The work reports on the development of a Strontium Iodide Coded Aperture (SICA) instrument for use in space-based astrophysics, solar physics, and high-energy atmospheric physics. The Naval Research Laboratory is developing a prototype coded aperture imager that will consist of an 8 x 8 array of SrI₂:Eu detectors, each read out by a silicon photomultiplier. The array would be used to demonstrate SrI₂:Eu detector performance for space-based missions. Europium-doped strontium iodide (SrI₂:Eu) detectors have recently become available, and the material is a strong candidate to replace existing detector technology currently used for space-based gamma-ray astrophysics research. The detectors have a typical energy resolution of 3.2% at 662 keV, a significant improvement over the 6.5% energy resolution of thallium-doped sodium iodide. With a density of 4.59 g/cm and a Z_eff of 49, SrI₂:Eu has a high efficiency for MeV gamma-ray detection. Coupling this with recent improvements in silicon photomultiplier technology (i.e., no bulky photomultiplier tubes) creates high-density, large-area, low-power detector arrays with good energy resolution. Also, the energy resolution of SrI2:Eu makes it ideal for use as the back plane of a Compton telescope.

Date Published: 24 August 2015
PDF: 12 pages
Proc. SPIE 9601, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XIX, 96010A (24 August 2015); doi: 10.1117/12.2195575

Published in SPIE Proceedings Vol. 9601:
UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XIX
Oswald H. Siegmund, Editor(s)