedy, Ehud Duchovni, D. R. Rust, H. Ihssen, S. W. Gensler, T. Kobayashi, P. Lennert, J. Banks, S. Weisz, R. D. Heuer, Fabrizio Fabbri, D. Van den plas, J. von Krogh, Peter Sherwood, R. W. Springer, J. Ludwig, K. Runge, P. Bock, P. Ashton, Dave Robinson, Sachio Komamiya, V. H. Winterer, S. R. Hou, T. P. Kokott, Rene Brun, N. K. Watson, S. W. O'Neale, Peter R Hobson, M. Hauschild, P. Paschievici, P R Poffenberger, D. J. Miller, H. Przysiezniak, O. Runolfsson, C. Wahl, L. Lessard, Claudio Grandi, P. W. Jeffreys, P. S. Wells, A. M. Lee, C. J. Virtue, C. P. Howarth, Terry Richard Wyatt, J. E. Pilcher, M. Coupland, O. Schaile, M. A. Whalley, A. Buijs, Richard Keeler, Claude Leroy, J. P. Pansart, and C. Milstene
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, Meson, Branching fraction, High Energy Physics::Lattice, Electron–positron annihilation, Nuclear Theory, High Energy Physics::Phenomenology, Hadron, Elementary particle, Nuclear physics, Pair production, Pion, High Energy Physics::Experiment, Nuclear Experiment
Abstract: In this paper an investigation of the production of D ∗ ± mesons produced in e + e − collisions at energies around the Z 0 pole is presented. Based on 115 D ∗ ± mesons with x D∗  2E D ∗ /E cm > 0.2 the properties of D ∗ mesons produced in the reaction Z 0 → c c are studied. Fixing the yield and the fragmentation function of bottom quarks to the values obtained at LEP using lepton tags, and average energy fraction of the D ∗ ± mesons from primary charmed quarks of 〈x c → D ∗ 〉 = 0.52 ± 0.03 +- 0.01 is found and Γ z 0 →c c = (323 ± 61 ± 35) MeV is determined. The first error is the combined statistical and systematic error from this experiment, and the second the total error from other sources.
Published: 1991
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14. A measurement of energy correlations and a determination of αs(M2Z) e+e- annihilations at √s=91 GeV

Author: F. X. Gentit, F. Odorici, H. Takeda, G. A. Snow, C. P. Ward, C. Y. Chang, M. S. Dixit, G. Mikenberg, G.W. Wilson, L. Janissen, R. Stroehmer, W. J. Collins, M. T. French, Mitsuaki Nozaki, Christoph Geich-Gimbel, P. Singh, Erez Etzion, B. J. Saunders, Gareth J. Barker, D. C. Imrie, T. W. Pritchard, P. Igo-Kemenes, S. Rossberg, Michael Dittmar, M. M. Deninno, M. J. Losty, R. W. L. Jones, R. P. Middleton, J. Kroll, G. Yekutieli, G. Maringer, T. Mashino, J. Goldberg, H. Jeremie, B. Nellen, Shlomo Dado, S. L. Lloyd, G. P. Siroli, P. Leblanc, P. Le Du, H. Kreutzmann, R. G. Kellogg, J. E. Conboy, R. E. Hughes-Jones, U. Maur, A. A. Carter, A. Jawahery, J.P. Pansart, N. K. Watson, P. G. Murphy, J. Grunhaus, M. Ogg, J. D. Gillies, M. J. Goodrick, Stefano Marcellini, T. J. Smith, H. Oh, I. Cohen, G. Tysarczyk-Niemeyer, D. G. Fong, V. Gibson, Kiyotomo Kawagoe, K. J. Anderson, A. Pouladdej, Peter Sherwood, Gideon Bella, J. Gascon, S. Wotton, N. C. Wood, H. J. Burckhart, P. Mättig, B. C. Shen, B. Wuensch, A. M. Rossi, J. M. Lorah, M. Weymann, G. D. Lafferty, Takashi Yoshida, R. W. Springer, A. P. Wagner, J. M. Roney, H. von der Schmitt, C. Fukunaga, D. E. Klem, G.T.J. Arnison, D. J. Miller, A. Buijs, J. Ludwig, K. Runge, P. Bock, Jacqueline Batley, A. A. Macbeth, M. Hauschild, Makoto Minowa, W. Mohr, I. J. Bloodworth, T. Tsukamoto, H. E. Stier, G. Knop, J. Mildenberger, Harold Nguyen, J. Hagemann, M. F. Turner, P. G. Estabrooks, S. Schreiber, T. J. McMahon, R. K. Carnegie, N. I. Geddes, M. Jimack, D. Karlen, O. Ganel, A. J. Martin, F. Lamarche, P. Lennert, Marcello Mannelli, T. P. Kokott, Rene Brun, C. N. P. Gee, J. A. Wilson, B. Poli, F. S. Merritt, C. M. Hawkes, J. Allison, Daniel Lellouch, P. M. Watkins, M. Jobes, U. Binder, W. J. Murray, R. J. Hemingway, R. Kowalewski, H. M. Fischer, D. Granite, Takehiko Mori, J. Ma, W. Schappert, D. Strom, P. Scharff-Hansen, Paul Kyberd, F. K. Loebinger, G. T. Zorn, P. Jovanovic, A. Michelini, I. Wingerter, W. J. Larson, J. D. Hobbs, M. Sasaki, E. K. U. Gross, A. Gaidot, P. E.L. Clarke, M. Kuwano, T. Behnke, Austin Ball, D. Menszner, M. W. Redmond, Wolfram Dietrich Zeuner, K. Riles, J. L. Pinfold, J. W. Gary, S. A. Robins, M. Sproston, A. Rollnik, M. W. Moss, M. Z. Akrawy, I. Harrus, A. M. Smith, P. M. Hattersley, M. J. Oreglia, M. H. Lehto, P. Routenburg, J. R. Carter, Alessandro Montanari, A. Dieckmann, H. Mes, G. Vasseur, J. von Krogh, J. Raab, B. Lorazo, F. G. Oakham, Andris Skuja, P. A. Elcombe, P. Ashton, B. Holl, S. W. O'Neale, Peter R Hobson, H. El Mamouni, Tohru Takeshita, R. Yaari, S. Bethke, Marco Cuffiani, D. L. Rees, A. Shapira, J. Becker, A. D. Schaile, I. P. Duerdoth, Georges Azuelos, S. J. Pawley, Claus Kleinwort, L. Köpke, Horst Breuker, G. N. Patrick, A. Simon, Otmar Biebel, K. W. Bell, Max Weber, O. Schaile, W. Gorn, P. S. Wells, J. C. Hill, G. Giacomelli, C. J. Virtue, Terry Richard Wyatt, D. G. Charlton, A. T. Watson, M. Coupland, E.J. Prebys, J. Banks, Gunter Quast, M. Couch, S. Weisz, R. D. Heuer, Fabrizio Fabbri, D. Van den plas, R. Humbert, Frans Meijers, J. T.M. Chrin, T. Kawamoto, V. H. Winterer, S. Orito, John H. Schwarz, S. R. Hou, J. G. Layter, C. Wahl, C. P. Howarth, J. E. Pilcher, N. Wermes, C. K. Hargrove, Ehud Duchovni, R. A. Sansum, H. Ihssen, S. Sanghera, S. W. Gensler, Phillip Allport, J. P. Martin, C. M. Roach, B.P. O'Neil, D. E. Plane, Stephen Hillier, G. M. Dallavalle, P. Farthouat, Gideon Alexander, Paolo Capiluppi, D. Hochman, N. J. Thackray, J. Hart, G. J. VanDalen, R. J. Barlow, P. Pfister, Y. Yang, D. J.P. Dumas, P. W. Jeffreys, J. C. Armitage, T. Kobayashi, A. M. Lee, K. Stephens, J. R. McNutt, P. Debu, M. Hansroul, R. J. Homer, John Baines, M. Regimbald, O. Runolfsson, A. J.P. O'Dowd, J. P. Walker, D. R. Ward, W. R. Gibson, C. Ho, A. Beck, E. Heflin, R. M. Brown, Lorne Levinson, L. Lessard, B. W. Kennedy, C. Milstene, and H. Hagedorn
Subjects: Coupling constant, Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, Electron–positron annihilation, Hadron, Nuclear physics, Renormalization, Particle decay, High Energy Physics::Experiment, Astrophysics::Earth and Planetary Astrophysics, Boson
Abstract: From an analysis of multi-hadron events from Z 0 decays, values of the strong coupling constant α s ( M 2 Z 0 )=0.131±0.006 (exp)±0.002(theor.) and α s ( M z 0 2 ) = −0.009 +0.007 (exp.) −0.002 +0.006 (theor.) are derived from the energy-energy correlation distribution and its asymmetry, respectively, assuming the QCD renormalization scale μ = M Z 0 . The theoretical error accounts for differences between O ( α 2 s ) calculations. A two parameter fit Λ MS and the renormalization scale μ leads to Λ MS =216±85 MeV and μ 2 s =0.027±0.013 or to α s ( M 2 Z 0 )=0.117 +0.006 −0.008 (exp.) for the energy-energy correlation distribution. The energy-energy correlation asymmetry distribution is insensitive to a scale change: thus the α s value quoted above for this variable includes the theoretical uncertainty associated with the renormalization scale.
Published: 1990
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15. Measurements of the decay of the Z0 into lepton pairs

