旭 耕一郎,1 市川 雄一,1 近森 正敏,1 大友祐一,1 彦田絵里,1 鈴木貴大,1土屋 真人,1

井上壮志,2 吉見 彰洋,3 古川 武,4 上野 秀樹,5 松尾 由香利,5 福山 武志6

1 東工大理工、2 東北大CYRIC、3 岡山大極限量子コア、 4 首都大東京理工、 5 理研仁科センター 、 6立命館大R-GIRO

原子にEDMを探す

Experimental search for EDM in a diamagnetic atom 129Xe with spin oscillator technique

理研仁科センター月例コロキウム, November20, 2012

OUTLINE:

1. Why EDM?

2. "Optically coupled" spin oscillator

3. Present status

4. Summary

2

+ + +

--

--

--

+qe

−qe

a [cm] EDM d

d = qa [e∙cm]

+

--

Neutral particle

≈

§1 Why EDM?

=

spin s

3

particle( ) dρ= ∫d r r ror,

5EDM 2i d Fν

µνµψσ γ ψ= −L

ds

=sd●Quantum mechanically, d ∝ s

● Field theoretically, its interaction is represented by:

[ ] ( )

5

i , i2

00

00

0 1 1 02i i

1 0 0 1

1 0 0 12i i

0 1 1 0

2

x y z

x z y

y z x

z y x

s

s

g

E E EE B B

F A AE B BE B B

F

F

E m EE m

µν µ ν µ ν µν

µν µ ν ν µ

µν

µν

µν

µν

σ γ γ γ γ

σ

σ γ

φ φψ

φ

≡ = −

− − ≡ ∂ − ∂ = − − − −

= − ⋅ − ⋅ −

= − ⋅ − ⋅ −

= + →⋅

+

EσBσ

EσBσ

σp

( )†

EDM

( / 0)0

2

s

s s

p m

d Eφ φ

→

∴

→ − ⋅σEL

5EDM 2i d Fν

µν

µψσ γ ψ= −L

Transformation property of an EDM

+ + +

--

--

--

+ + +

--

- Spin: s −s EDM: d d

(Time: t −t) Time Reversal

d

s

d --

Standard Model (SM) Predicts EDMs that are undetectably

small -- 10-5 times the present limits. Theories beyond the SM allow sizes of EDM to be reachable

with “a-step-forward” experiments

Thus... EDM violates T , and hence CP (by CPT theorem)

+ + +

--

--

--

+ + +

-- -- --

Spin: s −s EDM: d d

Time: t −t

One-loop diagram for EDM

Non-zero EDM

Evidence for an existence of New Physics

= (e.g.) SUSY

EDM = 0 SM

Time Reversal

≈

Standard Model Big Bang in Cosmology

But … we know today that ・SM particles share only 4.5 % of the Universe’s energy content！ The rest are ・Dark energy 73 % ・Dark matter 22 %

Standard Model Big Bang in Cosmology

But … we know today that ・SM particles share only 4.5 % of the Universe’s energy content！ The rest are ・Dark energy 73 % ・Dark matter 22 %

Even further, …. Formation of matter in the Universe --- A Puzzle ・CP violation within the SM is too small to

explain the predominance of matter over antimatter

・Extra CP violation is needed ! EDM is an exclusively excellent NEW PHYSICS indicator, free from the SM “background”

CP violation in the Standard Model

13

13

13 13

1

3

3

1

13 13 12 12

23 23 12 12

23 23 13 13

12 13 12 13 13

12 23 12 13 23 12 23 12 13 23 13 23

12 23 12 13 23 12 23 12

i

i

i i

i

i

1 0 0 e

e

0 00 0

e

e ee

1 0 00 0 0 0 1

c s c sV c s s c

s c s c

c c s c ss c c s s c c s s s c s

s s c s c c s s

δ

δ

δ

δ δ

δ

−

−

= − − −

= − − −− − − 13i

13 23 13 23e

ud us

cd c

ub

td

s cb

ts tb

s c c c

V VV VV

VV V

V

δ

≡

Supersymmetry

From: CERN Webpage

Minimal Supersymmetric Standard Model (MSSM)

