Radon-EDM Experiment

Transcription

1 Radon-EDM Experiment Eric Tardiff, Tim Chupp, Wolfgang Lorenzon (University of Michigan) John Behr, Matt Pearson, Gordon Ball, Greg Hackman, Martin Smith (TRIUMF) Carl Svensson, Andrew Phillips (Guelph) Mike Hayden (SFU) Norbert Pietralla, Georgi Rainovsk, Gene Sprouse (SUNY Stony Brook) TRIUMF E929 Spokesmen: Timothy Chupp & Carl Svensson E-929 Collaboration(Guelph, Michigan, SFU, TRIUMF) TRIUMF Canada's National Laboratory for Particle and Nuclear Physics Funding: NSF-Focus Center, DOE, NRC (TRIUMF), NSERC

2 What I did on my Summer Vacation I went backward in time and discovered Parity Violation.

3 Atomic Electric Dipole Moment Separation of Charge along J: <d>=g d <J> + _ P or T gd > 0 gd < 0 if T symmetry, g d =-g d <d>= e rρ d 3 r d E is P&T even We measure g d <J E>: EDM Motivations Undiscovered Study CP violation: mass scale Signal of NEW PHYSICS (beyond SM - CKM) Cosmological Baryon Asymmetry E

4 Octupole Deformation-Parity Doublets (see Feynman vol 3.) NH 3 a> β 3 b> ψ ± >= 1 ( a> ± b> ) E ++ - S ~ <+ ηr 3 cos θ -> ~ ηβ 2 β 2 3 ZA2/3 r 0 3 E + -E - E + -E - + J

5 Nuclei with Octupole Deformation/Vibration (Haxton & Henley; Auerbach, Flambaum, Spevak; Engel, Hayes & Friar, etc.) S ~ <+ ηr 3 cos θ -> ~ ηβ 2 β 2 3 ZA2/3 r 0 3 E + -E - E + -E E J Ref: Dzuba PRA66, (2002) - Uncertainties of 50% *Based on Woods-Saxon Potential Nilsson Potential Prediction is 137 kev NOTES: Ocutpole Enhancements Engel et al. agree with Flambaum et al. Even octupole vibrations enhance S (Engel, Flambaum& Zelevinsky)

6 Radon EDM Experiment 929 at TRUMF (Vancouver BC) Sarah Nuss-Warren, Eric Tardiff, W. Lorenzon, TC - UM J Behr, M. Pearson, C. Svensson, A. Phillips, M. HaydenG. Hackman, G. Ball QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture.

7 REDM

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9 Atomic Electric Dipole Moment + _ P or T 2µ. B-d. E Δω gd > 0 gd < 0 B E Γ E - E + T 2 RF power B homogeneity Precision: (σ d ) -1 = 4EΓ 1 (S/N) signal (volts) time ( μsec) S/N = A 2 N Rn Analyzing power Need high radon polarization and long relaxation.

10 4th 3rd 2nd most sensitive EDM measurement.

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12 Spin-Exchange Optical Pumping Optically pump the Rb with circularly polarized laser light. Spin-exchange collisions transfer the polarization to the radon nuclei. Buffer gas collisions 5p 1/2 1/2 2/3 1/3 1/2 m s =-1/2 m s =+1/2 5s 1/2 Rb Rb 209 Rn 209 Rn Binary Collision: τ~10-12 sec. N 2 Rb 209 Rn Rb 209 Rn N 2 van Der Waals Molecule: τ is dependent on 3rd body (N 2 ) pressure.

13 Gamma Ray Anisotropies Polarized nuclei emit gamma rays with calculable directional distributions. (W(0º)-W(90º))/(W(0º)+W(90º)) for j f =j i +1 W (θ) = 1 4π j i (2 j i 1) j f =j i -1 pure dipole transition m i m 2 i a mi 1 3 j ( j +1) i i P (cosθ) 2 j f =j i +1 j f =j i δ W(θ) W(θ) δ δ θ θ

14 14x10 3 Counts per bin 12x Counts per bin 10 Time (s) Time (s)

15 Studies with 209 Stony Brook 209 Fr (50 s) 197 Au ~100 MeV 16 O heating 5 kv HPGe2 HPGe1 Laser: LDA 1. Make 209 Fr and implant in foil Fr (50s) _ > 209 Rn (28.5 m) 3. Heat foil: release to target chamber 4. Freeze to cold finger 5. PUSH to cell (buffer gas) 6. Get about 500, Rn in cell

