Hello everyone,
I am working on the characterization of an HPGe detector with MCNP.
I have voxelized the active germanium crystal into many small cells and assigned an F8 pulse-height tally to each voxel. By integrating the counts under the full-energy peak for each voxel and normalizing by the sum over all voxels, I obtain a spatial distribution.
My question is whether this distribution can legitimately be interpreted as a map of the local contribution to the detector full-energy peak efficiency, or if it should only be considered as a map of where the pulse-height events deposit their energy.
I understand that a photon contributing to the photopeak can deposit energy in several voxels, so the normalized voxel values are not independent contributions.
An alternative would be to perform one simulation per voxel, removing (or making inactive) a single voxel each time, and defining the sensitivity as
Δεi=ε−εi\Delta \varepsilon_i = \varepsilon - \varepsilon_iΔεi=ε−εi
where εi\varepsilon_iεi is the full-energy peak efficiency after removing voxel iii. However, this only provides a marginal sensitivity, and the effects are not additive when several voxels are removed simultaneously because of interaction correlations.
Has anyone worked on a similar problem?
- Is there an accepted way to build a spatial efficiency contribution map in MCNP?
- Is there a better tally or an adjoint/sensitivity approach for this purpose?
- Are there any publications dealing with this type of detector response analysis?
Any references or suggestions would be greatly appreciated.
Thank you!
