Compton telescope with coded aperture mask: Imaging with the INTEGRAL/IBIS Compton mode

TL;DR

This paper introduces a novel Compton telescope design combining a coded mask with a Compton detection unit, significantly improving angular resolution and background correction capabilities for gamma-ray imaging.

Contribution

It presents a new experimental design that enhances angular resolution and background correction in Compton telescopes by integrating a coded mask with the IBIS instrument on INTEGRAL.

Findings

Achieved at least tenfold improvement in angular resolution.

Maintained Compton performance with a reduced efficiency by a factor of two.

Demonstrated imaging with 12 arcminute resolution over a 29x29 degree field.

Abstract

Compton telescopes provide a good sensitivity over a wide field of view in the difficult energy range running from a few hundred keV to several MeV. Their angular resolution is, however, poor and strongly energy dependent. We present a novel experimental design associating a coded mask and a Compton detection unit to overcome these pitfalls. It maintains the Compton performance while improving the angular resolution by at least an order of magnitude in the field of view subtended by the mask. This improvement is obtained only at the expense of the efficiency that is reduced by a factor of two. In addition, the background corrections benefit from the coded mask technique, i.e. a simultaneous measurement of the source and background. This design is implemented and tested using the IBIS telescope on board the INTEGRAL satellite to construct images with a 12' resolution over a 29 degrees x 29 degrees field of view in the energy range from 200 keV to a few MeV. The details of the analysis method and the resulting telescope performance, particularly in terms of sensitivity, are presented.