Experimental Results of the Gamma-Ray Imaging Capability With a Si/CdTe Semiconductor Compton Camera

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A semiconductor Compton camera that combines silicon (Si) and Cadmium Telluride (CdTe) detectors was developed, and its imaging capability was examined with various kinds of gamma-ray targets such as a point source, arranged point sources and an extended source. The camera consists of one double-sided Si strip detector and four layers of CdTe pad detectors, and was designed to minimize the distance between a scatterer and the target. This is because the spatial resolution with Compton imaging improves as the target approaches the scatterer. This new camera realizes a minimum distance of 25 mm. By placing the target at a distance of 30 mm from the detector, resolving power better than 3 mm was demonstrated experimentally for a 364 keV <formula formulatype="inline"> <tex Notation="TeX">$(^{131}{\rm I})$</tex></formula> gamma-ray. Positional determination with accuracy of 1 mm was also demonstrated. As a deconvolution method, we selected the iteration algorithm (called List-Mode Expectation-Maximizing Maximum Likelihood), and applied it to several kinds of experimental data. The Compton back projection images of the arranged point sources and an extended object were successfully deconvolved. </para>