原子にedmを探すseminar/monthlycolloquium/12_11...edm を探す experimental search for edm in...
Post on 09-Sep-2020
5 Views
Preview:
TRANSCRIPT
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.
top related