Rotation symmetry 1

1x x

yy

A AAA

ξξ

′ = − ′

ξ x

x’

y y’

2

1( ) ( )1( ) ( )

x xi ix xµ

µ

ξφ φσ σ ξχ χ∗

⋅′ = − ∂′

ξ bosonic component

y’ fermionic component

From: CERN Webpage

Minimal Supersymmetric Standard Model (MSSM)

●低エネルギー（E < 100 GeV)（我々の世界）ではSUSYは見掛け上破れている！

ー低エネルギーでの現実の粒子

である標準理論の粒子はそれぞれ、自分よりずっと重くて現実には見えない超対称パートナー粒子の影を引きずりながら存在する。

EDM in the Standard Model

EDM in the MSSM

Tl, Fr, Cs… 129Xe, 199Hg, Rn, Ra…

M. Pospelov and A. Ritz, Annals of Phys. 318, (2005) 119-169

EDM in a 129Xe atom •stable particle •macroscopic number of particles •EDM generated by a nuclear

Schiff moment •P,T-violating NN interaction

Schiff moment

Sites of EDM searches • neutron dn • paramagnetic atoms (Tl, Fr, Cs, ...) de • diamagnetic atoms (129Xe, 199Hg, Rn, Ra, ...) Snucl • molecules (TlF, YbF, PbO, ThO, ...) de • charged particles (µ, p, d, ions, ...) dµ , dp, dd, dnucl, … dD

J-PARC/Muon

The present talk

CYRIC, Tohoku U

KEK-RCNP

Nucleus

Electron cloud

(singlet)

In a diamagnetic atom

+

d

+Ze

=

∆x = d/Ze

− Ze +Ze

(1) For a point nucleus

Nucleus

Electron cloud

(singlet)

In a diamagnetic atom

+

d

+Ze

=

∆x = d/Ze

− Ze +Ze

Atomic electrons do not "know" that the nucleus has EDM.

(Schiff’s theorem)

(1) For a point nucleus

Nucleus

EDM d

q

=

Electron cloud

(singlet)

In a diamagnetic atom

(2) For a finite-size nucleus

Nucleus

EDM d

q

=

Electron cloud

(singlet)

In a diamagnetic atom

(2) For a finite-size nucleus

Nontrivial charge distribution in the nucleus generates an EDM in atom:

Schiffatom

0

Schiff

0

0ˆˆ0 0 where , 0 0

ˆ0 02

ii P P

P P

P ee P

E E

P P eE E

ϕ

ϕ

−= = − ≈ +

−

−≈

−

∑ ∑

∑

d D D R

D

Schiffˆ4 ( )ϕ π δ= ⋅∇S R

2 2 3

nucleus

1 5ˆ ( ) d10 3

r rρ ≡ − ∫S r r r Schiff moment

datom ≠0

Nucleus

Electron cloud

+ + +

-

-

- E

In a diamagnetic atom

(2) For a finite-size nucleus

( ) ( ) ( ) ( )

( ) ( )( )1 2

(0) (1) (2)

(1)

2π

PT 1 2 1 2 1 2 1 2 1 2 1 2 1 2N

1 2 1 2 1 2 21 21 2

1( ) 38π2

1 112

NN NN NN

NN

z z z z

m

z z

g g g

g

gmVm

emm

π

π π π

πππ

τ τ τ τ τ τ τ τ

τ τ− −

− = − − ⋅ − ⋅ − + + − ⋅

− + ⋅ − − + − −

r r

r rσσr r

σσr rr rr r

P-,T-violating pion-mediated NN interaction

Nuclear structure

π

N

N

●Schiff moment from fundamental sources of CPV

NNgπ

NNgπ

N

N

Nucl Nucl

Nucl 1 2

2

Nucl 1 2 0 Nucl 1 2

ˆ

where ( , , , ) is a solution for the Schroedinger equation

( , ) ( , , , ) ( , , , )2

A

Ak

j k A Aj k

V Em <

= Ψ Ψ

Ψ

+ Ψ = Ψ

∑

S Sr r r

p r r r r r r r r

If VPT = 0, then S = 0

Non-zero S is induced by VPT

CP-violating effective Lagrangian for the strong interactions of light quarks (up to those of dimension 5):

