XRD of CsI scintillators
EMSL Project ID
30996
Abstract
As part of a PNNL LDRD project exploring possible causes of the non-proportional response of scintillator light output to gamma-ray energy, we have measured the optical emission spectra at a pair of gamma-ray energies, which have a large difference in light yield. We observe a difference in our measured emission spectra for all three of our samples of cesium iodide doped with thallium. In addition to the possible explanation that this difference is related to the non-proportional response, there are other possible causes for this difference. Subsurface damage is one alternative explanation given the much different penetration depths of the two gamma ray energies. The lower gamma ray energy, 60 keV, only penetrates about 0.3 mm below the crystal surface, while the higher energy gamma rays, 662 keV, almost uniformly irradiate the crystals since they have about 70% transmission through our 1 cm thick crystals. To test this alternative explanation, we wish to use x-ray diffraction measurements to look for disorder near the surface in our cesium iodide crystals doped with approximately 0.2 atomic percent of thallium. If low levels of disorder are found near the surface, this will eliminate the alternative explanation, while if significant disorder is found, then the case for the spectral differences being related to non-proportionality will be weakened.
Project Details
Project type
Limited Scope
Start Date
2008-08-20
End Date
2008-09-20
Status
Closed
Released Data Link
Team
Principal Investigator