Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

A small scale sample nuclear waste package, consisting of a 28 mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500 keV), with a source size of <0.5 mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30 cm2 scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10 Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned

Thermal neutron fluence measurement by Cadmium differential method at laser-driven neutron source

We generated high-energy neutrons by (d, n) and (p, n) reactions on a Be target with protons and deuterons that were accelerated up to 30 and 10 MeV/u, respectively, by laser-plasma interactions. Thermal neutrons were subsequently generated through deceleration by a small moderator with conjunction on the Be target. Here we report the measurements on the thermal neutron fluence using the activation method with/without Cd filters. The unstable isotopes of 198Au, 56Mn, 60Co, and 181Hf were produced through (n, γ) reactions by a single laser shot. The nuclear reaction rates were evaluated by measurring the γ-rays emitted from these unstable isotopes. The thermal neutron fluences from the four nuclides are consistent within their experimental uncertainties. The fluence is evaluated to be (2.2±0.4)×105 neutrons/cm2 at the distance of approximately 9-mm at 90◦ against the laser axis. The present result shows that the method to generate thermal neutrons from a compact neutron source with a diamater of 44 mm and length of 46 mm is expected to be a useful tool for various nuclear experiments

High Flux Neutrons Provided by a Laser driven Neutron Source and its Application to Nuclear Astrophysics

We demonstrated that (n, 2n) and (n, gamma) reactions are induced by a high-flux pulse of fast neutrons provided from a Laser-driven Neutron Source (LDNS). Several kinds of metal targets are exposed to the fast neutrons with energies of approximately 10-20 MeV. As a result, 180Hfm,181Hf, 56Mn, 198Au, and 60Co are produced by (n, gamma) reactions. Furthermore, unstable isotopes such as 54Mn, 58Co, 175Hf, and 196Au are produced by (n, 2n) reactions. We evaluate the neutron fluence and energy spectrum using the activation method in conjunction with a time-of-flight (TOF) method.The 16th international symposium on nculei in cosmo

Direct evaluation of high neutron density environment using (n,2n) reaction induced by laser-driven neutron source

We demonstrated that (n, 2n) and (n, gamma) reactions are induced by a high-flux pulse of fast neutrons provided from a Laser-driven Neutron Source (LDNS). The maximum energy of the broadband neutrons reaches a few tens MeV. Several kinds of metal targets are exposed to the fast neutrons. As a result, unstable isotopes such as 54Mn, 58Co, 175Hf, and 196Au are produced by (n, 2n) reactions and 180Hfm,181Hf, 56Mn, 198Au, and 60Co are produced by (n, gamma) reactions. We evaluate the neutron fluence and energy spectrum using the activation method in conjunction with a time-of-flight (TOF) method. The present scheme provides a method to evaluate high density neutrons seen in stellar environments, which are expected to be generated from future LDNSs

A miniature thermal neutron source using high power lasers

Dataset underpinning the results presented in the article titled, "A miniature thermal neutron source using high power lasers" published in Journal of Applied Physics (2020) Absstract of the paper: The continuous improvement of high power laser technologies is recasting the prospects of small-scale neutron sources to enable scientific communities and industries performing experiments that are currently offered at extensive accelerator-driven facilities. This paper reports moderation of laser-driven fast neutrons to thermal energies using a compact modular moderator assembly. A significant thermal (25 meV) flux of 106 n/sr/pulse was measured from water and plastic moderators in a proof-of-principle experiment employing a relatively moderate power laser delivering 200 J on the target in 10 ps. Using Monte Carlo N-Particle eXtended simulations, the experimental results are reproduced and discussed

Experimental demonstration of a compact epithermal neutron source based on a high power laser

Dataset underpinning the results presented in the article titled, "Experimental demonstration of a compact epithermal neutron source based on a high power laser" published in Journal of Applied Physics (2017