sCPV 5

, ,

( )8 2 q s

q u d s

iGG qg Gd q

ασ γ

πθ

=

= + ∑

( )( 0 ) (1) 2 3 0)0 (

CPV 3a

NN NN NN

a a aNN N N NN N Ng Ng Ngπ π π

π τ π π τ π τ π+ + −=

π

N NNgπ N

New physics

CPVN i Nπ ・PCAC ・QCD sun rule ・Baryon mass spectrum …..

e.g. [Hisano & Shimizu, PRD70(04)093001]

( )( )

( 0 )

(1)

( 2 ) 0

NN

NN u d

NN

u dg

g d d

g

d dπ

π

π

∝

∝ −

+

=

where

199 (0) (1) (2) 3( Hg) 0.0010 0.074 0.018 fmNN NN NN NN NN NNS g g g g g g eπ π π π π π= − + +

With SkO' interaction, [de Jesus & Engel, 2005]

●Case of 199Hg

199 (0) (1) (2) 3( Hg) 0.016 0.006 0.019 fmNN NN NN NN NN NNS g g g g g g eπ π π π π π= − +

[Ban, Dobaczewski, Engel and Shukla. 2010]

199 (0) (1) (2) 3( Hg) 0.086 0.086 0.172 fmNN NN NN NN NN NNS g g g g g g eπ π π π π π= − − +

199 (0) (1) (2) 3( Hg) 0.0004 0.055 0.009 fmNN NN NN NN NN NNS g g g g g g eπ π π π π π= − − +

[Flambaum et al., 1986]

[Dmitriev et al., 2003]

Hartree-Fock-Bogoliubov calc. with SLy4 interaction modified to include CP-odd π-exch. NN int.

“The calculations presented here are more sophisticated and inclusive than any yet attempted, but it may very well be that still more sophistication is required.”

129Xe vs. 199Hg

d(129Xe) = 6.7×10−26 η ecm

d(199Hg) = 4.0×10−25 η ecm

( dn = −5×10−23 η ecm )

Previous calculation [Flambaum, Khriplovich, Sushkov, 1985]

× 6

But, ….

●Case of 129Xe ・ Work by Flambaum, Khriplovich, Sushkov, 1985 ・ New calculation is strongly anticipated !

●Case of 129Xe (nuclear structure consideration)

129Xe (Z=54, N=75)

( ) ( ) ( )

( ) ( ) ( )

1/21/2

0 0 0129 4 2 1 43/2 11/2 1/2 7/2

1/23/2

0 2 24 2 1 43/2 11/2 1/2 7/2

Xe, 1/2 d h s g

d h s g

(others ....)

J

J

ν π

α ν π

++ + +

++ + +

=

+ − − −

=

− − −

≈ ⊗

+ ⊗

+

A simple-minded g.s. wave function:

PT

. .

2 2p p pch

ˆ ˆg.s. . .

1 5ˆ10 3

z

g s ii

z

S i i V g sS

E E

S e r z r z

=−

≡ −

∑

VPT

●Case of 129Xe (nuclear structure consideration)

129Xe (Z=54, N=75)

( ) ( ) ( )

( ) ( ) ( )

1/21/2

0 0 0129 4 2 1 43/2 11/2 1/2 7/2

1/23/2

0 2 24 2 1 43/2 11/2 1/2 7/2

Xe, 1/2 d h s g

d h s g

(others ....)

