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Issue A&A
Volume 411, Number 1, November III 2003
Special letters issue on: first science with integral
Page(s) L91 - L100
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20031501



A&A 411, L91-L100 (2003)
DOI: 10.1051/0004-6361:20031501

Letter

SPI/INTEGRAL in-flight performance

J. P. Roques1, S. Schanne2, A. von Kienlin3, J. Knödlseder1, R. Briet4, L. Bouchet1, Ph. Paul1, S. Boggs5, P. Caraveo6, M. Cassé2, B. Cordier2, R. Diehl3, P. Durouchoux2, P. Jean1, P. Leleux7, G. Lichti3, P. Mandrou1, J. Matteson8, F. Sanchez9, V. Schönfelder3, G. Skinner1, A. Strong3, B. Teegarden10, G. Vedrenne1, P. von Ballmoos1 and C. Wunderer3

1  Centre d'Étude Spatiale des Rayonnements, CNRS/UPS, BP 4346, 31028 Toulouse, France
2  DSM/DAPNIA/SAp, CEA-Saclay, 91191 Gif-sur-Yvette, France
3  Max-Planck-Institut für extraterrestrische Physik, Postfach 1603, 85740 Garching, Germany
4  CNES/CST, 18 avenue Édouard Belin, 31401 Toulouse Cedex 4, France
5  Space Science Laboratory, University of California, Berkeley, CA 94720, USA
6  IASF, via Bassini 15, 20133 Milano, Italy
7  Institut de Physique Nucléaire, Université catholique de Louvain, 1348 Louvain-La Neuve, Belgium
8  UCSD/CASS, 9500 Gilman Drive, La Jolla, CA 92093-0111, USA
9  IFIC, University of Valencia, 50 avenida Dr. Moliner, 46100 Burjassot, Spain
10  Laboratory for High Energy Astrophysics, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA

(Received 31 July 2003 / Accepted 23 September 2003)

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 3 $\sigma$ sensitivity of the instrument at 1 MeV is $8\times10^{-7}$ ph cm -2 s -1 keV -1 for the continuum and $3\times10^{-5}$ ph cm -2 s -1 for narrow lines.


Key words: gamma-ray: instrument, observations -- space telescope: INTEGRAL/SPI

Offprint request: J. P. Roques, roques@cesr.fr




© ESO 2003

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