Developent of dosimetry method for synchrotron radiation X rays using photoacoustic spectroscopy

光声光谱学的最初目的是利用光通过吸收光产生的热量来检测材料表面。本研究的目的是将该方法应用于辐射检测。这种方法的优点是(1)通过吸收辐射来测量热；(2)任何类型的材料都可以作为靶样品。从热和吸收的能量相等的角度来看，这种探测器具有量热计的特点。我们测试了三种类型的辐射，如同步辐射X射线、200kVPX射线和回旋质子束。对于靶材，对金属箔、金属粉末、有机薄膜和有机粉末进行了测试。首先，我们构建了一个由探测器、前置放大器、锁定放大器和个人计算机组成的光声剂量计系统。金属箔和金属粉末的信号强度足以作为剂量计使用，然而，从有机材料中观察到低信号强度。我们发现，输入X射线强度与输出光声信号强度之间存在良好的线性关系。在以金属样品为靶材的情况下，该系统可作为一种新型的吸收剂量计。然而，在以有机材料为靶材的情况下，探测器的灵敏度必须提高10倍以上，才能用作吸收剂量计。

Original purpose of the photoacoustic spectroscopy is to use light to examine material surface by heat that is created by the absorprion of the light. The aim of this study is to apply this methed to the detection of the radiation. Merits of this method are (1) to measure heat by the absroption of radiation and (2) any sort of material can be used as target samples. From the equality of heat and the absorbed energy, this detector would have a chracteristics as a calorimeter. We tested three types of radiations, such as synchrotron radiation X rays, 200 kVp X rays and cyclotron proton beams. As for the target materials, metal foils, metal powdwes, organic films and organic powders were tested. At first, we constructed a photoacoustic dosimeter system combining a detector, a preamp, a lock-in-amp and a personal computer. Signal intensity from the metal foils and metal powders were enough for the use as a dosemeter, however, low signal intensities were obserbed from orginic materials. We found good linear relationship between the input X-ray imtensities and output photoacoustic signal intensities. In the case using metal samples as targets, this system can be used as a new type of an absorbed dosemeter. However, in the case using organic materials as targets, improvemant of the detector sensitivity more than 10 times is necessory to be used as a absorbed dosemeter.