Low-frequency nuclear spin maser and

search for atomic EDM of 129Xe

A. YoshimiRIKEN

SPIN20042004/10/11-16Trieste, ITALY

Collaborator : K. Asahi (Professor, Tokyo Inst. of Tech./RIKEN) S. Emori (Tokyo Inst. of Tech.) S. Oshima (Tokyo Inst. of Tech.)

Electric Dipole Moment

d 0 T-violation CP-violation

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

s

+++

---

s

+++

---Time reversal

Time: t -t

Spin: s -s

EDM: d d

CPT theorem

Standard Model (SM) : Predicted EDM is about 105 smaller than the present experimental upper limitBeyond the SM : Detectable EDM

Detection of non-zero EDM CP-violation beyond the standard model

Recent EDM experiment of diamagnetic atoms

cm10)3.37.0( 27 ed

cm10)1.13.0( 26 ed

01129

54 S5Xe

1984. Vold et. al., Phys. Rev. Lett. 52 (1984) 2229.

2001. Rosenberry and Chupp,

Phys. Rev. Lett. 86 (2001) 2

2.

1987. Lamoreaux et. al.,

　　　　　 Phys. Rev. Lett. 59 (1987) 2275.

cm10)5.17.0( 26 ed

cm10)49.006.1( 28 ed

01199

80 S6Hg

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

cm101.2 28 ed

Supersymmetric modelStandard model

810

cm105 34Xe ed

EDM theory

cm101.2Hg 28 ed

cm106.1e 27 ed

cm103.6n 26 ed

npNAA RRd

Present experimental upper limit

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

cm106 33Hg ed

Upper limit of CP-violating complex phasesin Supersymmetric model

M=250GeV M=500GeV

(O.P. Sushkov et al., JETP 60 (1984) 873)

cmTeV1

1022

27Hg e

Md

)1(CP O

Energy scale of superpartner

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

Project of atomic EDM experiment of 129Xe at RIKEN-TIT

Continuous nuclear spin maser

Free Induction Decay Continuous oscillation

2/32/1

Large polarization of Xe nucleus

Spin exchange with optical pumped Rb atomNuclear polarization O(10) % @ 100 torr (1018 /cc)

129Xe

Rb

Rapid decrease of frequency precision

Spin maser at low frequency

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

Spin MASER

Polarization vector : M

Feedback field : Bfb

B0

Feedback torque

Relaxation, pumping

T2 relaxation

Polarization’s growing(pumping effect)

Feedback torque

pump Feedbacksystem

Zeeman level

Transverse magnetic field - synchronism with spin precession -

Phase : perpendicular to the transverse polarizationAmplitude : proportional to the transverse polarization

Population inversion

Feedback EM-field synchronism with emitted photon

Polarization

Inducedcurrent

C

B0

L

I nPQ

BFB

Pumping light LCB

10

Spin maser with the tuned coilof tank circuit

NMR-based spin maser

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

Optical-detection-feedback spin maser

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.

Experimental apparatus

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

Xe gas cell

Pyrex 　 spherical grass cellSurfaSil coated

Magnetic shield (3 layers )　 Parmalloy 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 ℃

Typical maser oscillation signal

0 1000 2000 3000 4000

B0 = 28.3 mG , ref = 33.20 Hz, feedback gain: 18 G/0.1mV

Feedback system ON

Steady state oscillation

Measured frequency:

0.0

0.2

-0.2

3000 3010 3020

0.1

0.0

-0.1

Hz32.0refprecbeat

Sig

nal

(mV

)

Time (s)

0 10 20 88940 88950 88960 302910 302920( 84 hours)

0.0

0.4

-0.4Sig

nal

(V

)

Time (s)

Frequency characteristics

Fourie spectrum ( 1 hr. run )

Conventional spin maser( = 3.56 kHz )

Low-frequency spin maser( = 33.5 Hz ) t (sec)

(

rad)

0

10000

0 100005000

= 0.96 Hz

= 277.20844 0.00096 mHz

10 100 1000

-3/2

Freq

uenc

y pr

ecis

ion

(H

z)

Time (s)

Precession angle

1

10

100

0.1

On-going developments 1 – magnetometer -

Fluctuation of magnetic field Main source of frequency noise in spin maser operation

Neutron EDM experiment….. Hg atomic magnetometerXe EDM experiment @ Michigan Gr. ….. 3He co-magnetometer

cm10 28atom ed nHz1 pG1B

kV/cm10E

kLinear polarized light

Alkali vapor

Faraday rotationB

1×104 rad/G, 4×10-12 G/Hz (B < 0.1G)

Atomic magnetometer with Rb using magneto-optical rotation

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

- 0.0035

- 0.0030

- 0.0025

- 0.0020

- 0.0015

- 0.0010

- 0.0005

0.0000- 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Magnetic field (G)

Far

aday

rot

atio

n an

gle

(rad

.)

- 0.0030

- 0.0020

- 0.0010

0.0000- 0.01 0.01 0.03 0.05

calibration run

On-going developments 2 – magnetic shield -

Construction of 4-layer shield

　 l = 1600 mm, R= 400 mm

Transverse: S ≈106

Longitudinal: S ≈104

Estimated shielding factor

- 100

- 80

- 60

- 40

- 20

0- 25 - 15 - 5 5 15 25

Measured residual field

z (cm)

Fie

ld (G

)

longitudinal

transverse

Shielding factor : S ≈104

cm1010)Xe( 3029 ed

Installation of atomic magnetometer into low frequency spin oscillator

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)

Estimation of experimental EDM-sensitivity

Probe light(Magnetometer)

(E=10kV/cm)

Conceptual setup

Estimation of frequency precision

1

2/3

1

1000 100 10 1 0.1 0.01

Pre

cisi

on (

H

z )

1 10 100 1000 10000 Time (s)

Summary and Future

Construction of the nuclear spin maser with an artificial feedback system, and operated it at low frequency 33 Hz ( under B = 28 mG ).

Frequency precision of 1 contiguous measurement presently reaches to 1 Hz. (without magnetometer/free-running)

Construction of 4-layer magnetic shield.

Installing the Rb magnetometer with magneto-optical rotation.

Aiming at search for the atomic electric dipole moment in Xe ; d(Xe) = 10-29 10-30 ecm.