In-Orbit Performances of the Hard X-Ray/Soft Gamma-Ray Telescope Sigma on Board the Soviet Spacecraft Granat Leray, J. P. ; Ballet, J. ; Goldwurm, A. ; Lebrun, F. ; Paul, J. ; Lei, F. ; Mandrou, P. ; Bouchet, L. ; Roques, J. P. ; Niel, M. Abstract Publication: International Cosmic Ray Conference Pub Date: August 1991 Bibcode: 1991ICRC....2..495L