  Direct investigation of ion-induced dynamics in matter on picosecond (ps,
10-12 s) timescales has been precluded to date by the relatively long
nanosecond (ns, 10-9 s) scale ion pulses typically provided by radiofrequency
accelerators1. By contrast, laser-driven ion accelerators provide bursts of ps
duration2, but have yet to be applied to the study of ultrafast ion-induced
transients in matter. We report on the evolution of an electron-hole plasma
excited in borosilicate glass by such bursts. This is observed as an onset of
opacity to synchronised optical probe radiation and is characterised by the 3.0
+/- 0.8 ps ion pump rise-time . The observed decay-time of 35 +/- 3 ps i.e. is
in excellent agreement with modelling and reveals the rapidly evolving electron
temperature (>10 3 K) and carrier number density (>10 17cm-3). This result
demonstrates that ps laser accelerated ion bursts are directly applicable to
investigating the ultrafast response of matter to ion interactions and, in
particular, to ultrafast pulsed ion radiolysis of water3-5, the radiolytic
decompositions of which underpin biological cell damage and hadrontherapy for
cancer treatment6.