Author: J. Waterhouse, B. J. Saunders, Phillip Allport, B. C. Shen, H. M. Fischer, T. J. McMahon, J. C. Armitage, E. J. Spreadbury, D. Duchesneau, J. A. Wilson, P. Grosse-Wiesmann, A. J.P. O'Dowd, I. Cohen, P. Le Du, D. Granite, C. Milstene, R. W.L. Jones, D. G. Fong, E. Jin, H. von der Schmitt, D. J.P. Dumas, S. R. Hou, Gideon Bella, J. von Krogh, J. Raab, G. A. Snow, C. P. Ward, G. Knop, Despina Hatzifotiadou, H. J. Burckhart, H. Jeremie, H. Kreutzmann, Jacqueline Batley, C. Geich-Gimbel, P. Ashton, R. M. Brown, G. T.J. Arnison, Marcello Mannelli, H. Wang, Andris Skuja, F. S. Merritt, G. D. Lafferty, Michael Dittmar, Kiyotomo Kawagoe, Tetsuro Mashimo, J. L. Pinfold, Gunter Quast, C. J. Virtue, J. P. Martin, F. Roehner, P. Kyberd, Paolo Capiluppi, J. M. Roney, Tohru Takeshita, K. W. Bell, P. Bock, D. G. Charlton, M. Couch, A. M. Rossi, D. E. Plane, W. Gorn, P. A. Elcombe, G. Yekutieli, W. R. Gibson, T. P. Kokott, B. Holl, Stephen Hillier, J. Heintze, P. G. Estabrooks, M. Jobes, D. Hochman, I. P. Duerdoth, D. L. Rees, P. Routenburg, R. Kowalewski, S. Schreiber, J. T.M. Chrin, C. K. Hargrove, C. M. Roach, B. P. O'Neill, D. Karlen, N. Lupu, A. Dieckmann, C. Fukunaga, P. Scharff-Hansen, W. J. Larson, A. Buijs, G. J. VanDalen, H. Boerner, G. P. Siroli, A. Jawahery, Peter Sherwood, T. Kawamoto, M. Jimack, R. W. Springer, M. Coupland, N. K. Watson, P. G. Murphy, U. Maur, C. N.P. Gee, A. M. Smith, H. El Mamouni, D. Strom, Horst Breuker, G. T. Zorn, P. M. Watkins, P. Igo-Kemenes, Wolfram Dietrich Zeuner, F. Beck, R. Ströhmer, A. Wagner, Rolf-Dieter Heuer, T. Tsukamoto, G. N. Patrick, B. Poli, M. Sproston, A. Rollnik, S. Orito, S. Zylberajch, S. Sanghera, C. Wahl, M. F. Turner, H. Oh, O. Runolfsson, P. Lennert, J. M. Lorah, H. Yamashita, B. Lorazo, M. Z. Akrawy, Makoto Minowa, H. E. Stier, T. W. Pritchard, M. Weymann, M. W. Moss, W. Mohr, M. M.B. Lasota, P. S. Hinde, M. Regimbald, P. M. Hattersley, A. Possoz, H. Takeda, I. Wingerter, C. Beard, C. Ho, Marco Cuffiani, J. W. Gary, E. Heflin, S. Bethke, B. W. Kennedy, J. C. Hill, Misao Sasaki, M. J. Oreglia, N. I. Geddes, G. J. Barker, N. C. Wood, M. M. Deninno, R. J. Barlow, A. A. Carter, D. J. Miller, J. Schwarz, J. Kroll, M. Ogg, J. R. Carter, R. Yaari, J. Ma, W. J. Murray, L. Levinson, P. Jovanovic, S. Wotton, Austin Ball, F. K. Loebinger, F. X. Gentit, J. E. Conboy, A. C. McPherson, W. Schappert, M. S. Dixit, Alessandro Montanari, B. Nellen, J. Banks, G. Azuelos, H. Mes, A. Simon, S. W. Gensler, R. E. Hughes-Jones, A. Shapira, Aldo Michelini, E. Gross, Fabrizio Fabbri, D. Van den plas, G. Tysarczyk, O. Ganel, K. Riles, M. W. Redmond, S. Weisz, P. Farthouat, A. Pouladdej, G. Mikenberg, T. Kobayashi, R. K. Carnegie, O. Schaile, D. C. Imrie, J. Ludwig, C. P. Howarth, J. Grunhaus, Terry Richard Wyatt, F. G. Oakham, J. E. Pilcher, E. Duchovni, M. Hansroul, A. A. Macbeth, G. W. Wilson, P. W. Jeffreys, S. J. Pawley, G. Maringer, Claus Kleinwort, L. Köpke, Masatoshi Koshiba, J. Hart, M. Hauschild, D. E. Klem, Harold Nguyen, V. H. Winterer, P. Leblanc, R. J. Homer, L. Lessard, K. J. Anderson, Y. Yang, Achim Müller, O. Biebel, John Allison, C. Y. Chang, A. D. Schaile, Stephen Lloyd, R. G. Kellogg, B. Gandois, Mitsuaki Nozaki, M. Weber, Stefano Marcellini, K. Stephens, Masatoshi Imori, John Baines, G. Bavaria, F. Odorici, D. R. Ward, F. Lamarche, M. T. French, O. W. Davies, M. J. Losty, Richard J Hemingway, S. W. O'Neale, Peter R Hobson, A. T. Watson, Rene Brun, J. Hagemann, I. J. Bloodworth, James D Gillies, A. Perez, R. A. Sansum, G. M. Dallavalle, J. Goldberg, T. J. Smith, P. Mättig, C. M. Hawkes, Daniel Lellouch, Takehiko Mori, R. P. Middleton, D. Menszner, M. J. Goodrick, J. G. Layter, J. D. Hobbs, G. Alexander, G. Giacomelli, S. Dado, H. Hagedorn, Frans Meijers, K. Runge, B. Wuensch, and N. Wermes
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics, Standard Model (mathematical formulation), Basis (linear algebra), Electron–positron annihilation, Hadron, Particle Physics - Experiment, Lepton
Abstract: We report on a measurement of the processes e+e−→e+e−, e+e−→μ+μ−, and e+e−→τ+τ− near the Z0 pole. On the basis of 163 e+e−, 101 μ+μ− and 87 τ+τ− events we obtain Γee=89±4±4 MeV, Γμμ=85±9±6 MeV and Γττ=87±10±8 MeV, compatible with the standard model. Combining these with our previous results on hadronic Z0 decays, we find a hadronic width Γhad=1787±81±90 MeV and an invisible width Γinv=552±85±71 MeV.
Published: 1990
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16. The OPAL vertex drift chamber

Author: P. A. Elcombe, R. J. Hemingway, R. K. Carnegie, J.L. Pinfold, A. C. McPherson, A.A. Carter, C. M. Roach, R.W.L. Jones, J.M. Roney, P. G. Estabrooks, D. Karlen, J. C. Armitage, F. G. Oakham, P. Routenburg, D. E. Klem, T.R. Wyatt, J. R. Carter, John Hill, T.W. Pritchard, Stephen Lloyd, M.M.B. Lasota, J. Waterhouse, and C. K. Hargrove
Subjects: Physics, Nuclear and High Energy Physics, Physics::Instrumentation and Detectors, Cosmic ray muons, Bar (music), Detector, Readout electronics, Space resolution, Nuclear physics, Electric field, Vertex (curve), Calibration, High Energy Physics::Experiment, Instrumentation
Abstract: A high precision vertex drift chamber has been installed in the OPAL experiment at LEP. The design of the chamber and the associated readout electronics is described. The performance of the system has been studied using cosmic ray muons and the results of these studies are presented. A space resolution of 50 μm in the drift direction is obtained using the OPAL central detector gas mixture at 4 bar.
Published: 1990
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17. Digital X-ray imaging using gas microstrip detectors

Author: M. S. Dixit, J. Dubeau, Paul C. Johns, F. G. Oakham, L. Diaconescu, J. C. Armitage, M. Grabari, D. Bouius, and D. Karlen
Subjects: Detective quantum efficiency, Physics, Full width at half maximum, Biological specimen, Photon, Optics, Atmospheric pressure, business.industry, X-ray, business, Noise (electronics), Energy (signal processing)
Abstract: Gas microstrip detectors (GMDs) could be ideal for use in digital X-ray imaging because of their ability to measure accurately, with virtually no noise, the energy and the position of X-ray photons at radiological counting rates. Thus a GMD based imaging system will have high detective quantum efficiency and will also be capable of dual energy radiography using a single X-ray exposure. As proof of principle, a prototype atmospheric pressure GMD imaging system has been built and its performance characterized by imaging standard phantoms and biological specimens. Using 8 keV X-rays from a copper target a line spread function with a FWHM of 230 /spl mu/m (determined by the photoelectron range of 190 /spl mu/m) was obtained for a gas mixture of 90% Ar and 10% isobutane.
Published: 2002
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18. FIRST IMAGES FROM THE CRIPT MUON TOMOGRAPHY SYSTEM

