Changqiao Li

Perspectives of a mid-rapidity dimuon program at the RHIC: a novel and compact muon telescope detector

Perspectives of a mid-rapidity dimuon program at the RHIC: a novel and compact muon telescope detector L Ruan 1 , G Lin 2 , Z Xu 1 , K Asselta 1 , H F Chen 3 , W Christie 1 , H J Crawford 4 , J Engelage 4 , G Eppley 5 , T J Hallman 1 , C Li 3 , J Liu 5 , W J Llope 5 , R Majka 2 , T Nussbaum 5 , J Scheblein 1 , M Shao 3 , R Soja 1 , Y Sun 3 , Z Tang 3 , X Wang 6 and Y Wang 6 July 17, 2009 This work was supported by the Director, Office of Science, Office of Nuclear Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Beam test results of two kinds of multi-gap resistive plate chambers

Abstract Beam test results of 6- and 10-gap Multi-gap Resistive Plate Chambers (MPRCs) are reported in detail. The corresponding experimental setup at CERN PS-T10 area is explained. The time resolution and detection efficiency of the 6-gap MRPC is around 65 ps , which is good enough for the TOF detector of STAR experiment, while the 10-gap MRPC has a time resolution below 55 ps .

New prototype multi-gap resistive plate chambers with long strips

A new kind of Multi-gap Resistive Plate Chamber (MRPC) has been built for the large-area Muon Telescope Detector (MTD) for the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). These long read-out strip Multi-gap Resistive Plate Chambers (LMRPCs) have an active area of 87.0 � 17.0 cm 2 and ten 250mm-thick gas gaps arranged as a double stack. Each read-out strip is 2.5 cm wide and 90 cm long. The signals are read-out at both ends of each strip. Cosmic ray tests indicate a time resolution of � 70 ps and a detection efficiency of greater than 95%. Beam tests performed at T963 at Fermilab indicate a time resolution of 60–70 ps and a spatial resolution of � 1 cm along the strip direction. & 2008 Elsevier B.V. All rights reserved.

Testing the time resolution of the BESIII end-cap TOF detectors

Modules of the end-cap time-of-flight detector (ETOF) for the Beijing spectrometer upgrade (BESIII) using different types of scintillators, BC408, BC404 and EJ204, were tested with an 800 MeV electron beam. Different wrapping materials were also tested to improve the light collection efficiency and time resolution. The enhanced specular reflector (ESR) film was found to be the best wrapping material. A time resolution of better than 80 ps over the full length of the ETOF module was achieved.

Calibration and performance of the STAR Muon Telescope Detector using cosmic rays

We report the timing and spatial resolution from the Muon Telescope Detector (MTD) installed in the STAR experiment at RHIC. Cosmic ray muons traversing the STAR detector have an average transverse momentum of 6 GeV/c. Due to their very small multiple scattering, these cosmic muons provide an ideal tool to calibrate the detectors and measure their timing and spatial resolution. The values obtained were ∼100 ps and ∼1-2 cm, respectively. These values are comparable to those obtained from cosmic-ray bench tests and test beams.

The ATLAS muon Micromegas R&D project: towards large-size chambers for the s-LHC

Detectors based on the bulk-Micromegas technology exhibit position resolution better than 100 μm at counting rates of up to several tens of kHz/cm2, along with trigger capabilities. These characteristics, combined with the detectors mechanical robustness and the possibility for cost-effective industrial production, makes them a promising candidate for the ATLAS Muon Spectrometer upgrade in a future luminosity enhancement of the LHC. The R&D project status will be presented together with the obtained results in the effort to define the baseline system specifications.

The CBM Time-of-Flight wall — a conceptual design

Charged hadron identification in the Compressed Baryonic Matter experiment (CBM) is realized via the Time-of-Flight method [1]. For this purpose the CBM-ToF collaboration designed a Time-of-Flight wall composed of Multi-gap Resistive Plate Chambers (MRPCs). Due to the high interaction rate in CBM of 10 MHz the key challenge is the development of high rate MRPCs above 25 kHz/cm2 which become possible after the development of low resistive glass with extremely good quality. In this article we present the actual conceptual design of the ToF-wall which is subdivided in three parts namely the outer wall, the inner wall and the forward zone that are discussed in detail.

Candidate magnetic rotation sequence in 86Sr

High-spin states in 86Sr have been investigated by using in-beam γ ray spectroscopy with the 82Se(9Be, 5n)86Sr reaction at a beam energy of 53 MeV. A new dipole sequence has been observed and the mixed configurations of unpaired valence nucleons and before the alignment and the configuration after the alignment are assigned respectively. Shell-model and self-consistent titled axis cranking relativistic mean-field model calculations are performed to interpret the rotational structure and the characteristic features of magnetic rotation have been presented for the sequence.

Monte Carlo simulation study of RPC-based 0.511 MeV photon detector with GEANT4

The Resistive Plate Chambers (RPC) are low-cost charged-particle detectors with good timing resolution and potentially good spatial resolution. Using RPC as gamma detector provides an opportunity for application in positron emission tomography (PET). In this work, we use the GEANT4 simulation package to study various methods improving the detection efficiency of a realistic RPC-based PET model for 511 keV photons, by adding more detection units, changing the thickness of each layer, choosing different converters and using the multi-gaps RPC (MRPC) technique. The balance among these factor is discussed. Its found that although RPC with materials of high atomic number can reach a higher efficiency, they may contribute to a poor spatial resolution and higher background level.

Net charge fluctuations in Au+Au collisions at root s(NN)=130 GeV

We present the results of charged particle fluctuations measurements in Au+Au collisions at We present the results of charged particle fluctuations measurements in Au+Au collisions at √(s NN) = 130 GeV using the STAR detector. Dynamical fluctuations measurements are presented for inclusive charged particle multiplicities as well as for identified charged pions, kaons, and protons. The net charge dynamical fluctuations are found to be large and negative providing clear evidence that positive and negative charged particle production is correlated within the pseudorapidity range investigated. Correlations are smaller than expected based on model-dependent predictions for a resonance gas or a quark-gluon gas which undergoes fast hadronization and freeze-out. Qualitative agreement is found with comparable scaled p+p measurements and a heavy ion jet interaction generation model calculation based on independent particle collisions, although a small deviation from the 1/N scaling dependence expected from this model is observed.We present the results of charged particle fluctuations measurements in Au + Au collisions at