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

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

2. 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

3. Fabrication and test beam operation of plastic MSGCs

Author

M. Salomon, G.C. Stuart, P. G. Estabrooks, T.D. Nichols, S.C. Taylor, J. C. Armitage, M. S. Dixit, J. Dubeau, J. P. Martin, Louis-Andre Hamel, and F. G. Oakham

Subjects
Nuclear and High Energy Physics, Fabrication, Materials science, business.industry, Amplifier, Detector, Atomic and Molecular Physics, and Optics, Microstrip, law.invention, Telescope, law, UPILEX, Optoelectronics, business, Lithography, Beam (structure)
Abstract

MicroStrip Gas Counters (MSGCs) have been fabricated with gold electrodes on ion-implanted Upilex (polyimide) using both wet-etch and lift-off processes. The quality of lithography from the wet-etch process has now improved to the point where there is less than one defect per (5 cm × 2 cm) print. Recently, four of these detectors were operated as a beam telescope at TRIUMF. They were read out through fast low-noise amplifiers into 100 MHz flash-ADCs and data are presented here on their efficiency, timing, and spatial resolution.

Published
1995

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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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