This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the si...This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the signal cable to PMT (R3600_06) and characters of the high voltage divider,terminal reflection method is used for measuring the signal attenuation with a practical way to eliminate contribution of the pulse baseline.Comparison measurement data-taking method (with charge-to-digital conversion) was carried out by using open-ended cables,confirming that terminal reflection method is a fast and convenient,and suitable to online calibration of the signal attenuation for Tibet MD-A.At 26℃,the measured attenuation coefficient with the 250-m cable connected permanently to the PMT,was ～13.9%.The cable frequency response was measured by using the sinusoidal signals.The method could be used to study time dispersion of signals produced with Tibet MD-A detector via Fourier analysis.展开更多
Background:The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment designed to measure the neutrino mass hierarchy using a central detector(CD),which contains 20 kton liquid scintilla...Background:The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment designed to measure the neutrino mass hierarchy using a central detector(CD),which contains 20 kton liquid scintillator(LS)surrounded by about 18,000 photomultiplier tubes(PMTs),located 700 m underground.Purpose:The rate of cosmic muons reaching the JUNO detector is about 3 Hz,and the muon-induced neutrons and isotopes are major backgrounds for the neutrino detection.Reconstruction of the muon trajectory in the detector is crucial for the study and rejection of those backgrounds.Methods:This paper will introduce the muon-tracking algorithm in the JUNO CD,with a least-squares method of PMTs’first-hit time(FHT).Correction of the FHT for each PMT was found to be important to reduce the reconstruction bias.Results:The spatial resolution and angular resolution are better than 3 cm and 0.4 degree,respectively,and the tracking efficiency is greater than 90%up to 16 m far from the detector center.展开更多
In order to observe gamma rays in the 100 TeV energy region, the 4500 m2 underground muon detector array using water Cherenkov technique is constructed, forming the TIBET Ⅲ＋MD hybrid array. Because the showers induc...In order to observe gamma rays in the 100 TeV energy region, the 4500 m2 underground muon detector array using water Cherenkov technique is constructed, forming the TIBET Ⅲ＋MD hybrid array. Because the showers induced by primary gamma rays contain much fewer muons than those induced by primary hadrons, significant improvement of the gamma ray sensitivity for TIBET Ⅲ＋MD array is expected. In this paper, the design and performance of the MD-A detector with large Tyvek bag is reported.展开更多
基金supported by the National Natural Science Foundation of China (No.111 072552430)the Key Laboratory of Particle Astrophysics,Institute of High Energy Physics,Chinese Academy of Sciences
文摘This work aims at online calibration of signal attenuation of the long cable used in Tibet water Cherenkov muon detector array-A (Tibet MD-A) under the Tibet air shower array.Based on a waterproof connection of the signal cable to PMT (R3600_06) and characters of the high voltage divider,terminal reflection method is used for measuring the signal attenuation with a practical way to eliminate contribution of the pulse baseline.Comparison measurement data-taking method (with charge-to-digital conversion) was carried out by using open-ended cables,confirming that terminal reflection method is a fast and convenient,and suitable to online calibration of the signal attenuation for Tibet MD-A.At 26℃,the measured attenuation coefficient with the 250-m cable connected permanently to the PMT,was ～13.9%.The cable frequency response was measured by using the sinusoidal signals.The method could be used to study time dispersion of signals produced with Tibet MD-A detector via Fourier analysis.
基金This work is supported by National Natural Science Foundation of China(Grant Nos.11575226,11605222)Joint Large Scale Scientific Facility Funds of NSFC and CAS(Grant No.U1532258)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA10010900)。
文摘Background:The Jiangmen Underground Neutrino Observatory(JUNO)is a multi-purpose neutrino experiment designed to measure the neutrino mass hierarchy using a central detector(CD),which contains 20 kton liquid scintillator(LS)surrounded by about 18,000 photomultiplier tubes(PMTs),located 700 m underground.Purpose:The rate of cosmic muons reaching the JUNO detector is about 3 Hz,and the muon-induced neutrons and isotopes are major backgrounds for the neutrino detection.Reconstruction of the muon trajectory in the detector is crucial for the study and rejection of those backgrounds.Methods:This paper will introduce the muon-tracking algorithm in the JUNO CD,with a least-squares method of PMTs’first-hit time(FHT).Correction of the FHT for each PMT was found to be important to reduce the reconstruction bias.Results:The spatial resolution and angular resolution are better than 3 cm and 0.4 degree,respectively,and the tracking efficiency is greater than 90%up to 16 m far from the detector center.
基金Supported by Ministry of Science and Technology of China, National Natural Science Foundation of China (10725524, 11135010,10875132, 11105156)Chinese Academy of Sciences (KJCX2-YW-N13, GJHZ1004, 2A20093111116010)Knowledge Innovation Fund(H85451D1U2) of IHEP, China
文摘In order to observe gamma rays in the 100 TeV energy region, the 4500 m2 underground muon detector array using water Cherenkov technique is constructed, forming the TIBET Ⅲ＋MD hybrid array. Because the showers induced by primary gamma rays contain much fewer muons than those induced by primary hadrons, significant improvement of the gamma ray sensitivity for TIBET Ⅲ＋MD array is expected. In this paper, the design and performance of the MD-A detector with large Tyvek bag is reported.
