possible measurement of electron edm in atoms with spatially alternating electric field
DESCRIPTION
Possible measurement of electron EDM in atoms with spatially alternating electric field. Overview of the planned experiment Recent development on co-magnetometer beam. T. Haseyama RIKEN, Japan ( The Institute of Physical and Chemical Research ). upper limit at present - PowerPoint PPT PresentationTRANSCRIPT
Possible measurement of electron EDM in atoms
with spatially alternating electric field
T. Haseyama RIKEN, Japan
( The Institute of Physical and Chemical Research )
• Overview of the planned experiment• Recent development on co-magnetometer beam
electron EDM
PRA50,2960(1994)
upper limit at present
|de| < 1.6×10-27 ecm Berkeley group 205Tl ground state 6 2 P1/2 ( F=1)
Tl: enhancement factor –585 (Z=81)PRL88,071805(2002)
Electric Dipole Moment
P-odd T-odd
Atomic EDM
PRA50,2960(1994)
e EDM Enhancement factor: dA /de ~ O (Z3α2) inner core region : relativistic motion a strong mixing between opposite-parity states
2 types of atomic EDM paramagnetic atom ← electron EDM diamagnetic atom ← nuclear Schiff moment ← quark chromo-EDM and θQCD
Direction of Electric Field in beam experiment
205Tl-exp. : E ⊥ v requirement: counter-propagating beams
Motional magnetism
v×E rotation
E // v preferable
voltage accumulation
E // v difficult to apply
Accumulation of EDM spin precessionin spatially alternating electric field
Accumulative EDM precessions in
Canceling Voltages
l o n g i t u d i n a l v i e w
F
π - f l i p
E D Mp r e c e s s i o n
F
v
E Bπ - f l i p
A t o m
H V
G N D
Spin rotates in each electrode by 180degrees with static magnetic field.
Longitudinal E-field
exact matching
mismatching
alternatingπ-flips
one-wayπ-flips
BADGOOD
v
EBπ
Small velocity-dependence of the sensitivityto the EDM spin precession
Rotation angle is velocity-dependent.EDM spin precession accumulates when the directions of the magnetic field are also alternating.
elapsed time(relative)
-0.01
-0.005
0
0.005
0.01
0.015
0.02
0.9 0.95 1 1.05 1.1
B_add 1radB_add 0.1radB_add 0.01radB_add 0.001rad
y-component of the polarization
Elapsed time factor
0
0.2
0.4
0.6
0.8
1
1.2
0.9 0.95 1 1.05 1.1
deriv. B_add 1radderiv. B_add 0.1radderiv. B_add 0.01radderiv. B_add 0.001rad
derivative to the EDM precession
Elapesed time factor
Sideward component
Derivative to the EDM precession
Advantages to use 220Fr
F
μd
BE AA
ω
The heaviest alkali atom, Z=87
Large enhancement from e EDM
dFr /de ~ 1×103
F=1/2 hyperfine structure valence electron 7s1/2 + nuclear spin I=1
spin precession
Sufficiently long lifetime τ=39.2 sec (T1/2 =27.2sec)
RIBF(RIKEN) production rate > 5×106 /sec
Neutralization areaDipole Magnet, RF cavity
RI
Electrodes Glass nozzle
Stopping chamber
Detector(QMS)
Yttrium
Spin Selection (1st)Hexapole Magnet
Spin Selection (2nd)Quadrupole Magnet
RIABR ( Radio Isotope Atomic Beam Resonance )
for other experiments requiringhigh nuclear polarization
production: slow neutral RI beam
applicable to Francium
Atomic excitation
m F
7 s 1 / 2
7 p 1 / 2
D 1 l i n e= 8 1 7 n mλ
F = 1 / 2
F = 3 / 2
F = 3 / 2
F = 1 / 2
2 2 0 F r
- 1 / 2+ 1 / 2
- 1 / 2+ 1 / 2+ 3 / 2
- 3 / 2
- 1 / 2+ 1 / 2
- 1 / 2+ 1 / 2+ 3 / 2
- 3 / 2
unpo
l.
σ+
- 3 5 0 0 0
- 3 0 0 0 0
- 2 5 0 0 0
- 2 0 0 0 0
- 1 5 0 0 0
- 1 0 0 0 0
- 5 0 0 0
0
7 s
8 s
9 s
1 0 s
7 p 1 / 2
8 p 1 / 2
9 p 1 / 2
7 p 3 / 2
8 p 3 / 2
9 p 3 / 2
6 d 3 / 2
7 d 3 / 2
8 d 3 / 2
6 d 5 / 2
7 d 5 / 2
8 d 5 / 2
5 f
6 f
C a lc u la te d b y D z u b a P h y s .L e t t .A 9 5 ,2 3 0 (1 9 8 3 )e t a l .
