Toward a user's toolkit for modeling scintillator non-proportionality and light yield

We present a numerical model of scintillator nonproportionality based on rate equations including carrier and exciton transport in assumed cylindrical electron tracks, solved by finite element method. Framed in volumetric excitation density n, these coupled rate equations describe hot and thermalized carrier transport, bimolecular exciton formation, carrier capture, and nonlinear quenching processes expressed in terms of physical rate constants and transport coefficients that have been measured and/or calculated independently of scintillation measurements in the example of CsI:Tl. The set of equations is solved in the spatial non-uniformities of an electron track and in times spanning the cooling of hot carriers up through thermalized transport and capture. The solution of the rate equations is combined with GEANT4 simulation of electron tracks to model electron energy response from the SLYNCI Compton-coincidence experiment.