The degree of enhancement in a gamma-ray image gleaned from recoil-electron tracking

In order to further enable the deployment of nuclear radiation imaging instruments, one can include the directional information of the products of a radiation’s interaction. In this paper, we quantify the degree of improvement that can be achieved for recoil-electrons in silicon, and further, how that enhancement depends on the electron energy as well as the detector’s lateral spatial resolution. The simulated results show that for detectors of even moderate spatial resolution, the gamma-ray direction can be highly localized. Specifically, if the detector has 100 micrometer spatial resolution, then the direction of the recoil-electron can be confined to 10° or better, for recoil energies greater than 300 keV, compared with a simple back-projection onto a 360° cone for Compton-scatter events. This same performance can be achieved with a 10 micrometer design down to a few 10’s of keV recoil-electron energy; that is, over the entire energy range of interest. I. INTRODUCTION