Geant4 Simulations for the Radon Electric Dipole Moment Search at

3.1 Introduction
3.1.1 Previous Work
The foundation of the RnEDM simulations was built on the existing Geant4
simulationsoftheTRIUMF-ISACGamma-RayEscapeSuppressed Spectrometer (TI-
GRESS) [35]. The geometry of the TIGRESS Geant4 simulation was constructed
from design drawings of the detector and suppression shields. The performance of
thesimulation was validated withmeasurements conducted with prototypeTIGRESS
γ-ray detectors [36]. As discussed in Section 2.4, the GRIFFIN γ-ray spectrometer
is very similar in external geometry to its sister spectrometer TIGRESS. The primary
difference between the two γ-ray spectrometers is the crystal segmentation.
The outer electrical contact of a TIGRESS crystal is highly segmented, to allow for
a three-dimensional localization of γ-ray interactions inside the crystal. GRIFFIN,
on the other hand, will be used primarily as a decay spectrometer with low-energy
radioactive ion beams and the crystal segmentation is therefore not necessary. The
performance of the GRIFFIN γ-ray spectrometer will, however, be very similar to
that of an unsegmented TIGRESS γ-ray spectrometer. As electrical contact segmentation
for TIGRESS has been incorporated at the analysis, rather than simulation,
stage, the fully verified Geant4 simulation framework for TIGRESS can, in fact, be
used as a Geant4 simulation of GRIFFIN.
3.1.2 Modifications
A significant number of modifications were made in the previous Geant4 code
used with TIGRESS for the RnEDM studies presented in this thesis. Firstly, the
code structure was initially “hard-coded” to only allow for one detection system in
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