Neutron time-of-flight spectrometry of high-energy proton bunches collectively accelerated in the Luce diode

Abstract

In this work, we investigated the possibility of detecting high-energy proton bunches collectively accelerated in a Luce diode by combining selective time-of-flight spectrometry of neutrons from the threshold reaction 11B(p,n)11C and instantaneous γ-spectrometry based on reactions 10B(p, αγ)7Be, 12C(p, γ)13N, and 11B(p, γ)12C, excited in B4C targets. It is shown that with an increase in the voltage across the Luce diode from 262 ± 15 to 312 ± 12 kV, on average in a series of 10 shots, the number of protons with energies above 3.02 MeV increases by two orders of magnitude — up to 3 ⋅ 1010 per shot, which opens up the possibility of ToF spectrometry of above-threshold neutrons with an average energy of about 0.3 MeV. It is shown that high-energy protons bunches noticeably outstrip the main proton bunches with an energy of 2.5eUd (e — electron charge, Ud — voltage on the diode) and up to 6 ⋅ 1014 protons per shot. This indicates that the smallest portions of protons can be captured first in the collective acceleration, which, due to the smaller lag behind the ion mover, are in the process of acceleration for a longer time and, thus, are accelerated to the highest energies.