Measurement of total gamma absorption for high energy gamma rays

Total gamma absorption cross sections are the most important data used in various fields related to the application of gamma rays. However, the measurements of the total gamma absorption cross section were difficult for high energy gamma rays since there were no suitable gamma ray sources. Recently, the nuclear photo-absorption measurement system using the laser-Compton backscattering (LCS) gamma rays and the high-resolution high-energy photon spectrometer (HHS) were developed. We have utilized the system to measure the total gamma absorption cross section, that is, the sum of the atomic and nuclear interactions. The total gamma absorption cross sections at 10MeV for Al and Cu have been measured with the system. The preliminary results show that the obtained values agree fairly with the theoretical ones. Total gamma absorption cross sections are the most impor- tant data used in various fields related to the application of gamma rays. However, the measurements of the total gamma absorption cross section were difficult for high energy gamma rays since there were no suitable gamma ray sources. The gamma sources for such experiments in the past were