The INTEGRAL mass model - TIMM

The INTEGRAL Mass Model (TIMM) was started in 1995 and aimed to create a detailed geometrical model of the whole INTEGRAL satellite on computer. In parallel, a comprehensive Monte Carlo simulation code (called GGOD) has been developed. The mass model and the Monte Carlo code together enable the in-flight operation of INTEGRAL to be simulated at the individual event level. Thus TIMM can be used to provide an independent evaluation of the performance of the individual instruments, to study the interference and complementarity between instruments, to generate test data for software development, and as a powerful tool for post-launch diagnosis. In this paper TIMM is briefly reviewed, some examples from ground calibration are presented, and preliminary comparison to flight data is shown. The future use of TIMM to flat field flight data is also briefly discussed.