; Xu Xun-Jiang
; Wang Jian-Hua] Chinese Acad Sci, Shanghai Inst Appl Phys, Shanghai 201800, Peoples R China
; [Liu Shu-Dong
; Li Jian-Ping] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China
The energy response calibration of the commonly used high pressure ionization chamber is very difficult to obtain when the gamma-ray energy is more than 3 MeV. In order to get the calibration of the higher part of the high pressure ionization chamber, we use the Fluka Monte Carlo program to perform the energy response in both the spherical and the cylindrical high pressure ionization chamber which are full of argon gas. The results compared with prior study when the gamma-ray energy is less than 1.25 MeV. Our result of Monte Carlo calculation shows agreement with those obtained by measurement within the uncertainty of the respective methods. The calculation of this study is significant for the high pressure ionization chamber to measure the high energy gamma-ray.