Recent Advances and Opportunities in TLD Materials: A Review

Abstract

Thermoluminescence (TL) is the thermally stimulated emission of light from an insulator or a semiconductor following the previous absorption of energy from ionizing radiation. TL dosimetry is used in many scientific and applied fields such as radiation protection, radiotherapy, industry, and environmental and space research, using many different materials. The basic demands of a thermoluminescent dosimeter (TLD) are good reproducibility, low hygroscopicity, and high sensitivity for very low dose measurements and good response at high doses in radiotherapy and in mixed radiation fields. In this review, we have discussed the past developments and the future opportunities in TLD materials and our efforts to make better future use of low cost materials in TLD applications. For this we have studied and discussed two efficient TLD phosphors with low cost and simple method of preparation on large scale for TLD materials. One of the phosphors is LiF:Mg,Cu,P (LiF: MCP), and another one is LiCaAlF6:Eu, which has the potential to replace conventionally used CaSO4:Dy TL dosimeter. LiF: MCP and LiCaAlF6: Eu phosphors are potential candidates for TL dosimetry and could be good replacement for commercially available phosphors. Apart from this, we have also studied thermoluminescence in Aluminate and Borate materials. We have discussed in detail all three types of TLD materials. First, our study includes complete detail of material properties, methods and dosimetric characterizations of LiF: MCP Phosphor; second, it includes a new TL Dosimeter, LiCaAlF6: Eu and its dosimetric characterizations; and lastly on some TL properties of Li5AlO4: Mn and MgB4O7: Dy,Na. In this review, we discus some recent developments in radiation dosimetry with regards to the measurement techniques and material preparations. Although many materials have been and are currently being studied for TLD, still there is a scope for the improvement in the material properties useful for the TLD, and the synthesis of new, more suitable materials. Contents of Paper

Review of the thermoluminescent dosimetry method for the environmental dose monitoring

“…This in di cated that in sit u a tion when sen si tiv ity is the only pa ram e ter of in ter est, sig nif i cant amount of time can be saved, us ing this re gime [37]. In [34] it was dem on strated that an neal ing at 240 °C in the TL reader was suf fi cient to re store the orig i nal TL sen si tiv ity of the LiF:Mg,Cu,P (MCP) and to re move the pre vi ous dose. Heat ing in the oven at any higher tem per a tures re duces the out put of this type of de tec tor.…”

“…Not much loss in TL in ten sity was ob served at dif fer ent heat ing rates. How ever, the main glow peak shifts from 220 °C to 232 °C grad u ally, with the in crease in the heat ing rate [34]. In prac tice, a heat ing rate of 10 °C per sec ond is con sid ered to be ad e quate.…”

“…For ex am ple, Omanware et al [34] in ves ti gated the ef fect of heat ing rate by heat ing a sam ple made of LiF:Mg,Cu,P and LiCaAlF6:Eu at dif fer ent heat ing rates, from 2 °C per second to 20 °C per sec ond. Not much loss in TL in ten sity was ob served at dif fer ent heat ing rates.…”

“…In par tic u lar, proper se lec tion of an neal ing tem per a ture is im por tant in or der to get the high est TL sen si tiv ity and to elim i nate the ef fects of the pre vi ous ir ra di a tions. It is also very much use ful to avoid high tem per a tures that may re sult in per ma nent loss of TLD sen si tiv ity [34].…”

Luminescence in LiCaAlF6:Eu,La phosphor

“…Applications in vacuum ultraviolet [1][2][3][4] (VUV) and lasers [5][6][7][8] are well known. Apart from these applications, the interest in this material arises from a variety of luminescence phenomena such as photoluminescence (PL) including photon cascade emission [9], radioluminescence [10][11][12][13] including scintillation [14], thermoluminescence [15,16] (TL) and optically stimulated luminescence [17][18][19] (OSL) it exhibits, and the associated applications. LiCaAlF 6 :Eu is useful as a neutron scintillator.…”