0000000000714145
AUTHOR
Robert Georgii
The INTEGRAL experiment
The International Gamma-ray Astrophysics Laboratory (INTEGRAL) is conceived as the next logical step in gamma-ray astronomy after the US Compton Gamma-Ray Observatory (CGRO) and the French/Russian SIGMA mission. The INTEGRAL scientific payload consists of two main instruments (Imager and Spectrometer) and two monitor instruments (X-Ray Monitor and Optical Transient Camera). The INTEGRAL spectrometer "SPI" is optimized for detailed measurements of gamma-ray lines and mapping of diffuse sources. It combines a coded aperture mask with an array of large volume, high-purity germanium detectors. The detectors make precise measurements of the gamma-ray energies over the 20 keV-8 MeV energy range. …
INTEGRAL/SPI ground calibration
Three calibration campaigns of the spectrometer SPI have been performed before launch in order to determine the instrument characteristics, such as the effective detection area, the spectral resolution and the angular resolution. Absolute determination of the effective area has been obtained from simulations and measurements. At 1 MeV, the effective area is 65 cm^2 for a point source on the optical axis, the spectral resolution ~2.3 keV. The angular resolution is better than 2.5 deg and the source separation capability about 1 deg. Some temperature dependant parameters will require permanent in-flight calibration.
Imaging test setup for the coded-mask /spl gamma/-ray spectrometer SPI
The European Space Agency's International Gamma-Ray Astrophysics Laboratory (INTEGRAL) will be launched in 2002. One of its two main instruments is the spectrometer SPI. It uses 19 HPGe detectors to observe the sky in the energy range of 20 keV to 8 MeV with a resolution of /spl Delta/E/E/spl ap/0.2%. Directional information is obtained using a coded mask. The expected angular resolution is about 20, The SPI imaging test setup (SPITS) was built at the Max-Planck-Institut fur Extraterrestische Physik, Germany, to allow experimental verification of the imaging properties of SPI. SPITS consists of a coded hexagonal uniformly redundant array (HURA) mask and two germanium detectors. The mask is …