Introduction Electron-neutron detector array(ENDA)is designed to measure thermal neutrons produced by hadronic interactions between cosmic ray extensive air showers(EAS)and the surrounding environment as well as elect...Introduction Electron-neutron detector array(ENDA)is designed to measure thermal neutrons produced by hadronic interactions between cosmic ray extensive air showers(EAS)and the surrounding environment as well as electrons around the cores of EAS.ENDA is located within Large High Altitude Air Shower Observatory(LHAASO).ENDA was expanded from an initial 16 detectors to 64 detectors in April 2023,so-called ENDA-64,and has been running alongside LHAASO.The stability and consistency of neutron detection are crucial for laying a solid foundation for subsequent data analysis and physical results.Methods We obtain the stability by studying variations of event rate and thermal neutron rate in each cluster and the consistency by comparing distribution of number of thermal neutrons between clusters.Additionally,we investigate the specific influences of the rainy and dry seasons,as well as the presence or absence of sand cubes under the detectors,to examine the environmental factors affecting neutron measurement performance.Results The calibration results indicate good consistency in thermal neutron detection across the clusters,with the maximum inconsistency of 6.85%.The maximum instability of event rate and thermal neutron rate over time are 4.68% and 11.0%,respectively.The maximum inconsistency between the clusters without the sand cubes is 18%.The use of sand cubes is effective in protecting the target material from rainwater,and the sand cubes help the cluster to increase collection of neutrons generated by EAS events.展开更多
By accurately measuring composition and energy spectrum of cosmic ray,the origin problem of so called“knee”region(energy>one PeV)can be solved.However,up to the present,the results of the spectrum in the knee reg...By accurately measuring composition and energy spectrum of cosmic ray,the origin problem of so called“knee”region(energy>one PeV)can be solved.However,up to the present,the results of the spectrum in the knee region obtained by several previous experiments have shown obvious differences,so they cannot give effective evidence for judging the theoretical models on the origin of the knee.Recently,the Large High Altitude Air Shower Observatory(LHAASO)has reported several major breakthroughs and important results in astro-particle physics field.Relying on its advantages of wide-sky survey,high altitude location and large area detector arrays,the research content of LHAASO experiment mainly includes ultra high-energy gamma-ray astronomy,measurement of cosmic ray spectra in the knee region,searching for dark matter and new phenomena of particle physics at higher energy.The electron and thermal neutron detector(EN-Detector)is a new scintillator detector which applies thermal neutron detection technology to measure cosmic ray extensive air shower(EAS).This technology is an extension of LHAASO.The EN-Detector Array(ENDA)can highly efficiently measure thermal neutrons generated by secondary hadrons so called“skeleton”of EAS.In this paper,we perform the optimization of ENDA configuration,and obtain expectations on the ENDA results,including thermal neutron distribution,trigger efficiency and capability of cosmic ray composition separation.The obtained real data results are consistent with those by the Monte Carlo simulation.展开更多
基金supported in China by the National Natural Science Foundation of China(NSFC,No.12320101005,No.12263005,No.12373105 and No.12205244)Natural Science Foundation of the Tibet Autonomous Region(grant No.XZ202501ZR0058).
文摘Introduction Electron-neutron detector array(ENDA)is designed to measure thermal neutrons produced by hadronic interactions between cosmic ray extensive air showers(EAS)and the surrounding environment as well as electrons around the cores of EAS.ENDA is located within Large High Altitude Air Shower Observatory(LHAASO).ENDA was expanded from an initial 16 detectors to 64 detectors in April 2023,so-called ENDA-64,and has been running alongside LHAASO.The stability and consistency of neutron detection are crucial for laying a solid foundation for subsequent data analysis and physical results.Methods We obtain the stability by studying variations of event rate and thermal neutron rate in each cluster and the consistency by comparing distribution of number of thermal neutrons between clusters.Additionally,we investigate the specific influences of the rainy and dry seasons,as well as the presence or absence of sand cubes under the detectors,to examine the environmental factors affecting neutron measurement performance.Results The calibration results indicate good consistency in thermal neutron detection across the clusters,with the maximum inconsistency of 6.85%.The maximum instability of event rate and thermal neutron rate over time are 4.68% and 11.0%,respectively.The maximum inconsistency between the clusters without the sand cubes is 18%.The use of sand cubes is effective in protecting the target material from rainwater,and the sand cubes help the cluster to increase collection of neutrons generated by EAS events.
基金This work was supported by the National Natural Science Foundation of China(NSFC,Nos.12320101005,12373105,U2031103,12205244,and 11963004)Hebei Natural Science Foundation(No.A2019207004).
文摘By accurately measuring composition and energy spectrum of cosmic ray,the origin problem of so called“knee”region(energy>one PeV)can be solved.However,up to the present,the results of the spectrum in the knee region obtained by several previous experiments have shown obvious differences,so they cannot give effective evidence for judging the theoretical models on the origin of the knee.Recently,the Large High Altitude Air Shower Observatory(LHAASO)has reported several major breakthroughs and important results in astro-particle physics field.Relying on its advantages of wide-sky survey,high altitude location and large area detector arrays,the research content of LHAASO experiment mainly includes ultra high-energy gamma-ray astronomy,measurement of cosmic ray spectra in the knee region,searching for dark matter and new phenomena of particle physics at higher energy.The electron and thermal neutron detector(EN-Detector)is a new scintillator detector which applies thermal neutron detection technology to measure cosmic ray extensive air shower(EAS).This technology is an extension of LHAASO.The EN-Detector Array(ENDA)can highly efficiently measure thermal neutrons generated by secondary hadrons so called“skeleton”of EAS.In this paper,we perform the optimization of ENDA configuration,and obtain expectations on the ENDA results,including thermal neutron distribution,trigger efficiency and capability of cosmic ray composition separation.The obtained real data results are consistent with those by the Monte Carlo simulation.