16 Rn (28.5 m) Before transfer kev 511 kev After transfer ~ 500, Rn kev 689 kev 745 kev

17 The 209 Rn Decay Scheme (7/2) - 7/ % 44% 5/2-209 Rn E.C. δ 2 = a a 2 a 1 =1 pure dipole 7/ % a 2 =1 pure quadrupole 9/2-209 At 0 require : a a 2 2 =1 γ-ray Energy Intensity δ (Mixing Ratio) > >2.86 from Table of Isotopes

18 Normalize 337 kev to 408 kev T=130 C Uncoated Pyrex Alignment 20% of maximum (bootstrap) N337/N Laser off Laser on Laser On - Laser Off P2(cos Θ) Theta Theta 60 80

19 Spin Exchange Pumping di/dλ (Watts/cm 2 /nm) di/dλ (Watts/cm 2 /nm) di/dλ (Watts/cm 2 /nm) Pressure broadening Gas concentration Detuning From nm (GHz) Detuning From nm (GHz) Detuning From nm (GHz) Laser Intensity Profile Radiation Trapping Buffer gas concentration Optical pumping rate Spin destruction rate Absorption Rate Rb Concentration Spin Exchange Rate Rb polarization radon relaxation (quadrupole) Radon polarization Total magnetic moment

20 Modeling Polarization Can calculate the expected angular distribution of gamma rays as a function of spinexchange and relaxation rates. The spin-exchange rate γ SE depends on the Rb density, which depends on cell temperature. The dipole and quadrupole relaxation rates, Γ 1 and Γ 2, must be determined from data. -5/2-3/2-1/2 1/2 3/2 5/2 1/7γ SE 8/35γ SE 9/35γ SE 8/35γ SE 1/7γ SE 1/21Γ 1 8/105Γ 1 3/35Γ 1 8/105Γ 1 1/21Γ 1 1/28Γ 2 9/140Γ 2 9/140Γ 2 1/28Γ 2 1/14Γ 2 1/35Γ 2 1/35Γ 2 1/14Γ 2 Γ 2 (T) = Γ 2 e ΔE/kT

21 Shows T2~4.5 h, dominated by Quadrupole Interactions (Γ 2 >>Γ 1 )

22 Modeling Polarization Quadrupole relaxation should be the dominant mechanism. As a first approximation, set Γ 1 =0, calculate γ SE for a given T, and calculate the expected anisotropies. j f =j i +1 j f =j i W(0º)/W(90º) W(0º)/W(90º) Γ Γ 2 1 Γ Γ 2 1

23 Fit for Γ 2 (T a =300 K) 0.05 Hz for uncoated 0.03 Hz for coateds Use 2.5x10-21 cm 2

24 Backgrounds σ ω = 2 1 = 2 1 T 2 (S/N) T 2 A 2 (1-B) 2 Nγ Build-up of decay products for γ-anistropy probe Change cells (weekly?) - good for systematics Scattered betas (beta asymmetry detection) Systematics Leakage currents -- must be minimized: Multiple species Electric quadrupole moment (gradients/walls) Change cells, cell shape/orientation: Multiple species Electric field effects on shields, electronics, etc. Check and measure with E=0 E 2 and E effects (Stark shifts) Multiple Species: J=1/2, 3/2, etc. Motional effects <vxe> (negligible in gas cells) Δ

25 What s next? We re done at Stony Brook Cell characterization with natural xenon: - 27% 129 Xe (J=1/2); 21% 131 Xe (J=3/2) Cell development: coatings/electrodes/temperatures Laser studies (LDA light absorption by Rb) TRIUMF set up measurements with xenon isotopes Measure Rn nuclear structure (8-π) Build up to EDM measurements (~ 3 years)

26 Beta Asymmetry No count rate limit (current detection mode) Discriminate species only by frequencies Scattered betas (lower effective A, Background)

27 Radon EDM Summary Progresss - but a lot remains to be done. 209 Rn work at Stony Brook Productive Move to TRIUMF beginning summer Rn EDM projections Gamma Anisotropy (A= ) T 2 = 30 s E=5 kv/cm