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Measurement of the Associated $γ+ μ^\pm$ Production Cross Section in $p \bar p$ Collisions at $\sqrt{s} = 1.8$ TeV

ArXiv hep-ex/9902001 (1999)

Aging study of a gas electron multiplier detector with microstrip gas chamber readout

IEEE Nuclear Science Symposium and Medical Imaging Conference 1 (1999) 598-602

Authors:

J Miyamoto, IPJ Shipsey

Abstract:

The aging behavior of wire chambers have been of great interest for many years. Recently a new generation of proportional chambers have been developed including the microstrip gas chamber (MSGC) microgap chamber (MGC) and gaseous electron multiplier (GEM). Aging studies of these detectors are of particular interest to the LHC (Large Hadron Collider) community because the baseline design of the CMS experiment includes MSGCs as part of the tracking system. We have performed an aging study of a GEM detector readout with a MSGC. The GEM is constructed from Kapton and copper, the MSGC is constructed from semiconductive glass and gold. When the detector is operated in argon and dimethyl ether (DME) gas mixture and irradiated with a 6 KeV photon beam, about 220 mC/cm of charge can be accumulated without degradation of the detector performance. This corresponds to about 20 years of operation at the LHC.

First Observation of the Decay τ- → K*-η ντ

Physical Review Letters 82:2 (1999) 281-285

Authors:

M Bishai, S Chen, J Fast, JW Hinson, N Menon, DH Miller, EI Shibata, IPJ Shipsey, S Glenn, Y Kwon, AL Lyon, S Roberts, EH Thorndike, CP Jessop, K Lingel, H Marsiske, ML Perl, V Savinov, D Ugolini, X Zhou, TE Coan, V Fadeyev, I Korolkov, Y Maravin, I Narsky, R Stroynowski, J Ye, T Wlodek, M Artuso, E Dambasuren, S Kopp, GC Moneti, R Mountain, S Schuh, T Skwarnicki, S Stone, A Titov, G Viehhauser, JC Wang, J Bartelt, SE Csorna, KW Mc Lean, S Marka, Z Xu, R Godang, K Kinoshita, IC Lai, P Pomianowski, S Schrenk, G Bonvicini, D Cinabro, R Greene, LP Perera, GJ Zhou, S Chan, G Eigen, E Lipeles, JS Miller, M Schmidtler, A Shapiro, WM Sun, J Urheim, AJ Weinstein, F Würthwein, DE Jaffe, G Masek, HP Paar, EM Potter, S Prell, V Sharma, DM Asner, J Gronberg, TS Hill, DJ Lange, RJ Morrison, HN Nelson, TK Nelson, D Roberts, BH Behrens, WT Ford, A Gritsan, H Krieg, J Roy, JG Smith, JP Alexander, R Baker, C Bebek, BE Berger, K Berkelman, V Boisvert, DG Cassel, DS Crowcroft, M Dickson, S Von Dombrowski, PS Drell, KM Ecklund, R Ehrlich, AD Foland, P Gaidarev, RS Galik

Abstract:

The decay τ-→ K*- η ν τ has been observed with the CLEO II detector. The K*- is reconstructed in two decay channels, K*-→ KSπ-→π+π- and K*-→ K-π0. The η is reconstructed from the decay η → γγ. The measured branching fraction isB(τ-→ K*-π η ντ)=(2.9 ± 0.8 ±0.4) × 10-44. We also measure the inclusive branching fractions without requiring the K* resonance, B(τ-→ KSπ- η ντ)=(1.10 ± 0.35 ±0.11) × 10-4 and B(τ-→ K-π0 η ντ)=(1.77 ± 0.56 ±0.71) × 10-4. The results indicate that the K*- resonance dominates the KSπ- mass spectrum. © 2000 The American Physical Society.

First Observations of ϒ(1S)→γπ+π- and ϒ(1S)→γπ+π0π0

Physical Review Letters 82:2 (1999) 286-290

Authors:

A Anastassov, JE Duboscq, KK Gan, T Hart, K Honscheid, H Kagan, R Kass, J Lee, H Schwarthoff, A Wolf, MM Zoeller, SJ Richichi, H Severini, P Skubic, A Undrus, M Bishai, S Chen, J Fast, JW Hinson, N Menon, DH Miller, EI Shibata, IPJ Shipsey, S Glenn, Y Kwon, AL Lyon, S Roberts, EH Thorndike, CP Jessop, K Lingel, H Marsiske, ML Perl, V Savinov, D Ugolini, X Zhou, TE Coan, V Fadeyev, I Korolkov, Y Maravin, I Narsky, R Stroynowski, J Ye, T Wlodek, M Artuso, E Dambasuren, S Kopp, GC Moneti, R Mountain, S Schuh, T Skwarnicki, S Stone, A Titov, G Viehhauser, JC Wang, J Bartelt, SE Csorna, KW Mc Lean, S Marka, Z Xu, R Godang, K Kinoshita, IC Lai, P Pomianowski, S Schrenk, G Bonvicini, D Cinabro, R Greene, LP Perera, GJ Zhou, S Chan, G Eigen, E Lipeles, JS Miller, M Schmidtler, A Shapiro, WM Sun, J Urheim, AJ Weinstein, F Würthwein, DE Jaffe, G Masek, HP Paar, EM Potter, S Prell, V Sharma, DM Asner, J Gronberg, TS Hill, DJ Lange, RJ Morrison, HN Nelson, TK Nelson, D Roberts, BH Behrens, WT Ford, A Gritsan, H Krieg, J Roy, JG Smith, JP Alexander

Abstract:

We report on a study of exclusive radiative decays of the ϒ(1S) resonance collected with the CLEO II detector operating at the Cornell Electron Storage Ring. We present the first observation of the radiative decays ?(1S)→γπ+#x03C0;- and ϒ(1S)→ γ #x03C0;0#x03C0;0. For the dipion mass regime m#x03C0;#x03C0; > 1.0 GeV we obtain B(ϒ(1S)→ γ#x03C0;+#x03C0;-)=(6.3±1.2±1.3)×10-5 and B(ϒ(1S)→ γ#x03C0;0#x03C0;0)=(1.7±0.6±0.3)×10-5. © 2000 The American Physical Society.

The measurement of sin(2β)

Proceedings of Science 3 (1999)

Abstract:

Since the first observation in 1964, CP violation remains one of the most elusive aspects of the standard model. The CDF collaboration has reported the first evidence of CP violation in the B system using the world's largest sample of B → J/ψKS0 decays. The direct measurement of sin(2β)=0.79+0.41−0.44(combined statistical and systematic error) agrees with the standard model predictions. New data collected from the B-factories and from the upgraded experiments at the Tevatron should allow a more precise measurement of sin 2β in the near future.