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Compact laser-based neutron sources have attracted great interest in the last years due to a growing field of applications. Neutrons interact via the nuclear force which results in relatively large penetration depths and isotope specific interaction cross-sections. This can be used to identify the isotopic composition of samples. This allows applications like the inspection of cargo containers for fissile material or explosives as well as the tracing of artifacts to their geological origin. While conventional neutron sources such as reactors and spallation sources are large in size, expensive and produce strong background radiation with large pulse widths, it is more desirable to have compact neutron sources with short pulse lengths which require less shielding. Laser-based neutron sources can fill this gap in the near future when modern high repetition rate laser systems can be used. In addition, the short neutron pulse length in the order of one nanosecond facilitates new applications such as neutron resonance spectroscopy and neutron resonance imaging.
Here, we present recent results from experimental campaigns at the PHELIX laser system at the GSI Darmstadt. In the experiment, protons and deuterons have been accelerated from thin foils up to 50 MeV. These ions were converted by nuclear reactions inside a catcher material into 10^10 neutrons per shot which were subsequently moderated down into the eV regime. With this epithermal neutron beam, it was possible to identify several isotopes inside a 2.7 mm thick sample using neutron resonance spectroscopy. In addition, laser-driven thermal neutron radiography was applied for measuring the thickness of indium cadmium plates behind a lead shielding. Also, the first demonstration of neutron resonance radiography will be presented. I will further give an outlook for future applications that will be enabled by high repetition rate laser systems and liquid leaf targets.
Laser-based neutron sources will be developed and applied at the international center for nuclear photonics at the TU Darmstadt in close cooperation with their industrial partner Focused Energy GmbH.
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