J

J

ν π

α ν π

++ + +

++ + +

=

+ − − −

=

− − −

≈ ⊗

+ ⊗

+

A simple-minded g.s. wave function:

PT

. .

2 2p p pch

ˆ ˆg.s. . .

1 5ˆ10 3

z

g s ii

z

S i i V g sS

E E

S e r z r z

=−

≡ −

∑

VPT

●Shell-model calculation of the 129Xe Schiff moment is presently under way, by N. Yoshinaga and co-workers (Saitama U.)

d(129Xe) < 4.1×10-27 ecm Rosenberry and Chupp, PRL 86 (2001) 22

d(199Hg) < 3.1×10-29 ecm Grifith et al., PRL 102 (2009) 101601

Standard Model (dn = 10-(31-33) )

Neutron EDM predicted values

d = 10−27 e·cm E = 10 kV/cm ∆ν = 10 nHz （ ∆ω ≈ 1°/day）

[Pendlebury and Hinds, NIM A 440 (00) 471]

Natural size of an EDM

d ~ e·[distance]·[weak force]·[CP]

~ e·10−13 cm · 10−7 · 10−3

~ 10−23 e·cm (?)

dn < 10−26 e·cm

12,800 km

d ~ 10−27 e·cm という大きさ

~10 fm

~0.01 µm ~ 10−27 cm

+ + + +

dEBH −−= µE // B

dEBH +−= µE // −B

Energy shift upon an E-field reversal

Shift in a precession frequency

hdEB 22 +

=+µν )//( BE

hdEB 22 −

=−µν )//( BE −

the difference ⇒ signal of an EDM

EdBμ ⋅−⋅−=H

21

=m

21

−=m

00

==

EB

0νh +νh −hν

BEB

//0≠

BEB

−≠//

000

=≠

EB

B E

+ν s

B E

−ν s

Energy levels for a spin 1/2 (for a case of µ > 0, d > 0)

hE 4

=−=∆ −+ ννν d

Detection of an EDM

Desires long precession times => Spin maser

Setup for the spin oscillator experiment

Probe laser ・DFB laser ・λ = 794.76 nm (Rb D1line) ・∆λ = 8.4×10-6 nm ・Power : 15 mW

Pumping laser ・λ = 794.76 nm (Rb D1line) ・∆λ = 3 nm ・Power ~ 11 W

PEM

Heater

λ/4 plate

Si photodiode ・Bandwidth : 0 ～ 500 kHz

magnetic shield (4-layer) ・permalloy

Solenoid coil (static field) ・B0 = 30.6 mG (I = 7.354 mA)

0B

C70≈T

spin precession signal

129Xe : 230 torr

N2 : 100 torr Rb : ~ 1 mg Pyrex glass

SurfaSil coating

129Xe gas cell

18 mm

Production of Polarization

30

Collisional Mixing Optical pumping

Rb Rb

Rb

Rb Rb Rb

N2

N2

129Xe Rb

Rb 129Xe

IS

129Xe

Rb

Rb

129Xe

Spin exchange interaction in Rb-Xe

2 body collision 3 body collision

W. Happer, Rev. Mod. Phys. 44 (1972) 169.

129Xe Rb N2

Enclosed

Optical Spin Detection

31

Transverse polarization of 129Xe transfer to Rb : Re-polarization

B0 B0

After half-period precession Probe laser beam

Maximum transmission

Minimum transmission

Circular polarized

Circular polarized

● P follows the Bloch equations:

or,

( )

( )

( ) ( )

02

02

01

d,

d d

,d d

.d

x xy z y

y yz x x

z zx y y x z

P PP B P B

t TP P

P B P Bt T

P PP B P B P P G

t T

γ

γ

γ

= − −

= − −

= − − + −

Spin oscillator

● 129Xe polarization vector P = ⟨I⟩/I

● Applied field B0 = (Bx, By, B0)

