Cascade gamma-gamma tomography and angular correlation measurements

摘要

Abstract: Cascade gamma-ray tomography depends on the measurement of two or more gamma-rays emitted from a radionuclide in coincidence. In using suitable detectors of appropriate timing resolution it may also be possible to obtain information about the 'chemical environment' of the radionuclide i.e. the binding site in the material to which it is attached by carrying out, simultaneously, time differential perturbed angular correlation (TDPAC) measurements. A dual block bismuth germanate (BGO) detector system, designed for use in positron emission tomography (PET) has been employed to perform cascade gamma-ray tomography with a point $+60$/Co source (1173 and 1332 keV). It is shown that despite the poor energy resolution of the coincidence system, the point source can be imaged with a multi-hole collimator, on one or both detectors, with a resolution (full width at half maximum) of 3.8 and 2.4 $POM 0.2 mm respectively, at the expense of significantly reduced sensitivity. Practical constraints limit usefulness of the system which new scintillation systems, with respect to time and energy resolution, should overcome. !10