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Coincidence counting


Postdoctoral position:

"Simulation of physicochemical processes related to scintillation at low energies using the Geant4 code"

Scientific Background:
The modeling of a liquid scintillation counter based on three photomultipliers dedicated to primary activity measurements is under development at Laboratoire National Henri Becquerel (CEA-List/LNE-LNHB). Using the Geant4 code, the objective is to simulate the propagation of photons from their creation (scintillation or Cerenkov effect) in the optical chamber to the production of photoelectrons in the photomultipliers. In the case of scintillation, ionization quenching depends on the concentration of ionized molecules and excited molecules in the solvent. In the current Geant4 modeling, this physicochemical process is modeled using the classical Birks formula with the kB factor.

The subject of the postdoctoral position is to refine the simulation of the ionization quenching by modeling more precisely the molecular processes at the origin of the light emission non-linearity for low energy deposition. A large amount of studies available in literature show the complexity of the physicochemical processes related to scintillation. In consequence, the first period of the postdoctoral work will be dedicated to the definition of a modeling that incorporates the more significant mechanisms of ionization quenching; this study will be carried out at Laboratoire Capteurs et Architectures Electroniques (CEA-List\DCSI\LCAE). The implementation of the modeling with the Geant4 code will be during a second period.

In order to candidate to the postdoctoral position, it is recommended to have a background in the field of molecular fluorescence. Candidates should send their CV with publication list.

1 year starting 2011 (extendable to 1 more year)

Christophe BOBIN: christophe.bobin (at) (CEA-List\LNE-LNHB)
Matthieu HAMEL: matthieu.hamel (at) (CEA-List\ DCSI\LCAE)

Related publications:
C. Thiam, C. Bobin, J. Bouchard, 2010. Simulation of Cherenkov photons emitted in photomultiplier windows induced by Compton diffusion using the Monte Carlo code Geant4. Appl. Radio. and Isot. 68, 1515-1518.
C. Bobin, C. Thiam, J. Bouchard, F. Jaubert. 2010. Application of a stochastic TDCR model based on Geant4 for Cherenkov primary measurements. Appl. Radio. and Isot. 68, 2366-2371.

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