D690 has significantly fewer coincidences in root file than mMR about stir-gate-connection HOT 1 OPEN

With the merge of #24 correcting the crystal material, I have centered the single voxel source and obtain the following numbers from 10 second GATE simulations.

Few counts in the mMR compared to previous as the single voxel actually was two voxels (yet constant between the previous scanner evaluations).

Based upon some back of the envelop calculations, the mMR should measure 2.18x more Singles, produced by the central point source, than the D690 due to scanner geometry.

Additional notes. The SinglesReadout tree in the root files corresponds to the unblured and unthresholded singles. the Singles tree is the filtered and blurred single events.

Therefore, for the most part the geometry and crystals seem to make sense in terms of relative measured counts. Future tests should aim use a line source, such as those used in:

mMR: 13.3 cps/kBq from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4766138/
D690: 7.5cps/kBq from http://dx.doi.org/10.1118/1.3635220
#14 (comment)

from stir-gate-connection.