Geant4 Simulations for the Radon Electric Dipole Moment Search at

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Schiff moment in the laboratory frame, an effective one-body potential is sufficient. The one-body potential describing the CP-odd nucleon-nucleon interaction can be expressed as [3] V PT 3G = −η 8π √ δ(R 2mr0 3 0 −r ′ ) , (1.7) where G is the Fermi constant, r 0 is the internucleon distance and η parametrizes the strength of the PT-odd interaction. From Equation 1.7, the collective Schiff moment in the laboratory frame can be estimated as [3] S lab ∼ 0.05eβ 2β 2 3 ZA2/3 ηr 3 0 |E + −E − | . (1.8) Equation 1.8 characterizes the Schiff moment in terms of the deformation parameters, Z and A of the nucleus and the energy splitting between the opposite parity states. The final enhancement factor derives from the large Z of the radon isotopes. In 1974, M.A. and C. Bouchiat demonstrated that parity-violating interactions in atoms increasewiththeatomicnumber fasterthanZ 3 [22,23]. Thissignificant enhancement encouraged (and continues to motivate) many studies for parity-violation studies in heavy atoms. An increase of parity-violating interactions in the atom would result in a larger observed EDM. Thus, heavier atoms are also more favourable for atomic EDM searches. These three factors, a collective octupole deformation of the nucleus, close-lying parity doublet states and the high Z of radon, give certain odd-A radon isotopes a large enhancement in the observable atomic EDM and thus make radon an excellent candidate for an EDM search. As noted previously, detailed calculations for 223 Rn [2] predict an enhancement of the observable atomic EDM by a factor of ∼600 relative to the 199 Hg atom, which currently has the best atomic EDM upper limit at 3.1 × 10 −29 e·cm [19]. 10
Chapter 2 RnEDM Experiment at TRIUMF Certainodd-Aradonisotopesarepredictedtoexhibitpermanentoctupole-deformation andareofparticularinterest foranEDMexperiment astheycouldhaveasignificantly enhanced sensitivity to fundamental CP-violating interactions [2]. These isotopes of radon ( 221,223,225 Rn) are relatively short lived, (half-lives of ≃ 25 minutes) which make it challenging to obtain large enough quantities to perform an EDM measurement using standard NMR techniques. Furthermore, these isotopes do not occur naturally in the decay chains of 238 U and 232 Th. Therefore, the RnEDM experimental program must be performed at a radioactive ion beam facility, such as TRIUMF, capable of producing exotic nuclei, rapidily ionizing them, and delivering them to experiments on timescales that are short compared to their half-lives. 2.1 The ISAC Facility at TRIUMF TRIUMF is Canada’s national subatomic physics laboratory located on the campus of the University of British Columbia in Vancouver. TRIUMF, TRI-University 11
Page 1 and 2: GEANT4 SIMULATIONS FOR THE RADON EL
Page 3 and 4: Dictated but not read. i
Page 5 and 6: Contents Acknowledgements ii 1 Intr
Page 7 and 8: 4 Results 60 4.1 γ-Ray Spectroscop
Page 9 and 10: List of Figures 1.1 An illustration
Page 11 and 12: Chapter 1 Introduction Thesearchfor
Page 13 and 14: ˆP ր ˆT ց Figure 1.1: An illust
Page 15 and 16: 1.1.1 CP Violation Following the ob
Page 17 and 18: Figure 1.2: Experimental upper limi
Page 19: Figure 1.3: Illustration of the dou
Page 23 and 24: Figure 2.1: A schematic of the ISAC
Page 25 and 26: a measurement cell. The RnEDM exper
Page 27 and 28: NMR techniques, and supplementing s
Page 29 and 30: Occupied Orbitals Fine Structure Hy
Page 31 and 32: energy levels are separated accordi
Page 33 and 34: (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
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30 Absolute Efficiency (%) 25 20 15
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11 10 9 8 7 6 5 4 3 2 1 0 1e+06 Cou
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4.2.1 Multipolarity Effects The sha
Page 79 and 80:
Figure 4.7: The time projections an
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distribution, this average intensit
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Table 4.1: The fit results for the
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12 10 linear regression: y = 0.2243
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15 Linear Counts (e+04) 10 5 0 1e+0
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Chapter 5 Conclusions and Future Di
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simulated given sufficient parent a
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Appendix A Figure A.1: Simulated de
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Figure A.3: Simulated decay scheme
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Figure A.5: Simulated decay scheme
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6 out = (1/(1+∆ˆ2))*(f(k,jf,L1,L
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44 return; 45 end 46 if abs(m) > j
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1 % LegendreP.m 2 function P = Lege
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39 xx(i+1,j+1) = r(i+1,1)*sin((i*re
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11 %warning('m1 + m2 + m3 must equa
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23 end 24 % ////////// 25 j1 = J1;
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33 if L1 == L2 && ∆ == 0 34 title
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Bibliography [1] J. M. Pendlebury a
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[25] P. G. Bricault, M. Dombsky, Je
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[47] RichardA.Dunlap. An introducti
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