ESA Science & Technology - Publication Archive

The spectrometer on INTEGRAL (SPI) is one of the two main telescopes of the future INTEGRAL observatory. SPI is made of a compact hexagonal matrix of 19 high-purity germanium detectors shielded by a massive anticoincidence system. A HURA type coded aperture modulates the astrophysical signal. The spectrometer system, its physical characteristics and performances are presented. The instrument properties such as imaging capability, energy resolution and sensitivity have been evaluated by means of extensive Monte-Carlo simulations. With the expected performances of SPI, it will be possible to explore the gamma-ray sky in greater depth and detail than it was possible with previous gamma-ray telescopes like SIGMA, OSSE and COMPTEL. In particular, the high-energy resolution will allow for the first time the measurement of gamma-ray line profiles. Such lines are emitted by the debris of nucleosynthesis and annihilation processes in our Galaxy. Lines from these processes have already been measured, but due to the relatively poor energy resolution, details of the emission processes in the source regions could not be studied. With the high-resolution spectroscopy of SPI such detailed investigations will be possible.

The International Gamma-Ray Astrophysics Laboratory (INTEGRAL), to be launched in 2001, is dedicated to the fine spectroscopy (DE: 2 keV FWHM @ 1.3 MeV) and fine imaging (angular resolution: 12' FWHM) of celestial gamma-ray sources in the energy range 15 keV to 10 MeV with concurrent source monitoring in the X-ray (3-35 keV) and optical (V, 550 nm) range. The mission is conceived as an observatory led by ESA with contributions from Russia and NASA. The INTEGRAL observatory will provide to the science community at large an unprecedented combination of imaging and spectroscopy over a wide range of gamma-ray energies. This paper summarises the key scientific goals of the mission, the current development status of the payload and spacecraft and it will give an overview of the science ground segment including the science data center, science operations and key elements of the observing program.

Proceedings of the 3rd INTEGRAL Workshop, Taormina 1998

The INTErnational Gamma Ray Astrophysics Laboratory (INTEGRAL) is being developed by ESA as the second medium-size satellite of the long-term scientific plan Horizon 2000. It is an observatory providing an excellent opportunity to the scientific community for detailed imaging and high-resolution spectroscopy of Gamma-ray sources.
After completion of the design and development phase the Structural Thermal Model of the Integral Spacecraft and its four scientific instruments is presently being tested. First tests took place in spring 1998 at the ESTEC test facilities. Late summer 1998 the Engineering Model test campaign will follow.
This paper summarises the key programmatic milestones of the project, highlights the final design characteristics of the satellite, reports on the first test results, and describes the orbital scenario of the mission and the herewith-related requirements to the satellite.

The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) is dedicated to the fine spectroscopy (Delta-E: 2 keV FWHM @ 1.3 MeV) and fine imaging (angular resolution: 12 arcmin FWHM) of celestial gamma-ray sources in the energy range 15 keV to 10 MeV with concurrent source monitoring in the X-ray (3 - 35 keV) and optical (V, 550 nm) range. The mission is conceived as an observatory led by ESA with contributions from Russia and NASA. The INTEGRAL observatory will provide to the science community at large an unprecedented combination of imaging and spectroscopy over a wide range of energies. Most of the observing time will be open to the scientific community. This paper summarises the key scientific goals of the mission, the current development status of the payload and spacecraft and it will give an overview of the science ground segment including data centre, science operations and the key elements of the observing programme

The Core Programme of the INTEGRAL mission is defined as the portion of the scientific programme covering the guaranteed time observations for the INTEGRAL Science Working Team. This paper describes the current status of the Core Programme preparations and summarizes the key elements of the observing programme. Letters & Communications, 1999

Proceedings of the 3rd Integral Workshop, Taormina 1998

The Compton Telescope (COMPTEL) telescope aboard the Compton Gamma-Ray Observatory (CGRO) is capable of imaging gamma-ray line sources in the MeV region with a sensitivity of the order 10^-5 photons/(cm²s). During two observations periods in July 1992 and February 1993 the Galactic plane in the region of the young supernova remnant Cas A was observed, showing evidence for line emission at 1.16 MeV from the decay of ⁴⁴Ti at a significance level of approximately 4 sigma. This is the first time a supernova remnant has been detected in the gamma-ray line from ⁴⁴Ti decay. Adopting a distance of 2.8 kpc to the Cas A remnant, the measured line flux (7.0 +/- 1.7) x 10^-5 photons/(cm²s), can be translated into a ⁴⁴Ti mass ejected during the Cas A supernova explosion, between (1.4 +/- 0.4) x 10^-4 solar mass and (3.2 +/- 0.8) x 10^-4 solar mass, depending on the precise value of the ⁴⁴Ti mean life time and on the precise date of the event. Implications of this result for supernova nucleosynthesis models are discussed.