Search for the Nuclear Schiff Moment of Radium- Search for the Nuclear Schiff Moment of Radium -225 225 I. Ahmad, K. Bailey, B. Graner, J.P. Greene, R.J. Holt, W. Korsch, Z.-T. Lu, P. Mueller, T.P. O’Connor, I.A. Sulai, W.L. Trimble Physics Division, Argonne National Lab Physics Department, University of Chicago Physics Department, University of Kentucky
Discrete Fundamental Symmetries Discrete Fundamental Symmetries Parity violation – First observation P Parity C Charge conjugation CP CP symmetry 60 Co T Time reversal CPT CPT – Exact symmetry in quantum field theory with Lorentz invariance C. S. Wu et al . (1957)
More CP- More CP -Violation Mechanisms? Violation Mechanisms? Supersymmetry More particles More CP-violating phases Matter-antimatter asymmetry Require additional CP-violation mechanism(s) Strong CP problem CP-violating phase in Quantum Chromodynamics Fortson, Sandars, Barr, Physics Today (June 2003)
Electric Dipole Moment (EDM) Violates Both P and T Electric Dipole Moment (EDM) Violates Both P and T A permanent EDM violates both time-reversal symmetry and parity + + - T P - - + EDM Spin EDM Spin EDM Spin Neutron Quark EDM Physics beyond the Diamagnetic Atoms Quark Chromo-EDM Standard Model: (Hg, Ra) SUSY, String… Paramagnetic Atoms (Tl) Electron EDM Molecules (PbO)
Measurability of Nuclear EDM Measurability of Nuclear EDM L.I. Schiff, Phys. Rev. (1963) Schiff shielding d d atom nucleus 0 d d d atom atom nucleus Incomplete cancellation 0 d d d atom atom nucleus 1) nucleus has finite size; 2) charge distribution EDM distribution. Nuclear Schiff moment is lowest order, P,T-odd, measurable electric Schiff moment (toy model) moment. r r c d 5 10 d d d atom nucleus nucleus 2 5 e r S 2 r p 3 r ch r atom p 10 2 2 S d r r p nucleus d c a ‘radially-weighted dipole moment’ 1 1 d S r r atom atom c
The Seattle EDM Measurement The Seattle EDM Measurement 199 Hg stable, high Z, J = 0, I = ½, high vapor pressure 2 2 B dE 15 Hz f E h 2 2 B dE 15 Hz f h E 0.6 nHz f f Courtesy of Michael Romalis Unit The best limit on atomic EDM +e EDM EDM ( 199 Hg) < 3 x 10 -29 e-cm cm -e Griffith et al ., Phys Rev Lett (2009)
225 Ra enhanced EDM of 225 Ra enhanced EDM of EDM of 225 Ra enhanced: • Large intrinsic Schiff moment due to octupole deformation; • Closely spaced parity doublet; • Relativistic atomic structure. Haxton & Henley (1983) Auerbach, Flambaum & Spevak (1996) Parity doublet Engel, Friar & Hayes (2000) | | Enhancement Factor: EDM ( 225 Ra) / EDM ( 199 Hg) Skyrme Model Isoscalar Isovector Isotensor SkM* 1500 900 1500 SkO’ 450 240 600 55 keV Schiff moment of 199 Hg, de Jesus & Engel, PRC72 (2005) Schiff moment of 225 Ra, Dobaczewski & Engel, PRL94 (2005)
225 Ra Search for Electric Dipole Moment of 225 Ra Search for Electric Dipole Moment of Advantages of an EDM measurement on 225 Ra atoms in a trap • EDM enhanced by ~ 10 2 -10 3 due to nuclear octupole deformation. • Trap allows the efficient use of the rare and radioactive 225 Ra atoms. • Long coherence time (~ 100 s), negligible “v x E” systematics, high electric field (100 kV/cm). 10 mCi Magneto-Optical 225 Ra sample Trap Proposed setup Atomic Beam 225 Ra Nuclear Spin = ½ Oven Electronic Spin = 0 t 1/2 = 15 days Transverse Cooling EDM-probing region • Our sensitivity goal: 1 x 10 -28 e-cm. • | d( 199 Hg) | < 3 x 10 -29 e-cm (95% C.L.) Griffith et al., PRL (2009) • Ra / Hg Enhancement factor ~ 10 2 -10 3 Optical Dipole Trap
225 Ra Source 225 Ra Source 229 Th 225 Ra 225 Ac 209 Bi Fr, At, Rn… 7300 yr 15 days 10 days ~ 4 hours stable • 2 mCi (or 60 ng) 225 Ra sources available from Oak Ridge National Lab • Test source: 300 nCi 226 Ra (1600 yr) -- invaluable for testing • Ra(NO 3 ) 2 reduced by Ba metal and Al in 700 C oven Rare Isotope Facility Rare Isotope Facility Yield for 225 Ra ~ 10 10 s -1 - 10 12 s -1 ?
