Abstract
In order to measure X-ray spectra of scattered radiation together with primary beam by using a planar Ge detector, we have measured the angular dependence of the response of the detector for obliquely incident pbotons of241 Am γ-rays. As a result, the active area of a 10mmφ×7mm detector: is 7mm in diameter and the available incident an is within 20°.
Taking into account these properties of the detector, we prepared conic Pb collimators whose maximum incident angle is 13°. Because high-energy photons penetrate the edge of the collimayor, it is unable to convert measured photon spectrum in photon counts into that per unit area only by dividing by the geometrical area of the smallest hole of the collimator. To solve this problem, we have corrected measured photon spectrum by avoiding the photons which penetrated the edge of the conic Pb collimator. In this correction, the shape of the collimator and linear attenuation coefficient of Pb were used.We carried out the measurement of photon spectra with scattered radiation using objects of 30mm Al and 25cm acrylic resin for various object-collimator distances. Experimental spectra had a good agreement with spectra calculated by using Monte Carlo method.
