Study of the 511-keV emission line resulting from the electron-positron annihilation would be precious to search for the location of positron sources in the Galaxy. In order to study galactic positrons and their sources through the 511-keV line, existing operating telescopes have to achieve a sensitivity leap by at least one order of magnitude. Thus, focusing optics are necessary to concentrate photons from a large collection area of a crystal diffraction lens onto a very small detector to improve the signal-to-noise ratio. Crystals having curved diffracting planes (CDP) are very promising for broad-band Laue lens, because they allow concentrating x and gamma rays with high reflectivity. For this aim, we propose to use bent Ge crystals to concentrate the 511-keV photons. The energy passband would be a water-bag distribution, as determined by the curvature of crystal. If such a distribution is tuned across the 511 keV line, very high signal-to-noise detection of such radiation is foreseen. A simulation of a narrow passband Laue lens tuned on the 511 keV electron-positron annihilation line is proposed. Very high effective area can be achieved at these energies. Moreover, thanks to CDP crystals, energy passband and FOV of the lens can be very well-controlled.
Proposal for a Laue lens tuned on the 511-keV annihilation line
CAMATTARI, Riccardo;BELLUCCI, Valerio;GUIDI, Vincenzo;NERI, Ilaria
2012
Abstract
Study of the 511-keV emission line resulting from the electron-positron annihilation would be precious to search for the location of positron sources in the Galaxy. In order to study galactic positrons and their sources through the 511-keV line, existing operating telescopes have to achieve a sensitivity leap by at least one order of magnitude. Thus, focusing optics are necessary to concentrate photons from a large collection area of a crystal diffraction lens onto a very small detector to improve the signal-to-noise ratio. Crystals having curved diffracting planes (CDP) are very promising for broad-band Laue lens, because they allow concentrating x and gamma rays with high reflectivity. For this aim, we propose to use bent Ge crystals to concentrate the 511-keV photons. The energy passband would be a water-bag distribution, as determined by the curvature of crystal. If such a distribution is tuned across the 511 keV line, very high signal-to-noise detection of such radiation is foreseen. A simulation of a narrow passband Laue lens tuned on the 511 keV electron-positron annihilation line is proposed. Very high effective area can be achieved at these energies. Moreover, thanks to CDP crystals, energy passband and FOV of the lens can be very well-controlled.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
