Laser-Wakefield-Driven Photonuclear and Laser-Driven DD Fusion Neutron Sources for Fast Neutron Capture: A Start-to-End Simulation Study

TL;DR

This study compares laser-driven neutron sources from DD fusion and LWFA photonuclear methods through comprehensive simulations, highlighting their potential for fast neutron capture in nuclear astrophysics and spectroscopy.

Contribution

First complete simulation comparison of DD fusion and LWFA-driven neutron sources for fast neutron capture, deriving scaling laws and evaluating experimental feasibility.

Findings

DD fusion produces quasi-monoenergetic 2.45MeV neutrons with <20ps pulses and high peak flux.

LWFA sources generate broader spectra with >50ps pulses but enable high repetition rates for cumulative studies.

Both sources are complementary: DD fusion for peak brightness, LWFA for high-throughput experiments.

Abstract

Laser-driven neutron sources offer ultrashort pulse durations and extreme peak fluxes inaccessible to conventional facilities, enabling novel time-of-flight(TOF) spectroscopy and nuclear astrophysics measurements. We present the first complete start-to-end simulation comparison of deuterium-deuterium (DD) bulk fusion and laser wakefield acceleration-driven photonuclear neutron sources, evaluated for fast neutron capture relevant to the r-process. The simulation chain couples particle-in-cell modeling of the laser-plasma interaction, Geant4 Monte Carlo neutron transport with shielding and background characterization, and a NON-SMOKER-based event generator for multi-neutron capture on Au197 and Rh103. We derive scaling laws for neutron yield, pulse duration, and peak flux from 1J terawatt to 250J petawatt-class systems, including DD bulk fusion scaling laws specific to the short-pulse regime where volumetric ion heating via plasma expansion timescales governs yield. Under realistic experimental conditions, DD fusion produces quasi-monoenergetic 2.45MeV neutrons with less than 20ps pulses, 100 micro source size, and peak fluxes exceeding 10^22 cm^(-2) s^(-1), ideal for high-resolution TOF spectroscopy. LWFA sources generate broader spectra with larger than 50ps pulses, but high repetition rates (up to 100 Hz) yield a 36x advantage in cumulative capture events for short-lived isomers. We conclude these sources are complementary: DD fusion maximizes per-shot peak brightness, while LWFA provides high-throughput accumulation for systematic studies. These results establish design criteria for the first direct laser-driven rapid neutron capture experiments at facilities including PHELIX, ELI-NP, and TW-class systems such as UT3.