1,2

1T

γ= − × −P B P P

Pumping term

relaxation term

( )

( )

( ) ( )

02

02

01

d,

d d

,d d

.d

y

x

y x

x xy z

y yz x

z zx y z

P PP B P

t TP P

P P B

B

B

B B

t TP P

P P P P Gt T

γ

γ

γ

= − −

= − −

= − − + −

Spin oscillator

B⊥(t)

● Now we apply a transverse field B⊥(t)

which is organized to follow P⊥ (t)

( ) ( )

( ) ( )x y

y x

B t P tB t P t

∝

∝ − B⊥(t)

Spin detection signal

P⊥

Taking (1) + i (2) and setting

( )

2

2

01

d 1 , (4)d d . (3')d

z

z zz

P P P

P PP

t

P

T

P Gt T

α

α

⊥⊥

⊥

= −

= − − + −

0( ) ( ) ( )i tx yP t iP t e P tω

⊥+ ≡

The steady state solutions (namely solutions under )

・Trivial solution:

・Non-trivial solution:

d d0 and 0d d

zP Pt t⊥ = =

eq eq 10

1

0, 1z

GTP P P

GT⊥ = =+

eq eq10

2 2

1 1 / 1, .zGTGP P P

T Tα α α⊥

+= − =

( ) ( )

02

02

01

d, (1)

d d

, (2)d d

. (3)d

xy z

y yx z y

z zx x y

xx

y z

t T

t T

P Gt T

P PP P P

P PP P P

P PP P P P P

ω α

ω α

α

= − + −

= + −

= − + − + − 0 0

x y

y x

B P

B P

B

αγ

αγ

ω γ

≡

≡ − ≡ −

( )

( )

( ) ( )

02

02

01

d,

d d

,d d

.d

x xy z y

y yz x x

z zx y y x z

P PP B P B

t TP P

P B P Bt T

P PP B P B P P G

t T

γ

γ

γ

= − −

= − −

= − − + −

(Natural) spin maser

B⊥

[T.E. Chupp et al, Phys. Rev. Lett. 72 (94) 2363] [M.A. Rosenberry and T.E. Chupp, Phys. Re. Lett. 86 (2001) 22]

● If the coil is coupled to a capacitor C forming a resonating circuit, the coil produces a transverse B field, B⊥(t),

( ) ( )

( ) ( )x y

y x

B t P tB t P t

∝

∝ −

Spin oscillator signal B0 = 28.6 mG (I0 = 7.0 mA) => ν0 = 33.7 Hz

Time [s]

Sign

al [V

]

Steady state Transient

Spin oscillator

Realization of maser oscillation at very low fields (≤ mG) Suppression of drifts in the B0 field => Suppression of drifts in ν

“Optically coupled” spin maser with a feedback field generated according to optical spin detection

P(t)

B⊥(t)

B0

ν0

P⊥(t)

Feedback torque

Pumping and relaxation effect

Static magnetic field : B0 ∼ mG

Pumping light

Photo diode

Feedback coil

Probe light Feedback circuit

Lock-in detection

precession signal

Feedback system

② Optical detection of the spin precession

①129Xe nuclear spin polarization by optical pumping

③Generation of a feedback field

④Self-sustained spin precession

Precision of Precession Frequency

38 mT

T

+ + · · · · +

T T T

Single-shot measurement

Multi-shot measurement

Long-term measurement

Solenoid coil Magnetic shield

Pumping, probe laser Feedback coil

Probe light

Pumping light

To photo diode

129Xe gas cell

EDM cell EDM cell •129Xe : ~ 200 torr •N2 : ~ 100 torr •Rb ~ 1 mg •SurfaSil coating •size: 10 mm×10 mm×10 mm

ITO conductive coating

Torr seal

10 mm

EDM cell

Time [s]

Sign

al [V

]

T2 ~ 170 s

Spherical cell

Sign

al [V

]

Time [s]

T2 ~ 200 s

129Xe free spin precession

Relaxation time comparable to that of spherical cell

Maser operation applying E0

●Major sources of frequency drift

(1) Solenoid current I0

(2) Cell temperature (3) Environmental field

(4) Other sources

ν0 – I0 correlation

The solenoid current drift induces the frequency drift.

