Large-volume liquid scintillator detectors with ultra-low background levels have been widely used to study neutrino physics and search for dark matter.Event vertex and event time are not only useful for event selectio...Large-volume liquid scintillator detectors with ultra-low background levels have been widely used to study neutrino physics and search for dark matter.Event vertex and event time are not only useful for event selection but also essential for the reconstruction of event energy.In this study,four event vertex and event time reconstruction algorithms using charge and time information collected by photomultiplier tubes were analyzed comprehensively.The effects of photomultiplier tube properties were also investigated.The results indicate that the transit time spread is the main effect degrading the vertex reconstruction,while the effect of dark noise is limited.In addition,when the event is close to the detector boundary,the charge information provides better performance for vertex reconstruction than the time information.展开更多
Background It is imperative that high-quality data should be accumulated to guarantee the correctness and accuracy of physics results in particle physics experiments.The top-up injection of BEPCII has achieved a defini...Background It is imperative that high-quality data should be accumulated to guarantee the correctness and accuracy of physics results in particle physics experiments.The top-up injection of BEPCII has achieved a definite improvement in integrated luminosity,but simultaneously has an obvious impact on the background level of the data acquired by the BESIII detector due to frequent beam injections.Methods An online trigger veto and an offline eventfilter have been developed and applied to eliminate the contaminated events from the data samples for physics research.Results and Conclusion The design and implementation of offline eventfilter are described in this article.The upgraded offline data processing procedure with offline eventfilter was executed smoothly in recent years and ensured data acquisition and processing with optimal efficiency and sufficient quality in BESIII experiment.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11805294 and 11975021)the China Postdoctoral Science Foundation(2018M631013),the Strategic Priority Research Program of Chinese Academy of Sciences(XDA10010900)+1 种基金the Fundamental Research Funds for the Central Universities,Sun Yatsen University(19lgpy268)in part by the CAS Center for Excellence in Particle Physics(CCEPP).
文摘Large-volume liquid scintillator detectors with ultra-low background levels have been widely used to study neutrino physics and search for dark matter.Event vertex and event time are not only useful for event selection but also essential for the reconstruction of event energy.In this study,four event vertex and event time reconstruction algorithms using charge and time information collected by photomultiplier tubes were analyzed comprehensively.The effects of photomultiplier tube properties were also investigated.The results indicate that the transit time spread is the main effect degrading the vertex reconstruction,while the effect of dark noise is limited.In addition,when the event is close to the detector boundary,the charge information provides better performance for vertex reconstruction than the time information.
基金supported in part by National Key R&D Program of China under Contract No.2020YFA0406304National Natural Science Foundation of China(NSFC)under Contracts Nos.U1832204,11875277,11575222.
文摘Background It is imperative that high-quality data should be accumulated to guarantee the correctness and accuracy of physics results in particle physics experiments.The top-up injection of BEPCII has achieved a definite improvement in integrated luminosity,but simultaneously has an obvious impact on the background level of the data acquired by the BESIII detector due to frequent beam injections.Methods An online trigger veto and an offline eventfilter have been developed and applied to eliminate the contaminated events from the data samples for physics research.Results and Conclusion The design and implementation of offline eventfilter are described in this article.The upgraded offline data processing procedure with offline eventfilter was executed smoothly in recent years and ensured data acquisition and processing with optimal efficiency and sufficient quality in BESIII experiment.
