Time-resolved γ -spectrometer to promptly control number and energy of protons collectively accelerated as different bunches

A two-channel $\gamma$-spectrometer with time resolution of 2.5 ns enables a prompt control of number and energy of collectively accelerated protons in their separate bunches dumped into a sustainable and refractory B${}_4$C target. The proton energy and number is determined within the range of 460 to 1600 keV and 10¹²–4$\cdot$10¹⁴ per pulse, respectively, by separate measurements of yields of prompt $\gamma$-rays with energies of 429 and 2366 keV and higher, induced in the B${}_4$C targets via the nuclear reactions ¹⁰B(p, $\alpha$ $\gamma$)⁷Be, ¹¹B(p, $\gamma$)¹²C and ¹²C(p, $\gamma$)¹³N, respectively. The simultaneous control of signals from two organic scintillators shielded with lead layers of 1 and 7 cm is used to reliably separate contributions of the analytical reactions. The radioactivity of ⁷Be and ¹³N radionuclides produced in the reactions is measured with a conventional HP Ge detector to calibrate the prompt technique.