Author: G. Jonkmans, J. Botte, R. Gazit, M. Thompson, R. Hydomako, P. L. Drouin, T. J. Stocki, Vinicius N.P. Anghel, A. Erlandson, J. C. Armitage, V. V. Golovko, Z. Liu, T. Cousins, E. Charles, Douglas Bryman, D. Waller, J. Bueno, G. Gallant, C. Jewett, A. Robichaud, K. Boudjemline, and S. Noel
Subjects: Physics, Muon tomography, Muon, Spectrometer, business.industry, Cosmic ray, computer.software_genre, Tracking (particle physics), Nuclear physics, Optics, Voxel, Scintillation counter, Tomography, business, computer
Abstract: The CRIPT Cosmic Ray Imaging and Passive Tomography system began data taking in September 2012. CRIPT is a “proof of principle” muon tomography system originally proposed to inspect cargo in shipping containers and to determine the presence of special nuclear materials. CRIPT uses 4 layers of 2 m x 2 m scintillation counter trackers, each layer measuring two coordinates. Two layers are used to track the incoming muon and two for the outgoing muon allowing the trajectories of the muon to be determined. The target volume is divided into voxels, and a Point of Closest Approach algorithm is used to determine the number of scattering events in each voxel, producing a 3D image. The system has been tested with various targets of depleted uranium, lead bricks, and tungsten rods. Data on the positional resolution has been taken and the intrinsic resolution is unfolded with the help of a simulation using GEANT4. The next steps include incorporation of data from the spectrometer section, which will assist in determining the muon's momentum and improve the determination of the density of the target.
Published: 2014
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19. Decay mode independent search for a light Higgs boson and new scalars

Author: Takehiko Mori, M. Jobes, R. P. Middleton, P. Scharff-Hansen, W. J. Larson, B. C. Shen, H. Ihssen, F. S. Merritt, L. Levinson, J. M. Lorah, R. Van Kooten, O. Schaile, M. H. Lehto, A. M. Smith, O. Ganel, K. Riles, D. Karlen, A. Dieckmann, J. Goldberg, T. J. Smith, I. J. Bloodworth, C. Moisan, James D Gillies, M. Settles, E. Duchovni, G. Eckerlin, G. P. Siroli, G. Beaudoin, U. Maur, B. Nellen, R. M. Brown, Phillip Allport, Andris Skuja, P. Mättig, J. A. McKenna, S. J. Pawley, Gunter Quast, N. C. Wood, S. Levegrün, Claus Kleinwort, G. W. Wilson, F. C. Grant, M. A. Whalley, L. Köpke, G. Tysarczyk-Niemeyer, D. G. Charlton, Sachio Komamiya, R. W.L. Jones, P. Singh, A. M. Lee, Kiyotomo Kawagoe, A. Beck, J. P. Martin, P. Bock, D. Strom, M. Couch, G. T. Zorn, L. Lessard, B. P. O'Neill, J. Ludwig, Tetsuro Mashimo, C. P. Howarth, A. Buijs, E. Ros, J. Becker, K. Stephens, P. Teixeira-Dias, D. E. Plane, W. R. Gibson, E. Etzion, M. Kuwano, Stephen Hillier, J. Gascon, K. J. Anderson, C. J. Oram, J. M. Roney, J. E. Pilcher, R. Yaari, G. Maringer, J. C. Armitage, J. Hagemann, P. Jovanovic, Wolfram Dietrich Zeuner, P. Pfister, J. von Krogh, R. F. McGowan, O. Biebel, M. Jimack, John Allison, A. Michelini, G. N. Patrick, R. Shypit, G. Transtromer, G. A. Snow, C. P. Ward, A. J. Martin, Rene Brun, B. Holl, G. M. Dallavalle, R. Ströhmer, R. Kowalewski, S. Schreiber, J. T.M. Chrin, P. Weber, T. P. Kokott, Austin Ball, W. Schappert, W. G. Scott, P. Ashton, W. Gorn, N. Wermes, J. Mildenberger, Dave Robinson, P. D. Acton, C. Y. Chang, M. S. Dixit, P. Kyberd, Paolo Capiluppi, G. Yekutieli, G. A. Bahan, J. Banks, G. Azuelos, A. D. Schaile, P. A. Elcombe, H. O. Ogren, I. Zacharov, Horst Breuker, Alan Watson, L. A. del Pozo, Alessandro Montanari, T. Kawamoto, Mitsuaki Nozaki, J. Hart, Tohru Takeshita, R. G. Kellogg, S. Rossberg, M. Hauschild, M. Coupland, M. M. Deninno, J. P. Walker, P. Poffenberger, J. D. Hobbs, S. Weisz, R. D. Heuer, E. Gross, Fabrizio Fabbri, P. Paschievici, D. Van den plas, P. Igo-Kemenes, D. L. Rees, G. G. Hanson, H. E. Stier, Richard Keeler, G. Alexander, Y. Yang, P. F. Harrison, J. Kroll, D. Axen, Stefano Marcellini, D. J.P. Dumas, S. Orito, F. X. Gentit, G. J. VanDalen, P. M. Watkins, James Letts, P. Leblanc, D. Hochman, R. Mir, B. B. Brabson, H. Oh, D. G. Fong, H. Takeda, V. Gibson, U. Binder, Michael Dittmar, D. J. Miller, P. Routenburg, H. von der Schmitt, J. E. Conboy, W. Mohr, Stephen Lloyd, D. R. Rust, P. W. Jeffreys, M. Cooper, X. C. Lou, M. Sproston, P. Lennert, M. W. Moss, B. Boden, J. L. Pinfold, T. W. Pritchard, A. Wagner, John Baines, J. W. Gary, R. K. Carnegie, R. Sobie, A. Jawahery, I. Wingerter, S. Sanghera, M. F. Turner, P. S. Wells, Silvia Arcelli, P. E.L. Clarke, T. Behnke, Misao Sasaki, N. K. Watson, D. E. Klem, E.J. Prebys, Harold Nguyen, P. M. Hattersley, P. Schenk, D. Menszner, C. K. Hargrove, A. Rollnik, Peter Sherwood, F. G. Oakham, H. Jeremie, H. Kreutzmann, R. W. Springer, G. Duckeck, P. Taras, S. Bougerolle, S. Dado, H. M. Fischer, T. J. McMahon, Marcello Mannelli, A. A. Carter, M. Ogg, M. J. Oreglia, V. H. Winterer, C. Ho, B. Poli, R. E. Hughes-Jones, J. R. McNutt, N. I. Geddes, R. J. Barlow, F. Odorici, J. Schwarz, D. R. Ward, J. R. Carter, E. Heflin, J. P. Pansart, A. Gaidot, M. J. Goodrick, M. Hansroul, S. W. Gensler, T. Kobayashi, J. A. Wilson, P. Le Du, Frans Meijers, D. A. Hinshaw, T. Mouthuy, Richard J Hemingway, G. J. Barker, S. Bethke, B. W. Kennedy, G. Vasseur, S. Wotton, I. Cohen, A. Simon, M. Weymann, B. Panzer-Steindel, S. W. O'Neale, H. Mes, R. J. Homer, O. Runolfsson, F. K. Loebinger, Peter R Hobson, Marco Cuffiani, H. M. Bosch, D. C. Imrie, J. G. Layter, L. Janissen, I. P. Duerdoth, F. Lamarche, G. Giacomelli, M. W. Redmond, Claudio Grandi, H. Przysiezniak, A. M. Rossi, P. Debu, T. Tsukamoto, A. Pouladdej, G. Mikenberg, Gideon Bella, A. Astbury, H. J. Burckhart, Jacqueline Batley, R. Humbert, John Hill, S. De Jong, C. Geich-Gimbel, S. A. Robins, M. J. Losty, M. Fincke-Keeler, K. Runge, C. J. Virtue, M. Weber, N. J. Thackray, T. R. Wyatt, S. Tarem, S. R. Hou, C. Fukunaga, C. Wahl, C. Leroy, B. Lorazo, W. J. Collins, G. D. Lafferty, K. W. Bell, P. G. Estabrooks, C. M. Hawkes, and Daniel Lellouch
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, High Energy Physics::Phenomenology, Scalar (mathematics), Elementary particle, Scalar boson, Higgs field, symbols.namesake, symbols, Higgs boson, High Energy Physics::Experiment, Higgs mechanism, Particle Physics - Experiment, Minimal Supersymmetric Standard Model, Boson
Abstract: Using data from e + e − collisions collected with the OPAL detector during the 1990 LEP run, a search was mode for a low mass Higgs boson (H 0 ) with arbitrary decay mode. The existence of a minimal standard model H 0 with mass in the range 0 ⩽ m H ⩽ 11.3 GeV/ c 2 is excluded at the 95% confidence level for all possible decay modes of the H 0 . Limits on the production of Higgs bosons predicted by the minimal supersymmetric standard model and new scalar particles that couple to the Z 0 are presented as a function of the scalar mass.
Published: 1991

