Scintillation

Every scintillating material has a characteristic light yield, \(Y\), [photons/MeV], and an intrinsic resolution which generally broadens the statistical distribution, \(\sigma_i/\sigma_s > 1\), due to impurities which are typical for doped crystals like NaI(Tl) and CsI(Tl). The average yield can have a non-linear dependence on the local energy deposition. Scintillators also have a time distribution spectrum with one or more exponential decay time constants, \(\tau_{i}\), with each decay component having its intrinsic photon emission spectrum. These are empirical parameters typical for each material.

The generation of scintillation light can be simulated by sampling the number of photons from a Poisson distribution. This distribution is based on the energy lost during a step in a material and on the scintillation properties of that material. The frequency of each photon is sampled from the empirical spectra. The photons are generated evenly along the track segment and are emitted uniformly into \(4\pi\) with a random linear polarization.