Single-event neutron time-of-flight spectroscopy with a petawatt-laser-driven neutron source

TL;DR

This paper demonstrates a stable, high-flux laser-driven neutron source capable of single-event time-of-flight spectroscopy, opening new avenues for nuclear research and applications with compact, high-repetition-rate systems.

Contribution

It provides the first proof-of-concept of stable, high-flux laser-driven neutron production suitable for single-event spectroscopy, using a diamond detector in a petawatt laser environment.

Findings

Produced 6-7×10^7 neutrons per shot above 1 MeV energy

Achieved over 200 shots at one shot per minute

Neutron detection aligned with Monte Carlo simulations

Abstract

Fast neutron-induced nuclear reactions are crucial for advancing our understanding of fundamental nuclear processes, stellar nucleosynthesis, and applications, including reactor safety, medical isotope production, and materials research. With many research reactors being phased out, compact accelerator-based neutron sources are becoming increasingly important. Laser-driven neutron sources (LDNSs) offer unique advantages -- ultrashort neutron pulsees for superior energy resolution, high per-pulse flux, and a drastically reduced footprint. However, their use in single-event fast neutron spectroscopy remains unproven, requiring stable multi-shot operation and detectors capable of functioning in the extreme environment of petawatt-class laser-plasma interactions. Here, we present a proof-of-concept experiment at the DRACO~PW laser in a pitcher-catcher configuration, stably producing 6-7e7 neutrons/shot with energies above 1 MeV, over more than 200 shots delivered at a shot-per-minute rate. Neutron time-of-flight measurements were performed using a single-crystal diamond detector, which is located only 1.5 m away from the source and capable of resolving individual neutron-induced reactions. Observed reaction rates are consistent with Monte Carlo simulations inferred by real-time diagnostics of accompanying gamma, ion, and electron fluxes. With the recent advances in repetition rate, targetry, and ion acceleration efficiency, this work establishes LDNSs as a promising, scalable platform for future fast neutron-induced reaction studies, particularly for measurements involving short-lived isotopes or requiring high instantaneous neutron flux.