The space-borne INTEGRAL-SPI gamma ray telescope: test and calibration campaigns

Abstract. The SPI instrument has been launched on-board the INTEGRAL observatory on October 17, 2002. SPI is a spectrometer devoted to the sky observation in the 20 keV-8 MeV energy range using 19 germanium detectors. The performance of the cryogenic system is nominal and allows to cool the 19 kg of germanium down to 85 K with a comfortable margin. The energy resolution of the whole camera is 2.5 keV at 1.1 MeV. This resolution degrades with time due to particle irradiation in space. We show that the annealing process allows the recovery of the initial performance. The anticoincidence shield works as expected, with a low threshold at 75 keV, reducing the GeD background by a factor of 20. The digital front-end electronics system allows the perfect alignement in time of all the signals as well as the optimisation of the dead time (12%). We demonstrate that SPI is able to map regions as complex as the galactic plane. The obtained spectrum of the Crab nebula validates the present version of our response matrix. The 3σ sensitivity of the instrument at 1 MeV is 8 × 10 −7 ph cm −2 s −1 keV −1 for the continuum and 3 × 10 −5 ph cm −2 s −1 for narrow lines.

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“…The interactions between the Ge-camera, ACS, PSD and DFEE (Schanne et al 2002) were adjusted as during on-ground tests (Schanne et al 2003).…”

Section: Internal Timing Performancementioning

confidence: 99%

“…The SPI-system level tuning-phase took place during the PV-phase. The interactions between the Ge-camera, ACS, PSD and DFEE (Schanne et Al. 2002) were adjusted as during on-ground tests (Schanne et al 2003).…”

Section: Internal Timing Performancementioning

confidence: 99%

SPI/INTEGRAL in-flight performance

Roques

Schanne

Kienlin

et al. 2003

A&A

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163

145

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“…In April 2001, day and night during one month, SPI was calibrated at CEA in Bruyères le Châtel [5] (see Fig. 9).…”

Section: The Spi Ground Calibrationmentioning

confidence: 99%

Observing with a space-borne gamma-ray telescope: selected results from INTEGRAL

Schanne¹

2006

J. Phys.: Conf. Ser.

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The International Gamma-Ray Astrophysics Laboratory, i.e. the INTEGRAL satellite of ESA, in orbit since about 3 years, performs gamma-ray observations of the sky in the 15 keV to 8 MeV energy range. Thanks to its imager IBIS, and in particular the ISGRI detection plane based on 16384 CdTe pixels, it achieves an excellent angular resolution (12 arcmin) for point source studies with good continuum spectrum sensitivity. Thanks to its spectrometer SPI, based on 19 germanium detectors maintained at 85 K by a cryogenic system, located inside an active BGO veto shield, it achieves excellent spectral resolution of about 2 keV for 1 MeV photons, which permits astrophysical gamma-ray line studies with good narrow-line sensitivity. In this paper we review some goals of gamma-ray astronomy from space and present the INTEGRAL satellite, in particular its instruments ISGRI and SPI. Ground and in-flight calibration results from SPI are presented, before presenting some selected astrophysical results from INTEGRAL. In particular results on point source searches are presented, followed by results on nuclear astrophysics, exemplified by the study of the 1809 keV gamma-ray line from radioactive 26 Al nuclei produced by the ongoing stellar nucleosynthesis in the Galaxy. Finally a review on the study of the positron-electron annihilation in the Galactic center region, producing 511 keV gamma-rays, is presented.

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“…For example using a 60 Co source, the measured 1332 keV peak showed a full width at half maximum (FWHM) between 2.1 and 2.6 keV for all 19 detectors over a large temperature range, confirming that a good energy resolution is expected in flight in case of low radiation damages or after annealing. During the month of April 2001 the SPI on-ground calibration campaign [10][11] took place at CEA in Bruyères le Châtel (France). In May 2001 the spectrometer was delivered to ESA and was integrated on board of the satellite at Alenia in Torino (Italy).…”

Section: Integration and Test Campaigns Of Spimentioning

confidence: 99%

“…The SPI on-ground calibration campaign [10] was performed during the whole month of April 2001 at the CEA center of Bruyères le Châtel (France). This site was selected since it offered the possibility for the manipulation of high activity radioactive sources as well as the use and modification of its accelerator complex.…”

Section: On-ground Calibration Of Spimentioning

confidence: 99%

Calibration of the spectrometer aboard the INTEGRAL satellite

et al. 2003

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SPI, the Spectrometer on board the ESA INTEGRAL satellite, to be launched in October 2002, will study the gammaray sky in the 20 keV to 8 MeV energy band with a spectral resolution of 2 keV for photons of 1 MeV, thanks to its 19 germanium detectors spanning an active area of 500 cm 2 . A coded mask imaging technique provides a 2° angular resolution. The 16° field of view is defined by an active BGO veto shield, furthermore used for background rejection. In April 2001 the flight model of SPI underwent a one-month calibration campaign at CEA in Bruyères le Châtel using low intensity radioactive sources and the CEA accelerator for homogeneity measurements and high intensity radioactive sources for imaging performance measurements. After integration of all scientific payloads (the spectrometer SPI, the imager IBIS and the monitors JEM-X and OMC) on the INTEGRAL satellite, a cross-calibration campaign has been performed at the ESA center in Noordwijk. A set of sources has been placed in the field of view of the different instruments in order to compare their performances and determine their mutual influence. Some of those sources had already been used in Bruyères during the SPI standalone test. For the lowest energy band calibration an X-ray generator has been used. We report on the scientific goals of this calibration activity, and present the measurements performed as well as some preliminary results.

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The space-borne INTEGRAL-SPI gamma ray telescope: test and calibration campaigns

Cited by 9 publications

References 5 publications

SPI/INTEGRAL in-flight performance

SPI/INTEGRAL in-flight performance

Observing with a space-borne gamma-ray telescope: selected results from INTEGRAL

Calibration of the spectrometer aboard the INTEGRAL satellite

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