Study Sensitivity Of "Double Front Shower" Events In The ARGO Experiment To Detect High-energy Gamma-ray Bursts

Gamma-ray bursts(GRBs),an astronomical phenomenon of violent energy outbreak in a short time,are important means of studying the origin of cosmic rays.Satellite experiments have detected more than 5000 gamma-ray bursts in keV-MeV.But for the high-energy(more than 10 GeV)GRBs,there are no definite observed results.High-energy GRBs can not only provide the direct evidence for the generation mechanism of GRBs,but it also examine current disputed models about GRBs,so its research is of great significance.In order to get complete information about GRBs whose energy are from low to high,it is necessary to combine satellite experiments and ground-based experiments.The high altitude,the wide field of view,and the large area make the ARGO and AS? experiments,located at YangBaJing,play an essential role in detecting high-energy GRBs.Particularly,"double front shower" events in the ARGO experiments have unique advantages of lowering energy threshold and improving sensitivity,which provides a new way to detect high-energy GRBs.Firstly,simulation of sensitivity of "double front shower" events to detect high-energy GRBs is presented in this paper.The result shows that:fluence of "double front shower"events to detect E>10 GeV GRBs varies from 10-4 erg/cm2 to 10-3 erg/cm2 with the time duration of 1s,zenith angle of 10� and no redshift.Compared with "triggered" events,the sensitivity of "double front shower" events is higher at Emax<30 GeV,so "double front shower" events have high possibility in detecting high-energy GRBs.Then,after analyzing the data of 1756 GRBs which are observed by the Fermi satellite from 2008 to 2015,and extending energy spectrums of these GRBs to the energy range of the ARGO and ASy experiments according to Band Model,fluence of these GRBs can be calculated.The result shows that:when the influence of EBL is overlooked,for Fermi GRBs in the YangBaJing field of view whose energy are in GeV,3 GRBs are within the sensitivity of the ARGO experiment during its work period,and 4 GRBs are within the sensitivity of the upgraded ASy experiment during its work period.This study will provide important information for ground-based experiments in YangBaJing(including "double front shower"events)in coincidence with satellite experiments to detect GRBs.Finally,by combining "double front shower" events' data of GRB100225703 in ARGO with the data of Fermi,the search for high-energy GRBs is implemented.The result shows that:the chance probability(Pb,as the fluctuation of background)of the highest-significance event is 1.72�10-6,which is equivalent to 4.643? in the Gaussian Distribution.However,after considering times of the experiment,this event can not be regarded as a GRB.