Various aspects of basic physical processes are being intensively studied in laser-plasma ion accelerators to get a better understanding of laser energy transfer to the charged particles and energy transport through the target. While the ion emission outside the target can be measured directly, the ion dynamics inside a dense target is difficult to access. Under these circumstances fusion neutron spectroscopy has been shown to be a powerful tool because neutrons produced in fusion reactions penetrate dense matter almost undisturbed while their energies reflect the ion collision kinematics. E.g., quantitative measurements of the spectra of deuterons and neutrons allowed one to analyze the outward and inward acceleration of deuterons from the droplet.
Furthermore, the laser produced intense neutron beam constitute a source for further applications. If the reaction volume and the exciting laser pulse duration are sufficiently small, a neutron pulse duration of several picoseconds is possible. Such a source could be used to study time-resolved neutron induced collision cascades in solid matter. Given sufficient flux, a fast neutron pump of matter and an accompanied probing of structural changes is envisioned.