Workshop on Physics on Nuclei at Extremes, Tokyo Institute of Technology, 26.01.2010 Institute for Nuclear Research and Nuclear Energy Bulgarian Academy of Science RISING & AGATA detectors in experiments with relativistic beams at GSI : Simulations and comparison with the experiments Pavel Detistov
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Workshop on Physics on Nuclei at Extremes, Tokyo Institute of Technology, 26.01.2010 Institute for Nuclear Research and Nuclear Energy Bulgarian Academy.
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Workshop on Physics on Nuclei at Extremes, Tokyo Institute of Technology, 26.01.2010
Institute for Nuclear Research and Nuclear EnergyBulgarian Academy of Science
RISING & AGATAdetectors in experiments with relativistic beams
at GSI : Simulations and comparison
with the experiments
Pavel Detistov
Workshop on Physics on Nuclei at Extremes, Tokyo Institute of Technology, 26.01.2010
What is the problem?What is the problem?
Long high energy background tail in the experimental spectra.
The passage of heavy ions through the matter is related to the interactions with the electrons from the electronic shells of the matter’s atoms.
The main processes identified to be responsible for the high energy gamma-ray emissions in such conditions are:
Radiative Electron Capture process
Primary Bremsstrahlung process
SEcondary Bremsstrahlung process
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0 200 400 600 800 1000 1200 1400
Counts
Energy, keV
Experimental Spectra
H.J. Wollersheim et al., Nuclear Instruments and Methods in Physics Research A 537 (2005) 637–657
Workshop on Physics on Nuclei at Extremes, Tokyo Institute of Technology, 26.01.2010
GEANT4GEANT4
Following the GEANT4 design philosophy the following new physics classes representing the respective processes has been developed:
G4ionRadativeElectronCaptureK
G4ionRadativeElectronCaptureL
G4ionPrimaryBremsstrahlung
SecondaryBremsstrahlung
How to create a model to see these processes in action?
GEANT4 (GEometry ANd Tracking) tool is a set of libraries written in C++ forming the complete toolkit for simulation of the passage of particles through matter.
It contains number of independent categories that could be combined together in a complete simulation model:
Why there is a difference between the simulations and the experiment?
RISING Experimental spectra
Simulation
The physical case:52Fe (2+ → 0+) 832 keV
The spectra is Doppler corrected for βt = v/c = 0.45
Workshop on Physics on Nuclei at Extremes, Tokyo Institute of Technology, 26.01.2010
The background radiation produced by an α particle.
Probably, the experimental spectra is an superposition of the spectra seen by the detector from the projectile of interest and the light particle induced spectra, both Doppler corrected for the energy of the projectile.
Performance of the AGATA detector array in such experiments will depend strongly on the possibility of the tracking algorithms to track events with higher multiplicity.
Workshop on Physics on Nuclei at Extremes, Tokyo Institute of Technology, 26.01.2010
Workshop on Physics on Nuclei at Extremes, Tokyo Institute of Technology, 26.01.2010
ConclusionConclusion
A model for background simulation has been developed and tested. The simulations have been compared to the experimental results taken from the RISING experimental campaigns. Good agreement between the simulations and experiment is found. The model could be used to estimate background radiation in any realistic experiment involving ions with relativistic energies.
Performance of the AGATA detector in similar to RISING experimental conditions is under evaluation. The high multiplicity of the background emission limits usage of the gamma-ray tracking in such conditions.
The benefit of AGATA for the “stopped” beam setup is the better efficiency compared to the RISING array.