119439783
The CLEO III ring imaging Cherenkov detector
Abstract The CLEO detector has been upgraded to include a state of the art particle identification system, based on the Ring Imaging Cherenkov detector (RICH) technology, in order to take data at the upgraded CESR electron positron collider. The expected performance as well as the preliminary results are reviewed from an engineering run during the first few months of operation of the CLEO III detector.
209963341
Measurement of B(Upsilon(5S) ---> B(*)(s) anti-B(*)(s)) Using phi Mesons
119969840
First spatial alignment of the LHCb VELO and analysis of beam absorber collision data
A first alignment of the LHCb Vertex Locator has been obtained from beam induced tracks at the LHC. A 450 GeV/c protons were collided on a beam absorber during the LHC synchronisation tests of the anti-clockwise beam in August and September 2008. The resulting particle tracks have been reconstructed by the Vertex Locator. This was the first full reconstruction of tracks induced by the LHC beam. The quality of the data obtained is discussed. A total of 2200 tracks were reconstructed from the full data sample, and a first spatial alignment was obtained. The detector is aligned to an accuracy of Slim in the sensor plane. The results confirm that all detector modules have not been displaced from their surveyed positions by more than 10 mm. (C) 2010 Elsevier B.V. All rights reserved.
42582723
Measurement of the Ds+ - Ds- production asymmetry in 7 TeV pp collisions
Article history: Received 4 May 2012 Received in revised form 30 May 2012 Accepted 1 June 2012 Available online 6 June 2012 Editor: W.-D. Schlatter Heavy quark production in 7 TeV centre-of-mass energy pp collisions at the LHC is not necessarily flavour symmetric. The production asymmetry, AP, between D+s and D−s mesons is studied using the φπ± decay mode in a data sample of 1.0 fb−1 collected with the LHCb detector. The difference between π+ and π− detection efficiencies is determined using the ratios of fully reconstructed to partially reconstructed D∗± decays. The overall production asymmetry in the D±s rapidity region 2.0 to 4.5 with transverse momentum larger than 2 GeV is measured to be AP = (−0.33 ± 0.22 ± 0.10)%. This result can constrain models of heavy flavour production. © 2012 CERN. Published by Elsevier B.V. All rights reserved.
14029193
Performance of the CLEO III LiF-TEA ring imaging Cherenkov detector in a high-energy muon beam
Abstract The CLEO III Ring Imaging Cherenkov detector uses LiF radiators to generate Cherenkov photons which are then detected by proportional wire chambers using a mixture of CH 4 and TEA gases. The first two photon detector modules which were constructed, were taken to the Fermilab and tested in a beam dump that provided high-momentum muons. We report on results using both plane and “sawtooth”–shaped radiators. Specifically, we discuss the number of photoelectrons observed per ring and the angular resolution. The particle separation ability is shown to be sufficient for the physics of CLEO III.
119287240
Searches for Majorana neutrinos in $B^-$ decays
Searches for heavy Majorana neutrinos in B- decays in final states containing hadrons plus a \mu- \mu- pair have been performed using 0.41/fb of data collected with the LHCb detector in proton-proton collisions at a center-of-mass energy of 7 TeV. The D+ \mu- \mu- and D*+ \mu- \mu- final states can arise from the presence of virtual Majorana neutrinos of any mass. Other final states containing \pi+, Ds+, or D0\pi+ can be mediated by an on-shell Majorana neutrino. No signals are found and upper limits are set on Majorana neutrino production as a function of mass, and also on the B- decay branching fractions.
124036431
Studies on electron cloud instability in the BEPC
The Electron Cloud Instability (ECI) may occur in a positively charged particle storage ring when the machine is operated with a multi-bunch beam. The related experiments have been carried out on the Beijing Electron Positron Collider (BEPC) since 1996. The phenomena of the ECI are mainly coupled bunch oscillation and transverse beam size blow up. The ECI studies at the BEPC are reviewed in this paper, both on experiments and on simulations. The potential methods to suppress the ECI in a positron storage ring have been summarized from the studies.
121984352
The BES detector
Abstract The Beijing Spectrometer (BES) is a general purpose solenoidal detector at the Beijing Electron Positron Collider (BEPC). It is designed to study exclusive final states in e + e − annihilations at the center of mass energy from 3.0 to 5.6 GeV. This requires large solid angle coverage combined with good charged particle momentum resolution, good particle identification and high photon detection efficiency at low energies. In this paper we describe the construction and the performance of BES detector.
31953693
Development and Application of Bunch-By-Bunch Measurement System of HLS
This paper is intended to present the newly implemented wideband (100MHz) bunch oscillation measurement system, which is in nature a different method from the narrow-band (< 5MHz) facilities employed before. Basic formalism and implementation details of the system is introduced to illustrate the function of observing coupled bunch instabilities in time and frequency domain. The designed function includes detecting of transverse oscillation, synchrotron phase oscillation, as well as bunch filling pattern. Some diagnostics results of machine instabilities and application of this system are also discussed.
54864896
BEAM INSTABILITIY STUDIES OF BEPC AND BEPCII
BEPC has been well operated for more than 15 years, and it will be upgraded to a double ring electron positron collider in the existing tunnel, namely BEPCII. This paper describes the recent studies on beam instabilities for the improvement of BEPC performance as well as for BEPCII. The instabilities caused by impedance and twostream effects are investigated. The experimental and simulation results are reported.
202135211
Evidence of b-Jet Quenching in PbPb Collisions at $\sqrt{s_{NN}}=2.76$ TeV