Luminescence quenching in liquid argon under charged-particle impact: Relative scintillation yield at different linear energy transfers

A theoretical model is presented for the linear-energy-transfer (LET) variation of the relative scintillation yield in liquid argon. It is based on energy partition between the core and the penumbra of the charged particle track with little quenching in the penumbra except for fission fragments. Scintillation from the core can be quenched significantly by a biexcitonic mechanism. Some detailed calculations indicate that the electron-ion recombination may occur before exciton self-trapping. Fairly good agreement with experiment has been obtained with respect to the relative variation of the scintillation yield with LET using a diffusion-reaction model of free excitons with a specific reaction rate within acceptable limits. At the same LET different heavy-ion tracks can develop different quenching ratios depending on the density of deposited energy in the core