Huai-Min Liu

Study of Photon Detection Efficiency and Position Resolution of BESIII Electromagnetic Calorimeter

We study the photon detection efficiency and position resolution of the electromagnetic calorimeter (EMC) of the BESIII experiment. The control sample of the initial-state-radiation (ISR) process of (e^+e^-rightarrow gamma mu ^+mu ^-) is used at (J/psi ) and (psi (3770)) resonances for the EMC calibration and photon detection efficiency study. Photon detection efficiency is defined as the predicted photon, obtained by performing a kinematic fit with two muon tracks, matched with real photons in the EMC. The spatial resolution of the EMC is defined as the separation in polar ((theta )) and azimuthal ((phi )) angles between charged track and associated cluster centroid on the front face of the EMC crystals.

A study of aging effects of barrel Time-Of-Flight system in the BESIII experiment

Abstract The Time-Of-Flight system consisting of plastic scintillation counters plays an important role for particle identification in the BESIII experiment at the BEPCII double ring e + e − collider. Degradation of the detection efficiency of the barrel TOF system has been observed since the start of physical data taking and this effect has triggered intensive and systematic studies about aging effects of the detector. The aging rates of the attenuation lengths and relative gains are obtained based on the data acquired in past several years. This study is essential for ensuring an extended operation of the barrel TOF system in optimal conditions.

Monte-Carlo study of the MRPC prototype for the upgrade of BESIII

A GEANT4-based simulation is developed for the endcap time of flight (ETOF) upgrade based on multi-gap resistive plate chambers (MRPC) for the BESIII experiment. The MRPC prototype and the simulation method are described. Using a full Monte-Carlo simulation, the influence of high voltage and threshold on time resolution and detection efficiency are investigated. The preliminary results from simulation are presented and are compared with the experimental data taken with the prototype MRPC modules.

Track segment finding with CGEM-IT and matching to outer drift chamber tracks in the BESIII detector

The relative differences in coordinates of Cylindrical Gas Electron Multiplier Detector-based Inner Tracker (CGEM-IT) clusters are studied to search for track segments in CGEM-IT for the BESIII experiment. With the full simulation of single muon track samples, clear patterns are found and parameterized for the correct cluster combinations. The cluster combinations satisfying the patterns are selected as track segment candidates in CGEM-IT with an efficiency higher than 99%. The parameters of the track segments are obtained by a helix fitting. Some χ2 quantities, evaluating the differences in track parameters between the track segments in CGEM-IT and the tracks found in the outer drift chamber, are calculated and used to match them. Proper χ2 requirements are determined as a function of transverse momentum and the matching efficiency is found to be reasonable.

Radiation studies for the MOMENT target station

The discovery of the neutrino mixing angle θ13 opens new opportunities for the discovery of leptonic CP violation at high intensity neutrino beams. MOMENT, a future neutrino facility with a high-power proton beam of 15 MW from a continuous-wave linac, is focused on that discovery. The high power of the proton beam causes extreme radiation conditions for the facility and especially for the target station, where the pion capture system of five superconducting solenoids is located. In this paper initial studies are performed for the effects of the radiation on the solenoid structure and the area surrounding it. A concept cooling system is also proposed.

Study of cluster reconstruction and track fitting algorithms for CGEM-IT at BESIII

Considering the aging effects of existing Inner Drift Chamber (IDC) of BESuppercaseexpandafter{romannumeral3}, a GEM based inner tracker is proposed to be designed and constructed as an upgrade candidate for IDC. This paper introduces a full simulation package of CGEM-IT with a simplified digitization model, describes the development of the softwares for cluster reconstruction and track fitting algorithm based on Kalman filter method for CGEM-IT. Preliminary results from the reconstruction algorithms are obtained using a Monte Carlo sample of single muon events in CGEM-IT.

Study of photon detection efficiency and position resolution of BESIII electromagnetic calorimeter

We study the photon detection efficiency and position resolution of the electromagnetic calorimeter (EMC) of the BESIII experiment. The control sample of the initial-state-radiation (ISR) process of (e^+e^-rightarrow gamma mu ^+mu ^-) is used at (J/psi ) and (psi (3770)) resonances for the EMC calibration and photon detection efficiency study. Photon detection efficiency is defined as the predicted photon, obtained by performing a kinematic fit with two muon tracks, matched with real photons in the EMC. The spatial resolution of the EMC is defined as the separation in polar ((theta )) and azimuthal ((phi )) angles between charged track and associated cluster centroid on the front face of the EMC crystals.

Calibration study of the X-T relation for the BESIII drift chamber

This paper introduces the calibration of the time-to-distance relation for the BESIII drift chamber. The parameterization of the time-to-distance relation is presented. The studies of left-right asymmetry and the variation with the entrance angle are performed. The impact of dead channels on the time-to-distance relation is given special attention in order to reduce the shifts of the measured momenta for the tracks passing near dead cells. Finally we present the spatial resolution (123 {mu}m) for barrel Bhabha events (|cos{theta}|<0.8) from J/{psi} data taken in 2012.Offline calibration plays an important role in BESIII offline data processing. In order to achieve good spatial and momentum resolution, it is necessary to implement high precision offline calibration for the BESIII drift chamber. This paper studies the time-to-distance relations, which are important calibration constants for track reconstruction. The parameterization of the time-to-distance relation, studies of left-right asymmetry and studies of variation with entrance angle are performed. The impact of dead channels on the time-to-distance relation is given special attention in order to reduce the shift in measured momentum for tracks passing near dead cells. Finally. we present the resolutions for barrel Bhabha events (vertical bar cos theta vertical bar < 0.8) from a J/psi data set taken in 2012. The average spatial resolution is 123 mu m and the momentum resolution for 1.548 GeV/c Bhabha tracks is 11.9 MeV/c.

Monte Carlo tuning for the BESIII time-of-flight system

Using experimental data, Monte Carlo tuning is implemented for performance parameters associated with the scintillation counters and readout electronics of the BESIII time-of-flight (TOF) system, as part of the full simulation model. The implementation of the tuning is described for simulations designed to reproduce the performance of a number of TOP system parameters, including pulse height, hit efficiency, time resolution, dead channels and background. In addition, comparisons with experimental data are presented.