# Generation of INTEGRAL/SPI Response Matrices

### B. J. Teegarden

### C. Shrader

### S. Sturner

## Abstract

The Spectrometer for INTEGRAL (SPI) is a gamma-ray spectral imager
with an angular resolution of 3 deg and an a typical energy resolution
of E/DE = 500 at 1 MeV. This combination of high energy
resolution and moderate angular resolution results in an instrumental
response function which covers a very large volume of phase space.
The generation of such a response function in full detail would
require prohibitive amounts of CPU time and storage capacity. Several
methods for generating and compressing the SPI response function are
under investigation at the Goddard Space Flight Center. They
generally involve separating the response function into spatial and
energy dependent components followed by a further separation based on
the point of first scatter of the incident photon. Extensive trial
response matrices have been generated using the MGEANT code (a
GSFC-developed variant of GEANT) which incorporates a detailed
mass/geometry model of SPI. These data sets have been used to test
various compression methods. Results of these tests are given in this
poster.

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On 16 Jul 1999, 09:18.