20. A study of Bose-Einstein correlations in $e^{+}e^{-}$ annihilations at LEP

Author: A. Simon, Otmar Biebel, D. G. Charlton, M. Couch, N. C. Wood, R. Humbert, J. T.M. Chrin, P. W. Jeffreys, J. Hart, T. Kawamoto, A. M. Lee, G. A. Snow, C. P. Ward, P. Pfister, O. Schaile, S. Orito, John H. Schwarz, Y. Yang, R. Mir, H. Oh, P. F. Harrison, J. C. Armitage, P. D. Acton, Stephen Lloyd, P. Igo-Kemenes, G. Maringer, H. Jeremie, R. E. Hughes-Jones, U. Maur, Andris Skuja, G. Beaudoin, M. J. Oreglia, D. R. Rust, J. M. Lorah, P. Lennert, W. Mohr, J. R. Carter, G. N. Patrick, Phillip Allport, Shlomo Dado, C. Wahl, F. S. Merritt, H. Przysiezniak, C. M. Hawkes, M. Cooper, Daniel Lellouch, Gideon Bella, Tetsuro Mashimo, P. A. Elcombe, C. P. Howarth, X. C. Lou, M. Hansroul, J. E. Pilcher, R. Van Kooten, M. H. Lehto, F. Odorici, D. E. Klem, D. L. Rees, D. E. Plane, H. J. Burckhart, J. Becker, Jacqueline Batley, Giora Mikenberg, Stephen Hillier, Michael Dittmar, G. J. VanDalen, G. M. Dallavalle, M. Hauschild, R. J. Homer, D. Hochman, N. J. Thackray, Gideon Alexander, J. A. McKenna, J. D. Hobbs, G. Yekutieli, P. Paschievici, K. Stephens, J. R. McNutt, O. Runolfsson, Paolo Capiluppi, S. J. Pawley, Claus Kleinwort, L. Köpke, E. K. U. Gross, Alan Watson, W. Gorn, A. Gaidot, D. J.P. Dumas, P. E.L. Clarke, T. Behnke, L. Lessard, C. Moisan, M. Kuwano, M. F. Turner, N. Wermes, G. G. Hanson, R. F. McGowan, M. Sproston, P R Poffenberger, V. Gibson, D. C. Imrie, J. P. Walker, J. Banks, P. Routenburg, A. Dieckmann, John Baines, Ehud Duchovni, A. A. Carter, P. Teixeira-Dias, S. Weisz, R. D. Heuer, Fabrizio Fabbri, Claudio Grandi, H. Mes, I. P. Duerdoth, D. Van den plas, J. D. Gillies, R. Shypit, H. O. Ogren, G. A. Bahan, P. S. Wells, C. J. Virtue, D. R. Ward, G. Transtromer, Christoph Geich-Gimbel, H. Ihssen, M. M. Deninno, D. A. Hinshaw, J. Kroll, E.J. Prebys, P. Schenk, F. X. Gentit, R. Yaari, S. Bethke, Marco Cuffiani, S. W. Gensler, C. Y. Chang, L. Janissen, W. R. Gibson, M. Coupland, J. E. Conboy, T. Kobayashi, C. Ho, M. Ogg, G. P. Siroli, P. Taras, P. Singh, A. Beck, E. Heflin, M. Jobes, U. Binder, A. Pouladdej, M. S. Dixit, S. Schreiber, Frans Meijers, R. M. Brown, Lorne Levinson, Mitsuaki Nozaki, R. J. Barlow, B. W. Kennedy, P. Scharff-Hansen, T. J. McMahon, R. W. L. Jones, D. J. Miller, Richard Keeler, P. Le Du, W. J. Larson, R. K. Carnegie, H. Kreutzmann, B. Panzer-Steindel, R. J. Sobie, J. P. Martin, John Hill, J. W. Gary, J. A. Wilson, S. De Jong, G. Giacomelli, W. Schappert, A. M. Smith, P. Debu, Claude Leroy, J. P. Pansart, N. K. Watson, F. C. Grant, G. Vasseur, M. A. Whalley, B. Lorazo, J. von Krogh, J. G. Layter, M. W. Moss, F. Lamarche, P. Ashton, Dave Robinson, B. B. Brabson, A. Buijs, D. G. Fong, L. A. del Pozo, P. M. Hattersley, R. J. Hemingway, J. Gascon, S. Sanghera, H. von der Schmitt, Kiyotomo Kawagoe, K. J. Anderson, A. P. Wagner, Marcello Mannelli, J. M. Roney, P. Jovanovic, P. Weber, S. W. O'Neale, Peter R Hobson, Austin Ball, D. Menszner, Sachio Komamiya, E. Ros, Alessandro Montanari, T. P. Kokott, Rene Brun, Tohru Takeshita, H. Takeda, Georges Azuelos, K. W. Bell, F. G. Oakham, Max Weber, Misao Sasaki, B. C. Shen, G. Duckeck, R. Ströhmer, D. Strom, W. G. Scott, G. T. Zorn, R. Kowalewski, H. M. Bosch, Wolfram Dietrich Zeuner, M. J. Losty, D. Axen, A. Jawahery, G. Tysarczyk-Niemeyer, Peter Sherwood, R. W. Springer, J. Ludwig, K. Runge, P. Bock, J. Goldberg, B. Nellen, P. Leblanc, M. J. Goodrick, I. Cohen, Erez Etzion, Gareth J. Barker, Shlomit Tarem, S. Rossberg, C. J. Oram, C. Milstene, R. P. Middleton, M. Jimack, John Allison, B. Holl, R. G. Kellogg, B. P. O'Neill, Stefano Marcellini, James Letts, I. Zacharov, J. Hagemann, Horst Breuker, Paul Kyberd, F. K. Loebinger, M. W. Redmond, A. Rollnik, J. Mildenberger, Harold Nguyen, Gunter Quast, H. E. Stier, P. G. Estabrooks, S. Bougerolle, W. J. Collins, G. D. Lafferty, P. M. Watkins, I. Wingerter, Silvia Arcelli, T. W. Pritchard, A. Astbury, H. M. Fischer, O. Ganel, A. Michelini, A. J. Martin, A. D. Schaile, K. Riles, S. Wotton, G. Eckerlin, M. Weymann, S. A. Robins, C. K. Hargrove, V. H. Winterer, T. R. Wyatt, S. R. Hou, T. Mouthuy, C. Fukunaga, J. L. Pinfold, A. M. Rossi, T. Tsukamoto, S. Levegrün, Takehiko Mori, N. I. Geddes, B. Boden, B. Poli, T. J. Smith, P. Mättig, I. J. Bloodworth, M. Settles, G. W. Wilson, D. Karlen, and Margret Fincke-Keeler
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, Electron–positron annihilation, Hadron, Detector, Function (mathematics), Bose–Einstein correlations, Radius, Nuclear physics, Pion, High Energy Physics::Experiment, Particle Physics - Experiment
Abstract: Bose-Einstein correlations between like-sign charged track pairs have been studied in e + e − annihilation hadronic events at centre-of-mass energies around the Z 0 peak as a function of Q , the four-momentum difference of the pair. The measurement was performed with the OPAL detector at LEP. Assuming the charged tracks to be pions, the observed Bose-Einstein enhancement was used to extract the values of the strength of the effect and the radius of the pion emitting source, which were found to be λ =0.866±0.032±0.140 and R 0 =0.928±0.019±0.150 fm, respectively, where the first error is statistical and the second is systematic. The results do not show significant variation in comparison to e + e − annihilation measurements at lower centre-of-mass energies. If non-pion track contamination is taken into account, the value of the strength λ becomes consistent with unity.
Published: 1991

