New materials for Radiation imaging

Abstract

The design, characterisation and development of new storage phosphors underpins new high-resolution imaging plates for medical radiography, security and non-destructive testing This thesis describes an experimental study of the properties of materials with potential application in x-ray and thermal neutron imaging plates based on the storage phosphor principle. The properties of known x-ray storage phosphors are first reviewed to background the investigation of new crystalline and glass-ceramic storage phosphors discussed later. An important property of storage phosphors is the depths of electron and hole traps, and a description is given of the design and development of a thermoluminescence spectrometer to measure trap depth. The structure and luminescence of the family of cubic x-ray storage phosphors MxBayXz:Eu2+ (M = Cs or Rb; X = Br or Cl) has been studied and it has been found that Rb2BaCl4:Eu2+, F- has the most promising storage phosphor characteristics. Finally, new thermal neutron storage phosphors are reported which are based on nanocrystallites of BaC12:Eu2+ or BaBr2:Eu2+ storage phosphors contained in a neutron sensitive lithium borate glass matrix. The BaCl2:Eu2+ based glass-ceramics are thermal neutron imaging plates with high neutron sensitivity, low Ƴ-sensitivity, little neutron activation and show potential for higher spatial resolution than commercial neutron imaging plates.