OPTICALLY STIMULATED LUMINESCENCE MATERIALS BASED ON CAS FOR GAMMA AND FAST-NEUTRON DOSIMETRY

The OSL selective dosimetrical materials based on CaS doped with Bi an d In ions were synthesised. Physicochemical properties of such materia ls are analysed in detail and a model of naps and recombination centre s is proposed. For CaS-In phosphors the emission in the range of 2.4-2 .1 eV is assigned to the defect Me(3+) Me(+) or Me(3+) Me(-), whereas for CaS-Bi phosphors the centres Bi3+ or Bi3+ Na+ are responsible for the emission at 2.7 eV. The traps revealed in OSL are attributed to in trinsic defects of CaS (energy level of 1.65 eV) and to a single Me(3) state (1.35-1.45 eV). The alpha/gamma ratio of 2000 (arb. units) is reached for the best OSL CaS-In samples synthesised. However, the pres ence of fading for elaborated OSL dosimetric materials needs further i mprovement in technology.