21. A study of $K_{S}^{0}$ production in $Z^{0}$ decays

Author: J. R. McNutt, C. Milstene, W. G. Scott, Sachio Komamiya, A. T. Watson, I. J. Bloodworth, N. C. Wood, J. Goldberg, B. Nellen, A. Simon, R. Kowalewski, V. Gibson, Otmar Biebel, H. O. Ogren, John Baines, F. Odorici, G. A. Snow, C. P. Ward, R. J. Sobie, Christoph Geich-Gimbel, T. P. Kokott, Rene Brun, G. Maringer, G. Beaudoin, C. Y. Chang, Shlomo Dado, P. Leblanc, M. Settles, X. C. Lou, P. G. Murphy, Giora Mikenberg, Michael Dittmar, H. M. Fischer, G. Yekutieli, D. G. Charlton, D. A. Hinshaw, H. Jeremie, P. Taras, M. Couch, M. J. Goodrick, M. M. Deninno, I. Cohen, Claude Leroy, J. Kroll, R. Humbert, Mitsuaki Nozaki, Silvia Arcelli, R. E. Hughes-Jones, U. Maur, D. R. Ward, M. J. Losty, P. Igo-Kememes, J. P. Martin, A. A. Carter, A. Michelini, J. P. Pansart, F. X. Gentit, J. E. Conboy, H. Takeda, S. De Jong, M. Ogg, Phillip Allport, J. T.M. Chrin, G. W. Wilson, B. P. O'Neill, M. A. Whalley, C. Wahl, F. G. Oakham, E. K. U. Gross, A. Gaidot, M. Hansroul, A. Pouladdej, M. Kuwano, B. Panzer-Steindel, J. Hagemann, D. R. Rust, M. Sproston, F. S. Merritt, T. Kawamoto, A. Buijs, P. Singh, P. Debu, S. W. O'Neale, Peter R Hobson, C. P. Howarth, P. Routenburg, Erez Etzion, S. Orito, John H. Schwarz, P. Lennert, F. Lamarche, Gareth J. Barker, R. J. Hemingway, A. Dieckmann, D. Hochman, R. J. Homer, R. Mir, N. J. Thackray, H. Oh, Shlomit Tarem, J. E. Pilcher, S. A. Robins, S. Schreiber, H. Mes, I. P. Duerdoth, R. W. L. Jones, P. A. Elcombe, J. D. Hobbs, G. G. Hanson, S. Rossberg, C. J. Oram, P. E.L. Clarke, P. Jovanovic, Tohru Takeshita, T. Behnke, T. J. McMahon, Austin Ball, C. Moisan, J. P. Walker, R. P. Middleton, D. Menszner, D. L. Rees, J. Becker, M. J. Oreglia, P. Le Du, H. Kreutzmann, Georges Azuelos, P. S. Wells, P. Teixeira-Dias, Alessandro Montanari, C. J. Virtue, J. Schwiening, R. F. McGowan, K. J. Anderson, M. Hauschild, G. J. VanDalen, S. Wotton, Terry Richard Wyatt, R. K. Carnegie, D. E. Klem, M. Coupland, J. R. Carter, N. K. Watson, K. W. Bell, P. Paschievici, G. N. Patrick, M. F. Turner, H. Przysiezniak, R. Yaari, S. Bethke, Max Weber, J. D. Gillies, Marco Cuffiani, J. C. Hill, M. Weymann, Misao Sasaki, J. A. Wilson, Gideon Bella, J. M. Lorah, G. Duckeck, P R Poffenberger, T. Mouthuy, R. J. Barlow, Gideon Alexander, D. J. Miller, H. J. Burckhart, W. Mohr, Jacqueline Batley, Paolo Capiluppi, W. Schappert, H. E. Stier, O. Schaile, L. Janissen, D. Strom, P. G. Estabrooks, J. von Krogh, J. Hart, R. K. Keeler, A. M. Rossi, G. T. Zorn, P. Ashton, Dave Robinson, T. Tsukamoto, S. Levegrün, H. M. Bosch, N. I. Geddes, P. M. Watkins, B. Poli, Wolfram Dietrich Zeuner, O. Runolfsson, Y. Yang, I. Wingerter, L. Lessard, J. Banks, D. Axen, A. Jawahery, G. Tysarczyk-Niemeyer, Claudio Grandi, Peter Sherwood, R. W. Springer, J. Ludwig, K. Runge, P. Bock, P. F. Harrison, P. W. Jeffreys, S. Weisz, R. D. Heuer, A. M. Lee, Stephen Lloyd, Fabrizio Fabbri, D. Van den plas, R. Van Kooten, M. H. Lehto, N. Wermes, S. Bougerolle, W. J. Collins, G. D. Lafferty, T. W. Pritchard, Ehud Duchovni, R. Shypit, A. D. Schaile, Andris Skuja, V. H. Winterer, S. R. Hou, S. J. Pawley, Claus Kleinwort, L. Köpke, H. Ihssen, Tetsuro Mashimo, S. W. Gensler, C. Fukunaga, T. Kobayashi, W. Gorn, G. A. Bahan, G. Giacomelli, B. B. Brabson, E.J. Prebys, D. G. Fong, P. Schenk, J. Gascon, H. von der Schmitt, Frans Meijers, J. L. Pinfold, Marcello Mannelli, M. Jobes, U. Binder, P. Scharff-Hansen, W. J. Larson, J. G. Layter, J. W. Gary, D. Karlen, A. M. Smith, C. M. Hawkes, M. Cooper, Daniel Lellouch, Takehiko Mori, G. Vasseur, B. Lorazo, D. E. Plane, S. Sanghera, Stephen Hillier, G. M. Dallavalle, D. J.P. Dumas, W. R. Gibson, C. Ho, A. Beck, E. Heflin, R. M. Brown, Lorne Levinson, B. W. Kennedy, T. J. Smith, P. Mättig, B. Holl, I. Zacharov, Horst Breuker, J. Mildenberger, Harold Nguyen, Gunter Quast, M. S. Dixit, Paul Kyberd, F. K. Loebinger, Margret Fincke-Keeler, A. Astbury, M. W. Redmond, A. Rollnik, O. Ganel, A. J. Martin, K. Riles, M. Jimack, John Allison, G. Eckerlin, C. K. Hargrove, P. Pfister, R. G. Kellogg, Stefano Marcellini, J. C. Armitage, M. W. Moss, P. M. Hattersley, D. C. Imrie, G. P. Siroli, Kiyotomo Kawagoe, A. P. Wagner, J. M. Roney, B. C. Shen, and K. Stephens
Subjects: Quantum chromodynamics, Physics, Nuclear and High Energy Physics, Particle physics, Annihilation, Meson, Electron–positron annihilation, High Energy Physics::Phenomenology, Hadron, Nuclear physics, Momentum, High Energy Physics::Experiment, Center of mass, Event (particle physics), Particle Physics - Experiment
Abstract: The production of K0 mesons in e+e− interactions at center of mass energies in the region of the Z0 mass has been investigated with the OPAL detector at LEP. The rate is found to be 2.10±0.02±0.14 K 0 , Z 0 per hadronic event. The predictions from the JETSET and HERWIG generators agree very well with both the rate and the scale invariant cross section (1/σhadβ) (dσ/dxE) for K0 production. Comparisons of the inclusive momentum spectrum with predictions of an analytical QCD formula and with data from lower center of mass energies are presented.
Published: 1991

22. Drift velocity measurement using MSGCs in a test beam

Author: J. Dubeau, F.G. Oakham, M. S. Dixit, J. C. Armitage, S.C. Taylor, and G.C. Stuart
Subjects: Physics, Nuclear and High Energy Physics, Drift velocity, Argon, Physics::Instrumentation and Detectors, business.industry, chemistry.chemical_element, Microstrip, chemistry.chemical_compound, Optics, chemistry, Test beam, Electric field, Isobutane, business, Instrumentation
Abstract: A novel method of determining electron drift velocity at high electric fields uses plastic MicroStrip Gas Counters (MSGCs) operating in a test beam. The data from angled tracks through a MSGC provided a distance versus time relationship from which a drift velocity of 36.5 ± 2 μm/ns was obtained for an 90 10 argon/isobutane gas mix and an electric field of 4 kV/cm.
Published: 1995
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23. Exclusive Production ofK+K−π+π−in Photon-Photon Collisions

Author: H. Aihara, M. Alston-Garnjost, J. C. Armitage, J. A. Bakken, A. Barbaro-Galtieri, A. R. Barker, A. V. Barnes, B. A. Barnett, H. -U. Bengtsson, D. L. Bintinger, B. J. Blumenfeld, G. J. Bobbink, A. D. Bross, C. D. Buchanan, A. Buijs, M. P. Cain, D. O. Caldwell, O. Chamberlain, C. -Y. Chien, A. R. Clark, A. Cordier, O. I. Dahl, C. T. Day, K. A. Derby, M. A. van Driel, P. H. Eberhard, A. M. Eisner, F. C. Erne, D. L. Fancher, H. Fujii, T. Fujii, B. Gabioud, J. W. Gary, W. Gorn, N. J. Hadley, J. M. Hauptman, W. Hofmann, J. E. Huth, J. Hylen, U. P. Joshi, T. Kamae, H. S. Kaye, K. H. Kees, R. W. Kenney, L. T. Kerth, Winston Ko, R. I. Koda, R. R. Kofler, K. K. Kwong, R. L. Lander, W. G. J. Langeveld, J. G. Layter, F. L. Linde, C. S. Lindsey, S. C. Loken, A. Lu, X. -Q. Lu, G. R. Lynch, L. Madansky, R. J. Madaras, K. Maeshima, B. D. Magnuson, J. N. Marx, K. Maruyama, G. E. Masek, J. A. J. Matthews, S. O. Melnikoff, E. S. Miller, W. Moses, R. R. McNeil, P. Nemethy, D. R. Nygren, P. J. Oddone, H. P. Paar, D. A. Palmer, D. A. Park, D. E. Pellett, A. Pevsner, M. Pripstein, P. R. Robrish, M. T. Ronan, R. R. Ross, F. R. Rouse, R. R. Sauerwein, K. A. Schwitkis, J. C. Sens, G. Shapiro, M. D. Shapiro, B. C. Shen, W. E. Slater, J. R. Smith, M. L. Stevenson, D. H. Stork, M. K. Sullivan, J. R. Thompson, H. K. Ticho, J. Timmer, N. Toge, R. van Tyen, B. van Uitert, G. J. VanDalen, R. F. van Daalen Wetters, W. Vernon, W. Wagner, E. M. Wang, Y. X. Wang, M. R. Wayne, W. A. Wenzel, J. T. White, M. C. S. Williams, H. Yamamoto, M. Yamauchi, S. J. Yellin, and W. -M. Zhang
Subjects: Physics, Nuclear physics, Pair production, Pion, Annihilation, Meson, Branching fraction, Hadron, Mass spectrum, General Physics and Astronomy, Particle identification
Abstract: We report a measurement of the reaction ..gamma gamma -->..K/sup +/K/sup -/..pi../sup +/..pi../sup -/ in both tagged and untagged events at PEP. The cross section rises with invariant ..gamma gamma.. mass to about 15 nb at 2 GeV and falls slowly at higher masses. We find clear evidence for the processes ..gamma gamma -->..phi..pi../sup +/..pi../sup -/ and ..gamma gamma -->..K/sup asterisk0/(892)K..pi... Upper limits (95% C.L.) of 1.5 and 5.7 nb in the mass range from 1.7 to 3.7 GeV are obtained for phirho/sup 0/ and K/sup asterisk0/K/sup asterisk0/ production, respectively.
Published: 1985
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24. Measurement of the total hadronic cross section in virtual photon-photon interactions

