Philip Harris

Electric-DipoleMoment Searches

*(mainly neutron)

*

• Room-temperature nEDM expt: latest results• CryoEDM: upcoming, 100x sensitivity• Other EDM expts

P. HarrisBEACH 2006

Electric Dipole Moments

EDMs are P odd T odd

Complementary approachto study of CPv; probenew physics

SM predictions v. small; othermodels typ. 106 larger...

E +

dn = dn s

P. HarrisBEACH 2006

Generating EDMs

E.g. in SUSY:

Assumptions: gg’, sin()1, 200 GeVGives u, d quark EDMs 3x10-24 ecm 100 x current limit

“SUSY CP” problem

q q

gaugino

squarkcouplingconst g g’ei

P. HarrisBEACH 2006

Constraints on SUSY parameters

Pospelov & Ritz, hep-ph/0504231

MSUSY = 500 GeVtan = 3

P. HarrisBEACH 2006

SUSY, cont’d

Lebedev et al., hep-ph/0402023

P. HarrisBEACH 2006

Measurement principle

() – () = – 4 E d/ h

assuming B unchanged when E is reversed.

B0 E<Sz> = + h/2

<Sz> = - h/2

h(0) h() h()

B0 B0 E

Level splitting we can resolve:<10-21 eV

Use (Ramsey) NMR on ultracold neutrons in B, E fields

P. HarrisBEACH 2006

Apparatus

N S

Magnetic shielding

Storage cell

Magnet & polarizing foil Ultracold

neutrons(UCN)

UCN detector

Approx scale 1 m

Magnetic field coil

B

High voltage lead

E

/analysingfoil

P. HarrisBEACH 2006

Apparatus

Neutronstoragechamber

HVfeedthru

B-fieldcoils

P. HarrisBEACH 2006

0 5 10 15 20 2529.9260

29.9265

29.9270

29.9275

29.9280

29.9285

29.9290

29.9295

Neu

tron

res

onan

t fr

eque

ncy

(Hz)

Run duration (hours)

nEDM measurement Keep track of neutron resonant frequency Look for n freq changes correlated with changes

in E

Electric Field

+-

ndE

P. HarrisBEACH 2006

0 5 10 15 20

7.7882

7.7884

7.7886

7.7888

7.7890

Run duration (hours)

Mer

cury

freq

uenc

y (H

z)

Mercury co-magnetometer

Compensates B drift...

P. HarrisBEACH 20060 5 10 15 20 25

29.9260

29.9265

29.9270

29.9275

29.9280

29.9285

29.9290

B = 10 -10 T

Raw neutron frequencyCorrected frequency

Pre

cess

ion

freq

uenc

y (H

z)

Run duration (hours)

nEDM measurement

29.9295

P. HarrisBEACH 2006

New systematic

rBz

Br

and, from Special Relativity, extra motion-induced field

2

1

c

EvB

Two effects:

P. HarrisBEACH 2006

Geometric Phase

Br

Br

Bnet

Bnet

Bv

Bv

Bv

Bnet

Bnet

... so particlesees additionalrotating field

Frequency shift E

Looks likean EDM

Bottle(top view)

J. Pendlebury et al., PRA 70 032102 (2004)P. Harris, J. Pendlebury, PRA 73 014101 (2006)

Unique signature:can eliminate it

P. HarrisBEACH 2006

Effect Shift UncertaintyStatistical 0 1.51Door cavity dipole; quadrupole fields

-1.10 0.45

Other GP dipole shifts 0 0.60(E x v)/c2 from translation 0 0.05(E x v)/c2 from rotation 0 0.10Light shift: direct & GP 0.35 0.08B fluctuations 0 0.24E forces – distortion of bottle 0 0.04Tangential leakage currents 0 0.01AC B fields from HV ripple 0 0.001Hg atom EDM 0 0.052nd order Exv 0 0.002

Total –0.75 1.51 stat, 0.80 sys

Error budget (10-26 e.cm)

P. HarrisBEACH 2006

Final Result

New limit:|dn| < 3.0 x 10-26 e.cm (90% CL)

(prev. limit 6.3 x 10-26 e.cm, PRL 82, 904 (1999))

