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, 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
Atomic Electric Dipole Moment Separation of Charge along J: <d>=g d <J> d =e r + < d > = g d < J > P or T g d < r > = ___ < J > _ e gd < 0 gd > 0 if T is a symmetry, g d =-g d < d > = e< r > = e ∫ r ρ d 3 r We measure g d <J•E> . E EDM Motivations Undiscovered Study CP violation: mass scale S ignal of NEW PHYSICS (beyond SM - CKM) Cosmological Baryon Asymmetry
Octupole Deformation-Parity Doublets (see Feynman vol 3.) NH 3 |a > β 3 |b > + - - + -- E - - J + + 1 S ~ <+ | η r 3 cos θ |-> ~ ηβ 2 β 2 | ψ ± > = ____ ( |a > ± |b > ) 3 ZA 2/3 r 0 3 √ 2 E + - E - E + - E -
Nuclei with Octupole Deformation/Vibration (Haxton & Henley; Auerbach, Flambaum, Spevak; Engel et al., Hayes & Friar, etc.) + - - S ~ <+ | η r 3 cos θ |-> ~ ηβ 2 β 2 3 ZA 2/3 r 0 3 + -- E - - J + E + - E - E + - E - + Ref: Dzuba PRA66, 012111 (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)
β decay Studies of Rn Structure 8 π @ TRIUMF - Very high-level density in the odd-A Rn isotopes within the β decay Q-value window (e.g. ~ 3.2 MeV for 223 At → 223 Rn). - - Many/most of the transitions will be highly converted. - Long chain of radioactive daughters requires flexible collect, count, move, cycles. - In this environment a γ -ray or electron singles spectrum is of little use in establishing structure - (i.e. a decay scheme). - High statistics β : γ - γ , γ -e, e-e are required (and then some painstaking spectroscopy). - The 8 π Spectrometer at ISAC is certainly the world’s best facility for such studies. - Timeline Issues: At beams at ISAC – late 2008 or 2009(?) is probably the earliest - : Although the experiments themselves could be short (< 1 week), - expect at least a year of spectroscopic analysis before definitive structure results are obtained.
8- π detector array E-929 Collaboration (Guelph, Michigan, SFU, TRIUMF) TRIUMF Canada's National Laboratory for Particle and Nuclear Physics
Atomic Electric Dipole Moment + P or T Δω 2µ . B-d . E _ gd < 0 gd > 0 B E 1.0 0.5 signal (volts) 0.0 Γ T 2 -0.5 E - E + -1.0 0.0 0.5 1.0 1.5 2.0 time ( µ sec) RF power B homogeneity Precision: ( σ d ) -1 = 4E Γ − 1 (S/N) S/N = √ A 2 N Rn Need high radon polarization and long relaxation.
Spin-Exchange Optical Pumping Buffer gas • Optically pump the Rb with collisions circularly polarized laser 5p 1/2 light. 1/2 1/2 2/3 1/3 • Spin-exchange collisions 5s 1/2 transfer the polarization to m s =-1/2 m s =+1/2 the radon nuclei. 209 Rn Rb 209 Rn Rb van Der Waals Binary Collision: N 2 Molecule: τ ~10 -12 sec. τ is dependent on 3rd body (N 2 ) pressure. Rb N 2 Rb 209 Rn 209 Rn
8-Trigress detectors Magnetic Shielding (Active + Passive) 3 4 2 5 1 6 7 8
Gamma Ray Anisotropies (W(0º)-W(90º))/(W(0º)+W(90º)) for j f =j i +1 • Polarized nuclei emit gamma rays with calculable directional distributions. δ j f =j i -1 pure dipole transition � � � � � � W ( � ) = 1 3 2 a m i � 1 � 4 � 1 + � m i 3 j i ( j i + 1) � P 2 (cos � ) � � 2 j i (2 j i � 1) � � � � � � � � m i j f =j i j f =j i +1 W( θ ) W( θ ) δ δ θ θ
3 3 12x10 12x10 Counts per bin Counts per bin 10 10 3 14x10 8 8 12 10 10 12 12 14 14 16 16 18 18 20 20 Counts per bin Time (s) Time (s) 10 8 6 0 10 20 30 40 50 60 Time (s)
Gamma Anisotropy (A=0.2 0.1 ) T 2 = 30 s E=5 kV/cm Statistics Limited by HPGe Count Rate � � � � � � W ( � ) = 1 3 2 a m i � 1 � 4 � 1 + � m i 3 j i ( j i + 1) � P 2 (cos � ) � � 2 j i (2 j i � 1) � � � � � � � � m i j f =j i +1 j f =j i
Beta Asymmetry • No count rate limit (current detection mode) • Discriminate species only by frequencies • Scattered betas (lower effective A, Background)
