The Calibration Of Pointing Direction And Gain Consistency Of Photomultiplier Tubes For CRTNT Prototypes

In recent years,sub-EeV cosmic ray becomes hot topic of the cosmic ray physics.Many experiments study on this area of sub-EeV energy in the world.but the observation results from every experiment are inconsistent,some even concluded reverse results.One important reason for this is that the precision of energy calibration from every experiment can't compare with each other.To overcome this difficulty, Chinese scientists invent Cosmic Rays Tau Neutrino Telescope(CRTNT).Up to end of October 2006,Two prototype telescopes have been constructed and mounted at the Yangbajing Cosmic Ray Observatory(30.11°N,90.53°E,4300m a.s.l.)near the ARGO-YBJ experiment site.This setup is used for debugging the telescopes and coincident measurement of cosmic ray showers for composition around knee region.This thesis is developed based on the calibration of the Cosmic Ray Tau Neutrinos Telescope(CRTNT)prototypes at Yangbajing building by IHEP of Chinese Academy of Sciences,the calibration of gain consistency of photomultiplier tubes and telescope pointing are included.The purpose of gain consistency calibration is compute the relative gain of every PMTs by analyzing the data through observing LED ultraviolet light,then the data of Cherenkov events from observation can be corrected offline,the corrected data will be more closed to true observation data,the energy of Cherenkov event from extensive air shower(EAS)can be constructed correctly. In addition,By analysing the data collected by Cosmic Rays Tau Neutrino Telescope(CRTNT)prototypes at Yangbajing through observing the sky background during February of 2007,the pointing calibration of the CRTNT has been done.During the calibration,the pointing of the CRTNT relative to the hall of ARGO-YBJ has been measured with the theodolite firstly,then the bright stars seen by CRTNT is taken as reference to calibrate the pointing.That is to say,the difference between the equatorial coordinates of the stars received from CRTNT and that from J2000 star table is used as reference to correct the pointing measured firstly.At the end,The pointing of the CRTNT is determined as(207°,52.75°)within 0.25°.The finishment of the pointing calibration is very important for the determining of the shower impact point and the reconstruction of primary direction of CRTNT.