Imaging detector development for nuclear astrophysics using pixelated CdTe

The concept of focusing telescopes in the energy range of lines of astrophysical interest (i.e., of energies around 1 MeV) should allow to reach unprecedented sensitivities, essential to perform detailed studies of cosmic explosions and cosmic accelerators. Our research and development activities aim to study a detector suited for the focal plane of a γ -ray telescope mission. A CdTe/CdZnTe detector operating at room temperature, that combines high detection efficiency with good spatial and spectral resolution is being studied in recent years as a focal plane detector, with the interesting option of also operating as a Compton telescope monitor. We present the current status of the design and development of a γ -ray imaging spectrometer in the MeV range, for nuclear astrophysics, consisting of a stack of CdTe pixel detectors with increasing thicknesses. We have developed an initial prototype based on CdTe ohmic detector. The detector has 11×11 pixels, with a pixel pitch of 1 mm and a thickness of 2 mm. Each pixel is stud bonded to a fanout board and routed to an front end ASIC to measure pulse height and rise time information for each incident γ -ray photon. First measurements of a 133Ba and 241Am source are reported here.