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Title: Experimental results obtained with the positron-annihilation- radiation telescope of the Toulouse-Argonne collaboration

Conference ·
OSTI ID:197222
; ; ;  [1]; ; ; ;  [2]
  1. Centre d`Etude Spatial des Rayonnements, Toulouse (France)
  2. Argonne National Lab., IL (United States)

We present laboratory measurements obtained with a ground-based prototype of a focusing positron-annihilation-radiation telescope developed by the Toulouse-Argonne collaboration. This balloon-borne telescope has been designed to collect 511-keV photons with an extremely low instrumental background. The telescope features a Laue diffraction lens and a detector module containing a small array of germanium detectors. It will provide a combination of high spatial and energy resolution (15 arc sec and 2 keV, respectively) with a sensitivity of {approximately}3{times}10{sup {minus}5} photons cm{sup {minus}2}s{sup {minus}1}. These features will allow us to resolve a possible narrow 511-keV line both energetically and spatially within a Galactic center ``microquasar`` or in other broad-class annihilators. The ground-based prototype consists of a crystal lens holding small cubes of diffracting germanium crystals and a 3{times}3 germanium array that detects the concentrated beam in the focal plane. Measured performances of the instrument at different line energies (511 keV and 662 keV) are presented and compared with Monte-Carlo simulations. The advantages of a 3{times}3 Ge-detector array with respect to a standard-monoblock detector have been confirmed. The results obtained in the laboratory have strengthened interest in a crystal-diffraction telescope, offering new perspectives for die future of experimental gamma-ray astronomy.

Research Organization:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
197222
Report Number(s):
ANL/XFD/CP-88285; CONF-9509280-1; ON: DE96004327
Resource Relation:
Conference: Workshop in imaging in high energy astronomy, Anacapri (Italy), 26-30 Sep 1995; Other Information: PBD: Oct 1995
Country of Publication:
United States
Language:
English