Laue Lens project

Hard X-ray astronomy has reached an advanced stage of development. One of its key roles is the determination of the emission mechanisms in X-ray sources, mainly compact objects, both galactic and extragalactic. The experience with satellites such as BeppoSAX, RossiXTE and INTEGRAL, has shown that, to investigate the physics at extreme regimes of densities and temperatures, the measurement of broad-band spectra from soft X-rays to gamma-rays, is crucial. Owing to their limited sensitivity, non-focusing telescopes are inadequate to acquire broad band spectra at hard X-ray/soft gamma-ray energies for the weakest sources.

A big leap in the continuum/line sensitivity and angular resolution with respect to that of the current hard X-/soft gamma-ray instrumentation based on direct-viewing of the sky (with or without a coded mask) is the development of broad-band focusing telescopes. Although, up to now, the technology (multi-layer telescopes) has become mature for energies below 80 keV, as brilliantly demonstrated by the NuSTAR satellite, further efforts must be made for more efficient instruments at higher energies. 

Laue lenses offer a viable solution to the implementation of a focusing telescope from 30-50 keV up to 600 keV and beyond. Laue lenses are expected to achieve sensitivities 2-3 orders of magnitude better than INTEGRAL at the same energies and better angular resolution (20 arcsec).  

There are two different approaches in Laue lens technique. Narrow band Laue lenses are mainly devoted to detect gamma-ray lines (e.g., the 511 keV positron annihilation line or the 847 keV 56Co line produced in the SN Ia explosions). On the other side broad band Laue lenses are promising tools (e.g. in the 50-600 keV energy range) to study continuum emission spectra and superposed lines. 

The IASF staff is involved, in collaboration with the Ferrara University, both in the Laue Lens mounting phase and in the performance testing phase, as INAF Institutes of Bologna and Palermo were also responsible for the procurement, testing and calibration of the LAUE focal plane detectors.