Gamma-ray astronomy - Gamma-ray line investigations with the Durham y-ray spectrometer

The study of y-ray lines of astrophysical origin has become more interesting with the introduction of cooled solid state detectors having a very good energy resolution, 1-2 keV at 100 keV, and ca. 2-3 keV around 1 MeV. Some of the single crystal spectrometers currently in use in y-ray astronomy are capable of detecting lines with intensities 3 x 10-3 ph cm-2 s-1 when used on balloon experiments. This is close to the y-ray intensities predicted from some celestial y-ray sources. Knowing the y-ray background precisely and with a reasonable although lengthy observation time it should be possible to detect lines from candidate celestial sources, for example neutron stars, Seyfert galaxies or the galactic centre.