Further studies on the new high sensitive CaSO4:Dy thermostimulated luminescence phosphor.
CaSO4:Dy phosphor prepared by a new recipe (denoted as N) is nearly 50% more sensitive than the presently used one (denoted as P). N consists of needle shaped crystals while P is mostly quadrilateral. In P most of the grains in as-grown condition are >75 microm in size while in N most of the grains are <75 microm. While the sensitivity of P increases with grain size, an exactly opposite trend is seen with N since higher sized grains (>105 microm) in N are agglomerates of particles and hence are opaque. The detection threshold of N (14.4 microGy) is nearly 4 times lower than that of P (54.2 microGy). The major glow peak(s) in both the phosphors occur in the 460-490 K (187-217 degrees C) region. But the low temperature peak near 390 K (117 degrees C) is very prominent in P while its presence is insignificant in N. The post-irradiation storage stability of N at approximately 30 degrees C was tested up to a period of 25 d and found to be better than that of P. The emission spectra of P and N are characteristic of Dy3+. In P, the 480 nm to 570 nm emission intensity ratio varies slightly with glow peak temperature, unlike that of N. The Dy concentration quenching effect in N is less serious than that in P. The intrinsic UV sensitivity of N is nearly a factor of 20 times lower than that of P.
Lakshmanan
A R
AR
Health and Safety Division, Indira Gandhi Centre for Atomic Research Kalpakkam, India. arl.igcar.ernet.in
Tomita
A
A
D002133:Calcium Sulfate / Q000737:chemistry / Q000528:radiation effects*; D003460:Crystallization; D004419:Dysprosium / Q000737:chemistry; D005720:Gamma Rays; D011854:Radiochemistry; D012680:Sensitivity and Specificity; D013819:Thermoluminescent Dosimetry / Q000379:methods* / Q000706:statistics & numerical data; D014466:Ultraviolet Rays
D004419:Dysprosium; D002133:Calcium Sulfate