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Development of Cold Neutron
Interferometer
with Wide-Gapped “BSE”s
for Precision Measurements
Y. Seki (Kyoto Univ. / RIKEN )
(京大理・関 義親)
K. Taketani (Kyoto Univ.)
H. Funahashi (Osaka Electro-Communication Univ.)
M. Kitaguchi, M. Hino (KURRI)
Y. Otake (RIKEN)
H. M. Shimizu (KEK)
SPIN2006 @ 京都
Y. Seki et al.
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Neutron Interferometer and Phase
Large dimensional cold-neutron interferometers are more sensitive
to small interactions than conventional ones.
path 1
l
phase
difference
V1
L
m : neutron mass l : neutron wavelength
h : Planck constant L : interaction path length
DV = V1 – V2
V2
path 2
small DV g enlarge l and L
cold-neutron interferometer
using multilayer mirrors
conventional neutron interferometer
(Si crystal, thermal neutron)
l ～ 10-100Å
L ～ 1m
l～ 2Å < 6Å
L ～ 10cm
DV ～ 1feV
Y. Seki et al.
SPIN2006 @ 京都
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Aharonov-Casher Effect
Our neutron interferometers with completely spatially separated
two paths are suitable to measure topological AC effect.
B
m
E
AC effect
e‐
AB effect
past experiments
• Si neutron interferometer
(A.Cimmino et al., Phys.Rev. Lett., 63 380 (1989))
→topological but poor precision The observed phase is nearly 2s above the
theoretical value.
• atom interferometer
( K.Zeiske et al., App.Phys. B60., 63 205 (1995))
→high precision but nontopological (particles do not go around the charge density.)
Y. Seki et al.
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Development
of Large
Cold-Neutron Interferometer
Enlargement
of theDimensional
spatial
separation between two paths
past
multilayer mirror + etalon → “BSE”
Jamin-type
cold-neutron spin interferometer
with 10mm gapped BSEs
→ interference fringes of 60% contrast
gap
Investigation of
phase resolution of
neutron spin
interferometry
measurement of small phase
shift induced by the magnetic
field of a helmholtz coil
→51.9±1.7mrad
now
development of
Jamin-type
cold-neutron spin interferometer
with 200mm gapped BSEs
pilot experiment of nontopological
Aharonov-Casher phase
～5mrad
Why do we want
to enlarge the gap?
future
Y. Seki et al.
How precise
can we determine
the phase shift?
precision measurement of small interaction
ex. topological AC phase,
gravitationally induced phase…
SPIN2006 @ 京都
4
Development
of Large
Cold-Neutron Interferometer
Enlargement
of theDimensional
spatial
separation between two paths
past
multilayer mirror + etalon → “BSE”
Jamin-type
cold-neutron spin interferometer
with 10mm gapped BSEs
→ interference fringes of 60% contrast
gap
Investigation of
phase resolution of
neutron spin
interferometry
measurement of small phase
shift induced by the magnetic
field of a helmholtz coil
→51.9±1.7mrad
now
development of
Jamin-type
cold-neutron spin interferometer
with 200mm gapped BSEs
pilot experiment of nontopological
Aharonov-Casher phase
～5mrad
Why do we want
to enlarge the gap?
future
Y. Seki et al.
How precise
can we determine
the phase shift?
precision measurement of small interaction
ex. topological AC phase,
gravitationally induced phase…
SPIN2006 @ 京都
4
Pilot Experiment -Nontopological AC Phase
We measured the nontopological AC phase in atom interferometer
–like setup to demonstrate the phase detectability in our facility.
Setup
polarizer
slit
JRR-3M MINE2 beamline
l = 8.8Å, Dl/l = 2.7% (FWHM)
electrode
p/2
E1
・ NSI without BSEs
・ |E1| = |E2| = 33.5kV/cm
(111.7 statV / cm)
・ L = 20cm
electrode
E2
・ Phase difference generated between E1 and E2
was observed.
slit
p
p/2
detector
analyzer
= 5.46mrad (theoretically)
DV = 4.04feV!
Y. Seki et al.
SPIN2006 @ 京都
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Data and Analysis
counts / 40sec
We obtained the phase shifts from the interference fringes.
E1
E2
(initial) phase [rad]
parameter of phase shifter
To determine initial phase f0 of fringes,
sin function was fitted.
precision of each phase ～7.4mrad．
E1
E2
run number
SPIN2006 @ 京都
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Analysis
We could detected the small phase shift ～5mrad with 38%
precision in 1 week on MINE2 beamline.
