EDM photo detector Outline: Rb vapor - - PowerPoint PPT Presentation

冷却フランシウム原子を用いた 電子EDM探索のためのルビジウム磁力計の開発

東北大学 サイクロトロンRIセンター(CYRIC) 内山愛子

Outline:

• 1. Motivation
• 2. Nonlinear magneto-optical

Rotation (NMOR) effect

• 3. Frequency modulated (FM)

NMOR

• 4. FM-NMOR spectroscopy for a

sensitive magnetometry

• 5. Summary

μ –metal shield photo detector Rb vapor cell coil laser light

Experimental upper limit :

|de|< 8.7 ×10-29 e cm

The ACME Collaboration et al., Science 343, 269 (2014)

Motivation to study the Rb Magnetometer

E d B H          

• 11. Feb. 2015

ICEPP Symposium 21st 2

T

B E E B

d

B E

P μ

• > EDM can be a probe to test the physics beyond the SM

10-20 10-25 10-30 10-35 10-40 Standard model (SM) Beyond the Standard model

• > search for electron permanent electric dipole moment (e-EDM)

If an elementary particles has the finite size of the permanent electric dipole moment (EDM) (d) along its spin direction, T and P are violated. de [e cm] μ: magnetic dipole moment d: electric dipole moment

How to search for the e-EDM?

• 11. Feb. 2015

ICEPP Symposium 21st 3

 

2 E d B h     



 

B=0 E=0 B≠0 E=0 B≠0 E≠0

• > measurement of the energy shifts of atom

e

d R d

Fr Fr 

Francium has large enhancement factor RFr~895 and can be cooled and trapped by using laser light.

   d E B 

• > precision measurement of magnetic field should be performed

and fluctuation of magnetic field should be suppressed.

dFr~10-26 e cm in E = 100 kV/cm requires the sensitivity of δB~0.1 fT

Zeeman effect

Earth’s magnetic field~50 μT

hν+ hν-

How to measure the magnetic field?

• 11. Feb. 2015

ICEPP Symposium 21st 4

• 1. The linearly polarized light

produces an alignment state of Rb atoms.

• 2. The atomic alignment precesses

in the magnetic field.

• 3. The polarization plane of the

light rotates due to an interaction with the atomic alignment.

Rotation angle:

gF: Landé g-factor, µB: Bohr magneton l: length of the cell, l0: absorption length

• D. Budker et al., Rev. Mod. Phys. 74, 1153 (2002)

2

2 1 2 l l B g B g

Z B F Z B F

              

• >using the frequency modulated nonlinear magneto-optical

rotation (FM-NMOR) effect

Magnetic field Bz Linearly polarized light

Rb

How to measure the magnetic field?

• 11. Feb. 2015

ICEPP Symposium 21st 5

• 1. The linearly polarized light

produces an alignment state of Rb atoms.

• 2. The atomic alignment precesses

in the magnetic field.

• 3. The polarization plane of the

light rotates due to an interaction with the atomic alignment.

Rotation angle:

gF: Landé g-factor, µB: Bohr magneton l: length of the cell, l0: absorption length

• D. Budker et al., Rev. Mod. Phys. 74, 1153 (2002)

2

2 1 2 l l B g B g

Z B F Z B F

              

• >using the frequency modulated nonlinear magneto-optical

rotation (FM-NMOR) effect

Magnetic field Bz Linearly polarized light

Rb

How to measure the magnetic field?

• 11. Feb. 2015

ICEPP Symposium 21st 6

• 1. The linearly polarized light

produces an alignment state of Rb atoms.

• 2. The atomic alignment precesses

in the magnetic field.

• 3. The polarization plane of the

light rotates due to an interaction with the atomic alignment.

Rotation angle:

gF: Landé g-factor, µB: Bohr magneton l: length of the cell, l0: absorption length

• D. Budker et al., Rev. Mod. Phys. 74, 1153 (2002)

2

2 1 2 l l B g B g

Z B F Z B F

              

• >using the frequency modulated nonlinear magneto-optical

rotation (FM-NMOR) effect

Magnetic field Bz Linearly polarized light

Rb

How to measure the magnetic field?

• 11. Feb. 2015

ICEPP Symposium 21st 7

• 1. The linearly polarized light

produces an alignment state of Rb atoms.

• 2. The atomic alignment precesses

in the magnetic field.

• 3. The polarization plane of the

light rotates due to an interaction with the atomic alignment.

Rotation angle:

gF: Landé g-factor, µB: Bohr magneton l: length of the cell, l0: absorption length

• D. Budker et al., Rev. Mod. Phys. 74, 1153 (2002)

2

2 1 2 l l B g B g

Z B F Z B F

              

• >using the frequency modulated nonlinear magneto-optical

rotation (FM-NMOR) effect

Magnetic field Bz Linearly polarized light

Rb

Frequency modulated NMOR (FM-NMOR)

• Modulated light enable to measure non-zero magnetic fields.
• 11. Feb. 2015

ICEPP Symposium 21st 8

B = 0 μT (νRb = 0 kHz) B = -0.54 μT (νRb = 2.5 kHz) B = +0.54 μT (νRb = 2.5 kHz) B = +1.08 μT (νRb = 5 kHz) B = -1.08 μT (νRb = 5 kHz) Magnetic Field [μT]

ΩL : Lamor frequency Ωm: modulation frequency FM-NMOR spectrum Ωm =5 kHz L m

n    2

h B g m

B F F L

 2  

Resonance frequency of FM-NMOR

• > Lamor frequency
• > Magnetic field

What should I do for the sensitive FM-NMOR magnetometer?

