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
-150
-100
-50
0
50
100
150
-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
-100
-50
0
50
100
150
-40 -20 0 20 40
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)
-50
-40
-30
-20
-10
0
10
20
30
40
50
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
29
0
30
7
32
4
34
1
35
8
37
5
39
2
40
9
42
6
44
3
46
0
47
7
49
4
51
1
52
8
54
5
56
2
57
9
59
6
61
3
63
0
64
7
66
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
-150
-100
-50
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
-150
-100
-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...
-150
-100
-50
0
50
100
150
-40 -20 0 20 40
R-1 (ppm)
ED
M (1
0-2
5 e
.cm
)
-150
-100
-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:
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