Geant4 Simulations for the Radon Electric Dipole Moment Search at

used around the measurement cell in order to maintain a static magnetic field. Unfortunately,
this shielding between the EDM cell and the γ-ray detectors will also
attenuate the emitted γ rays from the decaying radon nuclei; thereby lowering the
over-all efficiency of the system. This effect was studied in the RnEDM simulations
and is presented in Chapter 4. The simulated µMetal was formulated from specifications
given by The MuShield Company[40]. µMetal has a density of 8.747 g/cm 3
and is composed of (by weight) 80.0% nickel, 14.93% iron, 4.20% molybdenum, 0.50%
manganese, 0.35% silicon and 0.02% carbon.
The simulated cerium-doped lanthanum bromide crystal was used in the construction
of Saint-Gobain’s BrilLanCe 380 detector. The performance of this scintillator
and its role in the RnEDM experiment is discussed in Section 3.5.2. According to
Saint-Gobain, their cerium-doped lanthanum bromide (LaBr 3 (Ce)) crystal has a density
of 5.08 g/cm 3 with approximately 5.0% cerium [41, 42].
3.2.3 Volumes and Geometry
Complex volumes and geometries are constructed from combinations of much
simpler shapes (cubes, spheres, cylinders, cones, etc.). Each shape may have its own
defined material (see Section 3.2.2). From these basic building blocks complicated
geometries, such as the RnEDM experimental setup shown in Figure 3.1, can be
constructed.
The entire Geant4 experimental geometry was built in a large cube defined as
the “experimental hall”. The “experimental hall” was usually constructed of vacuum,
but couldalsobedefinedasairoranyother material. Eachcomponent ofthedetector
and experimental setup was then added into this volume, defined around a point of
origin in the three-dimensional space. The origin was reserved for particle emission
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