Change of the neutron sensitivity and neutron/gamma value of CaSO4:Dy thermal neutorn TL pellet(P-KCT-306) with the grain size

CaSO4:Dy phosphor is known to have very high sensitivity to gamma, but the neutron capture cross section of the constituents of CaSO4:Dy are so small that the interactions between thermal neutron and the phosphor are rare. So, CaSO4:Dy TL material cannot be applied to neutron dosimeter in spite of good TL characteristics for beta and gamma radiation. One method to improve the neutron interaction is by introducing an impurity ion with a large thermal neutron captures cross section into the phosphor to act as a neutron target centre. 6Li has much more sensitivity to thermal neutron than to fast neutron or photons, due to the large cross-section reaction 6Li(n,')3H. Thermal neutron is detected indirectly by detecting α-particle and 3H. Making this material enriched by 6Li isotopes can further enhance the sensitivity of TL material to thermal neutrons. Recently Korea Atomic Energy Research Institute (KEARI) has developed a new type of CaSO4:Dy TL materials embedded with phosphorous (KCT-300) to detect beta and gamma radiation with a very high sensitivity. This paper presents the development of CaSO4:Dy TL pellets embedded with 6Li3PO4 compound for a thermal neutron measurement(P-KCT-306). And this paper presents the change of neutron sensitivity and neutron/gamma value with grain size of CaSO4:Dy TL phosphors too