Next generation laser-driven neutron sources for ultrafast studies

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Neutrons are one of the fundamental particles of an atom with no charge. Because of their unique ability to reach nuclei, neutrons provide unique and valuable insights to many aspects of the physics of matter beyond the capability of any charged particle or ionizing radiation probes. We are now seeing the world at the very limits of our existing neutron probes - the key limitation being the temporal resolution. The possibility of ultrafast (significantly faster than a millionth of a second) studies using neutrons, either as a pump or a probe, has not yet been considered because no high flux sources of such short neutron pulses exist. Thanks to the continuing developments in laser technology and related areas, access to ultra-intense laser pulses (well above 10^15 watts of pulsed power focussed down to a spot of a fraction of the diameter of human hair) has opened several new avenues of research in plasma physics. One of them is the bourgeoning field of ion acceleration driven by the intense laser light pressure (also called radiation pressure (RP)). Depending on laser and target parameters, the interaction produces either moderate kinetic energy (corresponding to a speed of 1000 Km/sec) and near solid density jets of high Mach numbers, or mono-energetic and collimated ion pulses of ultra-high energy (orders of magnitude higher than the jet ions). The proposal is aimed to develop, test and apply a novel laser based neutron source, exploiting the unique combination of parameters at the frontier of RP driven ion bunches, Since the source is driven by the ions accelerated by a highly efficient laser driven ion acceleration mechanism, it lays a foundation towards next generation neutron facility in light of the rapid development in laser technology. The source with enhanced characteristics will enable expansion of our understanding of ultrafast molecular dynamics in a wide range of discipline, from physics to biology. A laser driven source may bring further advantages in terms of cost reduction and compactness, reduction of radioactive pollution and ability of radiation confinement by closed-coupled irradiation experiments, which will make the source more appealing for industrial, technological and medical applications, such as cancer therapy centre based on a novel, highly promising technique employing neutrons.