Hard X-ray emission from the galaxy cluster A3667

We report the results of a long BeppoSAX observation of Abell 3667, one of the most spectacular galaxy clusters in the southern sky. A clear detection of hard X-ray radiation up to similar to 35 keV is reported, while a hard excess above the thermal gas emission is present at a marginal level that s hould be considered as an upper limit to the presence of nonthermal X-ray r adiation. The strong, hard excesses reported by BeppoSAX in Coma and A2256 and the only marginal detection of nonthermal emission in A3667 can be expl ained in the framework of the inverse Compton model. We argue that the nont hermal X-ray detections in the Phoswich Detection System energy range are r elated to the radio index structure of halos and relies present in the obse rved clusters of galaxies.