Gamma ray spectroscopy with CsI(Tl) scintillator coupled to silicon drift chamber

A /spl gamma/-ray detector, designed around a silicon drift chamber having a diameter of 3 mm and coupled to a CsI(Tl) scintillator of the same diameter and 10 mm thick, has been realized and extensively tested. This detector may operate over a wide energy band with a minimum energy threshold that may be set around 10 keV at room temperature or at around 4 keV at 0/spl deg/C. At the typical energy of 662 keV used to characterize a /spl gamma/-ray spectrometer, an energy resolution of 4.4% full-width at half-maximum has been measured at room temperature. This detector shows high energy resolution over the full energy range explored, 6 keV-1.27 MeV, and to our knowledge the results reported are the best ever obtained with a scintillator.