results from a search for the permanent electric dipole
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Results from a Search for the Permanent ElectricDipole Moment (EDM) of 199Hg
B. HeckelPhysics Department, University of Washington
Collaborators:T. Loftus and E.N Fortson: Physics Department, University of Washington
M. D. Swallows: JILA, University of ColoradoW.C. Griffith: Los Alamos National Laboratory
M. V. Romalis: Princeton University
Time
From the 199Hg EDM to Models for CP Violation
199Hg Atomic EDM
Atomic Physics
199Hg Schiff Moment
Nuclear Physics
CP‐Violating Pion‐Nucleon Coupling
QCD
CP‐Violating QCD Term, Quark Chromo‐EDMs
Model‐Dependent CP‐Violating Parameters
SUSY, etc …
Contributions to S from p, n EDMs
d(n)d(p)
Hyperfine Coupling: d(e)
Semileptonic Interactions: CS CP CT
Naturalness Parameters
E
ωMT
ωMB
B E
Cancels Common-mode B-Field Fluctuations
2‐Cell, 199Hg Magnetometer
Cosine Coil
Uniform to 0.01% over ±1 cm
25 ppb current source (100 s)
2‐Cell, 199Hg Magnetometer
2001 199Hg EDM Measurement
60 days of data from Feb. to Aug. 200040,000 electric field reversals
dHg = -(1.06 ± 0.49stat ± 0.40sys)x10-28 e cm
|dHg| < 2.1x10-28 e cm
0.4 nHz (~ 0.03 ppb)
4-Cell
ωOT
ωOB
BE
ωMT
ωMB
E
Cancels up to 2nd order gradient noiseSame EDM sensitivity as Middle Difference
4‐Cell, 199Hg Magnetometer
Cancels Linear Gradient NoiseSensitive to Leakage Currents & Other Spurious B-Field Systematics
Zero for a True EDM
ωOT
ωOB
BE
ωMT
ωMB
E
Other Frequency Combinations
Transverse Pumping / Optical Rotation
B
254 nm σ+
Pump Phase
B
254 nm Linear
Probe Phase ωL
Linear Polarizer
Detector
Blind Analysis of HV Correlated Signals
Analysis program adds an unknown, HV‐correlated, EDM‐mimicking offset δ/2 to the
middle cell frequencies
Produced an EDM‐like signal between± 2 ×10−28 e cm
ωOT
ωOB
E
ωMT + δ/2
ωMB + δ/2
E
Masked the measured EDM
Revealed only after the data collection, data cuts, and error analysis were complete
EDM Data by Sequence
Raw Dataset
No BlindOffset
No BlindOffset
Excluded Sequences
No Blind OffsetMicro-Sparks
χ2/ν = 0.7
Systematic Errors and Tests for Systematic Effects
No Statistically Significant Dependence on:• The Vapor Cells or Electrodes (or their orientation)• The DAQ Channel Ordering• The Vessels
Systematic Errors and Tests for Systematic Effects
No Statistically Significant Dependence on:• The Vapor Cells or Electrodes (or their orientation)• The DAQ Channel Ordering• The Vessels
Systematic Errors and Tests for Systematic Effects
No Statistically Significant Dependence on:• The Vapor Cells or Electrodes (or their orientation)• The DAQ Channel Ordering• The Vessels
99% of Total Error
Systematic Errors and Tests for Systematic Effects
No Statistically Significant Dependence on:• The Vapor Cells or Electrodes (or their orientation)• The DAQ Channel Ordering• The Vessels
99% of Total Error
Systematic Errors and Tests for Systematic Effects
No Statistically Significant Dependence on:• The Vapor Cells or Electrodes (or their orientation)• The DAQ Channel Ordering• The Vessels
99% of Total Error
Systematic Errors and Tests for Systematic Effects
No Statistically Significant Dependence on:• The Vapor Cells or Electrodes (or their orientation)• The DAQ Channel Ordering• The Vessels
99% of Total Error
Systematic Error Budget
Statistical Error 12.90
Leakage Currents
Upper Cell: (-0.35 ± 2.85)x10-9 rad/(sec-pA), 13% Correlation Probability
Lower Cell: (-0.04 ± 3.55)x10-9 rad/(sec-pA), 1% Correlation Probability
Vessel: (0.01 ± 0.19)x10-9 rad/(sec-pA), 8% Correlation Probability
Leakage Currents
Worst Case Scenario of Helical Current Flow
Average Single-Cell Current: 0.42 pA
Effective Current: √2(0.42 pA) = 0.59 pA
Maximum Helical Path (cell geometry): ½ Full Turn
Averaging Due to Cell Flips: Factor of 2
4.5 x 10-30 e cm
Stark‐Induced Interference
Non‐Zero M1, E2 Amplitudes for 1S0 – 3P1 Due toE‐Field Induced Mixing of Opposite Parity States
EDM‐Mimicking Vector Light Shift
Shifts linear in E when k x ε along main Β
Shift proportionalto Light Intensity
Central Field Estimate
Zeeman shifts from a virtual magnetic field along k x ε
Measurements of the Stark Interference Amplitude
181 Nights of Data
> 75,000 HV Reversals
Factor of 10 in Probe Intensity
δνstat = 0.13 nHz
Non‐null vector configurations
Null vector configurations
Measurements of the Stark Interference Amplitude
181 Nights of Data
> 75,000 HV Reversals
Factor of 10 in Probe Intensity
δνstat = 0.13 nHz
Null vector configurations
Measurements of the Stark Interference Amplitude
181 Nights of Data
> 75,000 HV Reversals
Factor of 10 in Probe Intensity
δνstat = 0.13 nHz
Relativistic Many‐Body EstimateK. Beloy, V. A. Dzuba, and A. Derevianko, Phys. Rev. A 79, 042503 (2009)
(aM1 + aE2) = 8x10‐9 (kV/cm)‐1
Preliminary Central Values
(aM1 + aE2) = (5.8 ± 1.5)x10‐9 (kV/cm)‐1
(δα/α)Null = (0.6 ± 1.8)x10‐9 (kV/cm)-1
New Bounds on CP Violating Parameters
d(199Hg) = (0.49 ± 1.29stat ± 0.76sys ) x 10‐29 e cm
| d(199Hg) | < 3.1 x 10‐29 e cm (95% CL)
Confidence Levels: 199Hg (95%), 205TI (90%), TIF (95%)
Summary
New Limit on the EDM of 199Hg
| d(199Hg) | < 3.1 x 10‐29 e cm (95% CL)
• Factor of 7 Reduction in Previous Upper Limit• Improved Bounds on CP Violating Parameters
• Expect Factor of 3‐5 in Experimental Sensitivity
Upgrading the Current Apparatus
• Balanced Polarimeter• Measurements in the dark• Modified Electrodes to Reduce Leakage Currents• Cells with Improved Transmission• Reduction of Sparks
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