results from a search for the permanent electric dipole

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

Constrained MSSM

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

Measuring an EDMs via Larmor Precession

B

μωL

d

E

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)


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


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

Vapor Cells

Pump

Probe

Cell Holding Vessel

Cell Holding Vessel

Laser System

SDL MOPA: 500 mW at 1015 nm

1st Doubler: 130 mW at 507 nm

2nd Doubler: 6 mW at 254 nm

Gradient Coils

Four Cell Frequencies Matched to Within a few Micro‐Hz

Transverse Pumping / Optical Rotation

B

254 nm σ+

Pump Phase

B

254 nm Linear

Probe Phase ωL

Linear Polarizer

Detector

Pump

Probe

Probe

Optical Rotation Angle Absorption

Transverse Pumping / Optical Rotation

Typical 24 Hour Run

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

Raw Dataset

EDM Data by Run

No BlindOffset

No BlindOffset

χ2/ν = 0.7

Raw Dataset

EDM Data by Sequence

No BlindOffset

No BlindOffset

χ2/ν = 0.7

EDM Data by Sequence

Raw Dataset

No BlindOffset

No BlindOffset

Excluded Sequences

No Blind OffsetMicro-Sparks

χ2/ν = 0.7

Spark Correlations / Cuts

HV passesthrough zero

Gain Switch

Spark

Average: 0.5 pA

Spark Threshold

Final Dataset and Statistical Error

d(199Hg) = (0.49 ± 1.29stat )x10-29 e cm

0.1 nHz (~ 7.5 ppt)

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



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


181 Nights of Data



δνstat = 0.13 nHz

Null vector configurations


181 Nights of Data



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

results from a search for the permanent electric dipole

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