We’ve started setting up at TIRUMF REDM
Romote Tracking of Laboratory Fields: (magnetometer at TRIUMF, Control in Michigan) 44.0 43.5 43.0 B x (mG) 42.5 42.0 41.5 41.0 0.0 0.5 1.0 1.5 2.0 2.5 Time (Hours)
Tigress Detectors have arrived
Progress: High efficiency tranfer of 120 Xe at TRIUMF: from millstones to milestones 120 Cs (30 keV) no radon at TRIUMF yet Maximum efficiency: ε max =75% 1. Bombard foil 2. Heat foil: release to target chamber 3. Freeze to cold finger 4. PUSH to cell (buffer gas)
NIM A vol 533 p 275 (2004) Before Push After Push 43% efficiency
Studies with 209 Rn @ Stony Brook 197 Au 209 Fr (50 s) 5 kV ~100 MeV 16 O heating HPGe1 1. Make 209 Fr and implant in foil 2. 209 Fr (50s) _ > 209 Rn (28.5 m) 3. Heat foil: release to target chamber HPGe2 4. Freeze to cell 5. Get about 500,000 209 Rn in cell Laser: LDA
209 Rn (28.5 m) 160 140 Before transfer 120 100 80 60 40 20 0 300 400 500 600 700 800 408 keV After transfer 600 ~ 500,00 209 Rn 511 keV 500 400 337 keV 300 745 keV 200 689 keV 100 0 300 400 500 600 700 800
The 209 Rn Decay Scheme 2 � 2 = a 1 5/2 - 209 Rn 1% 2 1097.64 a 2 (7/2) - E.C. 745.78 44% 7/2 - a 1 = 1 � pure dipole 408.33 15% a 2 = 1 � pure quadrupole 7/2 - 2 + a 2 2 = 1 9/2 - 0 require : a 1 209 At γ -ray Energy Intensity δ (Mixing Ratio) 337.45 14.5 ∞ 408.32 50.3 0 689.26 9.7 >3.57 745.78 22.8 >2.86 from Table of Isotopes
Alignment ≈ 20% Normalize 337 keV to 408 keV of maximum T=130° C Uncoated Pyrex (bootstrap) 0.42 0.02 0.5 Laser On - Laser Off Laser off 0.40 -P2(cos � ) 0.00 0.0 N337/N408 0.38 -0.02 -0.5 Laser on 0.36 -0.04 -1.0 0.34 -0.06 0 20 40 60 80 0 20 40 60 80 Theta Theta
Spin Exchange Pumping Pressure broadening Gas concentration Radiation Laser Intensity Profile Buffer gas concentration Trapping Optical pumping rate Spin destruction rate Absorption Rate Rb Concentration Rb polarization Spin Exchange Rate radon relaxation (quadrupole) Radon polarization Total magnetic moment
Modeling Polarization -5/2 -3/2 -1/2 1/2 3/2 5/2 • Can calculate the expected 1/7 γ SE 8/35 γ SE 9/35 γ SE 8/35 γ SE 1/7 γ SE angular distribution of gamma rays as a function of spin- exchange and relaxation rates. 1/21 Γ 1 8/105 Γ 1 3/35 Γ 1 8/105 Γ 1 1/21 Γ 1 • The spin-exchange rate γ SE depends on the Rb density, 1/28 Γ 2 9/140 Γ 2 which depends on cell temperature. 9/140 Γ 2 1/28 Γ 2 • The dipole and quadrupole relaxation rates, Γ 1 and Γ 2 , 1/14 Γ 2 1/35 Γ 2 1/35 Γ 2 1/14 Γ 2 must be determined from data. � e � E / k T � 2 (T) = � 2
Shows T2~4.5 h, dominated by Quadrupole Interactions ( Γ 2 >> Γ 1 )
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 2 Γ 2 Γ 1 Γ 1
Fit for Γ 2 (T a =300°K) 0.05 Hz for uncoated 0.03 Hz for coateds Use 2.5x10 -21 cm 2 Improved by extensive measurements of P Rb under varying conditions
EDM Cell Development We want a single cell @ 200C Problems: leakage currents, materials Silica (Fused Quartz) or Sapphire IN PROGRESS (Celia Cunnigham)
Backgrounds 2 1 2 1 ___ ______ = ____ ________________ σ ω = T 2 (S/N) T 2 √ A 2 (1-B) 2 N γ 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 Δ E 2 and |E| effects (Stark shifts) Multiple Species : J=1/2, 3/2, etc. Motional effects <v x E > (negligible in gas cells)
What’s next? Cell development: coatings/electrodes/temperatures Laser Development Cell characterization with natural xenon: - 27% 129 Xe (J=1/2); 21% 131 Xe (J=3/2) TRIUMF set up (EDM) measurements with xenon isotopes Measure Rn nuclear structure (8- π ) Build up to RADON EDM measurements (~ 3 years)
Radon EDM Summary 223 Rn EDM projections Gamma Anisotropy (A=0.2 0.1 ) T 2 = 30 s E=5 kV/cm Production rates: 1x10 7 (ISAC)
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