The building of a large-scale external-target experiment, abbreviated as CEE, in the cooling storage ring at the Heavy Ion Research Facility in Lanzhou has been planned. The CEE is a multi-purpose spectrometer that wi...The building of a large-scale external-target experiment, abbreviated as CEE, in the cooling storage ring at the Heavy Ion Research Facility in Lanzhou has been planned. The CEE is a multi-purpose spectrometer that will be used for various studies on heavy-ion collisions. A multi-wire drift chamber(MWDC) array is the forward tracking detector of the CEE. In this work, GEANT4 simulations were performed for the MWDC forward tracking array with a focus on the track reconstruction algorithm. Combined with the time of flight information,particle identification is achieved. The residue is about 30 μm, while the tracking efficiency is higher than 90%with the current redundancy. In addition, a prototype of the forward tracking system using three MWDCs was assembled and tested using a high-energy proton beam. The firing efficiency of the detector and the reconstruction accuracy of the prototype were derived. The track residue for the protons at about 400 MeV/c is better than 300 μm, meeting the requirements of the CEE. Suggestions for improving the performance of the forward tracking system are given.展开更多
A new inner drift chamber has been built which can replace the aged part of the BESIII drift chamber when needed. The design of the new inner drift chamber can minimize the ineffective area in the very forward and bac...A new inner drift chamber has been built which can replace the aged part of the BESIII drift chamber when needed. The design of the new inner drift chamber can minimize the ineffective area in the very forward and backward region and hence reduce the background event rate. With this design, the new inner drift chamber is expected to have a longer lifetime and improved performance due to the lower occupancy. The endplates and the cylinder were machined with high precision. Wire stringing was performed after the mechanical structure was assembled, and good quality of wire stringing was ensured by measurement of the tension and leakage current of the wires. After completion of the physical construction of the new chamber, a cosmic-ray test was carried out to test its performance. The results of the cosmic-ray test show that the new inner chamber achieves a spatial resolution of127 μm and a d E/dx resolution of 6.4%, which satisfies the design specifications.展开更多
As the main tracking detector of BESIII, the drift chamber provides accurate measurements of the position and the momentum of the charged particles produced in e+e- collisions at BEPCII. After six years of operation,...As the main tracking detector of BESIII, the drift chamber provides accurate measurements of the position and the momentum of the charged particles produced in e+e- collisions at BEPCII. After six years of operation, the drift chamber is suffering from aging problems due to huge beam-related background. The gains of the cells in the first ten layers show an obvious decrease, reaching a maximum decrease of about 29% for the first layer cells. Two calculation methods for the gain change (Bhabha events and accumulated charges with 0.3% aging ratio for inner chamber cells) give almost the same results. For the Malter effect encountered by the inner drift chamber in January 2012, about 0.2% water vapor was added to the MDC gas mixture to solve this cathode aging problem. These results provide an important reference for MDC operating high voltage settings and the upgrade of the inner drift chamber.展开更多
Background The multilayer drift chamber(MDC)is one of the key detectors at the BESIII,which is mainly responsible for the precise measurement of charged particles.High reconstruction efficiency of charged particles wi...Background The multilayer drift chamber(MDC)is one of the key detectors at the BESIII,which is mainly responsible for the precise measurement of charged particles.High reconstruction efficiency of charged particles with a wide range of momentums is a basic requirement for the MDC reconstruction software.Purpose The purpose is to improve the tracking efficiency at the low transverse momentum region.Methods The Hough transform is a mathematical method that can map hits in a detector to parameter space to find tracks globally.In this paper,we have used it as the basis for developing a new tracking algorithm to find tracks in MDC.In addition,the drift distances of hits are considered when implementing Hough transform.Results This tracking algorithm is implemented in the BESIII offline software system,and its performance is checked using both Monte Carlo and data.The results show that this tracking method improves reconstruction efficiency at the low transverse momentum region.Conclusions The tracking algorithm based on Hough transform is proved to be beneficial for the MDC low transverse momentum tracking,and has been used in BESIII offline data reconstruction .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
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
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 Flash-ADC data acquisition (DAQ) system has been developed for the drift chamber array designed for the External-Target-Experiment at the Cooling Storage Ring at the Heavy Ion Research Facility, Lanzhou. The simpl...A Flash-ADC data acquisition (DAQ) system has been developed for the drift chamber array designed for the External-Target-Experiment at the Cooling Storage Ring at the Heavy Ion Research Facility, Lanzhou. The simplified readout electronics system has been developed using the Flash-ADC modules and the whole waveform in the sampling window is obtained, with which the time and energy information can be deduced with an offiine processing. A digital filter algorithm has been developed to discriminate the noise and the useful signal. With the digital filtering process, the signal to noise ratio (SNR) is increased and a better time and energy resolution can be obtained.展开更多
After the construction of the BESⅢ drift chamber, a long period of cosmic rays test is necessary to verify its performance. This also provides a good opportunity to integrate the detector readout electronics and Dete...After the construction of the BESⅢ drift chamber, a long period of cosmic rays test is necessary to verify its performance. This also provides a good opportunity to integrate the detector readout electronics and Detector Control System (DCS) into a unified working system. The goal of the DCS is to guarantee reliable physics data quality and the safe operation of the detector. It monitors and controls the HV, gas, VME crates and the environmental variables. The upper-level system is mainly developed from LabVIEW and the lower-level system mainly uses MCU and PLC technology. The system is designed to be highly flexible and scalable so that it can be applied to other detectors with little or no change. In the immediate future, it will be integrated into the entire BESⅢ Slow Control System.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
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
基金supported by the National Basic Research Program of China(973)(No.2015CB856903)the National Science Foundation of China(No.U1332207)
文摘The building of a large-scale external-target experiment, abbreviated as CEE, in the cooling storage ring at the Heavy Ion Research Facility in Lanzhou has been planned. The CEE is a multi-purpose spectrometer that will be used for various studies on heavy-ion collisions. A multi-wire drift chamber(MWDC) array is the forward tracking detector of the CEE. In this work, GEANT4 simulations were performed for the MWDC forward tracking array with a focus on the track reconstruction algorithm. Combined with the time of flight information,particle identification is achieved. The residue is about 30 μm, while the tracking efficiency is higher than 90%with the current redundancy. In addition, a prototype of the forward tracking system using three MWDCs was assembled and tested using a high-energy proton beam. The firing efficiency of the detector and the reconstruction accuracy of the prototype were derived. The track residue for the protons at about 400 MeV/c is better than 300 μm, meeting the requirements of the CEE. Suggestions for improving the performance of the forward tracking system are given.
