Free access article

A&A 411, L107-L112 (2003)
DOI: 10.1051/0004-6361:20031156

Letter

SPI instrumental background characteristics

P. Jean¹, G. Vedrenne¹, J. P. Roques¹, V. Schönfelder², B. J. Teegarden³, A. von Kienlin², J. Knödlseder¹, C. Wunderer², G. K. Skinner¹, G. Weidenspointner^{1, 3, 4}, D. Attié⁵, S. Boggs⁶, P. Caraveo⁷, B. Cordier⁵, R. Diehl², M. Gros⁵, P. Leleux⁸, G. G. Lichti², E. Kalemci⁶, J. Kiener⁹, V. Lonjou¹, P. Mandrou¹, Ph. Paul¹, S. Schanne⁵ and P. von Ballmoos<sup>1

1</sup>  Centre d'Étude Spatiale des Rayonnements, CNRS/UPS, BP 4346, 31028 Toulouse Cedex 4, France
²  Max Planck Institut fuer extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
³  Laboratory for High Energy Astrophysics, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
⁴  Universities Space Research Association, 7501 Forbes Blvd. Seabrook, MD 20706-2253
⁵  DSM/DAPNIA/Service dAstrophysique, CEA Saclay, 91191 Gif-sur-Yvette, France
⁶  Space Science Laboratory, University of California Berkeley, CA 94720, USA
⁷  Istituto di Fisica Cosmica del CNR "G. Occhialini", via Bassini 15, 20133 Milan, Italy
⁸  Institut de Physique Nucleaire, Universite catholique de Louvain, 1348 Louvain-la-Neuve, Belgium
⁹  Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, IN2P3-CNRS, 91405 Orsay Campus, France

(Received 15 July 2003 / Accepted 30 July 2003)

Abstract
In its space environment the INTEGRAL observatory is subject to an intense irradiation by energetic cosmic-ray particles that leads, via nuclear interactions with the telescope and spacecraft materials, to an important background of false events. In this paper we present the characteristics of the instrumental background that is observed in the spectrometer SPI (SPectrometer of INTEGRAL). We explain the tuning that has been performed on the parameters of the anticoincidence system in order to optimise the telescope sensitivity over the full energy range. Temporal variations of the instrumental background are discussed and methods are proposed that allow for their modelling in first order.

Key words: gamma-ray: instruments

Offprint request: P. Jean, jean@cesr.fr

© ESO 2003

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

• If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
• You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
• You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.