Preprint hep-ex/0602020provisional acceptance PRL

www.neutronedm.org

P. HarrisBEACH 2006

2. CryoEDM

100-fold improvement in sensitivity!

n = 8.9 Å; E = 1.03 meV

Landau-Feynman dispersion curve for 4He excitations

Dispersion curve for free neutrons

R. Golub and J.M. Pendlebury Phys. Lett. 53A (1975), Phys. Lett. 62A (1977)

•More neutrons•Higher E field•Better polarisation•Longer coherence time

P. HarrisBEACH 2006

CryoEDM overviewNeutron beam input

Transfer section

Cryogenic Ramsey chamber

P. HarrisBEACH 2006

Cryogenic Ramsey chamber

Superfluid He

HV electrode

n storage cells(eventually 4)

HV feed

P. HarrisBEACH 2006

CryoEDM

Turns onOctober 2006

P. HarrisBEACH 2006

3. Other EDM experiments: PSI

spallation target D2O moderator currently testing

apparatus from ILL

P. HarrisBEACH 2006

Other nEDM experiments: USA

SNS at ORNL

• LANL-led• testing underway• not yet funded

P. HarrisBEACH 2006

Electron EDM: Berkeley

Final result:de<1.6 x 10-27 e.cm(systematics limited)

Use unpaired e-

in paramagnetic atom

Pairs of Tl beams in opposite E fields

Na beams as comagnetometer

Up beam

E field

B field

Statepreparationlaser

Stateanalyser laser Down beam

P. HarrisBEACH 2006

Electron EDM measurements

Group System Advantages Projected gain

D. Weiss (Penn St.) Trapped Cs Long coherence ~100!

D. Heinzen (Texas) Trapped Cs Long coherence ~100!

H. Gould (LBL) Cs fountain Long coherence ?

L. Hunter (Amherst) GdIG solid Huge S/N 100?

S. Lamoreaux (LANL)C.-Y. Liu (Indiana)

GGG solid Huge S/N 100?-100,000?

E. Hinds (Imperial) YbF beam Large Internal E 3, then 30

D. DeMille (Yale) PbO* cell Int.E+good S/N 30-1,000?

E. Cornell (JILA) trapped HBr+ Int. E + long T ??

N. Shafer-Ray (Okla.) trapped PbF Int. E + long T ??

(This slide mainly from DeMille, PANIC ’05)

P. HarrisBEACH 2006

pump laser

detectionlaser

PMT

statesplitter

staterecombiner

Imperial College Electron EDM experiment

Pulsed supersonic YbF beam source

E B

Molecule interferometer

pulsed YAG laser

Yb target

Ar+SF6

skimmer

J.J.Hudson, B.E. Sauer, M.R. Tarbutt, & E.A. Hinds,

PRL. 89, 023003 (2002).

• Now taking data• Studying systematics• Results soon

P. HarrisBEACH 2006

199Hg EDM

Optically pumped 199Hg atoms precess in B, E fields, modulating absorption signal

Dual cells remove effect of drifts in B

Result: d(199Hg) < 2.1 x 10-28 e cm

Provides good limit on CPv effects in nuclear forces, inc. QCD

P. HarrisBEACH 2006

... and more!

Muon EDM: from g-2 (7E-19; proposal at JPARC for ~10-24)

Deuterium EDM: similarprinciple (may reach ~10-29 e.cm)

Tau weak dipole moment – look for CP-odd observables in diff. x-sec at Z res.(6E-18 e.cm from LEP data)

Sensitivity to physics BSM depends on source of CPv

P. HarrisBEACH 2006

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0

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-10 0 10 20 30 40

R-1 (ppm)

EDM

(10

-26

e.c

m)

Conclusions

New nEDM limit, 3.0 x 10-26 e.cm Tightens the constraints on beyond-SM CPv

Systematics understood as never before CryoEDM coming soon – 100x more

sensitive Several new measurements starting up Watch this space!

-150

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0

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R-1 (ppm)

ED

M (

10-2

5 e

.cm

)

-10

-8

-6

-4

-2

0

2

4

6

8

10

500 700 900 1100 1300 1500 1700 1900 2100

ED

M (

10-2

5 e.c

m)

P. HarrisBEACH 2006

spare slides

P. HarrisBEACH 2006

Cryogenic Ramsey chamber

Superfluid He

HV electrode

n storage cells

P. HarrisBEACH 2006

Ramsey method of Separated Oscillating Fields

4.

