The Check Of The High Energy Hadronic Interaction Models And The Monte Carlo Simulation Of Yangbajing Air Shower Core Detector

So far, the direct observation of primary cosmic rays by board satellite or balloon experiments can only reach 1014 eV,but the study of the composition of cosmic rays above 1014 eV has to rely on the indirect observation of air showers (ASs) produced by primary particles. To interprete the EAS data, Monte Carlo(MC) simulations are inevitable. Any hadronic interaction models used in Monte Carlo codes are based on the knowledge obtained from some theoretical models. These models have been checked by accelerator experiments only up to the hadron collider energies, but there exist two questions:(1) Above hadron collider energies, One has to use extrapolation of the laws established in lower energies. Obviously, the correctness of the extrapolation determines the correctness of the description of EASs in higher energies. (2) But up to the present, the warranty gotten from accelerator experiment is deficient. At higher energy, because of the lack of information in the forward region, the warranty is more and more inadequate, so there has some suppose(Like Feynman scaling) in Monte Carlo models. For the development of the air showers, the most forward region of the produced secondaries in the hadronic interactions is important. In many knee composition studies of recent years, significant discrepancies exist among different measurements, This situation asked for a further check and an improvement of the currently used interaction models.Yangbajing ASy experiment is one of the cosmic ray observation experiments.AS y experiment has been located at Yangbajing town, China(90.53°E,30.11°N,4,300m above sea level) which atmospheric depth are 606g/cm2. because of advantaged geographical character at Yangbajing, it's eximious to record those AS core events that are produced at low heights, thus it would be effective to check the hadronic interaction models at the forward region. A new hybrid experiment has been started by Yangbajing ASy experiment in April,2009. The new hybrid experiment consists of a newly developed air shower core detector-YAC, the Tibet-Ⅲarray and moun detector(MD).YAC have three plans, and different physical results can be obtained for each plan. YAC-Ⅰis used to check inelastic interaction cross section, transverse momentum of secondary particles, Feyman-Ⅹin forward region used in hadronic interaction models currently used for air-shower simulations through the multip-parameter measurement. This paper will analyse the newest experimental data to check hadronic interaction models YAC-Ⅱand YAC-Ⅲare used to obtain the individual component spectra of primary cosmic rays in a wide 3 range over 3 decades between 50 TeV and 100 PeV in the near future. YAC-Ⅰhas started data taking and successfully operated simultaneously with Tibet-Ⅲsince April,2009. On-line trigger condition for YAC-Ⅰdetector is set as signal amplitude is greater than 10 mV, DAQ is triggered. Trigger rate of each detector is 30 Hz approximately. The Tibet-Ⅲarray provides the total energy and the direction of air showers. YAC-Ⅰcan record high energy electromagnetic component in the core region of air showers to separate the primary cosmic-ray nuclei. This paper analyse the experimental data obtain by YAC-Ⅰand Tibet-Ⅲin the same manner as for the MC data in QGSJET01c,SIBYLL2.1 model, in order to check inelastic interaction cross section, transverse momentum of secondary particles, Feyman-Ⅹin forward region. The newest results show that the physical goals can be satisfactorily be realized by the new hybrid experiment Comparing MC with experiment, it shows at about 80 TeV energy region, these two hadronic interaction models have the corresponding events absolute flux within 30% error range, also have the same slope among the distribution of main experimental parameters. So, we think at that energy region, the inelastic interaction cross section, the inelasticity, Feyman-Ⅹare convinced within 30% error range. More careful and higher energy check will be developed when the experimental data is accumulated enough.Finally, this paper optimized 100 core detectors of YAC-Ⅱarray. In order to increase detect efficiency, we suppose to enlarge the area of the scintillator and try to find some better conditions for selecting high energy air shower core events.