Development of fading correction method for a quantitative evaluation using Imaging Plates as an integral dosemeter

由BaFBr：Eu^（2+）磷光体制成的成像板（IP）作为二维图像的探测器具有许多优点，并且已经在许多领域中得到应用。然而，由于IPs具有较大的衰减效应，将IPs作为积分型探测器应用的报道相对较少，本研究的目的是通过阐明IPs的衰减特性，确定衰减校正的函数方程，并发展一种定量评价方法，结果如下：1.通过将Arkyius方程应用于实验结果，衰落效应被表示为具有两个变量的方程：经过的时间（t）和温度（K），作为几个指数衰减分量的和。由公式计算的活化能随组分从0.53到0.90 eV的增加而增加，表明衰减是按活化能较低的组分的顺序发生的。2.研究了α、β和γ辐射及其能量对IPs光致发光衰减模式的影响。发现衰减效应与入射β射线和γ射线的类型和能量无关，但第一分量在α射线照射后衰减很快.提出了一种新的消除第一短半衰期组分的方法，该组分具有相对较低的活化能。利用衰减校正方程确定了定量测量的最佳实用条件。4.0在此条件下，将IP应用于γ射线监测的月积分剂量计，并对其有效性进行了评价。

An imaging plate (IP) made of BaFBr:Eu^<2+> phosphor has many advantages as a detector of two-dimensional images, and has been utilized in a number of fields. However, there are relatively few reports of applying IPs as an integral-type detector, because IPs have a large fading effect.The aim of this research is to determine functional equation for the fading correction by clarifying a characteristic of fading and develop a quantitative evaluation method.The results are listed below;1. By applying Arrhenius' equation to the experimental results, the fading effect is expressed as an equation having two variables: elapsed time(t) and temperature(K), as the sum of a few exponentially-decaying components. The activation energy, calculated from an equation, becomes higher as the component proceeds from 0.53 to 0.90 eV, indicating that fading occurs in the order of the component having the lower activation energy.2.The dependence of fading patterns of photo-stimulated luminescence (PSL) from IPs on alpha, beta, and gamma radiation and their energies is investigated. It is found that the fading effect is independent of the type and the energies of the incident beta and gamma rays except for the first component, which fades out very quickly after irradiation with alpha rays.3. A new method that eliminates the first short half-life component, which has a relatively low activation energy, has been developed by annealing an IP. The practical optimum condition for quantitative measurement is determined by using the fading correction equation.4.0n this condition, IPs are applied to a month integral dosemeter for gamma ray monitoring and its usefulness is evaluated.