Systematic effects induced on IBIS detectors by background and inhomogeneity of the spatial responseL. Natalucci, A. J. Bird, A. Bazzano, P. Ubertini, J. B. Stephen, R. Terrier and L. LerusseA&A, 411 1 (2003) L209-L213DOI: https://doi.org/10.1051/0004-6361:20031225