Letter to the Editor

SPI: The spectrometer aboard INTEGRAL

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

Corresponding author: J. Knödlseder, knodlseder@cesr.fr

Received: 19 July 2003
Accepted: 20 September 2003

Abstract

SPI is a high spectral resolution gamma-ray telescope on board the ESA mission INTEGRAL (International Gamma Ray Astrophysics Laboratory). It consists of an array of 19 closely packed germanium detectors surrounded by an active anticoincidence shield of BGO. The imaging capabilities of the instrument are obtained with a tungsten coded aperture mask located 1.7 m from the Ge array. The fully coded field-of-view is , the partially coded field of view amounts to , and the angular resolution is . The energy range extends from 20 keV to 8 MeV with a typical energy resolution of 2.5 keV at 1.3 MeV. Here we present the general concept of the instrument followed by a brief description of each of the main subsystems. INTEGRAL was successfully launched in October 2002 and SPI is functioning extremely well.