Comprehensive Study On Underground Muon Detector And Surface Scintillator Detector

With the improvement of the Cherenkov technology, more than 150 sources of TeV gamma rays have been discovered by ground-based atmospheric Cherenkov telescopes, and more than 3000 sources in 100 MeV energy range have been discovered by Fermi telescope since 2004. In particular, the observation of supernova remnants IC443 and W44 and the energy spectrum measurement of GeV gamma rays leads to a possible match to the characteristics of π0 decay, which provides strong evidence for the accelerating mechanism of SNRs in GeV energy range for cosmic ray nuclei. However, this does not confirm the origin of cosmic rays of higher energy and observation and detection of gamma rays of higher energy is required in order to solve the ultimate origin question. Gamma rays with leptonic origins merely exist in the energy range around 100 TeV while hadronic interactions contribute mainly to gamma rays in 100 TeV energy range. Hence, observation of gamma rays in 100 TeV energy range is of great importance to the study of hadronic origin model.Tibet ASy experiment with large effective area, large field of view and high duty cycle has a great advantage in observing 100 TeV gamma rays. In order to distinguish primary gamma rays and cosmic rays effectively,4500 m2 underground muon detector array has been built under the surface of Tibet-III array. The underground muon detector array and the Tibet-Ⅲ array have been put into operation since March 2014.This thesis mainly focus on the sub muon detector, MD-A, including the installation, testing and data analysis of this sub detector. In order to make the time measurement of the trigger given by the surface array, a trigger board has been introduced to the DAQ system and a DAQ program has been written by the author. Long-term stability of muon detector is analyzed, including muon signal, trigger rate and TDC variation. The result that the muon signal amplitude decreased by 24% in 2 years with muon peak resolution unchanged over time indicates a fair single muon resolution.Also a method for precise real-time cable length calibration has been developed. This method improves the measurement accuracy of signal transmission time in cable when the TDC accuracy is undesirable and has been realized by using the Front-End-Electronic board from Daya Bay experiment.In order to improve the detecting sensitivity to gamma rays in 100 TeV energy range, ASy group in China proposed a project to enlarge the ground detector array. The elec-tronic system used in this array is based on White Rabbit protocol and was tested as part of this thesis project. Besides,a DAQ system has been set up. The long term stability analysis results indicate that the electronics work fairly and scintillator detectors perform reliably as expected.Comprehensive analysis of the coincidence between MD-A and the surface scintil-lator detector array was made using data. In the reconstructed coincidence events, the fitted sigma parameter of the time residual of MD-A is about 15 ns as expected.