(initial) phase [rad]
on
off
= 3.5±2.1mrad
～±1/3000cycle
E1
E2
= 5.46mrad
run number
phase shift [rad]
on
Y.phase
Seki et
al.[rad]
shift
Null
experiment
(E1 = E2 = 0)
total counts
on : 2.0×106n
off : 1.6×106n
in 1 week
SPIN2006 @ 京都
off
phase shift [rad]
7
Development
of Large
Cold-Neutron Interferometer
Enlargement
of theDimensional
spatial
separation between two paths
past
multilayer mirror + etalon → “BSE”
Jamin-type
cold-neutron spin interferometer
with 10mm gapped BSEs
→ interference fringes of 60% contrast
gap
Investigation of
phase resolution of
neutron spin
interferometry
measurement of small phase
shift induced by the magnetic
field of a helmholtz coil
→51.9±1.7mrad
now
development of
Jamin-type
cold-neutron spin interferometer
with 200mm gapped BSEs
pilot experiment of nontopological
Aharonov-Casher phase
～5mrad
Why do we want
to enlarge the gap?
future
Y. Seki et al.
How precise
can we determine
the phase shift?
precision measurement of small interaction
ex. topological AC phase,
gravitationally induced phase…
SPIN2006 @ 京都
Multilayer Neutron Mirror
Multilayer mirrors are artificial one-dimensional lattice which can
Bragg reflect cold neutrons.
normal multilayer mirror
potential
50～
200Å
two materials with different optical
potential
m: neutron mass
n: average number density
b: neutron scattering length of nucleus
magnetic multilayer mirror
selective reflection about spin
potential to up-spin
ferromagnetic
potential to down-spin
Ｂ
SPIN2006 @ 京都
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Requirements for mirror arrangement
In order to obtain the clear interference fringes we need to the
recombine the two beam in the coherent volume without the large
crossing angle.
degree of freedom of mirrors
recombination of the two subbeam
coherence length
q
moire fringe
50nm
(vertical)
g
dx
detectable
region
17nm
2μm
(horizontal)
coherence
volume
two mirrors
crossing angle
dx < 1.4mm
g < 8.4mrad
a pair of two mirrors
α
q < 4mrad
a < 40mrad
SPIN2006 @ 京都
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Beam Splitting Etalon (BSE)
BSEs satisfy the requirements for the two mirrors arrangement.
BSEs divide neutron beam into the two spin components.
The parallelism of two planes in a BSE ensures that the two
subbeam are also parallel to each other.
specifications of etalon
(within 32mm diameter)
flatness (λ/ 100)
parallelism λ/ 100 at λ = 633nm
roughness (RMS) less than 2Å
up-spin
normal
mirror
Y. Seki et al.
space
length
parallel
magnetic
mirror
SPIN2006 @ 京都
BSE
down-spin
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Jamin-type Neutron Spin Interferometer (NSI)
We succeeded in constructing a Jamin-type interferometer using
two BSEs with 10mm gap.
B_guide
BSE
polarizer
up-spin
phase shifter
coil
B
p
spin
flipper
p/2
spin
flipper
BSE
contrast of 60%
down-spin
Y. Seki et al.
SPIN2006 @ 京都
M.Kitaguchi et al.,
p/2 Phys. Rev. A67,
spin 033609 (2003)
flipper
analyzer
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Enlarging Gap of BSE
We
For have
experimental
confirmed
applications,
the beam separation
we have towith
enlarge
200mm
thegapped
gap of BSEs
BSEs.
from 10mm to 200mm and separate the beam completely .
B_guide
p/2
10mm
BSE
counts / 500sec
polarizer
300±30mm
(incident angle
1.05)
BSE
up-spin
phase shifter
coil
B
BSE
p
500mm
200mm
p/2
BSE
scanning position [mm]
down-spin
Y. Seki et al.
BSE
SPIN2006 @ 京都
analyzer
12
Enlarging Gap of BSE
The requirement for the two BSEs arrangement is achivable
enough .
BSE
BSE
a
relative angle
tilting angle
500mm
b
40
Y. Seki et al.
130
SPIN2006 @ 京都
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Summary and Future Plan
past
We develop
large-dimension
multilayer
neutron mirror +interferometers
etalon → “BSE” for long-wavelength
neutrons with wide gapped BSEs, which enable us to carry out
precision measurements of small interactions.
Jamin-type
cold-neutron spin interferometer
with 10mm gapped BSEs
→ interference fringes of 60% contrast
measurement of small phase
shift induced by the magnetic
field of a helmholtz coil
→51.9±1.7mrad
• We have confirmed the complete • We have demonstrated that small
now
beam separation.
phase shifts ～5mrad(DV～4feV) is
of
with of
thenontopological
precision of ～
• Wedevelopment
have established
the method to detectable
pilot
experiment
Jamin-type
1/3000
cycle in 1week
on MINE2.
estimate
alignment of two BSEs.
