Nuclear spin maser at highly stabilized low magnetic fieldand

search for an atomic EDM

A. YoshimiRIKEN

K. Asahi, T. Inoue, M. Uchida, N. HatakeyamaDept. Phys., Tokyo Inst. Tech.

The 18th International Symposium on Spin Physics (SPIN08), UVa,2008/10/6-11.

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Time: t -t

Spin: s -s

EDM: d d

EDM and physics beyond the standard model

Non-zero EDM associated with spin Direct evidence of violation of time reversal symmetry

Time Reversal

In the standard model…. only possibility is CKM complex phase δCKM : → predicted EDM is too small to detect (105 smaller than the present experimental upper limit)

Beyond the standard model … detectable size of EDM is suggested : more than two CP violating phases

W W

f’fL fLe+iδ e -iδ

E

fL fR

E

Lie Rie

f~

f~

~

No EDM effect from one loop diagram

EDM effect from one loop diagram

EDM search with various species

Neutron EDM

EDM in diamagnetic atom

EDM in paramagnetic atom

Direct detection of neutronExperiment with UCN

Small EDM due to “Schiff shielding”Sensitive to T-violating interaction between nucleons.

Detection of electron EDM (small)Large enhancement in heavy element

129Xe, 199Hg, Ra, Rn

Cs, Tl, Fr

Other Molecule (YbF, PbO), deuteron, …

|dn| < 2.9×10-26 ecm (C.A. Baker et al., PRL. 97 (2006) 131801)

|de| < 1.6×10-27 ecm (B.C. Regan et al., PRL. 88 (2002) 071805)

|dHg| < 2.1×10-28 ecm (M.V. Romalis et al., PRL. 86 (2001) 2505)

Limit the SUSY-particle mass

CP phase in SUSY:A,

Phase pattern in M=500GeV case

From experimental upper limit of different elements …

T. Falk et al., hep-ph/9904393

EDM search in diamagnetic atom

cm10)3.37.0( 27 ed

cm10)1.13.0( 26 ed

Xe12954

1984. Vold et. al., PRL 52 (1984) 2229.

2001. Rosenberry and Chupp, PRL 86 (2001) 22.

1987. Lamoreaux et. al., 　　　　　 Phys. Rev. Lett. 59 (1987) 2275.

cm10)5.17.0( 26 ed

cm10)49.006.1( 28 ed

Hg19980

2001. Romalis et. al.,

　　　　 Phys. Rev. Lett. 86 (2001) 2505.Operation of continuous spin maserOne shot measurement … 2000 sec.

Repetition of FID measurement…. 300 – 500 sec/1run

Optical pumping of Hg atomOptical pumping spin-exchange in Rb-Xe

About 129Xe

Large spin polarization through spin exchange with polarized atom

Spin exchange with optical pumped Rb atomP > 10 % for Xe atomic density of 1018 /cm3

Long coherence time of atomic spin

No chemical interactionNo quadrupole interaction of nucleus ( I=1/2 )

Continuous spin maser technique

129Xe

Rb

Free precession

TimeTra

nsve

rse

spin ‘Spin maser’ state

TimeTra

nsve

rse

spin

Optical detection of nuclear spin precession

• Low static field experiment ( mG ) Small field fluctuation Use of the ultra high sensitive magnetometer

Spin maser with 129Xe at low static field

Inducedcurrent

C

B0

L

I nPQ

BFB

Pumping light LCB

10

Spin maser with the tuned coilof tank circuit

200

2 1

2

1

TInPQ

> kHz (B0 = 1 G)

Oscillation threshold

Artificial feedback throughthe optical spin detection

Operation at low magnetic fieldSmall field fluctuationHigh-sensitive magnetometerLong intrinsic T2

B0 　 mG

Probe laserbeam

Pumping laser beam

Lock-in detection

Phase shifter

Photo diode

Feedback coil

Nuclear spin

M. Richards et al., J. Phys. B 21 (1988) 665.T. Chupp et al., PRL 72 (1994) 2363. A. Yoshimi et al., PLA 304 (2002) 13.

Spin polarization of 129Xe and Optical detection of nuclear precession

Spin polarization of 129Xe Detection of precession of 129Xe

2

1sm

2

1sm

2/1P5

2/1S5

D1 line ： 794.7 nm

IS

129Xe

Rb

Rb

129Xe

N2

N2

129Xe Rb

Rb 129Xe

Rb

Xe

Xe Xe

Circular polarization(modulated by PEM)

