Ultrafast Nanodosimetry for proton interactions in matter: The role of nanoscale structure and dynamics on radiation chemistry
durch
Prof.Brendan Dromey(QUB)
→
Europe/Berlin
Beschreibung
Ionisation dynamics on the nanoscale seed the processes that govern pathways to macroscopic equilibrium in irradiated matter. Therefore, understanding the conditions that underpin this transition is critical in a wide range of applications from healthcare to radiation science. Recently we have demonstrated that laser driven ion accelerators can provide an ultrafast tool for studying this inherently multiscale regime with temporal resolution < 0.5 ps [1-3]. Here we discuss how it is possible to interrogate these ultrafast processes in real-time by contrasting how recovery scales with interaction dimensionality for different ionising species. We employ single-shot optical streaking to track the decay time constant, tc, of free carriers in matter irradiated by picosecond-scale (ps, 10-12 s) pulses of X-rays and protons from a single laser-driven accelerator. First by exploiting the nanoscopically heterogeneous density of SiO2 aerogels, our results reveal a sharp discontinuity in the scaling of tc with average density (rav) for proton and X-rays interactions.
Next, we demonstrate how this technique can be exploited to reveal delays in the onset of solvation of electrons ionised by the passage of protons in pristine H2O i.e. no scavenging agents [3] (Figure 1). Modelling again reveals how this delay is linked to nanocavitation associated with the generation of proton tracks in H2O. Combined, these results open a new window onto how dynamics and structure on the nanoscale can play a significant role in determining the long-term effects of radiation damage in matter.
