| Very high energy gamma-ray astronomy is an emerging discipline that has gradually developed in recent decades,opening a new window for us to know and understand the universe.Because it is electrically neutral,it cannot be deflected by the magnetic fields of interstellar and interplanetary space.Therefore,gamma rays are currently the best probes for our study of the origin of cosmic rays.Satellite experiments have made great contributions to the observation of gammaray bursts,making people’s understanding of gamma-ray bursts much improved.However,since satellite experiments need to launch probes into outer space,this also limits their probes to not be too large,generally only having a detection area of～1 m2.This results in satellite experiments that can only detect lower-energy gamma rays(10 Mev～100 GeV),but cannot do anything about higher-energy gamma rays.Moreover,according to the observed energy spectrum of gamma rays,its energy spectrum shows no signs of truncation at>100 GeV,so if you want to observe higher energy gamma rays,you have to find another way.Cosmic rays interact with atomic nuclei in the upper atmosphere,producing secondary particles that trigger secondary cascade reactions,a process known as "extensive air shower”.People can realize indirect observation of cosmic rays through the detection of air showers.Common ground observation experiments include the extensive air shower secondary particle detection experiment,the water Cherenkov experiment,and the imaging atmospheric Cherenkov experiment.extensive air shower secondary particle detection experiments,such as the YBJ-ASγ experiment jointly conducted by China and Japan,have a large field of view and can operate all day,but have a high threshold energy and low sensitivity in the～100 GeV energy region,which is not conducive to gamma-ray bursts observation.The water Cherenkov experiment,although the threshold energy is low,has not yet observed gamma-ray bursts.And the imaging atmospheric Cherenkov experiment,the observation of gamma-ray bursts in recent years is exciting.On September 20,2019,the MAGIC and H.E.S.S.experiments of the Atmospheric Imaging Cherenkov Telescopes(IACTs)announced for the first time that the radiation of a gamma-ray burst close to the TeV energy band was observed,revealing a new radiation composition and opening the very high-energy afterglow stage of the gamma-ray burst(>100 GeV)radiation observation window.However,due to the limitation of the field of view of the Atmospheric Cherenkov Telescope,it is difficult to observe the short-time-scale burst phenomenon.So far,the observation of the instantaneous emission of very high-energy gamma rays is still blank.Based on the above situation,Chinese researchers proposed the High Altitude Astroradiation Detection(HADAR)experiment,which aims to solve the problem of the narrow field of view of the Atmospheric Cherenkov Telescope Ma observes the short board for the 10GeV-100GeV energy region.This paper focuses on the performance and physical goals of the HADAR experiment.The main work is as follows:(1)The optical performance of the water lens is studied in detail by applying optical software,and key optical parameters such as the focal length,spot diameter,field of view,etc.of the optical system are obtained.(2)Developed a set of software for case simulation and reconstruction analysis for HADAR experiments,systematically studied the triggering method,direction reconstruction,energy resolution and background exclusion capabilities of gamma-ray cases,and gave the sensitivity prediction of HADAR experiments.(3)Based on the HADAR experiment,the detection ability of very high-energy gamma rays in the instantaneous radiation stage of gamma-ray bursts is studied,and the annual detection rate of the HADAR experiment is greater than 1.(4)The ability of HADAR experiment to detect very high-energy radiation from pulsars is studied,and it is found that HADAR has more advantages at the low-energy end than MAGIC and other experiments.The research on the HADAR experiment in this paper lays the foundation for the subsequent advancement of the experiment and physical analysis research.However,because the water lens technology is just in its infancy,and the atmospheric Cherenkov technology is not yet mature in China,some researches in this paper are not very deep.However,we hope that based on this,it will kick off the smooth implementation of the HADAR project.In the follow-up work,we will conduct more and more indepth research and achieve more good physical results.It is hoped that the HADAR experiment will be completed as soon as possible,and experimental data with physical significance will be obtained as soon as possible!... |
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