3.

2.

1.

Free precession...

Apply /2 spinflip pulse...

“Spin up” neutron...

Second /2 spinflip pulse.

P. HarrisBEACH 2006

Ramsey resonance “2-slit” interference pattern Phase gives freq offset from resonance

29.7 29.8 29.9 30.0 30.1

10000

12000

14000

16000

18000

20000

22000

24000

xx

x = working pointsResonant freq.

xx

Spi

n-U

p N

eutr

on C

ount

s

Applied Frequency (Hz)

P. HarrisBEACH 2006

nEDM apparatus

N S

Four-layer mu-metal shield High voltage leadQuartz insulating cylinder

Coil for 10 mG magnetic field

Upper electrodeMain storage cell

Hg u.v. lamp

PMT to detect Hg u.v. lightVacuum

wallMercury

prepolarising cell

Hg u.v. lampRF coil to flip spins

Magnet

UCN polarising foil

UCN guide changeover

Ultracold neutrons

(UCN)

UCN detector

P. HarrisBEACH 2006

Neutron EDM results (binned)

-10

-8

-6

-4

-2

0

2

4

6

8

10

500 700 900 1100 1300 1500 1700 1900 2100

ED

M (

10-2

5 e.c

m)

Stat. limit now 1.51 x 10-26 e.cm

P. HarrisBEACH 2006

Neutron EDM results (individual runs)

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0

10

20

30

40

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1

18

35

52

69

86

10

3

12

0

13

7

15

4

17

1

18

8

20

5

22

2

23

9

25

6

27

3

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0

30

7

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4

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1

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2

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0

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7

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4

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1

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2

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6

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3

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0

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7

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4

68

1

69

8

ED

M (

10-2

5 e.c

m)

What’s going on here,for example?

P. HarrisBEACH 2006

Geometric Phase How to measure it

Consider

Should have value 1 R is shifted by magnetic field

gradients Plot EDM vs measured R-1:

n

Hg

Hg

nR

P. HarrisBEACH 2006

Geometric Phase

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0

50

100

150

-40 -20 0 20 40

R-1 (ppm)

ED

M (

10-2

5 e.c

m)

Magnetic field down

z

B

P. HarrisBEACH 2006

Geometric Phase

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-50

0

50

100

150

-10 0 10 20 30 40

R-1 (ppm)

ED

M (

10

-26 e

.cm

)

Magnetic field up

z

B

P. HarrisBEACH 2006

Results

R-1

EDM

0

B down

B up The answer?

Nearly...

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0

50

100

150

-40 -20 0 20 40

R-1 (ppm)

ED

M (1

0-2

5 e

.cm

)

-150

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-50

0

50

100

150

-10 0 10 20 30 40

R-1 (ppm)

EDM

(10

-26

e.c

m)

P. HarrisBEACH 2006

Results

R-1

EDM

0

Small dipole/quadrupole fields can pull lines apart

& add GP shiftsB up

B down

P. HarrisBEACH 2006

Results

R-1

EDM

0

Small dipole/quadrupole fields can pull lines apart

& add GP shiftsB up

B down

Measure and apply correction

...difficult!

P. HarrisBEACH 2006

History

Factor 10every 8 yearson average

Now

CryoEDM

P. HarrisBEACH 2006

Other nEDM experiments: Mainz

Testing UCN source at TRIGA, Mainz for later installation at FRM, Munich

Reactor channel

Neutronvalve

UCN guide tubeDeuterium converterin in-pile cryostat

Neutron storage volume

Test cryostat

Reactor channel

Neutronvalve

UCN guide tubeDeuterium converterin in-pile cryostat

Neutron storage volume

Test cryostat

P. HarrisBEACH 2006

EDM given by fringe shiftwith reversal of E or B

Magnetic field (nT)

Fluorescence signalThe interference fringes

Data being taken now. Systematics being studied.

de = _ ± 5 x 10-28 e.cmCurrent status:

de = _ ± 5 x 10-29 e.cmExpected 2010: