Radioactivity produced by a repetitive laser-driven proton beam using a shot-to-shot proton spectral measurement and a direct activation method

A proton beam driven by a repetitive high-intensity-laser is utilized to induce a ⁷Li(p,n) ⁷Be nuclear reaction. The total activity of ⁷Be are evaluated by two different methods. The activity obtained measuring the decay gamma-rays after 1912 shots at 1 Hz is 1.7 ± 0.2 Bq. This is in good agreement with 1.6 ± 0.2 Bq evaluated from the proton energy distribution measured using a time-offlight detector and the nuclear reaction cross-sections. We conclude that the production of activity can be monitored in real time using the time-of-flight-detector placed inside a diverging proton beam coupled with a high-speed signal processing system.