The Design of Cosmic Ray Tau Neutrinos Telescope and the Calibration of Photomultipliers
|School||Southwest Jiaotong University|
|Keywords||sub-EeV cosmic ray τ neutrino telescope structure telescope optics calibration of PMT|
This thesis is developed based on the design and calibration of the Cosmic Ray Tau Neutrinos Telescope （CRTNT） project building by IHEP of Chinese Academy of Sciences.There are three parts in the thesis. In the first part the knowledge of cosmic ray and neutrino is introduced simply firstly, then the significance in physics and the prospective aim of CRTNT project in detailed. In the second part I discuss the design of the configuration and the optics of the CRTNT, the optical test is discussed too. In the third part I study many kinds of performance and parameter of the XP 3062/FL photomultiplier tubes made by Photonis Co. using in CRTNT project.In recent years, there are many importance progresses in ultra-high energy cosmic ray （UHECR）. But there are many problems puzzled astrophysical scientists in this energy range, such as we still can’t explain completely the significant deviation around the 0.1 EeV from the general E-3 spectrum, i.e. the "second knee", where the cosmic ray flux undergoes a sudden decrease and composition has a significant transition. There are many UHECR experiments in the world. But many results of these experiments are not according with each other. One of the important reasons is that the calibrated accuracy of these experiments is not enough. In order to resolve this problem researcher Cao Zhen of IHEP of CAS put forward a Cosmic Ray Tau Neutrinos Telescope （CRTNT） project which measures sub-EeV cosmic ray and ultra high energy t neutrino.In order to obtain a better performance of the CRTNT, we should optimize the design, improve the testing precision of the optical production, and calibrate all the important parameters of the PMT accurately. In the thesis, I use simulation tools to optimize the design of configuration and optics. Firstly I build a suit of simulation program. Adjusting continually the parameters of the telescope, I can improve the effective area of the reflection and the consistency of the spot on PMTcluster. In this thesis several methods used for optical test are developed. They can resolve the difficulty of testing the radius of curvature and roughness of large optical mirror without touch. In addition, I calibrate the PMT by mimicking the optical configuration of the CRTNT telescope. The design, test and calibration play significant roles in reconstructing energy and direction of cosmic ray.