Thermoluminescence in CaF2:Dy and CaF2:Mn induced by monoenergetic parallel beam, 81.0 meV diffracted neutrons

The thermal neutron thermoluminescent response of CaF2:Dy(TLD-200, 0.35% wt Dy) and CaF2:Mn (TLD-400, 2% wt Mn) has been measured by exposure to a monoenergetic, parallel beam of 81.0 MeV neutrons from a Kandi-II diffractometer. The TL dosemeters were rectangular and of 0.165 x 0.165 x 0.83 cm dimensions. The measured integral TLD-200 response for a neutron fluence of 1010n cm-2 was 0.21 +- 0.013 R of 60Co which translated to 0.33 +- 0.021 R 60Co for a Maxwellian neutron energy distribution at T = 293.6 K. The measured integral TLD-400 response for a neutron fluence of 1010n cm-2 was 0.09 +- 0.006 R 60Co which similarly translated to 0.14 +- 0.010 R 60Co for a Maxwellian neutron energy distribution at T = 293.6 K. The thermoluminescent response of both materials was both theoretically and experimentally shown to be composed of a thermal neutron induced prompt gamma component (approximately 20%) as well as the major component due to the thermal neutron induced beta decay of 165Dy and 56Mn. It is pointed out that the thermal neutron thermoluminescent response of both materials was size and geometry dependent. (author)