A tabletop, ultrashort pulse photoneutron source driven by electrons from laser wakefield acceleration

Abstract

Relativistic electron beams driven by laser wakefield acceleration were utilized to produce ultrashort neutron sources. The experiment was carried out on the 38 fs, ∼0.5 J, 800 nm Ti:Sapphire laser in the 10 TW UT3 laser lab at University of Texas at Austin. The target gas was a high density pulsed gas jet composed of 90% He and 10% N2. The laser pulse with a peak intensity of 1.5 × 1018 W/cm2 interacted with the target to create a cylindrical plasma channel of 60 μm radius (FWHM) and 1.5 mm length (FWHM). Electron beams of ∼80 pC with the Gaussian energy distribution centered at 37 MeV and a width of 30 MeV (FWHM) were produced via laser wakefield acceleration. Neutron fluences of ∼2.4 × 106 per shot with hundreds of ps temporal length were generated through bremsstrahlung and subsequent photoneutron reactions in a 26.6 mm thick tungsten converter. Results were compared with those of simulations using EPOCH and GEANT4, showing agreement in electron spectrum, neutron fluence, neutron angular distribution and conversion rate.

Enhanced laser-driven hadron sources with nanostructured double-layer targets

“…Our estimation for the neutron flux suggests that it could be comparable with that of other proposed compact laser-driven neutron sources reported in the literature, where for 'compact' we mean relying on tabletop Ti:sapphire lasers not exceeding ∼100 TW. For instance, the interaction of a few mJ laser at kHz frequency with a heavy-water jet [80,81] has been reported to lead to an average neutron yield of 2×10 5 , while 2×10 6 neutrons per shot have been obtained via photoneutron generation with wakefield-accelerated electrons driven by a 0.5 J, 10 TW laser at ∼10 −2 Hz [82]. Concerning schemes similar to that proposed here, where a target for ion acceleration and a separate converter for neutron generation are used, a yield of ∼10 6 neutrons per steradian per shot can be obtained with few J lasers, but relying on deuterated targets (see [29] and references therein).…”

Forward-looking insights in laser-generated ultra-intense γ-ray and neutron sources for nuclear application and science

“…Depending on the neutron generation process, the neutron source properties differ from each other in the energy distribution, the directionality and the pulse duration. Compared to the proton/deuteron induced neutron generation processes, the pulse duration of the gamma-driven neutrons is much shorter 52 , 53 due to the relativistic feature of the electron beam generating γ -rays. Nowadays, the high-yield laser-driven γ and neutron-beam production schemes are based on applications of high-intensity multi-petawatt-class laser systems, where the current state-of-the-art research is discussed in 52 , 53 .…”

New insights in laser-generated ultra-intense gamma-ray and neutron sources for nuclear applications and science

“…Depending on the neutron generation process, the neutron source properties differ from each other in the energy distribution, the directionality and the pulse duration. Compared to the proton/deuteron induced neutron generation processes, the pulse duration of the gamma-driven neutrons is much shorter [47,48] due to the relativistic feature of the electron beam generating γ-rays. Nowadays, the high-yield laser-driven γ and neutron-beam production schemes are based on applications of high-intensity multi-petawattclass laser systems, where the current state-of-the-art research is discussed in [47,48].…”