The impact of a front cooling plate of aluminium on the energy resolution was studied. The cooling plate was placed in front of the crystals (distance: 3mm) and its thickness was varied between 0mm and 10mm.

The geometry can be seen in the following figures.
Unfortunately the inner cooling plate (inner red ring) was set to a thickness of 10mm instead of 1mm. This worsens the energy resolution for the inner crystals. In the final set-up a thickness of 1mm is foreseen.

Materials:

PRIMAUniformDiscGenerator was used to shoot electrons equally distributed on the detector. Electron energies of 100MeV, 500MeV, 1000Mev and 15000MeV were used. For each energy and front cooling plate thickness 10M events were generated.
The extraction of the energy resolution for each crystal was done analogue to First Cooling Studies.
As an example the results for 1000MeV electrons and a front cooling plate of 1mm, 2mm, 6mm and 10mm are shown. Please click on the images for a detailed view.

In order to have a better overview of the impact of the front cooling plate thickness on the energy resolution, the mean of the energy resolution of the crystals of eight inner submodules was calculated. The used submodules are depicted in the following picture.

The mean energy resolution and the std of those 8*16=128 inner crystals was calculated and plotted against the front cooling plate thickness.
The plots show a worsening of the energy resolution with a thicker cooling plate. But still the absolute difference for no cooling plate and a 10mm cooling plate is from 4.7% (3.04%) to 4.85% (3.12%) for an energy of 500Mev (1000MeV).