RbXe

Xe

Xe

RbXe

Probe laser beam : single mode diode laser (794.7nm)

Transverse polarization transfer : 129Xe nuclei → Rb atoms (re-pol)

Spin-echange in Rb-Xe

Optical pumping Rb atom

After half-period precession

B0

Detector

Enriched 129Xe : 230 torr Rb : ~ 1 mg Pxe ~ 10 % 18 mm

Xe gas cell

Pyrex spherical grass cellSurfaSil coated

Magnetic shield (3 layers )　 Permalloy Size : l = 100 cm, d = 36, 42, 48 cm Shielding factor : S = 103

Pumping LASER

Tunable diode laser = 794.7 nm ( Rb D1 line ), = 3 nm Output: 18 W

Probe LASER Tunable diode laser with external cavity = 794.7 nm ( Rb D1 line ), = 10-6 nm Output: 15 mW

Solenoid coil (for static field)　　 B0 = 28.3 mG ( I = 3.58 mA)

PEM Mod. Freq. 50 kHz

Si photo diode

Freq. band width: 0 – 500 kHz NEP: 810-13 W/Hz

Heater Tcell = 60 ~ 70 ℃

Experimental Setup

129Xe cell

Feedback coil

Heater - tube Probe Laser

PEMPumping Laser

Magnetic shield (4 layer)Φ : 400 mm, L = 1600 mm

Solenoid coilΦ : 254 mm, L = 940 mm

Static magnetic field ： B0 = 28.3 mG ((Xe)=33.5 Hz)

90°RF pulse （ 33.5 Hz , t = 3.0 ms, B1 = 70 mG )

Transverse relaxation ： T2 = 350 s 　；

0 100 200 300 400 500 600Time (s)

0.0

0.2

-0.2

100 110 120

Sign

al (

mV

)

0.16

-0.16

0.00Frequency:

Hz23.0refprecbeat

T2 350 s

Free precession signal of 129Xe

0 20000 40000 60000 80000

0 1000 2000 3000 4000 5000 60000 60020 60040

0.8

0.4

0.0

-0.4

-0.8

Sign

al (V

)

Time (s)

transient steady-state oscillation

-0.8

-0.4

0.0

0.4

0.8

0.00.10.2

-0.2-0.1

B0 = 30.6 mG 0 = 36.0 Hz

Maser oscillation signal

3.542600

3.542800

3.543000

3.543200

3.543400

3.543600

3.543800

3.544000

10000 12000 14000 16000 18000 20000 22000 24000 26000 28000 30000Time (s)

Sole

noid

cur

rent

(mA)

3.542820

3.542825

3.542830

3.542835

3.542840

3.542845

10000 12000 14000 16000 18000 20000 22000 24000 26000 28000 30000

Time (s)

Sole

noid

cur

rent

(mA)

New one

Previous current source

5nA

200nA

Improvement of field fluctuation

Replacement of the reference voltage diode low-noise IC at low frequency

I ≈ 200nA (610-5)

I ≈ 5nA (1.410-6)

Main source frequency fluctuation

B0 - field fluctuation Current fluctuation for solenoid

At time scale of 10000 s…

Fabrication of new current source

)(X tV )(Y tV

Frequency precision

Measurement by lock-in detection ( beat freq. = maser freq. – reference freq. ）Two signals (X, Y – compnents) ; their phases differ by π/2.

