Development of Germanium Detector Simulations with the Geant 4 Toolkit Andrew Mather 12th UK Postgraduate Nuclear Physics Summer School St. Andrews September 1st - 14th 2003

Presentation Overview Geant 4 – Introduction Geant 4 – Simulation Structure Why use Simulations HP Germanium Detectors Simulated Results Conclusion

Geant 4 - Introduction Developed at Cern by HEP. Based on Object Orientated Architecture, Using C++ Used in HEP, Nuclear, Medical and Accelerator Physics. Fully open source, extremely flexible and extendable due to OO nature.

Geant 4 – Simulation Structure

Why use Simulations Back-up (or otherwise!) experimental observations. Ability to retrieve information not accessible from real detectors. (e.g. exact position and interaction type of gamma-ray interactions) Can produce higher statistics for certain results. Help decide properties that will yield best experimental results before commencing the experiment. Cost and time saving, giving information that would not have been feasible to measure experimentally.

HP Germanium Detectors Simulated (All sizes in mm)

Results – “GMX45PAS” mm Single Crystal Ge Detector (GMX45PAS) Geant 4MCNP*Penelope* Peak to Compton 60:164:182:1- Relative Efficiency 46%29 %27 % * MCNP and Penelope results courtesy of Mark Ibison

Results – “Tigre” mm 24 fold segmented Ge Detector (Tigre) Geant 4 Relative Efficiency 64%34 %

Results – Multiplicity 122 Kev

Results – Multiplicity 1408 Kev

Results – Spectra Simulation Vs Exp

Results – First Interaction

Results – 511 Kev 1 st 2 nd 3 rd interaction

Results – Event ID

Results – Doppler Broadening

Conclusion Simulations have produced results mostly in agreement with experiment. Produced some interesting results to be followed up experimentally in the future. (Tigre Hit-Patterns and Multiplicity data) Greater understanding from retrieved data normally lost or hard to measure in experiments.