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Title: Monte Carlo simulation of gamma-ray response of BaF{sub 2} and CaF{sub 2}

We have employed a Monte Carlo (MC) method to study intrinsic properties of two alkaline-earth halides, namely, BaF{sub 2} and CaF{sub 2}, relevant to their use as radiation detector materials. The MC method follows the fate of individual electron-hole (e-h) pairs and thus allows for a detailed description of the microscopic structure of ionization tracks created by incident γ-ray radiation. The properties of interest include the mean energy required to create an e-h pair, W, Fano factor, F, the maximum theoretical light yield, and the spatial distribution of e-h pairs resulting from γ-ray excitation. Although W and F vary with incident photon energy at low energies, they tend to constant values at energies higher than 1 keV. W is determined to be 18.9 and 19.8 eV for BaF{sub 2} and CaF{sub 2}, respectively, in agreement with published data. The e-h pair spatial distributions exhibit a linear distribution along the fast electron tracks with high e-h pair densities at the end of the tracks. Most e-h pairs are created by interband transition and plasmon excitation in both scintillators, but the e-h pairs along fast electron tracks in BaF{sub 2} are slightly clustered, forming nanoscale domains and resulting in the higher e-hmore » pair densities than in CaF{sub 2}. Combining the maximum theoretical light yields calculated for BaF{sub 2} and CaF{sub 2} with those obtained for CsI and NaI shows that the theoretical light yield decreases linearly with increasing band gap energy.« less
Authors:
; ; ; ; ; ; ;  [1]
  1. Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)
Publication Date:
OSTI Identifier:
22217858
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 17; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BARIUM FLUORIDES; CALCIUM FLUORIDES; COMPUTERIZED SIMULATION; ELECTRONS; EV RANGE; EXCITATION; FANO FACTOR; GAMMA RADIATION; KEV RANGE; MONTE CARLO METHOD; RADIATION DETECTORS; SODIUM IODIDES; SPATIAL DISTRIBUTION