~ 1.5 mHz <=> ~ 40 ppm

Maser frequency

Time [s]

Freq

uenc

y [H

z]

~ 350 nA <=> ~ 50 ppm

Solenoid current

Time [s] C

urre

nt [m

A]

Suppression of current drift => Construction of new stabilized current source

Introduction of the stabilized current source

○ New stabilized current source

～1Ω

Solenoid coil

Digital voltmeter Feedback

Standard resistor 1000 Ω WWW

Current source 1 ～6.5mA

Current source 2 ～0.5mA

σ＝0.98 nA

～1Ω

Solenoid coil

Digital current meter Current source 1 ～7 mA

○ Previous current source

~ 300 nA <=> ~ 40 ppm

●Major sources of frequency drift

(1) Solenoid current I0

→ New stabilized current source (2) Cell temperature (3) Environmental field

(4) Other sources

Tcell [℃] ν 0

[Hz]

ν0 – Tcell correlation

Time [s]

ν 0 [H

z]

Maser frequency

0.4 mHz

Cell temperature

Time [s]

T cel

l [℃

]

0.2 ℃

Frequency shift of 129Xe due to Rb magnetization

[ ] zsB SgIh

Rb3

81Rb-Xe

Xe

XeXe κµπµν −=∆

S. Schaefer et al., PRA39 (1989) 5613.

( ) ( )2.0 C, 70 CmHz/ 6.1~ RbcellXe ==∆→ PT νδ

0.4 mHz

0.2 ℃

Xe frequency shift due to Rb magnetization : proportional to Rb density [Rb] => Drift of frequency shift in Xe : [Rb] drift => Low cell temperature : suppuration of frequency drift due to temperature drift Maser operation under low cell temperature (~ 50℃)

●Major sources of frequency drift

(1) Solenoid current I0

→ New stabilized current source (2) Cell temperature → Operation at low cell temperature (~50 ̊C) (3) Environmental field

(4) Other sources

ν0 – Benv correlation

Time [s]

ν 0 [H

z]

Maser frequency

0.4 mHz

Environmental field

Time [s]

B env

[mG

]

0.4 mG Benv fluctuation => B0 fluctuation

μHz 12.0~mG 1.0 ,10 ~ :(SF)factor Shielding

0

env3

ν∆=>=∆B

ν 0 [H

z]

Benv [mG]

0.4 mHz

0.2 mG

Benv stabilization system construction

Environmental field stabilization system

•Benv measurement - fluxgate magnetometer noise level: ~ 70 nGrms/√Hz • Correction coils - Coli1,3: ~ 88 A•turn - Coil2 : ~ 26 A•turn

Correction coils

Current source ~ 10 mA

DMM

GPIB to Ethernet

Feedback

PC

GPIB

Ethernet

Fluxgate magnetometer Correction coils

Coil1 Coil2

Coil3

for detail see: T. Nanao’s poster

Feedback outside the shield

Suppression of short term fluctuation and long term drift

Magnetic shield

129Xe cell (inside)

Fluxgate magnetometer (noise level: ~ 70 nGrms/√Hz)

Time [s]

B env

[mG

]

0.5 mG

Without feedback

1 a.m. ~ 5 a.m.

Time [s]

B env

[mG

]

With feedback

1 a.m. ~ 5 a.m.

