Inter-track radical recombination rates at FLASH dose rates
In plain words
At very high dose rates the chemical fragments made by different particle tracks overlap and can react with each other before reaching biological targets. The size of this effect is unknown.
Precise statement
Determine the yields of hydroperoxyl, peroxyl and organic radicals, and of hydrogen peroxide, as a function of instantaneous dose rate from $100\ \text{to}\ 10^{9}\,\mathrm{rad}/\mathrm{s}$ in oxygenated aqueous and lipid-containing media, including inter-track overlap. Required inputs: second-order rate constants, radical diffusion lengths and the spatial density of tracks at a given dose per pulse. An answer is measured and computed yield curves $G(\text{dose rate})$ accurate to about 10 percent.
What would settle it
Pulse-radiolysis and chemical-probe measurements of radical and peroxide yields spanning the dose-rate range, matched by stochastic track-chemistry simulation.
Status in the literature
Measurements of reduced peroxide yield at ultra-high dose rate exist but do not yet constrain the biologically relevant organic radical channels.
Related problems
- Special case of Physical mechanism of normal-tissue sparing at ultra-high dose rate
- Special case of Radiation chemistry beyond the homogeneous stage