6 ns Radium Atom Energy Level Diagram Radium Atom Energy Level Diagram 7p 1 P 1 V. Dzuba, V. Flambaum et al. , PRA 61 (2000) 1e-1 1429 nm, repump, diode laser 0.4 ms 6d 1 D 2 • Linewidth ~ 400 kHz 2e-6 • Cooling 7 K, 14 mm/s 6 s 5e-2 • B gradient ~ 1 G / cm 7p 3 P 2 483 nm 5e-4 6d 3 D 3 5e-2 2e-2 420 ns 7e-10 2e-2 70 7p 3 P 1 714 nm, cycling, Ti:S ring laser 6d 3 D 2 4e-5 2e-3 1 0.7 ms 6e-4 6d 3 D 1 7p 3 P 0 * Without repump, 1.7 10 4 cycles. * With repump at 1428 nm, 1.7 10 7 cycles. 7s 2 1 S 0
225 Ra and 226 Ra Atoms Laser- -Trapping of Trapping of 225 Ra and 226 Ra Atoms Laser 1 P 1 Repump • Key 225 Ra frequencies, lifetimes measured 3 P 1 Scielzo et al. PRA (2006) • 225 Ra laser cooled and trapped! 3 D 1 Guest et al. PRL (2007) Laser-cooling Ra atom trap! Ra fluorescence signal 1 S 0 100x Ra atomic beam 0 -4 -3 -2 -1 0 1 2 3 4 Probe frequency shift (MHz)
3/2 -> 3/2 226 Ra and 225 Ra 226 Ra and 225 Ra Hyperfine constants and Hyperfine constants and 3 D 1 P isotope shift on 3 D 1 - 1 P 1 isotope shift on 1 - 1 Ra-226 Ra-225 F 540(4) MHz 1 P 1 3/2 1/2 4196(2) MHz ISOLDE: 4195(4) MHz* 6999.83 cm -1 3/2 1/2 -> 3/2 3 D 1 3/2 -> 1/2 1/2 -> 1/2 1/2 7031(2) MHz *Ahmad et al., Phys. Lett. 133B , 47 (1983) Guest et al . PRL (2007)
1 P 1 Radium Atom Repump Dynamics Radium Atom Repump Dynamics 2000 Blackbody spectrum @ 298K 1429nm 482nm Repumping (k B T/hc) = 210cm -1 ) to 1 P 1 cm -1 3 P 1 3.4 E1 9.9 E1 3.4 E1 3 D 1 0.6 ms Laser-cooling 7.4 E1 1.5 E3 2.2 E2 3 P 0 0 N( ) 298 K thermal transition rates A ij B ji g i B ij ( ij , T ) e E / k B T 1, B ij g j 1 S 0
Oven: 225 Ra EDM measurement on 225 Ra EDM measurement on 225 Ra Transverse cooling Zeeman Slower Magneto-optical trap Statistical uncertainty: 10 days 100 kV/cm Optical 10% 10 s 10 4 dipole trap EDM measurement d = 3 10 -26 e cm Ra / Hg Enhancement factor ~ 10 2 -10 3 Best experimental limit: d( 199 Hg) < 3 10 -29 e cm
Oven: 225 Ra EDM measurement on 225 Ra EDM measurement on 225 Ra Transverse cooling Zeeman Slower Magneto-optical trap Statistical uncertainty: 10 days 100 days 100 kV/cm Optical 10% 100 s 10 s 10 6 10 4 dipole trap EDM measurement d = 3 d = 3 10 -26 e cm 10 -28 e cm Ra / Hg Enhancement factor ~ 10 2 -10 3 Best experimental limit: d( 199 Hg) < 3 10 -29 e cm
B- -Field: Shields, Coils, Magnetometers Field: Shields, Coils, Magnetometers B Design Goal B = 10 mG Stability: < 1 ppm in 100 sec Uniformity: < 1% / cm -shields: Shielding factor = 2 x 10 4 Rb cell magnetometer: Budker design B gradient < 10 μ G/cm
E- E -Field: 100 kV / cm Field: 100 kV / cm -- -- Done. Done. • 20 kV over 2mm vacuum gap • < 50 pA leakage currents observed
Optical Dipole Trap Optical Dipole Trap 1 2 H dE E 0 4 Polarizabilities at 1550 nm • Fiber laser: -- calculated by V. Dzuba = 1.55 m, Power = 8 W s = 270 a.u. (+/- 1 S 0 : 5%) • Focused to 100 m diameter s = 271 a.u. (+/- 3 P 1 : 5%) 120 K trap depth t = 28 a.u. • Raman excitation rate ~ 10 -5 s -1
Nuclear EDM Searches Nuclear EDM Searches Isotope Current Limit Institution Technique (e cm) Neutron < 2.9E-26 SNS Superfluid He Grenoble Grenoble 199 Hg < 3E-29 Washington 4 cells Washington (0.7 129 Xe Princeton Liquid cell 3.3)E-27 Michigan 225 Ra N/A Argonne Trap KVI 223 Rn N/A Michigan & Cell TRIUMF 2 H N/A Brookhaven Storage ring
T + + - - EDM EDM Spin Spin He Ra e Kr He - 6 He 6 Li + Supported by DOE, Office of Nuclear Physics
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