Feedback interval: 0.1 sec

Gμ 5<σ

●Major sources of frequency drift

(1) Solenoid current I0

→ New stabilized current source (2) Cell temperature → Operation at low cell temperature (~50 ̊C) (3) Environmental field

→ Field compensation system (4) Other sources

ν0 – Troom correlation Maser frequency

Time [s]

ν 0 [H

z]

0.2 mHz

Room temperature

T roo

m [℃

]

Time [s]

0.3 ℃ Room temperature Troom fluctuation → Shielding factor of magnetic shield fluctuation → Maser frequency fluctuation

ν 0 [H

z]

Troom [℃]

• Temperature stabilization around the shield • Measurement of local magnetic field applied to 129Xe nucleus, ← 3He co-magnetometer or Rb magnetometer (the next presentation by Prof. Yoshimi)

0.2 mHz

0.3 ℃

Frequency precision under stabilized I0, Benv and low Tcell

1-m

-3/2m

TT

∝

∝

δν

δν

δν = 7.9 nHz δd = 8×10-28 ecm (with 10 kV/cm)

phase noise

Frequency noise

2/32

212

−∆

= mTt

πσ

δν φ

Development of high-precision magnetometer using nonlinear magnet-optical rotation (NMOR)

Rb cell with Paraffin coating: commercial paraffin mixture (Paraflint) (CH2)n

φ 25 – 30 mm

Field coil (3-axis) ECDL

mG37.0=∆B

Magnetic field (mG)

Rot

atio

n an

gle

(mra

d)

rad/G1.160

=

∂∂

=BzzBφ

Balabas cell

mG28.0=∆B

Magnetic field (mG)

Rot

atio

n an

gle

(mra

d)

rad/G8.370

=

∂∂

=BzzBφ

The cell made by Prof. M.V. Balabas：φ60 mm, T1 ̴ 2s.

Balabas cell Thanks to Prof. Hatakeyama (Tokyo Univ. Agri. Tech.)

No large difference in NMOR width → Wall performance does not limit the width → residual field…

( ) [ ]ms402/ 1 =−πγ ( ) [ ]ms502/ 1 =−πγ

(1) High sensitivity magnetometers (3) 3He comagnetometer (2) Rb comagnetometer

・ Not comagnetometer ・ Rb magnetometer near maser cell ・ Only Xe and Rb (small, and not pol)

Xe He

Xe

Rb

Rb

・ Comagnetometer of Rb ・ Only Xe and Rb (small, and not pol) ・ Probrem of Rb – Xe interaction ? ( Low density Xe gas ? ) Polarizability problem

・ Comagnetometer of 3He ・ S/N for He precession for laser probing .

HzG/10 11−=Bδ

100 s –run ( if constant ):

G10 12−=Bδ

HzG/?=Bδ

Maser probe

Rb Magnetometer probe

Xe

Magnetometer for Low freq-Spin maser EDM experiment

Magnetometer probe

57

3He Co-magnetometer

Scheme of 3He Co-magnetometer

58

EDM measurement

Monitor and stabilize B0

EDM is roughly proportional to Z2

Negligible EDM in 3He

Monitor & stabilize B0

Suppress systematic uncertainty

Principles of 3He co-magnetometer

59

B0 Probe laser

beam

Photo detector

Monitor precession signal of 129Xe

Monitor precession signal of 3He

Stabilize B0 through 3He signal

L. A. 1

L. A. 3

L. A. 2

Feedback

Amplify signal

L. A. 0

Enable to measure precession signal of 129Xe under locked B0

Production of Polarization of 3He

60

Circular polarized light

GE180 cell : Low magnetic impurity Low leakage of 3He

129Xe : 50 Torr N2 : 100 Torr He : 470 Torr Rb : ~1 mg

Enclosed

He Xe

Rb Rb

Rb Rb

Production of Polarization of 3He/129Xe cell

61

Typically P(3He) = ~ 3 % T1(3He) = 100 hours

@ 100 ℃

Checked by AFP-NMR measurement Adiabatic Fast Passage

Nuclear Magnetic Resonance

Experimental setup for 3He maser oscillation test

62

Heater

λ/4 plate

0B3-layer magnetic shield Permalloy

Photo diode

Probe laser λ：794.76 nm （tunable） Line width：～10 MHz Max power：10 mW

Pumping Laser λ：794.76 nm （Rb D1 line） Line width：～3 THz Max power：18 W

3He cell 3He：560 Torr N2：100 Torr Rb：～1 mg GE180

20 mm

63

3He：560 Torr N2：100 Torr Ge180 Magnetic shield

Pumping laser Power：18 W (3 THz)

