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The hard X-/soft gamma-ray band is still not well explored in astrophysics in spite of several unanswered science questions that can only be settled in this energy band, such as the origin of the 511 keV positron annihilation line from the Galactic Center region. The main reason is that this band has been explored so far with non-focusing instruments, that can achieve a limited sensitivity and angular resolution. Our goal is the development of a focusing telescope based on a Laue lens made of bent crystals of Silicon and Germanium, that diffract photons in the 50-700 keV band, with unprecedented angular resolution and sensitivity to continuum spectrum and to lines. Here some result will be reported concerning the elastic bending of the crystals by pressing them on substrates with one of the two main surfaces worked in order to get the same curvature of the lens. This is achieved thanks to accurately anodic bonding them to these substrates, avoiding/without the use of glue, in such a way to satisfy the required angular orientation of the crystals in the lens.

A new detection system for X-/Gamma-ray broad energy passband detectors for astronomy has been developed. This system is based on Silicon Drift Detectors (SDDs) coupled with scintillator bars; the SDDs act as a direct detector of soft (<30 keV) X-ray photons, while hard X-/Gamma-rays are stopped by the scintillator bars and the scintillation light is collected by the SDDs. With this configuration, it is possible to build compact, position sensitive detectors with unprecedented energy passband (2 keV – 10/20 MeV). The X and Gamma-ray Imaging Spectrometer (XGIS) on board the THESEUS mission, selected for Phase 0 study for M7, exploits this innovative detection system. The Wide Field Monitor - Imager and Spectrometer (WFM-IS) of the ASTENA (Advanced Surveyor of Transient Events and Nuclear Astrophysics) mission concept consists of 12 independent detection units, also based on this new technology. For the WFM-IS, a coded mask provides imaging capabilities up to 150 keV, while above this limit the instrument will act as a full sky spectrometer. However, it is possible to extend imaging capabilities above this limit by alternatively exploiting the Compton kinematics reconstruction or by using the information from the relative fluxes measured by the different cameras. In this work, we present the instrument design and results from MEGAlib simulations aimed at evaluating the effective area and the imaging performances of the WFM-IS above 150 keV.

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