The in-flight background of IBIS/PICsIT

Abstract

The PICsIT instrument is the high-energy imaging detector of IBIS on board INTEGRAL and comprises 4096 individual scintillator elements each working in the energy range from about 175 keV to 10 MeV. Images of the sky are created using the coded aperture technique wherein each point in the detection plane contributes to the final image. For this reason the sensitivity at any point in the image is highly dependent on both the total background and its spatial and temporal uniformity. Herein we describe the PICsIT in-flight background, for the principal modes of operation, from the point of view of total count rate and spectrum, and discuss both the spatial and temporal stability.