Probe laser Power：10 mW

Maser Oscillation of 3He

64

Free induction decay

Feedback ON

Maser oscillation

T = 99 ℃ ν = 9.63 Hz νbeat = 0.1 Hz

L.A

. out

put [

V]

Time [s]

Succeeded in optical detection

Concurrent operation of 129Xe/3He

65

3He maser signal

3He Feedback ON

129Xe maser signal

129Xe Feedback ON

(Preliminary) Freq. Precision

（For 100 s average）

129Xe : 10 Torr N2 : 100 Torr He : 470 Torr Rb : ~1 mg

Enclosed

Experimental setup for EDM measurement

66

Major improvement TADFB laser Power : 1 W, Width : 10 MHz

Vibration isolated table

Stabilization of Env. field

Stabilization of static field

Present aim

67

Future Perspective

129Xe/3He cell for EDM measurement

68

1 cm

ITO transparent electrodes

Torr seal

cell

Probe laser light

Probe laser light Pyrex GE180

cell

・Pyrex cubic shaped glass ・SurfaSil coating

・Gas pressure 129Xe : 1 Torr 3He : 470 Torr N2 : 100 Torr Rb : ～1 mg

New magnetic shield

69

Outer: 800mmΦ×1300mm×2mmt

Middle: 600mmΦ×1000mm×2mmt

Inner: 400mmΦ× 680mm×2mmt

Caps for each layer

New 3-layer magnetic shield Residual field |B| < few 10μGauss

Shielding factor～104

Cf.)～103 for old one

129Xe/3He double spin detection

Pulses with ν(129Xe) and ν(3He) applied. ⇒Double spin detection ⇒129Xe/3He double spin maser

Xe He

Temperature：103 ℃ Xe：10 Torr、He：470 Torr T2(129Xe)～7 s、T2(3He)～2000 s ν(129Xe)～4.0 Hz、ν(3He)～10.7 Hz [Lock-in] T.C. (129Xe)：300 ms、T.C. (3He)：1 s [signal before ampl] V(129Xe)～250μV、V(3He)～25μV

Operation of a 129Xe/3He double-spin maser

Temperature：103 ℃ Xe：10 Torr He：470 Torr N2：100 Torr νfeedback (129Xe)= 3.75 Hz νbeat (129Xe)～ 0.2 Hz νfeedback (3He)= 10.53 Hz νbeat (3He)～ 0.1 Hz [Lock-in amplifier] Time const (129Xe)：300 ms Time const (3He)：1 s [signal before amplification] V(129Xe)～250μV V(3He)～2.5μV

3Heフィードバック on

129Xeフィードバック on

Xe

He

Summary

● Precession of 129Xe spins is maintained for unlimitedly long times, by application of a feedback field generated from optically detected spins. The merit of this optically coupled spin maser as a scheme for the EDM search is the capability of operation at very low B0 fields, as mG or below.

● Sources of frequency drifts have been identified, and steps taken to overcome them, such as (1) the current source renewal, (2) adoption of low cell temperatures, (3) installation of a field compensation system, and (4) development of a Rb NMOR magnetometer and 3He co-magnetometer.

● Frequency precision presently reached is 7.9 nHz, which corresponds to an EDM sensitivity of 8×10-28 ecm (E=10kV/cm).

● EDM cell equipped with transparent electrodes was prepared.

● 3He co-magnetometer is being developed, and recently the operation of a 3He/129Xe double-spin maser has been tested.