Software alignment is quite important for a tracking detector to reach its ultimate position accuracy and momentum resolution. We developed a new alignment algorithm for the BESⅢ Main Drift Chamber using the Kalman F...Software alignment is quite important for a tracking detector to reach its ultimate position accuracy and momentum resolution. We developed a new alignment algorithm for the BESⅢ Main Drift Chamber using the Kalman Filter method. Two different types of data which are helix tracks and straight tracks are used to test this algorithm, and the results show that the design and implementation is successful.展开更多
Based on real data, a new parameterized model of the main drift chamber response is proposed. In this model, we tune the ratio of good hits and the residual distribution separately. By data quality checking, the difer...Based on real data, a new parameterized model of the main drift chamber response is proposed. In this model, we tune the ratio of good hits and the residual distribution separately. By data quality checking, the diference between simulation and data in track reconstruction efciency reduces from 1% to 0.5% averagely for the pion in J/ψ→π＋π π0, and the momentum resolution agreement improves significantly for the proton in J/ψ→ppˉ.展开更多
A method to determine precisely three-dimensional wire positions in the BESⅢ drift chamber using physics events is introduced. In part the proposed technique takes advantage of the possibility that the magnetic field...A method to determine precisely three-dimensional wire positions in the BESⅢ drift chamber using physics events is introduced. In part the proposed technique takes advantage of the possibility that the magnetic field can be turned off, thereby providing a huge sample of straight tracks for which effects due to multiple scattering, energy loss and non-uniformity of the magnetic field are minimized during the calibration process. A toy Monte Carlo study is performed to demonstrate the viability of the method. As a result of the calibration process, the rms of the distribution of wire position deviation is reduced from 35 μm to 10 μm.展开更多
The BESⅢ drift chamber and its subsystems need a cosmic-ray test after the chamber construction to check the chamber construction quality,testing the joint operation of the whole system and the performance of the cha...The BESⅢ drift chamber and its subsystems need a cosmic-ray test after the chamber construction to check the chamber construction quality,testing the joint operation of the whole system and the performance of the chamber.The noise performance,drift time and charge measurements,and the scanning of channels were examined specifically.The preliminary results of the test indicate that the whole system works well.展开更多
After examination of the designed high voltage power supply system of the BESⅢ drift chamber in the beam test of the full length prototype of drift chamber, a full system covering all the channels of high voltage was...After examination of the designed high voltage power supply system of the BESⅢ drift chamber in the beam test of the full length prototype of drift chamber, a full system covering all the channels of high voltage was installed. The system＇s training and the high voltage value adjustment were carried out in the cosmic ray test of the BESⅢ drift chamber. The cosmic ray test for the full system and its final installation on the BESⅢ drift chamber were reported. The full system of high voltage power supply works stably and reliably.展开更多
Offiine calibration plays an important role in BESⅢ offiine data processing. In order to achieve good spatial and momentum resolution, it is necessary to implement high precision offline calibration for the BESⅢ dri...Offiine calibration plays an important role in BESⅢ offiine 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 （｜cosθ｜ 〈0.8） from a J/ψ data set taken in 2012. The average spatial resolution is 123 μm and the momentum resolution for 1.548 GeV/c Bhabha tracks is 11.9 MeV/c.展开更多
A track fitting algorithm based on the Kalman filter method has been developed for BESⅢ of BEPCⅡ. The effects of multiple scattering and energy loss when the charged particles go through the detector, non-uniformity...A track fitting algorithm based on the Kalman filter method has been developed for BESⅢ of BEPCⅡ. The effects of multiple scattering and energy loss when the charged particles go through the detector, non-uniformity of magnetic field （NUMF） and wire sag, etc., have been carefully handled. This algorithm works well and the performance satisfies the physical requirements tested by the simulation data.展开更多
基金Supported by CAS Knowledge Innovation Project (U-602, U-34)National Natural Science Foundation of China (10491300,10491303, 10605030)100 Talents Program of CAS (U-25, U-54)
文摘Software alignment is quite important for a tracking detector to reach its ultimate position accuracy and momentum resolution. We developed a new alignment algorithm for the BESⅢ Main Drift Chamber using the Kalman Filter method. Two different types of data which are helix tracks and straight tracks are used to test this algorithm, and the results show that the design and implementation is successful.
基金Supported by Ministry of Science and Technology of China(2009CB825200)Joint Funds of National Natural Science Foundation of China(11079008,U1232201)+1 种基金Natural Science Foundation of China(11275266,11205184,11205182,11275210)SRF for ROCS of SEM
文摘Based on real data, a new parameterized model of the main drift chamber response is proposed. In this model, we tune the ratio of good hits and the residual distribution separately. By data quality checking, the diference between simulation and data in track reconstruction efciency reduces from 1% to 0.5% averagely for the pion in J/ψ→π＋π π0, and the momentum resolution agreement improves significantly for the proton in J/ψ→ppˉ.
基金BEPCⅡ/BESⅢ Construction Project and Knowledge Innovation Project of Chinese Academy of Sciences(U-602,U-34(IHEP))
文摘A method to determine precisely three-dimensional wire positions in the BESⅢ drift chamber using physics events is introduced. In part the proposed technique takes advantage of the possibility that the magnetic field can be turned off, thereby providing a huge sample of straight tracks for which effects due to multiple scattering, energy loss and non-uniformity of the magnetic field are minimized during the calibration process. A toy Monte Carlo study is performed to demonstrate the viability of the method. As a result of the calibration process, the rms of the distribution of wire position deviation is reduced from 35 μm to 10 μm.
文摘The BESⅢ drift chamber and its subsystems need a cosmic-ray test after the chamber construction to check the chamber construction quality,testing the joint operation of the whole system and the performance of the chamber.The noise performance,drift time and charge measurements,and the scanning of channels were examined specifically.The preliminary results of the test indicate that the whole system works well.
文摘After examination of the designed high voltage power supply system of the BESⅢ drift chamber in the beam test of the full length prototype of drift chamber, a full system covering all the channels of high voltage was installed. The system＇s training and the high voltage value adjustment were carried out in the cosmic ray test of the BESⅢ drift chamber. The cosmic ray test for the full system and its final installation on the BESⅢ drift chamber were reported. The full system of high voltage power supply works stably and reliably.
基金Supported by National Natural Science Foundation of China(11205184,11205182,11121092,11179020)Joint Funds of National Natural Science Foundation of China(U1232201)
文摘Offiine calibration plays an important role in BESⅢ offiine 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 （｜cosθ｜ 〈0.8） from a J/ψ data set taken in 2012. The average spatial resolution is 123 μm and the momentum resolution for 1.548 GeV/c Bhabha tracks is 11.9 MeV/c.
基金Supported by CAS Knowledge Innovation Project(U-602, U-34)National Natural Science Foundation of China (10491300,10491303, 10605030)100 Talents Program of CAS (U-25, U-54)
文摘A track fitting algorithm based on the Kalman filter method has been developed for BESⅢ of BEPCⅡ. The effects of multiple scattering and energy loss when the charged particles go through the detector, non-uniformity of magnetic field （NUMF） and wire sag, etc., have been carefully handled. This algorithm works well and the performance satisfies the physical requirements tested by the simulation data.
