The cosmic X-ray background level at its emission peak

We discuss an accurate measurement of the CXB in the 15-50 keV range performed with the Phoswich Detection System. (PDS) instrument aboard the BeppoSAX satellite, whose results have already been recently reported elsewhere (Frontera F. et al., Astrophys. J., 666 (2007) 86). Unlike the recently reported 2-10keV CXB measurements obtained with the imaging instruments aboard the X-ray satellites BeppoSAX, XMM-Newton, and Chandra that give CXB intensities systematically higher than those obtained with HEAO-I, using the BeppoSAX PDS pointings at high galactic latitude (vertical bar b vertical bar > 15 degrees) we measure a CXB spectrum and intensity level in the 15-50 keV energy band, which are consistent with those obtained with HEAO-1. Astrophysical consequences are discussed.