Study On The Effects Of Thunderstorms Electric Field On Energy Of Cosmic Rays At Lhaaso

Observations show that the maximum electric field intensity during thunderstorms is between 850-1300 V/cm,and some even exceed 2000 V/cm,which lasts for several tens of minutes.Under the acceleration/deceleration of such a strong thunderstorm electric field,the characteristics of the secondary charged particles of the cosmic rays will be negligible.Wilson pointed out for the first time that electrons with small mass in cosmic rays secondary particles can be accelerated to high energy by thunderstorm electric fields.In 1985,Alexeenko et al.first detected variation of cosmic rays intensity during thunderstorms through the Baksan Carpet array,and then many high altitude ground cosmic rays experiments detected the phenomenon of cosmic rays enhancement.Although these phenomena are consistent with the Relativistic Runaway Electron Avalanche(RREA)proposed by Gurevich in 1992,they can not exclude the possibility of other physical mechanisms.The ARGO experiment observed the decline of the intensity of the ground cosmic rays during thunderstorms.The RREA mechanism could not give a reasonable explanation.What is the acceleration mechanism for this phenomenon?The Large High Altitude Air Shower Observatory(LHAASO)located in Daocheng,Sichuan Province,is featured with frequent thunderstorms in summer.It is beneficial to study the influence of atmospheric electric field on cosmic rays during Thunderstorms.In this paper,Monte Carlo simulations were performed to study the effects of thunderstorms electric field on the energy of secondary positrons and electrons at LHAASO.If the effect of electric field is not considered,the results show that the number of electrons on the LHAASO detector surface is 2 ~ 3 times more than that of the muons;the muons have a wide range of horizontal distribution,while the electrons are of concentrated distribution;the muon's energy is much larger than that of the electron.The changes in energy distribution of electrons occur under the electric field.In the low energy region,the total number of electrons and positrons increases significantly,while at high energies,it does not change obviously.To be concrete,in the electric field of 1700 V/cm(above the threshold field of the RREA process),electrons with energy less than 120 MeV can be accelerated.Within the range of energy less than 60 MeV,the number of electrons increases exponentially,with an increase amplitude up to 2252%.The physical mechanism of accelerated electrons in the thunderstorms electric field is consistent with the theory of RREA.In the electric field of 1000 V/cm below the threshold of the RREA process,electrons with energy less than 70 MeV can be accelerated,and its quantity is significantly increased,but the amplification(86%)is far lower than that of the critical field of the RREA process.The physical mechanism of secondary electrons of accelerated cosmic rays in the thunderstorms electric field below the critical field of the RREA process was also discussed.The preliminary results provide important information to understand the characteristics of the LHAASO experimental data and study the variations in the intensity of cosmic rays of the LHAASO detection surface during thunderstorms.