The Moon Shadow Of The Primary Cosmic Ray Studied With The YBJ-HA Experiment

When the primary cosmic ray particles are propagating to the earth,they will be blocked by the moon,which will cause the defect of the cosmic ray flow in this direction,and form the cosmic ray missing effect,that is,the primary cosmic ray moon shadow effect.The study of the shadow of the moon is one of the important physical contents of the ground cosmic ray experiment.By analyzing the observed moon shadow data,on the one hand,the detector performance parameters such as the angular resolution and pointing accuracy of the ground detector array can be checked,and on the other hand,the absolute energy of the ground EAS array can be calibrated.In addition,information such as the proton and antiproton flux ratios in the primary cosmic rays can also be studied.The study of the primary cosmic ray moon shadow has always been the premise of the data analysis of the EAS experiment.This paper is based on the work during my master's degree and revolves around the Yangbajing Hybrid Array(YBJ-HA)experiment.The first chapter of this paper briefly introduces the basic knowledge and detection methods of cosmic rays,and then introduces the physical significance and research status of the study of cosmic ray moon shadows.Chapter 2 briefly introduces the YBJ-HA experiments used in this work,including experimental composition,data reconstruction,data simulation,and data inspection.The third chapter introduces the methods and ideas used for this moon shadow analysis,including two background estimation methods commonly used in cosmic ray research:equal zenith angle method and equal declination method;two commonly used source finding methods:localization Source-finding method and all-sky area scanning method.Afterwards,in the data analysis,the data of the fifth phase of the YBJ-HA experiment from the 326th day in 2016 to the 278th day in 2019was analyzed using the equal zenith angle method,and the significance was obtained at the position of 0.025^o west and 0.375^o south.Moon shadow of 5.53?(smooth radius 1.1^o).Using the same method to analyze the data of the YBJ-HA experiment(2017053-2019126),a solar shadow with a significance of 6.44?(smooth radius 0.9^o)was obtained at the position of 0.075^o west and 0.125^o north.Since the sun and the moon have similar apparent radii,the analysis process of the two negative sources can be combined,and the two negative sources can be regarded as one negative source to obtain a more significant sun-moon shadow.At the position of 0.125^o west and 0.025^o north,a sun and moon shadow with a significance of 7.72?(smooth radius 0.9^o)was obtained.On this basis,the observed moon shadow data were analyzed to obtain the main performance indicators of the YBJ-HA experiment.The angular resolution of the array was about 1.2^o,and the system pointing error was0.2^o to the south.At the same time,the long-term operation of the array was verified.stability.Finally,using the principle that the westward offset of the moon shadow center decreases with the increase of cosmic ray energy,the energy resolution ability of the experiment is tested.