テルル化カドミウム検出器で測定したX線スペクトルの補正

Abstract

Since the cadmium telluride detector has about fourfold the photeolectric absorption probability as compared to germanium, the detector area can be miniaturixed. However, it is difficult to increase the thickness of the particles because of the decreased positive hole mobility, resulting in the high probability of photon escape. When measuring the continuous spectum of the rradiation source with the detector, the spectrum form becomes distorted towards the lower energy region by reason of these problems. We applied an unfolding-method to the measured spetrum. This method presupposes that the tail region should be flat if measured by a mono-energy radiation source. A respoonse function and an efficiency curve were obtained easily from the spectrum distribution of standard sources. The reponse function was expressed with about a 200-degree square triangularmatrix. Since the absorption edge of cadmium and tellurium is around 30keV, characteristic X-rays emitted from standard sources were used for the determination of detection efficiency. The original spectrum was obtained easily by those xorrections. We consider that quality control of X-ray equipment and the assessment of exposure doses can be done correctly using this spectrum.