• 11. Feb. 2015

ICEPP Symposium 21st 9

ΔB = ℏΓ/gFμB

,

1

  



         B B

large magnitude of slope = high sensitivity ΔV=l0/l

gF: Landé g-factor, µB: Bohr magneton l: length of the cell, l0: absorption length

B V B     

frequency [Hz] Noise [V/√Hz]

50 150 100 200 250 10-6 10-5 10-4 10-3 10-2 0.1 1 10

The best sensitivity is now δB ~ 3 nT/√Hz

• > find the best condition for the FM-NMOR

Experimental apparatus

• 11. Feb. 2015

ICEPP Symposium 21st 10 Magnetic shield 3-axis coil and Rb cell

DFB Laser (Rb D1 line) Function generator λ/2

PBS

Lock-in amplifier

PBS

Photo detector

Magnetic shield Rb cell

λ/2

Saturated absorption spectroscopy

3-axis coil

Frequency Modulation

SYNC <- frequency monitor

DFB laser

• 11. Feb. 2015

ICEPP Symposium 21st 11 Magnetic shield 3-axis coil and Rb cell

DFB Laser (Rb D1 line) Function generator λ/2

PBS

Lock-in amplifier

PBS

Photo detector

Magnetic shield Rb cell

λ/2

Saturated absorption spectroscopy

3-axis coil

Frequency Modulation

SYNC <- frequency monitor

DFB laser

• 11. Feb. 2015

ICEPP Symposium 21st 12 Magnetic shield 3-axis coil and Rb cell

DFB Laser (Rb D1 line) Function generator λ/2

PBS

Lock-in amplifier

PBS

Photo detector

Magnetic shield Rb cell

λ/2

Saturated absorption spectroscopy

3-axis coil

Frequency Modulation

SYNC <- frequency monitor

DFB laser

NMOR effect.

• 11. Feb. 2015

ICEPP Symposium 21st 13 Magnetic shield 3-axis coil and Rb cell

DFB Laser (Rb D1 line) Function generator λ/2

PBS

Lock-in amplifier

PBS

Photo detector

Magnetic shield Rb cell

λ/2

Saturated absorption spectroscopy

3-axis coil

Frequency Modulation

SYNC <- frequency monitor

DFB laser

NMOR effect.

FM parameter dependence

• 11. Feb. 2015

ICEPP Symposium 21st 14 slope (mV/μT) 5 1 1 5 20 25

100 200 300 400 500 600 700 800

laser power (µW)

900

slope (mV/μT) 5 10 15 20 25

200 400 600 800 1000 1200 1400 1600 1800

scan width (MHz)

• long coherence time
• large absorption = large alignment

high sensitivity

slope (mV/μT)

5 10 15 20 25

Cell dependence

• 11. Feb. 2015

ICEPP Symposium 21st 15 Best cell 3 1 2

Cell No. Cell size Coating Cleaning Buffer gas NMOR signal 1 f30 mm×L30mm Paraffin HNO3 － ○ 2 f30 mm×L30mm Paraffin HF － ○ 3 f25mm×L25 mm Paraffin ? He 1 torr ○ 4 f20mm×L20 mm Paraffin HF － × 5 f25mm×L25 mm － ? N2 50 torr × 6 f25mm×L25 mm － ? － ×

Summary

• 11. Feb. 2015

ICEPP Symposium 21st 16

The Rb atomic magnetometer based on the FM-NMOR effect was studied for the electron EDM search using the laser cooled Fr atoms. The dependences on the frequency scan width, the laser power, and the cell production procedure for the field sensitivity were measured. The best magnetic sensitivity is now 3 nT/√Hz at the present condition.

Collaboration

• 11. Feb. 2015

ICEPP Symposium 21st 17

Cyclotron and Radioisotope Center (CYRIC), Tohoku University

• S. Ando, T. Aoki, H. Arikawa, K. Harada, T. Hayamizu, T. Inoue*, T. Ishikawa,
• M. Itoh, K. Kato, H. Kawamura*, K. Sakamoto, A. Uchiyama, and Y. Sakemi

*Frontier Research Institute for Interdisciplinary Sciences (FRIS), Tohoku University

The University of Tokyo

• T. Aoki

Tokyo Metropolitan University

• T. Furukawa

Tokyo Univ. Agri. Tech.

• A. Hatakeyama

Japan Atomic Energy Agency

• K. Imai

Kyoto University

• T. Murakami

Indian Tech. Roorkee

• H. S. Nataraj

Tokyo Inst. Tech.

• T. Sato

Tohoku University

• Y. Shimizu

Osaka University

• H. P

. Yoshida

Osaka University

• K. Hatanaka

Kyushu University

• T. Wakasa

Tokyo Inst. Tech

• K. Asahi

Okayama University

• A. Yoshimi

Foreign students

• J. Mathis (ENSICAEN), L. Koehler (TU Darmstadt)