Relative thermoluminescence response of CaS04:Dy to alpha and gamma rays

Thermoluminescence (TL) response of CaSO4:Dy to alpha particles has been studied with variation of sample thickness, grain-size and dose and it is compared with the TL response of CaS04:Dy to gamma rays. It is found that: (i) gamma induced TL glow curve structure undergoes changes with the gamma exposure, whereas alpha induced TL glow curve shows only a single sharp glow peak up to a dose level of 105R Co-60 gamma equivalent. (ii) The TL response to alpha particles decreases with the grain size whereas the gamma induced TL response increases with the grain size. (iii) The alpha response does not change appreciably between 4 and 8 mg/cm2 thickness of the phosphor layer and is maximum for 2 mg/cm2 thickness. An effort is made to explain the supralinearity of gamma and alpha response of CaS04:Dy. (author)