)()(2

)(

)(tan)(

0ref0ref

1

t

tV

tVt

X

Y

X, Y signals Precession phase φ Phase fluctuation : obs(t) – fit(t)

4500 4505 4510 4515 4520 4525 4530

0.00

-0.20

0.20

0

10000

20000

0 10000 20000 30000

0.0

0.4

0.8

-0.8

-0.4

0 10000 20000 30000

(9nHz)

Hz0000000090 123115067.00ref .ν

(rad) (rad)

(V)

(s)

(s) (s)

Determination precision of the maser with different measurement time

Frequency precision

10-5

10-6

10-7

10-8

10-9

Fre

qu

en

cy p

recis

ion

(H

z)

10-4

102 103 104 105

Measurement time (s)

10

with previous setup

2/3

0.6 μHz@ 3x104 s

Determination precision of the maser with different measurement time

10-5

10-6

10-7

10-8

10-9

Fre

qu

en

cy p

recis

ion

(H

z)

102 103 104 105

Measurement time (s)

9 nHz@ 3x104 s

2/3

1

Frequency precision

10

10-4

with previous setup

with present setup

750 nHz@ 3x104 s

2 orders improvement

350 nA ; 1.4 μG ∼ 1.7 mHz

1.5 mHz

Drift of solenoid current

Frequency drift of the maser

2mHz driftNow investigating

Long term stability of the maser frequency

why δν -1/2 in t > 1000 s ? why δν get worse in t > 30000 s ?

Frequency fluctuation in 1000s-avaraging

10 nA ; 40 nG ∼ 50 μHz

100 μG → 100 nG → 125 μHz

1.) drift of solenoid current in 1000 s time scale

2.) drift of environmental magnetic field in 1000 s time scale

100 μHz

0 20000 40000 60000 80000(s)

0 20000 40000 60000 80000(s)

123.0

122.9

123.1

123.2

123.3

0 10000 20000 30000

(mHz)

(s)

Long term drift in solenoid B0 field

122

123

124

125

7.3537

7.3538

7.3539

7.3540

7.3541(m

A)

(mH

z)

Ongoing R&D for EDM experiments

High-sensitive Rb magnetometerTemperature control and current

Solenoid current

Temperature

∼2.5℃

Time (h)0 24 48 72 96 120

Long term drift of room temperature : δT 2.5 ℃ → drift of solenoid current : δI 500 nA

Temperature stabilization of current source　　　→ 0.1 ℃ in 1-day time scale　　　→　 5 nA fluctuation （ 20 nG ）　

Nonlinear Magneto-Optical effect of Rb atom

High sensitive magnetometer

D. Budker et al.,PRA 62 (2000) 043403.

k

Linear polarized light

Rb atom

Faraday rotation

B

1×104 rad/G, 4×10-12 G/Hz (B < 0.1G)

7.3530

7.3520

500 nA

20

22

24

( )℃

(mA)

10-13 G → 0.1 nHz → 10-29 ecm

Ongoing R&D for EDM experiments

Electric field application

Now testing the fabricate the field plate and cell in which the leakage current is Suppressed.

Digital feedback control

Temperature control

Test cell for electric field applicationAl – electric plate ： 40 mmφGlass cell (Corning 7740, 7056) ： 20 mm(h)

Calculation of feedback field by computer-based device.

Stabilization of cell temperature → Polarization, magnetic noise

68.7

68.8

0 5 10 15 20 25Time (h)

( )℃ 0.04 ℃

Summary and Future

● New scheme of spin maser -optical-coupling spin maser- has been constructed, and successfully operated at frequency as low as 33 Hz (under B0 = 28 mG)

● The spin maser has been operating with a stable static field (δB ~ 10nG).

● Frequency precision of the maser has reached 9 nHz, corresponding to an EDM sensitivity of 910-28 ecm (E=10kV/cm).

● Further improvements and developments are now being proceeded: Temperature control of current source and cell, Precise magnetometer, Electric field application, Precise maser feedback system.

● Measured fundamental characteristics indicate that this scheme would provide promising means to pursue a search for EDM in 129Xe atom down to a level of d(129Xe) = 10-29 ecm. ( 0.1 nHz).

Main frequency noise in EDM experiment

　　・ Sensitivity limit of the magnetometer : 10-13 G → 0.1 nHz → 10-29 ecm.

　　・ Magnetic noise of Rb atom in collision : 0.2 nHz → 10-29 ecm.