文摘A new inner drift chamber has been built which can replace the aged part of the BESIII drift chamber when needed. The design of the new inner drift chamber can minimize the ineffective area in the very forward and backward region and hence reduce the background event rate. With this design, the new inner drift chamber is expected to have a longer lifetime and improved performance due to the lower occupancy. The endplates and the cylinder were machined with high precision. Wire stringing was performed after the mechanical structure was assembled, and good quality of wire stringing was ensured by measurement of the tension and leakage current of the wires. After completion of the physical construction of the new chamber, a cosmic-ray test was carried out to test its performance. The results of the cosmic-ray test show that the new inner chamber achieves a spatial resolution of127 μm and a d E/dx resolution of 6.4%, which satisfies the design specifications.
基金Supported by the CAS Center for Excellence in Particle Physics(CCEPP)
文摘As the main tracking detector of BESIII, the drift chamber provides accurate measurements of the position and the momentum of the charged particles produced in e+e- collisions at BEPCII. After six years of operation, the drift chamber is suffering from aging problems due to huge beam-related background. The gains of the cells in the first ten layers show an obvious decrease, reaching a maximum decrease of about 29% for the first layer cells. Two calculation methods for the gain change (Bhabha events and accumulated charges with 0.3% aging ratio for inner chamber cells) give almost the same results. For the Malter effect encountered by the inner drift chamber in January 2012, about 0.2% water vapor was added to the MDC gas mixture to solve this cathode aging problem. These results provide an important reference for MDC operating high voltage settings and the upgrade of the inner drift chamber.
基金Funding was provided by National Key Basic Research Program of China under Contract No.2015CB856706National Natural Science Foundation of China(NSFC)under Contracts Nos.11475208,11775245,11335009,U1632106,11575222Chinese Academy of Sciences(CAS)President’s International Fellowship Initiative under Contract No.2018PM0004.
文摘Background The multilayer drift chamber(MDC)is one of the key detectors at the BESIII,which is mainly responsible for the precise measurement of charged particles.High reconstruction efficiency of charged particles with a wide range of momentums is a basic requirement for the MDC reconstruction software.Purpose The purpose is to improve the tracking efficiency at the low transverse momentum region.Methods The Hough transform is a mathematical method that can map hits in a detector to parameter space to find tracks globally.In this paper,we have used it as the basis for developing a new tracking algorithm to find tracks in MDC.In addition,the drift distances of hits are considered when implementing Hough transform.Results This tracking algorithm is implemented in the BESIII offline software system,and its performance is checked using both Monte Carlo and data.The results show that this tracking method improves reconstruction efficiency at the low transverse momentum region.Conclusions The tracking algorithm based on Hough transform is proved to be beneficial for the MDC low transverse momentum tracking,and has been used in BESIII offline data reconstruction .
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.
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 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Supported by National Basic Research Program of China(973)(2015CB856903 and 2014CB845405)partly by National Science Foundation of China(U1332207 and 11375094)by Tsinghua University Initiative Scientific Research Program
文摘A Flash-ADC data acquisition (DAQ) system has been developed for the drift chamber array designed for the External-Target-Experiment at the Cooling Storage Ring at the Heavy Ion Research Facility, Lanzhou. The simplified readout electronics system has been developed using the Flash-ADC modules and the whole waveform in the sampling window is obtained, with which the time and energy information can be deduced with an offiine processing. A digital filter algorithm has been developed to discriminate the noise and the useful signal. With the digital filtering process, the signal to noise ratio (SNR) is increased and a better time and energy resolution can be obtained.
文摘After the construction of the BESⅢ drift chamber, a long period of cosmic rays test is necessary to verify its performance. This also provides a good opportunity to integrate the detector readout electronics and Detector Control System (DCS) into a unified working system. The goal of the DCS is to guarantee reliable physics data quality and the safe operation of the detector. It monitors and controls the HV, gas, VME crates and the environmental variables. The upper-level system is mainly developed from LabVIEW and the lower-level system mainly uses MCU and PLC technology. The system is designed to be highly flexible and scalable so that it can be applied to other detectors with little or no change. In the immediate future, it will be integrated into the entire BESⅢ Slow Control System.
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 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.