F r a n c i u m
Ene
rgy
leve
l[cm
]-1
i o n i z a t i o n e n e r g y 4 . 0 7 e V( 2 n d s m a l l e s t o f a l l t h e a t o m s )
Francium D1 line: transition between 7s1/2 and 7p1/2 states (λ= 817nm)
Rn-like closed shell + 1 valence electron
Optical Pumping
mF = +1/2 : stable mF = -1/2 : unstable → fluorescence
7s1/2 F=1/2 states
D1: 817nm
D2: 718nm
D2 line: used for atomic cooling transition between 7s1/2 and 7p3/2 states (λ= 718nm)
Slow Alkali Beams
saturation intensity (Fr D2-line)
22
30
0 mW/cm 67.2 π12
ω
cI
Na
PRA55,605(1997)
Na
to reduce transverse momentum
2 -D Optical Molasses Doppler Limit 8.3cm/s
or sub-Doppler cooling as required
Longer time for EDM precession
Zeeman technique
6Li co-magnetometerStable alkali with nuclear spin I=1
thermal atomic beam: available
similar configuration of angular momentum
Atomic magnetic moment: close to 220Fr
relative difference: O(10-3)
Negligible EDM dLi /dFr ~ 4×10-6
trajectory combination onto 220Fr-path
thermal Li-beam source
Ext.Cav. Diode Laser systemsystem
Deceleration of 6Li beam with Zeeman slower method
thermal 6Li atomic beamlow-velocity component: too tiny a portion….
7.0E-4
0.0E+0
1.0E-4
2.0E-4
3.0E-4
4.0E-4
5.0E-4
6.0E-4
30000 500 1000 1500 2000 2500
Velocity Distibution
300℃400℃500℃
Velocity[m/s]Deceleration is Required!
Head-on collisions with photons
a deceleration with a single laser
position
resonance with applied magnetic field
atoms entering with high velocity
atoms entering with low velocity
Basic concept of the deceleration
cancellation
Doppler shift ⇔ Zeeman shift
Momentum transfer with photon
cycling transition for deceleration D2 line (2s1/2→ 2p3/2) 671.0nm (446.8THz, 1.848eV)
(F, F’) = (3/2, 5/2) circular polarizationAlthough hyperfine transitions, (F, F’) = (3/2, * ) are irresolvable,circular polarization allows only (3/2, 5/2) for successive transitions.
Momentum : 1.87×104eV/cDoppler shift : 1.49GHzCompensating field : 0.1065T (for v=1000m/s)
successive scatterings of ~104 photons
Radiative lifetime (2p3/2) 26.9ns
1 - p h o t o n m o m e n t u m1 . 8 4 8 e V / c0 . 0 9 9 m / s
l a s e rb e a m
F l u o r e s c e n c e( r a n d o m d i r e c t i o n )
F l u o r e s c e n tr e c o i l
L a s e r a b s o r p t i o n
r e c o i l o ni n d u c e d e m i s s i o n
6 L i a t o m
A t o m i cm o m e n t u m
6Li Deceleration RateLight absorption and scattering rate
20
0
]/)(2[1
2/
D
p s
s
22
30
0 mW/cm 56.2 π12
ω ,
limit) capture 3.97m/s (equiv. MHz92.5π2
shiftDoppler :
included)shift (Zeeman
resonance from detuninglaser :
cIIIs ss
D
01 FWHM sΓ power-broadened line width
0
1 107
2 107
3 107
4 107
480 490 500 510 520
sat. fact 1sat. fact 3sat. fact 10sat. fact 30
Ph
oton
Sca
tter
ing
Rat
e[s-1
]velocity [m/s]
Bz = 5.33 x 10-2 T
260max sm1084.1
2
Mca
maximum deceleration (s0→∞)
field, gradient and laser power 1
22
0
2
0
0
0max 1/mT 10085.2
1
dzdB
Bs
cs
sa
dz
dBB
B
This condition should NOT be satisfied at the exit.
220Fr 7.57MHz, 5.44m/s2.67mW/cm2
220Fr 6.01×104m/s2
220Fr 5.952×10-4 T2 / m
magnet
Profile coil: field gradientBias coil: uniform shift Extraction coils: sudden drop
6Li beamentrance
6Li beamexit
inhomogeneoussolenoids
MAX 0.12T
MAX 0.01T MAX 0.02T
Example of parameter setting
929m/s→ 200m/s 6 L i a t o m L a s e r
additional slowering as required
Summary
Electron EDM measurment w/ spatially alternating electric fieldLongitudinal electric field to reduce v×E systematics Spatially alternating longitudinal electric field avoids potential accumulation. π-flip at each boundary accumulationEffect of velocity spread is minimized by alternating π-flips.Fr atomic beam, RIABR, Zeeman slowering, …Deceleration of 6Li co-magnetometer beam design and construction
Francium the heaviest alkali atomaccelerator prduction requiredLargest enehancement ( ~1000 )
PRA50,2960(1994)
Alkali•Low excitation enerygy•Small saturation intensity ~ 3mW/cm2
•Polarization or atomic cooling
220Fr 7s1/2 (F=1/2)
Maximum EDM spin rotation224,226Fr: same spin, but small production rates
6Li : spin analogue negligible EDM
“Spin Echo”-like Method tough against velocity mismatching
exact matching
mismatching
alternatingπ-flips
one-wayπ-flips
BADGOOD
Magnitude of the Spin-Flip field
Lande-factor
1,0,
3
2
)1(2
)1()1()1(
2)1(2
)1()1()1(1
21
ILFSJ
FF
IIJJFFgg
JJ
LLSSJJg
JF
J
MHz/gauss87.12
32
F
B
Rotation frequency in magnetic field
passage time in spin-flip field
s10250m/s
m10
v4-
2
atom
flipL
Magnitude of the Spin-Flip field
gauss1036.1s)102(MHz/gauss)87.1(2
1 3-4-
1eV⇔241.80THz10-19eV ⇔24μHz