USE OF A NEURAL-NETWORK TO EXPLOIT LIGHT DIVISION IN A TRIANGULAR SCINTILLATING CRYSTAL

This work presents a novel way of exploiting light division in a scint illating crystal to localise the point of interaction using a neural n etwork. Because sensitivity at the centre of a positron tomograph woul d be significantly increased for a spherical geometry compared to a cy linder with the same area of detection, we explored the possibility of developing a position-sensitive triangular block detector that might be used ultimately as an element of a spherical shell. With 3 PMTs cou pled on each side of a triangular BaF2 crystal of about 8 cm(2) x 1 cm , we obtain spatial resolutions less than 4 mm FWHM over the whole sur face of the triangle and energy resolutions of about 14% FWHM for 662 keV impinging photons. Experimental measurements are compared with Mon te Carlo simulations and prospects for different configurations are di scussed.