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Modelling

An important activity for instrument performance is software modelling, which allows us to understand the complex interplay of factors that affect performance. Software models help in two respects:

  1. Prediction of performance of an instrument. This can indicate whether the instrument will achieve its requirements/goals, and which parameters need to be optimised
  2. Comparison of a software model with actual behaviour. This can help identify problems in an instrument or areas where further improvements can be made, or it can confirm that the instrument is behaving as well as it was designed to.

We use various modelling tools for different instruments and detectors:

  • Optical ray-tracing: We use packages (usually Zemax) to calculate the performance of photon illumination systems.
  • Radiation/absorption modelling: Packages such as GEANT4 and the MULASSIS (MUlti-LAyered Shielding SImulation Software) front-end allow simulation of the absorption of radiation particles either desirably in detectors, or undesirably as sources of damage for electronic components.
  • Bespoke software: In many cases, there is no convenient off-the-shelf package to do exactly what we want. In this case, we write our own code to simulate instument performance, e.g. sensitivity as a function of wavelength, effects of noise on performance. The code can be implemented as spreadsheets, in graphical tools such as LabVIEW, or using more conventional programming languages.

Page last modified on 07 sep 11 15:48