Research On The Large-Scale Anisotropy Of High Energy Cosmic Rays With Combined Data From ARGO-YBJ And AS? Experiment

The study of cosmic rays began in 1912 when Hess discovered the cosmic rays in a hot air balloon.But the origin,acceleration and propagation of cosmic rays are still uncertain.The ARGO-YBJ experiment and the AS? experiment are both located at the Yangbajing cosmic ray observatory in Tibet,and have accumulated a large amount of useful data for analysis after a long-term operation.This paper introduces a series of analysis work about cosmic ray anisotropy based on ARGO-YBJ experiment and AS? experiment.Previous studies have shown that cosmic ray large-scale anisotropy has obvious energy dependence.With the change of energy,the large scale anisotropy structure will change obviously.In a dozen TeV energy segments,a excess feature around the right ascension of50°-100°,and a deficit feature around the right ascension of 150°-250°.Nagashima et al.called these two anisotropy structures "Tail-in" and "Loss-cone".When the energy increases to 50 TeV,we find that the "Tail-in" gradually disappears.We guess that the formation of the "Tail-in" originates from the solar system and the formation of the "Loss-cone" originates from other galaxies.Therefore,the energy corresponding to the "Tail-in" is relatively low,so the "Tail-in" disappears when the energy increases gradually.Various experiments also shown that the distribution of anisotropy structures will change greatly when the energy increase to about 100 TeV,but there is no definite conclusion about how the changes occur.The ARGO-YBJ ran from 2006 to 2013.It has the advantages of all-weather,high altitude,wide field of view and low energy threshold.Complete data for the five years from2008 to 2012 are selected for this work.The AS? experiment has been built since 1990 and accumulated a large number of effective data.The data selected for this exercise is from the Tibet-?,11 years from 2000 to 2010.Running time is long and the amount of data accumulated is more.In this paper,the anisotropy of cosmic rays is analyzed and discussed with the observation data of ARGO-YBJ experiment and AS? experiment.The first chapter introduces the background of cosmic ray anisotropy,including the latest research progress.The second chapter introduces the basic situation of ARGO-YBJ experiment and AS?experiment as well as its detection principle and data simulation and screening.The third chapter introduces two research methods frequently used to analyze cosmic ray anisotropy.The fourth chapter introduces the background estimation method based on the zenith angle to analyze the ARGO-YBJ experimental data and the high-energy part of AS?experimental data.The evolution and long-term stability of cosmic rays with energy were studied.From the previous studies,we find that the "Tail-in" began to disappear at 50 TeV,and an obvious change took place in the anisotropic structure at 100 TeV.At about 100 TeV,due to the high energy,the number of cases is relatively small,so my work is to choose ARGO-YBJ experiment and AS? experiment to analyze the cases in 100 TeV,and combine the experimental data of the two experiments to improve the statistical amount of experimental data.It can be seen from the analysis that the distributions of the two experiments at 100 TeV are not very consistent.And when we add up the two experiments and look at the anisotropy distribution of 100 TeV,we can find that the distribution of anisotropy is quite consistent with the results of other experiments.The "Tail-in" has basically disappeared,and there is a tendency to change the location excess the structure and the deficit structure,and one more excess structure has appeared in the area on the right.And it is worth noting that in right ascension 30 °-100 °,declination at 20 °-80 ° range,there is a not obvious deficit structure.This means that in the process of changing the location of the deficit structure,the high-latitude part first appears the deficit structure.