First Compton Imaging Tests With I-Ted

The objective of this work is to demonstrate the Compton imaging capabilities of a novel gamma-ray Total-Energy Detector called i-TED. The latter is intended for neutron-capture cross-sections measurements of astrophysical interest, thereby enhancing detection sensitivity by means of the simultaneous combination of Time-of-Flight with Compton-imaging techniques. The developed i-TED demonstrator comprises five position-sensitive radiation detection modules of high energy resolution, which feature an overall position-sensitive field-of-view of 125 cm(2), and thus a high efficiency. Each detector module is based on 50x50 mm(2) large LaCl3 (Ce) monolithic crystals optically coupled to 8x8 pixels silicon photomultipliers. In previous works we have investigated the attainable energy resolution (similar to 3.92(3)% at 662 keV) and spatial resolution (1-3 mm FWHM) for the detectors used in i-TED. In this work we present first Compton imaging tests carried out with i-TED and report on the interplay between scatter-absorber distance, image resolution and efficiency. This is an important aspect for the future implementation of i-TED in (n, gamma) cross-section measurements, where a balance between efficiency and angular resolution has to be found, in order to optimize measuring time and background rejection. Finally, a discussion focused on the technique and scope of the project will be given.