# Radiation response of inorganic scintillators: Insights from Monte Carlo simulations

## Abstract

The spatial and temporal scales of hot particle thermalization in inorganic scintillators are critical factors determining the extent of second- and third-order nonlinear quenching in regions with high densities of electron-hole pairs, which, in turn, leads to the light yield nonproportionality observed, to some degree, for all inorganic scintillators. Therefore, kinetic Monte Carlo simulations were performed to calculate the distances traveled by hot electrons and holes as well as the time required for the particles to reach thermal energy following γ-ray irradiation. CsI, a common scintillator from the alkali halide class of materials, was used as a model system. Two models of quasi-particle dispersion were evaluated, namely, the effective mass approximation model and a model that relied on the group velocities of electrons and holes determined from band structure calculations. Both models predicted rapid electron-hole pair recombination over short distances (a few nanometers) as well as a significant extent of charge separation between electrons and holes that did not recombine and reached thermal energy. However, the effective mass approximation model predicted much longer electron thermalization distances and times than the group velocity model. Comparison with limited experimental data suggested that the group velocity model provided more accurate predictions. Nonetheless, bothmore »

- Authors:

- Publication Date:

- Research Org.:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 1178882

- Report Number(s):
- PNNL-SA-104163

NN2001000

- DOE Contract Number:
- AC05-76RL01830

- Resource Type:
- Conference

- Resource Relation:
- Conference: Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XVI, August 18-20, 2014, San Diego, California. Proceedings of SPIE, 9213:Paper No. 92130L

- Country of Publication:
- United States

- Language:
- English

### Citation Formats

```
Prange, Micah P., Wu, Dangxin, Xie, YuLong, Campbell, Luke W., Gao, Fei, and Kerisit, Sebastien N..
```*Radiation response of inorganic scintillators: Insights from Monte Carlo simulations*. United States: N. p., 2014.
Web. doi:10.1117/12.2063818.

```
Prange, Micah P., Wu, Dangxin, Xie, YuLong, Campbell, Luke W., Gao, Fei, & Kerisit, Sebastien N..
```*Radiation response of inorganic scintillators: Insights from Monte Carlo simulations*. United States. doi:10.1117/12.2063818.

```
Prange, Micah P., Wu, Dangxin, Xie, YuLong, Campbell, Luke W., Gao, Fei, and Kerisit, Sebastien N.. Thu .
"Radiation response of inorganic scintillators: Insights from Monte Carlo simulations". United States.
doi:10.1117/12.2063818.
```

```
@article{osti_1178882,
```

title = {Radiation response of inorganic scintillators: Insights from Monte Carlo simulations},

author = {Prange, Micah P. and Wu, Dangxin and Xie, YuLong and Campbell, Luke W. and Gao, Fei and Kerisit, Sebastien N.},

abstractNote = {The spatial and temporal scales of hot particle thermalization in inorganic scintillators are critical factors determining the extent of second- and third-order nonlinear quenching in regions with high densities of electron-hole pairs, which, in turn, leads to the light yield nonproportionality observed, to some degree, for all inorganic scintillators. Therefore, kinetic Monte Carlo simulations were performed to calculate the distances traveled by hot electrons and holes as well as the time required for the particles to reach thermal energy following γ-ray irradiation. CsI, a common scintillator from the alkali halide class of materials, was used as a model system. Two models of quasi-particle dispersion were evaluated, namely, the effective mass approximation model and a model that relied on the group velocities of electrons and holes determined from band structure calculations. Both models predicted rapid electron-hole pair recombination over short distances (a few nanometers) as well as a significant extent of charge separation between electrons and holes that did not recombine and reached thermal energy. However, the effective mass approximation model predicted much longer electron thermalization distances and times than the group velocity model. Comparison with limited experimental data suggested that the group velocity model provided more accurate predictions. Nonetheless, both models indicated that hole thermalization is faster than electron thermalization and thus is likely to be an important factor determining the extent of third-order nonlinear quenching in high-density regions. The merits of different models of quasi-particle dispersion are also discussed.},

doi = {10.1117/12.2063818},

journal = {},

number = ,

volume = ,

place = {United States},

year = {Thu Jul 24 00:00:00 EDT 2014},

month = {Thu Jul 24 00:00:00 EDT 2014}

}