Core Detector And Test Of The Forward Particle Production Of The Hadronic Interaction Models At Around~*10TeV

The interpretation of the extensive air showers (EAS) is known to inevitably de-pend on the Monte Carlo simulations which are based on some hadronic interaction models and cosmic ray composition models. At present, the simulation code COR-SIKA that is comprehensively used in the surface cosmic ray studies includes many interaction models. For multi-parameter measurements of EASs, it is known that no interaction model can explain all data consistently. Therefore, the hadronic interaction models need to be checked and further improved.In this paper, I report the approach and results to check the hadronic interaction models QGSJETOlc, QGSJET II-03, QGSJET II-04, EPOS1.99,EPOS LHC(v3400) and SIBYLL2.1at an energy region of*10TeV using the data obtained by the newly constructed YAC-I (Yangbajing Air shower Core detector, the first stage). The energy region of*10TeV is chosen by the following considerations:1) The primary com-position at this energies has been better measured by direct measurements, and the uncertainty is smaller.2) The corresponding energies in the center-of-mass system are around*100GeV,for that SppS collider made good measurements on the inelastic cross section and on the particle production in the near forward region. The uncertain-ty from the extrapolation to the very forward region is relatively small.3) The check of interaction models should be step-by-step executed from lower energies to higher energies.4) Due to the high altitude of our Tibet experiment we could have good EAS core events recorded by YAC-I at*10TeV region.Two steps of YAC experiment have been accomplished. YAC-I is used to check hadronic interaction models currently used for air-shower simulations. YAC-II are used to obtain the individual component spectra of primary cosmic rays between50TeV and lOPeV. YAC-I is an array consisting of16prototype detectors (10m2) located near the center of the Tibet-III array. In this paper, I used a data set collected from May1st2009through February23rd2010by the YAC-I. The effective live time used for the present analysis is169.95days and the event number of the data is1796542.In this work, two primary composition models are used, the heavy dominan-t model (HD) and the non-linear acceleration model (NLA). By setting three event selection conditions, three Monte Carlo samples are obtained with the mode energy at～35TeV，～70TeV,～90TeV.The fractions of P+He of the all component in all cases are about90%. By comparing the distribution of parameters from the two pri-mary composition models, it is found that the discrepancies from brought by primary composition models is less than5%. So the interference from component uncertainty is excluded.The shape of the distributions of sumNb,Nb/sumNb,Nbtcp are consistent between the YAC-I data and simulation data in all cases, indicating that in the*10TeV en-ergy region the particle production spectrum of all hadronic interaction models may correctly reflect the reality within our experimental systematic uncertainty of a level about10%. So in*TeV region, the Feynman scalling is not break. The comparison of event absolute intensities of sumNb,Nb/sumNb,Nbtcp in all cases shows:Experi-mental Data normally shows a higher intensity than Monte Carlo simulation data. The absolute intensity of SIBYLL2.1is about10%below experimental data, QGSJET II-03and EPOS LHC (v3400) is about20%below experimental data, QGSJETOlc and EPOS1.99are about30%-40%below experimental data. So the lower values for the p-air inelastic cross section should be used in hadronic interaction models. The shape of the distributions of＜R＞and＜Nb*R＞, are consistent between the YAC-I data and simulation data in all cases, indicating that in the*10TeV energy region the transverse momenta of all hadronic interaction models may correctly reflect the reality within our experimental systematic uncertainty of a level about18%.