Geant4 Simulations for the Radon Electric Dipole Moment Search at

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25 20 20.48% Absolute Efficiency (%) 15 10 5 6.92% 0 10 100 1000 10000 γ-ray Energy (keV) Figure4.12: Geant4generated absoluteefficiency curve foraring ofeight BrilLanCe 380 detectors. 223 Rn relative to 199 Hg, the RnEDM experiment would need a sensitivity on the order 1 × 10 −26 ecm [27], to be competitive with the current 199 Hg measurement of d( 199 Hg) ≤ 3.1×10 −29 ecm [19]. 4.3 LaBr 3 (Ce) Detectors The cerium-doped lanthanum bromide detectors (Saint-Gobain’s BrilLanCe 380 detectors) could offer a unique advantageto the RnEDMexperiment. The fast timing properties of LaBr 3 (Ce) (∼200 ps) provides a drastically increased count rate capability compared to HPGe detectors. However, the compromise is in energy resolution, as shown in Figures 3.8(a) and 3.8(b) for a direct comparison between the energy resolution of a BrilLanCe 380 detector and a GRIFFIN detector. Unlike high-purity germanium detectors the cerium-doped lanthanum bromide detectors will not be able 76
15 Linear Counts (e+04) 10 5 0 1e+05 10000 Logarithmic Counts 1000 100 10 1 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 γ-ray Energy (keV) Figure 4.13: γ-ray energy spectrum from the β decay of 120 million 223 Rn nuclei from an initial 8 billion nuclei located inside the EDM cell surround by a ring of eight BrilLanCe 380 detectors. The EDM cell, oven, magnet and 1 mm of µMetal shielding were included in the simulation. The initial polarization was 100% and both the spinrelaxation (T 1 ) and the spin-decoherence (T 2 ) times were simulated to be 30 seconds, resulting in a combined depolarization time of 15 seconds. to resolve most individual photopeaks in the 223 Rn decay spectrum. Therefore the time projections which produce the frequency signal will be “contaminated” with other photopeaks. The absolute efficiency of eight BrilLanCe 380 detectors in a ring configuration is presented in Figure 4.12; the detectors have an efficiency of 20.5% at 100 keV and 6.9% at 1 MeV. Figure 4.13 illustrates the γ ray singles spectrum from the β decay of 120 million 223 Rn nuclei, from an initial 8 billion nuclei inside the EDM cell. The EDM cell, oven, magnet and 1 mm of µMetal shielding were also included in this simulation. The simulation had identical properties to that of the simulation of 77
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GEANT4 SIMULATIONS FOR THE RADON EL
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Dictated but not read. i
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Contents Acknowledgements ii 1 Intr
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4 Results 60 4.1 γ-Ray Spectroscop
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List of Figures 1.1 An illustration
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Chapter 1 Introduction Thesearchfor
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ˆP ր ˆT ց Figure 1.1: An illust
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1.1.1 CP Violation Following the ob
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Figure 1.2: Experimental upper limi
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Figure 1.3: Illustration of the dou
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Chapter 2 RnEDM Experiment at TRIUM
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Figure 2.1: A schematic of the ISAC
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a measurement cell. The RnEDM exper
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NMR techniques, and supplementing s
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Occupied Orbitals Fine Structure Hy
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energy levels are separated accordi
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(σ + ) along the axis of the B fie
Page 35 and 36: atom and absorbed by another. Radia
Page 37 and 38: anaverageof120kHzphotopeakcountrate
Page 39 and 40: Figure 2.7: One GRIFFIN/TIGRESS HPG
Page 41 and 42: (a) One GRIFFIN detector in the HPG
Page 43 and 44: 3.1 Introduction 3.1.1 Previous Wor
Page 45 and 46: energies, branching ratios, emissio
Page 47 and 48: used around the measurement cell in
Page 49 and 50: 3.2.5 Simulated Data Thecodewaswrit
Page 51 and 52: lower its total energy. Internal co
Page 53 and 54: 10000 1000 2 χ red = 1.21 t 1/2 =
Page 55 and 56: as [47] I(E) = G 2π 3 7 c 6 | M i
Page 57 and 58: was to use an average X-ray energy
Page 59 and 60: 1.5 1.4 1.3 1.2 P = 100% P = 75% P
Page 61 and 62: where (a b c d | e f) are Clebsch-G
Page 63 and 64: 2 2 1.5 J i = 5/2, J f = 5/2 J i =
Page 65 and 66: of radius 10 cm, allowing the GRIFF
Page 67 and 68: (a) Screenshot showing the detector
Page 69 and 70: 3.6.2 Output Data and Sort Codes Th
Page 71 and 72: (user-defined option), secondly toa
Page 73 and 74: 30 Absolute Efficiency (%) 25 20 15
Page 75 and 76: 11 10 9 8 7 6 5 4 3 2 1 0 1e+06 Cou
Page 77 and 78: 4.2.1 Multipolarity Effects The sha
Page 79 and 80: Figure 4.7: The time projections an
Page 81 and 82: distribution, this average intensit
Page 83 and 84: Table 4.1: The fit results for the
Page 85: 12 10 linear regression: y = 0.2243
Page 89 and 90: Chapter 5 Conclusions and Future Di
Page 91 and 92: simulated given sufficient parent a
Page 93 and 94: Appendix A Figure A.1: Simulated de
Page 95 and 96: Figure A.3: Simulated decay scheme
Page 97 and 98: Figure A.5: Simulated decay scheme
Page 99 and 100: 6 out = (1/(1+∆ˆ2))*(f(k,jf,L1,L
Page 101 and 102: 44 return; 45 end 46 if abs(m) > j
Page 103 and 104: 1 % LegendreP.m 2 function P = Lege
Page 105 and 106: 39 xx(i+1,j+1) = r(i+1,1)*sin((i*re
Page 107 and 108: 11 %warning('m1 + m2 + m3 must equa
Page 109 and 110: 23 end 24 % ////////// 25 j1 = J1;
Page 111 and 112: 33 if L1 == L2 && ∆ == 0 34 title
Page 113 and 114: Bibliography [1] J. M. Pendlebury a
Page 115 and 116: [25] P. G. Bricault, M. Dombsky, Je
Page 117: [47] RichardA.Dunlap. An introducti
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