Complementary Characterization of Radioactivity Produced by Repetitive Laser-Driven Proton Beam Using Shot-to-Shot Proton Spectral Measurement and Direct Activation Measurement

The precision of the time-of-flight method for measuring proton spectra is confirmed by the activation method using a Li-7(p, n)Be-7 nuclear reaction. The proton beam driven by a repetitive high-intensity laser is utilized to induce the nuclear reaction. The activity measured by direct gamma-ray measurement after 1912 proton beam shots at 1Hz is 1.7 +/- 0.2 Bq. This is in accordance with the activity of 1.6 +/- 0.2 Bq obtained from the shot-to-shot proton energy distribution measured using the time-of-flight detector. (c) 2012 The Japan Society of Applied Physics