The Background of the INTEGRAL SPI Anticoincidence Shield and the Observations of GRBs
2004 (English)In: PROCEEDINGS OF THE 5TH INTEGRAL WORKSHOP ON THE INTEGRAL UNIVERSE / [ed] Battrick, B, European Space Agency, 2004, Vol. 552, 649-652 p.Conference paper (Refereed)
The anti-coincidence shield, ACS, of the spectrometer, SPI (Vedrenne et al., 2003), on INTEGRAL provides the possibility to study temporal properties of gamma-ray bursts (GRBs) with high resolution (Rau et al. 2004). To correctly interpret the results of the analysis, a good understanding of the back,ground and noise levels of the instrument is required. The back-round noise of the ACS, oil timescales up to the length of a GRB, has a Gaussian distribution and its power is independent of frequency, that is, it is white noise. However, it does not follow a Poisson statistic since on average the variance is similar to 1.6 times larger than the mean, and varies significantly. We find a systematic relation between the mean count rate and its variance. The ratio, variance/mean, decreases as the mean count rate increases. As well as helping to understand the cause of this effect, this characterisation is useful when modelling the time variability of GRBs. To illustrate the discussion we present some GRB light curves detected by the SPI/ACS and shortly discuss the analysis that has been made of them.
Place, publisher, year, edition, pages
European Space Agency, 2004. Vol. 552, 649-652 p.
, ESA Special Publications, ISSN 0379-6566 ; 552
GRBs, SPI ACS
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:kth:diva-80180ISI: 000227471700118ScopusID: 2-s2.0-23844526787ISBN: 92-9092-863-8OAI: oai:DiVA.org:kth-80180DiVA: diva2:496038
5th INTEGRAL Workshop on The INTEGRAL Universe; Munich; 16 February 2004 through 20 February 2004
QC 201202192012-02-092012-02-092012-02-19Bibliographically approved