Pump-probe studies of radiation induced defects and formation of warm dense matter with pulsed ion beams

We report results from the 2$^{\mathrm{nd}}$ generation Neutralized Drift Compression Experiment at Berkeley Lab. NDCX-II is a pulsed, linear induction accelerator designed to drive thin foils to warm dense matter (WDM) states with peak temperatures of $\sim$ 1 eV using intense, short pulses of 1.2 MeV lithium ions [1]. Tunability of the ion beam enables pump-probe studies of radiation effects in solids as a function of excitation density, from isolated collision cascades to the onset of phase-transitions and WDM. Ion channeling is an in situ diagnostic of damage evolution during ion pulses with a sensitivity of \textless 0.1{\%} displacements per atom [2]. We will report results from damage evolution studies in thin silicon crystals with Li$+$ and K$+$ beams. Detection of channeled ions tracks lattice disorder evolution with a resolution of $\sim$ 1 ns using fast current measurements. We will discuss pump-probe experiments with pulsed ion beams and the development of diagnostics for WDM and multi-scale (ms to fs) access to the materials physics of collision cascades e.g. in fusion reactor materials.\\[4pt] [1] W.L. Waldron, et al., NIM A733,226(2014);\\[0pt] [2] T. Schenkel, et.al., NIM B315, 350(2013)