Author: G. Masek, E. S. Miller, M. C.S. Williams, J. R. Thompson, U.P. Joshi, M. K. Sullivan, R. R. McNeil, J. Timmer, A. M. Eisner, F. C. Erné, R. L. Lander, H. P. Paar, Winston Ko, S. J. Yellin, D. A. Palmer, Willem G. J. Langeveld, M. P. Cain, J. R. Smith, K. A. Schwitkis, J. C. Armitage, A. Lu, W. Vernon, D. E. Pellett, J.C. Sens, J. T. White, D. Bintinger, K. H. Kees, Kaori Maeshima, M.A. Van Driel, B. van Uitert, A. Buijs, and D. O. Caldwell
Subjects: Nuclear physics, Physics, Particle physics, Photon, Meson, TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY, Hadron, General Physics and Astronomy, Virtual particle, Elementary particle, Quantum field theory, Helicity, Boson
Abstract: The total hadronic cross section for virtual photon-photon interactions is reported for center-of-mass energy, W, between 2 and 20 GeV. The data were obtained via the process e/sup +/e/sup -/..-->..e/sup +/e/sup -/..gamma..(..gamma..(..-->..e /sup +/e/sup -/+hadrons with both scattered e/sup +/ and e/sup -/ detected. Each photon's four-momentum squared, q/sup 2/, ranges from -0.1 to -1.6 GeV/sup 2/. Dependence upon q/sup 2/ agrees with a generalized vector-meson-dominance model. The total cross section shows little W dependence, averaging 125 nb at q/sub 1//sup 2/ = q/sub 2//sup 2/ = -0.3. Photon helicity interference terms are determined.
Published: 1985
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25. Measurements of the anisotropy ratio between longitudinal and transverse diffusion in argon based gas mixtures

Author: J. Waterhouse, J. C. Armitage, and L. Wong
Subjects: Physics, Nuclear and High Energy Physics, Argon, Drift velocity, Physics::Instrumentation and Detectors, Monte Carlo method, chemistry.chemical_element, Computational physics, Transverse plane, chemistry, Statistical physics, Diffusion (business), Anisotropy, Instrumentation
Abstract: A special drift cell with proportional wire readout has been constructed to make simultaneous measurements of the drift velocity, the longitudinal and this ratio with percentage of quencher used, and also compare favourably with existing Monte Carlo models. A simple method of parametrizing the data is suggested that should allow prediction of the diffusion properties given the drift velocity.
Published: 1988
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26. The OPAL vertex detector prototype

Author: J.M. Roney, Stephen Lloyd, L. Godfrey, A. C. McPherson, J.L. Pinfold, R.K. Carnegie, A. A. Carter, P. A. Elcombe, J. C. Armitage, G.L. Giles, J. Waterhouse, C. K. Hargrove, R. J. Hemingway, John Hill, T.W. Pritchard, and J. R. Carter
Subjects: Physics, Nuclear and High Energy Physics, Argon, Large Hadron Collider, Physics::Instrumentation and Detectors, Bar (music), Resolution (electron density), Detector, chemistry.chemical_element, Tracking (particle physics), Charged particle, Nuclear physics, chemistry, Vertex (curve), High Energy Physics::Experiment, Instrumentation
Abstract: The prototype test results of a high resolution charged particle tracking detector are reported. The detector is designed to measure vertex topologies of particles produced in the e+e− collisions of the OPAL experiment at LEP. The OPAL vertex detector is a 1 m long, 0.46 m diameter cylindrical drift chamber consisting of an axial and stereo layer each of which is divided into 36 jet cells. A prototype chamber containing four axial and two stereo cells was studied using a pion test beam at CERN. The studies examined the prototype under a variety of operating conditions. An r−φ resolution of 60 μm was obtained when the chamber was operated with argon (50%)-ethane (50%) at 3.75 bar, and when CO2(80%)-isobutane (20%) at 2.5 bar was used a 25 μm resolution was achieved. A z measurement using end-to-end time difference has a resolution of 3.5 cm. The details of these prototype studies are discussed in this paper.
Published: 1989
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27. A study of the effect of methane and carbon dioxide concentration on gas amplification in argon based gas mixtures

Author: Sean P. Beingessner, R. K. Carnegie, John Waterhouse, E.F. Ritchie, and J. C. Armitage
Subjects: Physics, Nuclear and High Energy Physics, Range (particle radiation), Quenching (fluorescence), Argon, Physics::Instrumentation and Detectors, Analytical chemistry, Proportional counter, chemistry.chemical_element, Fraction (chemistry), Methane, chemistry.chemical_compound, chemistry, Carbon dioxide, Coaxial, Instrumentation, Astrophysics::Galaxy Astrophysics
Abstract: Proportional counter gas amplification has been studied for argon based gas mixtures with methane and carbon dioxide as the quenching agent. Measurements of gas gain have been made using coaxial proportional tubes with different wire radii over a wide range of chamber voltages and pressures. The reduced gain function was found to be dependent on the reduced field E a P , and the fraction of the quenching minority gas and approximately independent of the choice of quencher in most of the proportional region. The full data sample for the ten different gas mixtures can be described by a function with only nine parameters.
Published: 1988
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28. Leptonic structure functions of the photon

Author: David O. Caldwell, J. R. Smith, J. Timmer, M.A. Van Driel, B. van Uitert, K. A. Schwitkis, J.C. Sens, Winston Ko, M. K. Sullivan, M. P. Cain, R. L. Lander, J. C. Armitage, U.P. Joshi, A. Buijs, S. Yellin, J. T. White, A. Lu, H. P. Paar, F. C. Erné, D. Bintinger, M. C.S. Williams, R. R. McNeil, W. Vernon, J. R. Thompson, K. H. Kees, A. M. Eisner, Kaori Maeshima, D. E. Pellett, G. Masek, D. A. Palmer, E. S. Miller, and W. G. L. Langeveld
Subjects: Physics, Nuclear and High Energy Physics, Particle physics, Muon, Photon, Structure function, Radiative transfer, High Energy Physics::Experiment
Abstract: An analysis of the production of muon pairs in γγ collisions is presented. The leptonic structure functions of the photon, F2 and 2xF1, are extracted for Q2 < 1.7 GeV2. Their x dependences agree well with QED predictions. Corrections are required to eliminate radiative effects in the 2xF1 data.
Published: 1984
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29. Mass limits for a standard model Higgs boson in e+e- collisions at LEP

Author: H. Wang, D. E. Plane, V. H. Winterer, Stephen Hillier, Gunter Quast, Kiyotomo Kawagoe, D. Hochman, D. Duchesneau, C. Wahl, A. P. Wagner, H. M. Fischer, Alan Watson, D. J.P. Dumas, M. J. Losty, Masatoshi Koshiba, R. W. L. Jones, M. T. French, J. M. Roney, G.T.J. Arnison, B. Holl, A. Michelini, G. Knop, T. J. Smith, P. Igo-Kemenes, P. Le Du, H. Kreutzmann, Harold Nguyen, A. Jawahery, G. Maringer, J. Steuerer, H. Jeremie, H. Yamashita, P. A. Elcombe, P. Farthouat, Horst Breuker, E. Jin, G. Giacomelli, P. Mättig, H. Oh, R. E. Hughes-Jones, U. Maur, B. Wuensch, Peter Sherwood, H. Hagedorn, Frans Meijers, S. Zylberajch, P. S. Hinde, P. W. Jeffreys, P. G. Estabrooks, I. J. Bloodworth, R. W. Springer, Gideon Bella, W. R. Gibson, C. Ho, H. J. Burckhart, Jacqueline Batley, H. Mes, John Allison, A. Possoz, H. Takeda, E. Heflin, Phillip Allport, R. M. Brown, Lorne Levinson, C. Y. Chang, P. Bock, M. M.B. Lasota, C. Fukunaga, O. W. Davies, N. K. Watson, H. El Mamouni, Tohru Takeshita, Shlomo Dado, D. L. Rees, B. W. Kennedy, M. J. Oreglia, D. Granite, D. Karlen, M. W. Moss, C. Milstene, O. Ganel, P. M. Watkins, P. G. Murphy, C. M. Hawkes, Daniel Lellouch, Mitsuaki Nozaki, A. C. McPherson, Takehiko Mori, R. G. Kellogg, P. M. Hattersley, R. Ströhmer, M. Jimack, Erez Etzion, G. M. Dallavalle, B. J. Saunders, K. Riles, I. P. Duerdoth, Georges Azuelos, D. Strom, Gareth J. Barker, F. Lamarche, G. T. Zorn, Giora Mikenberg, G. J. VanDalen, J. Schwarz, A. Shapira, F. Odorici, J. R. Carter, G. N. Patrick, A. Simon, Stefano Marcellini, Otmar Biebel, Wolfram Dietrich Zeuner, K. Runge, R. J. Hemingway, F. Beck, N. I. Geddes, K. W. Bell, Colin Roach, J. D. Hobbs, I. Wingerter, D. G. Charlton, D. C. Imrie, F. Roehner, M. Couch, G. P. Siroli, P. Jovanovic, Misao Sasaki, G. A. Snow, C. P. Ward, J. Ma, F. K. Loebinger, J. L. Pinfold, E. J. Spreadbury, B. C. Shen, Norbert Wermes, J. T.M. Chrin, M. W. Redmond, Austin Ball, D. Menszner, T. Kawamoto, P. Grosse-Wiesmann, O. Runolfsson, K. Stephens, B. Poli, A. Rollnik, L. Lessard, R. Yaari, John Baines, O. Schaile, M. Regimbald, R. P. Middleton, H. E. Stier, D. R. Ward, M. Z. Akrawy, Alessandro Montanari, E. K. U. Gross, S. Orito, S. Bethke, Marco Cuffiani, M. Sproston, R. Kowalewski, J. Goldberg, T. R. Wyatt, P. Routenburg, A. Dieckmann, S. R. Hou, B. Nellen, Gideon Alexander, M. S. Dixit, S. Wotton, J. D. Gillies, P. Leblanc, Despina Hatzifotiadou, P. Kyberd, Paolo Capiluppi, G. D. Lafferty, N. C. Wood, K. J. Anderson, A. D. Schaile, J. M. Lorah, T. W. Pritchard, R. J. Barlow, Makoto Minowa, D. J. Miller, D. E. Klem, A. M. Rossi, J. Ludwig, T. Tsukamoto, M. J. Goodrick, Joachim Heintze, I. Cohen, M. F. Turner, C. K. Hargrove, W. J. Murray, Ehud Duchovni, B. P. O'Neill, R. A. Sansum, J. Hagemann, S. W. Gensler, T. Kobayashi, J. Hart, W. Mohr, Y. Yang, C. J. Virtue, M. Hansroul, M. Coupland, Stephen Lloyd, R. J. Homer, Christoph Geich-Gimbel, B. Gandois, M. M. Deninno, J. Kroll, F. X. Gentit, G. Bavaria, J. E. Conboy, M. Ogg, F. G. Oakham, A. Pouladdej, J. Banks, S. Schreiber, F. S. Merritt, T. J. McMahon, J. C. Armitage, A. J.P. O'Dowd, R. K. Carnegie, S. Weisz, D. G. Fong, R. D. Heuer, J. G. Layter, M. S. Weber, J. A. Wilson, Fabrizio Fabbri, S. Sanghera, J. P. Martin, D. Van den plas, John Hill, G. Tysarczyk, A. Buijs, H. von der Schmitt, W. Schappert, J. von Krogh, P. Lennert, J. Raab, Marcello Mannelli, C. N. P. Gee, P. Ashton, M. Jobes, T. P. Kokott, Rene Brun, P. Scharff-Hansen, C. P. Howarth, W. J. Larson, Michael Dittmar, G. Yekutieli, J. E. Pilcher, J. W. Gary, J. Grunhaus, A. A. Carter, A. A. Macbeth, G. W. Wilson, A. M. Smith, M. Hauschild, B. Lorazo, M. Weymann, Andris Skuja, Tetsuro Mashimo, S. J. Pawley, M. Imori, Claus Kleinwort, L. Köpke, S. W. O'Neale, Achim Müller, Peter R Hobson, J. Waterhouse, and W. Gorn
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics, Electron–positron annihilation, High Energy Physics::Phenomenology, Higgs boson, High Energy Physics::Experiment, Particle Physics - Experiment, Standard Model
Abstract: A search for the minimal standard model Higgs boson has been performed with data from e+e− collisions in the OPAL detector at LEP. The analysis is based on 825 nb−1 of data taken at centre-of-mass energies between 88.3 and 95.0 GeV. The search concentrated on the reactions e + e − →(e + e − or μ + μ − or v v )H 0 ,H 0 →( q q or τ + τ − ) , for Higgs masses above 3 GeV/c2. No Higgs boson candidates have been observed. The present study excludes the existence of a standard model H0 with mass in the range 3.0⩽mH⩽19.3 GeV/c2 at the 95% confidence level.
Published: 1989

