From 2002, January 23rd to February 6th, an international team has fulfilled a very important calibration campaign on the whole INTEGRAL payload, in one of the clean room of ESA/ESTEC (The Netherlands). The satellite was in its in-flight configuration, with the FM model of the two gamma-ray telescope IBIS and SPI, and the two X-ray monitors JEM-X [see Figure 1].
At the end of the campaign, more than two billions of photons were recorded and analysed by the different calibration teams. These photons had energies between 17 keV and 2750 keV, and was emitted at several different incidences. We have then measured the capability of the IBIS telescope to make images from 17 keV (with the ISGRI detector), up to 2,75 MeV (with the PICSIT detector) [see Figure 2]. The analysis of this huge amount of data - equivalent to one year of source photons in flight - will enable the calibration teams to harmonise the spectral response of the different instruments over the whole INTEGRAL energy range, and also to measure the perturbations induced by the surrounding materials on each of these instrument [see Figure 3].
A calibration device, developed and built by the CEA Saclay, has enabled the positioning of different type of calibration sources with the position accuracy required by the alignment process [see Figure 4]. This device is composed of an X-ray generator, a carrousel of fluorescence targets, and a source holder in order to accommodate the 14 radioactive sources used during the campaign. The CEA/DAPNIA has also built for this campaign a Fast Acquisition System which has enable to accelerate the recording of the IBIS events, and then has shortened the calibration duration.
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Pour en savoir plus
Publication in the magazine ScintillationS .(in french, n° 52, octobre 2001, version PDF 1105 Ko)
Integral at l'ESA (english website)
Information ESA : Calibration of the IBIS l'instrument (english website)
