Geant4 Simulations for the Radon Electric Dipole Moment Search at

1.5
1.4
1.3
1.2
P = 100%
P = 75%
P = 50%
P = 25%
P = 0%
1.1
W(θ)
1
0.9
0.8
0.7
0.6
0.5
0 π π 3π π 5π 3π 7π 2π
4 2 4 4 2 4
θ
Figure 3.3: β particle angular distributions for various degrees of polarization. The
beta-asymmetry correlation coefficient was simulated to be 0.45.
As the degree of polarization reduces from its maximum value of 100% to 0% the
angular distribution of the electrons becomes more isotropic as shown in Figure 3.3.
3.4.2 Gamma-Ray Anisotropies
The theory of angular distributions of γ radiation from oriented nuclei is well
established [51, 52, 53]. The work from H.A. Tolhoek and J.A.M. Cox [51] derives
formula for oriented nuclear spins assuming pure multipole transitions. For a more
general approach, T. Yamazaki [52] has outlined the general theory and tabulated
coefficients for γ-ray angular distributions for aligned and partially-aligned nuclei
for pure and mixed multipolarities. Alignment, polarization and orientation can have
variousdefinitions. Inthis workand thework ofYamazaki they aredefined asfollows.
Alignment refers to symmetric populations of magnetic substates about m = 0, thus
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