EDM in diamagnetic atom

SRd AA

EextEext + Eint = 0

0intext EEd

Eint

Schiff shielding

Total EDM effect with E is canceled I

SrdrZ

rdreSI

rdrr

3232 1

3

5

10

1

Electron angular momentum = 0

Sensitive to P,T- odd effect in nucleus

Atomic EDM is induced by the nuclear Schiff moment S

Schiff moment is induced by P,T-odd nuclear force

NRS

udF ddmf

mgG

~~32ππ

20πpp1

CP-odd pion exchange is dominated by chromo-EDM of quarks

cmfm/100.4)Hg( 317 eeSd

cmfm/107.2)Xe( 318 eeSd

Feedback system

Lock-in amp.

Lock-in amp.

Operation circuit Wave generator

Modulated signal　　 PEM Modul. Freq. （ 50 kHz) 129Xe Larmor Freq.(33.5 Hz)

Probe light 4 turns 20cm

= 0° = -90°

Si photo-diode

R = 10 – 50 k

VX

VY

PSD-signal（ 0.2 Hz)

Feedback signal (33.5 Hz)

Feedback 磁場

BFB =1

T2

Feedback coil

1 G ( T2=100s) 1V

3.6 G

Pumping light

ref. ( 33.3 Hz )

ref.(50kHz)

Producing the feedback field delayed by 90° in phase to precession signal

Low pass filtering ( fcut ~ 0.8 Hz )Reconfiguration of precession – correlated signal

High S/N feedback signal

)sin()( 0 tVtV ss

)()(cos2

1)( 00 rrrsX tVVtV

)()(sin2

1)( 00 rrrsY tVVtV

Detection of spin precession

Frequency transformation forlow pass filtering

)sin()( 0rrr rtVtV

)()()()()( 21 tVtVtVtVtV rXrYFB

)cos(2

1 2srs tVV

Construction of feedback signal

(33.5 Hz)

(0.2 Hz)

(33.5 Hz)

Fre

quen

cy (

Hz) 33.592

33.588

33.584

33.580 T2 = 6.2 s

T2 = 240 s

T2 = 14.8 s33.480

33.484

33.488

33.492

33.480

33.484

33.488

33.492

-20 -10 0

-20 -10 0

-20 -10 0

(deg)

(deg)

Frequency shift due to the feedback phase error

Phase error of feedback field

Frequency shift due to the feedback phase error

20

20

)(

)(

T

PBPBP

dt

dP

T

PBPBP

dt

dP

yxxz

y

xyzy

x

)(~

)(~

FB tPeitB Ti

)(~

)(~

FB tPitB TIdeal feedback field:

20 2

tan

T

)(~

)()(~

)(1

)(~

TT02

T tBtPitPiT

tPdt

dz

T2=300 s, = 1º = 10 Hz

Feedback

field

spin

Source of frequency fluctuation

10 nA ; 40 nG ∼ 50 μHz

100 μG → 100 nG ∼ 125 μHz

1.) drift of solenoid current in 1000 s time scale

2.) drift of environmental magnetic field in 1000 s time scale

Expected sensitivity for EDM experiment

cm1010)Xe( 3029 ed

Installation of atomic magnetometer into low frequency spin maser

sensitivity : 10-11 10-12 G/Hz B 10-13 G ( (Xe) 0.1 nHz )

Main source of frequency noise

interaction with Rb atomic spins (109/cc) P(Rb) 0.01 % ( re-polarization from Xe ) (Xe) 0.2 nHz (T 0.01˚C)

Conceptual setup

Probe light(Magnetometer)

(E=10kV/cm)

● Frequency noise (intrinsic frequency fluctuation in spin maser)

● Magnetic field fluctuation

● Magnetic fluctuation due to collision with Rb atoms

Feedback phase error : [n] 22

][tan

Tn

1

)/(2

2

2

mase

TNS

tr

= 0.7 nHz (S/N=1000) for 5 days run

Installation of atomic magnetometer into low frequency spin oscillator

sensitivity : 10-11 10-12 G/Hz dB 10-13 G ( (Xe) 0.1 nHz )

interaction with Rb atomic spins P(Rb) 0.01 % ( re-polarization from Xe ) (Xe) 0.2 nHz (T 0.01˚C)

Expected sensitivity to EDM

Estimation of frequency precision

1

2/3

1

1 10 100 1000 10000

Time (s)