30. A search for acoplanar pairs of leptons or jets in Z0 decays: mass limits on supersymmetric particles

Author: Gunter Quast, J. P. Martin, A. Buijs, D. G. Fong, O. Schaile, H. von der Schmitt, Gideon Bella, H. J. Burckhart, M. T. French, Jacqueline Batley, Michael Dittmar, G. Yekutieli, J. Steuerer, G. Tysarczyk, F. Roehner, Marcello Mannelli, C. N. P. Gee, G.T.J. Arnison, D. Hochman, Kiyotomo Kawagoe, P. Igo-Kemenes, K. J. Anderson, H. E. Stier, P. G. Estabrooks, A. A. Carter, N. K. Watson, P. M. Watkins, G. Maringer, B. C. Shen, O. Ganel, J. Hart, A. P. Wagner, Christoph Geich-Gimbel, S. Wotton, K. Stephens, Y. Yang, H. Jeremie, A. Simon, Andris Skuja, C. M. Roach, J. G. Layter, I. Wingerter, R. E. Hughes-Jones, U. Maur, J. M. Roney, K. Riles, Otmar Biebel, D. G. Charlton, C. J. Virtue, M. M. Deninno, Tetsuro Mashimo, C. M. Hawkes, M. M.B. Lasota, C. Y. Chang, Stephen Lloyd, O. W. Davies, M. Couch, Ana Beatriz Alvarez Perez, S. Sanghera, Terry Richard Wyatt, S. J. Pawley, J. Kroll, G. Knop, M. Coupland, R. Kowalewski, Claus Kleinwort, L. Köpke, Mitsuaki Nozaki, C. Milstene, H. Hagedorn, W. Gorn, J. D. Hobbs, C. Wahl, John Baines, M. Regimbald, B. Holl, Daniel Lellouch, Phillip Allport, G. Bavaria, C. P. Howarth, J. E. Conboy, M. Ogg, A. C. McPherson, A. Jawahery, J. T.M. Chrin, G. Giacomelli, J. E. Pilcher, M. Jobes, J. C. Armitage, F. Lamarche, F. X. Gentit, P. Scharff-Hansen, D. R. Ward, P. Lennert, R. J. Hemingway, F. G. Oakham, Shlomo Dado, F. Odorici, A. A. Macbeth, M. Imori, A. Pouladdej, W. J. Larson, D. E. Klem, D. E. Plane, G. W. Wilson, M. Hauschild, Takehiko Mori, J. W. Gary, J. von Krogh, J. Raab, Horst Breuker, P. Farthouat, Peter Sherwood, T. Kawamoto, R. W. Springer, S. W. O'Neale, D. C. Imrie, Stephen Hillier, R. W. L. Jones, F. S. Merritt, S. Orito, John H. Schwarz, Frans Meijers, E. J. Spreadbury, H. Oh, M. F. Turner, J. Ludwig, A. M. Smith, B. Lorazo, P. Ashton, P. Le Du, Achim Müller, Peter R Hobson, J. Waterhouse, G. P. Siroli, G. M. Dallavalle, A. D. Schaile, A. J.P. O'Dowd, Gideon Alexander, P. Kyberd, N. Lupu, Paolo Capiluppi, John Allison, P. Jovanovic, Austin Ball, D. Menszner, H. Kreutzmann, P. S. Hinde, K. Runge, P. Bock, J. Grunhaus, C. K. Hargrove, Ehud Duchovni, D. J.P. Dumas, E. Jin, Erez Etzion, H. El Mamouni, M. J. Oreglia, M. Z. Akrawy, Alessandro Montanari, Tohru Takeshita, W. J. Murray, P. G. Murphy, B. J. Saunders, Giora Mikenberg, R. A. Sansum, P. Grosse-Wiesmann, S. W. Gensler, J. D. Gillies, I. P. Duerdoth, J. R. Carter, Georges Azuelos, S. Schreiber, T. J. McMahon, Gareth J. Barker, T. Kobayashi, A. T. Watson, V. H. Winterer, J. Banks, G. N. Patrick, K. W. Bell, M. W. Moss, M. Weymann, P. M. Hattersley, N. C. Wood, R. K. Carnegie, Max Weber, S. Weisz, T. P. Kokott, Rene Brun, R. D. Heuer, J. C. Hill, Misao Sasaki, R. Ströhmer, O. Runolfsson, R. J. Barlow, D. J. Miller, S. R. Hou, J. A. Wilson, Fabrizio Fabbri, D. Van den plas, G. A. Snow, R. G. Kellogg, D. Strom, G. T. Zorn, C. P. Ward, Norbert Wermes, D. Duchesneau, W. Schappert, L. Lessard, M. Hansroul, M. S. Dixit, Despina Hatzifotiadou, B. Gandois, Wolfram Dietrich Zeuner, F. Beck, G. D. Lafferty, W. R. Gibson, Stefano Marcellini, H. Yamashita, C. Ho, R. J. Homer, T. J. Smith, T. W. Pritchard, E. Heflin, P. Mättig, A. Possoz, B. Wuensch, R. M. Brown, Lorne Levinson, I. J. Bloodworth, H. Takeda, B. W. Kennedy, P. W. Jeffreys, J. Ma, F. K. Loebinger, H. Mes, R. P. Middleton, C. Fukunaga, M. W. Redmond, D. Karlen, M. Jimack, A. Rollnik, J. L. Pinfold, Masatoshi Koshiba, Harold Nguyen, A. M. Rossi, T. Tsukamoto, B. P. O'Neill, N. I. Geddes, B. Poli, H. M. Fischer, M. J. Losty, A. Michelini, J. Hagemann, P. A. Elcombe, D. L. Rees, G. J. VanDalen, J. Goldberg, B. Nellen, P. Leblanc, J. M. Lorah, Makoto Minowa, W. Mohr, M. J. Goodrick, Joachim Heintze, I. Cohen, E. K. U. Gross, M. Sproston, P. Routenburg, A. Dieckmann, S. Zylberajch, R. Yaari, S. Bethke, Marco Cuffiani, A. Shapira, D. Granite, and H. Wang
Subjects: Nuclear physics, Physics, Nuclear and High Energy Physics, Particle physics, Chargino, Electron–positron annihilation, High Energy Physics::Phenomenology, High Energy Physics::Experiment, Particle Physics - Experiment, Lepton
Abstract: We have searched for Z 0 decays into acoplanar pairs of leptons or jets. The data were recorded with the OPAL detector during an energy scan around the Z 0 peak and correspond to about 17000 produced Z 0, s. We have determined model independent limits on branching ratios for the Z 0 to decay into pairs of heavy particles with subsequent decays leading to the above topologies. In the context of supersymmetric models, mass bounds close to the kinematic limit were obtained for the scalar leptons, ẽ, gm, gt, and for the chargino, X ± .
Published: 1989

