Astrophysics with Radioactive Isotopes

The tunable Laue lens – a new telescope for MeV gamma rays

Not scheduled

20m

Oral Presentation

Speaker

Niels Lund

Description

Observations of the gamma rays from radioactive decays in astrophysical sources are severely hampered by limited instrument sensitivities and the dominant background caused by interactions of high energy cosmic rays inside the spacecraft and the instrument. Background suppression is essential and can be most effectively implemented by exploiting the geometric constraints in the Compton process. This was demonstrated 30 years ago with the successful COMPTEL experiment. A new NASA mission, ‘COSI’, with much improved sensitivity is now in preparation for a 2025 launch. COSI will certainly be an important milestone in the development of MeV gamma astronomy. Still, the angular resolution of COSI will in the 5-degree range at MeV energies and the effective area in the few hundred cm2 range. To go much beyond this a COSI-like detector must be supplemented by a focusing telescope. The Laue telescopes have since long been proposed for such a next step. But due to the peculiarities of crystal diffraction optics Laue telescopes have appeared as applicable only in selected, narrow energy bands. It will be shown that a tunable Laue lens can overcome many of the limitations of the classical fixed-energy telescopes and moreover, that tunability can be implemented in simpler ways and with much smaller weight penalty than indicated in the first experiments with this idea.