31. A search for the top and b' quarks in hadronic Z0 decays

Author: J. D. Hobbs, G. Giacomelli, Frans Meijers, J. G. Layter, Ana Beatriz Alvarez Perez, S. Sanghera, M. T. French, C. Beard, A. J.P. O'Dowd, A. T. Watson, J. Hart, J. P. Martin, G. Tysarczyk, A. Shapira, P. Igo-Kemenes, G. Maringer, H. Jeremie, B. Holl, F. Lamarche, R. J. Hemingway, Christoph Geich-Gimbel, Kiyotomo Kawagoe, I. J. Bloodworth, C. Fukunaga, H. Oh, R. E. Hughes-Jones, U. Maur, H. M. Fischer, Gideon Bella, J. Banks, G.T.J. Arnison, M. M. Deninno, M. J. Losty, A. P. Wagner, D. E. Klem, Jacqueline Batley, J. Ma, T. P. Kokott, Rene Brun, P. Jovanovic, S. Weisz, Austin Ball, E. K. U. Gross, R. D. Heuer, Fabrizio Fabbri, D. G. Fong, D. Menszner, J. Kroll, M. Jimack, M. M.B. Lasota, B. J. Saunders, H. E. Stier, D. Van den plas, J. M. Roney, M. Sproston, F. X. Gentit, H. von der Schmitt, Gareth J. Barker, A. Michelini, M. Z. Akrawy, Alessandro Montanari, O. W. Davies, A. Jawahery, G. Bavaria, J. E. Conboy, M. Ogg, F. K. Loebinger, P. Routenburg, G. Knop, H. El Mamouni, M. J. Oreglia, C. Milstene, H. Hagedorn, A. C. McPherson, A. Dieckmann, Y. Yang, J. D. Gillies, A. Pouladdej, Tohru Takeshita, N. C. Wood, P. A. Elcombe, J. L. Pinfold, F. Odorici, P. G. Estabrooks, P. Lennert, C. M. Roach, M. F. Turner, R. J. Barlow, M. W. Redmond, F. S. Merritt, D. J. Miller, J. R. Carter, G. N. Patrick, M. S. Dixit, Peter Sherwood, J. Grunhaus, A. Simon, D. Hochman, Otmar Biebel, Despina Hatzifotiadou, D. G. Charlton, F. Roehner, D. L. Rees, G. D. Lafferty, A. Rollnik, I. P. Duerdoth, Marcello Mannelli, K. Stephens, M. Couch, R. W. Springer, C. N. P. Gee, H. Yamashita, G. A. Snow, C. P. Ward, N. K. Watson, Georges Azuelos, M. Jobes, D. Karlen, G. J. VanDalen, W. J. Murray, R. W. L. Jones, J. Ludwig, A. Possoz, J. C. Armitage, C. M. Hawkes, T. W. Pritchard, Stephen Lloyd, H. Takeda, P. Farthouat, Daniel Lellouch, P. M. Watkins, P. Le Du, K. Runge, P. Bock, H. Kreutzmann, P. Scharff-Hansen, Horst Breuker, W. J. Larson, D. Granite, J. T.M. Chrin, Takehiko Mori, K. W. Bell, Masatoshi Koshiba, S. J. Pawley, E. Jin, R. P. Middleton, John Baines, S. Zylberajch, Claus Kleinwort, L. Köpke, Max Weber, J. W. Gary, M. Imori, P. S. Hinde, E. J. Spreadbury, M. Regimbald, Harold Nguyen, T. Kawamoto, J. C. Hill, A. D. Schaile, S. W. O'Neale, W. R. Gibson, C. Y. Chang, M. Hansroul, Peter R Hobson, A. M. Smith, N. I. Geddes, J. Waterhouse, Misao Sasaki, P. Grosse-Wiesmann, C. Ho, B. C. Shen, R. Ströhmer, I. Wingerter, M. W. Moss, D. R. Ward, J. M. Lorah, N. Wermes, M. Weymann, D. Duchesneau, V. H. Winterer, P. W. Jeffreys, B. Lorazo, Mitsuaki Nozaki, P. M. Hattersley, D. Strom, S. Orito, John H. Schwarz, H. Wang, Makoto Minowa, H. Mes, B. P. O'Neill, W. Mohr, Andris Skuja, G. T. Zorn, Shlomo Dado, S. R. Hou, C. K. Hargrove, Ehud Duchovni, R. J. Homer, E. Heflin, T. J. Smith, Gunter Quast, R. M. Brown, Wolfram Dietrich Zeuner, J. Hagemann, Tetsuro Mashimo, John Allison, D. C. Imrie, P. Mättig, R. Kowalewski, Lorne Levinson, F. Beck, G. M. Dallavalle, P. G. Murphy, R. Yaari, B. Wuensch, B. Poli, S. Bethke, W. Gorn, B. W. Kennedy, Marco Cuffiani, Giora Mikenberg, R. A. Sansum, G. P. Siroli, R. G. Kellogg, J. Goldberg, Stefano Marcellini, D. E. Plane, B. Nellen, O. Ganel, Stephen Hillier, H. Boerner, P. Leblanc, K. Riles, D. J.P. Dumas, A. M. Rossi, T. Tsukamoto, S. W. Gensler, B. Gandois, M. J. Goodrick, Joachim Heintze, I. Cohen, T. Kobayashi, F. G. Oakham, H. J. Burchart, Phillip Allport, O. Schaile, O. Runolfsson, Gideon Alexander, P. Kyberd, N. Lupu, Paolo Capiluppi, A. Buijs, A. A. Macbeth, G. W. Wilson, M. Hauschild, C. J. Virtue, Terry Richard Wyatt, M. Coupland, Achim Müller, C. Wahl, C. P. Howarth, J. E. Pilcher, Michael Dittmar, G. Yekutieli, A. A. Carter, L. Lessard, S. Schreiber, T. J. McMahon, R. K. Carnegie, S. Wotton, J. A. Wilson, W. Schappert, J. von Krogh, J. Raab, P. Ashton, and K. J. Anderson
Subjects: Physics, Nuclear and High Energy Physics, Top quark, Particle physics, High Energy Physics::Lattice, Nuclear Theory, High Energy Physics::Phenomenology, Down quark, Top quark condensate, Omega baryon, Bottom quark, Sigma baryon, Nuclear physics, Quark star, Up quark, High Energy Physics::Experiment, Particle Physics - Experiment
Abstract: We report on a search for new quarks in hadronic Z° decays. From the event shape analysis of a data sample containing 2185 multihadronic annihilation events, we observe no evidence for the top or b' quarks. We derive limits for the top and b' quark masses under the assumption of various possible standard model and non-standard model decay schemes. Our search is sensitive to quark masses larger than 23 GeV/c2; it yields the following lower limits at a 95% confidence level: 44.5 GeV/c2 for the top quark mass and 45.2 GeV/c2 for the b′ quark mass.
Published: 1989

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31 results on '"J. C. Armitage"'

1. A plastic scintillator-based muon tomography system with an integrated muon spectrometer

2. Development of gas microstrip detectors for digital X-ray imaging and radiation dosimetry

3. Results for electrons from the 1995 ATLAS forward calorimeter prototype testbeam

4. Construction, commissioning and first data from the CRIPT muon tomography project

5. Machine learning for the cosmic ray inspection and passive tomography project (CRIPT)

6. Passivation of gas microstrip detectors and stability of long-term operation

7. Gas microstrip detectors on resistive plastic substrates

8. Cosmic ray muon tomography system using drift chambers for the detection of Special Nuclear Materials

9. Measurement of three-jet distributions sensitive to the gluon spin ine + e − annihilations at $$\sqrt s = 91$$ GeV

10. Measurement of branching ratios and τ polarization from τ→eνν−,τ→μνν−,andτ→π(K)ν decays at LEP

11. A search for scalar leptoquarks in Z0 decays

12. Measurement of theZ 0 line shape parameters and the electroweak couplings of charged leptons

13. A study of - in Z0 decays

14. A measurement of energy correlations and a determination of αs(M2Z) e+e- annihilations at √s=91 GeV

15. Measurements of the decay of the Z0 into lepton pairs

16. The OPAL vertex drift chamber

17. Digital X-ray imaging using gas microstrip detectors

18. FIRST IMAGES FROM THE CRIPT MUON TOMOGRAPHY SYSTEM

19. Decay mode independent search for a light Higgs boson and new scalars

20. A study of Bose-Einstein correlations in $e^{+}e^{-}$ annihilations at LEP

21. A study of $K_{S}^{0}$ production in $Z^{0}$ decays

22. Drift velocity measurement using MSGCs in a test beam

23. Exclusive Production ofK+K−π+π−in Photon-Photon Collisions

24. Measurement of the total hadronic cross section in virtual photon-photon interactions

25. Measurements of the anisotropy ratio between longitudinal and transverse diffusion in argon based gas mixtures

26. The OPAL vertex detector prototype

27. A study of the effect of methane and carbon dioxide concentration on gas amplification in argon based gas mixtures

28. Leptonic structure functions of the photon

29. Mass limits for a standard model Higgs boson in e+e- collisions at LEP

30. A search for acoplanar pairs of leptons or jets in Z0 decays: mass limits on supersymmetric particles

31. A search for the top and b' quarks in hadronic Z0 decays

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31 results on '"J. C. Armitage"'

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