Aharonov-Casher
phase
cold-neutron spin interferometer
200mm gapped BSEs
nearwith
future
～5mrad
• Establishment of the interferogram of Jamin-type cold-neutron
interferometer with 200mm gapped BSEs.
future
precision measurement of small interaction
• Development of BSEs adapted to white beam with super mirrors.
ex. topological AC phase,
→ J-PARC spallation
neutron
source
(beam intensity : ×10 ～100)
gravitationally
induced
phase…
Y. Seki et al.
SPIN2006 @ 京都
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Jamin-type Neutron Spin Interferometer (NSI)
B
B_guide
=
polarizer
+
BSE
BSE
SPIN2006 @ 京都
ΔΦ
analyzer
Ｉ
p spin
flipper
p/2 spin
flipper
phase shifter
p/2 spin
B
flipper detector
multilayer
mirror
laminogram of
multilayer mirror
with transmission
electron
microscope
SPIN2006 @ 京都
Specifications of Beam Splitting Etalon
Ge / Pa
Ni / Ti
Φ = 54mm
effective diameter
（clear aperture）: 32mm
width : 12mm × 2
gap ： 189μm
Ni / Ti
magnetic
mirror
flatness : λ/ 100
parallelism : λ/ 100 at λ = 633nm
(in clear aperture)
normal
mirror
spacer
gap
manufactured by
SLS Optics (UK)
SPIN2006 @ 京都
MINE2 beamline on JRR-3M in JAEA
wavelengthλ = 0.88nm，
bandwidth 2.7% in FWHM
SPIN2006 @ 京都
measurement of
wavelength by TOF
Requirement for mirror arrangement
difference between two subbeam
coherence length
moire finge
detectable
region
17nm
crossing angle
2μm
(horizontal)
coherentce
volume
cause of difference
degree of freedom of two mirrors
→
degree of freedom of two BSEs
y
y
50nm
(vertical)
x
α
x
z
z
x
y
z
relative angle
SPIN2006 @ 京都
tilting
angle
β
220mm
Beam Operation by Solenoid
120mm
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Vertical Coherence Length
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Measurement of Relative Angle
between Two BESs
polarizer
detector
SPIN2006 @ 京都
Measurement of Tilting Angle
between Two BSEs
d
level laser
2θ
L
2θ = d / L
The tilt angle is adjusted with shims.
SPIN2006 @ 京都
θ
Adaptive Optical Devices
(Quadrupole magnet, Solenoid)
α relative
x
x
y
z
y
angle
↓
longitudinal
shift
z
Q
Q
z
220mm
y
x
112mm
tilting angle
↓
β
vertical shift
120mm
requirement for the arrangement of
two BSEs
112mm
SPIN2006 @ 京都
Beam Operation with Quadrupole Magnets
direction of magnetic gradient（G = 0.471Gauss/mm at 3A）
40.5nm at 3A
300mm
135nrad at 3A
112mm
correction
SPIN2006 @ 京都
parallel shift
crossing angle
112mm
as adaptive optical device…
correction
Precision Measurement of Gravitational Interaction
（beyond COW Experiment）
COW
experiment
λ：neutron wavelength
A ：space enclosed by two paths
θ：tilting angle of interferometer
S.A.Werner et al, Physica B 151(1988) 22
K.C.Littrell et al, Phys.Rev.A 56(1997) 1767
→Result of the COW experiment with a Si neutron interferometer had a
discrepancy of 0.8% with the theoretical value.
Disagreement with Newton approximation?
Our cold-neutron interferometer with multilayer mirrors is ten
times more sensitive to the phase shift than Si ones.
And they are also free from dynamical diffraction effect.
SPIN2006 @ 京都
Mach-Zehnder type Neutron Interferometer with
BSEs
30mm
BSE (solid etalon)
rigid base
500mm
• BSEs are arranged on a precisely flat (l/20) rigid base.
• Because the space enclosed by the two paths is large (20cm2),
this interferometer is suitable for measurement of gravitational
interaction.
SPIN2006 @ 京都
Precedent Measurement of AC Phase
Si neutron interferometer
atom interferometer
A.Cimmino et al., Phys.Rev. Lett., 63 380
(1989)
K.Zeiske et al., App.Phys. B60., 63 205 (1995)
high precision
but particle with a
magnetic moment
does not enclose the
charge distribution
(nontopological)
= 1.50mrad
= 2.19±0.52mrad
dynamical diffraction
effect
large dimengional cold-neutron interferometer with BSEs
• Interaction path length is longer (～1m) , so more sensitive to the phase
shifts
• Dynamical diffraction can be negligible.
• Path can be separated completely spatially (topological).
SPIN2006 @ 京都
Ｓｕｐｅｒ Ｍirror
Measurement of small phase shift
induced by magnetic field
polarizer
π/2
small magnetic field
～10.5mGauss
phase shifter
detector
π/2
analyzer
Helmholtz coil
off
on
1run： 1cycle 125sec × 9points
2巻
125mm
125mm
counts / 125sec
25k
0.03A: 34.6mrad～1/180 cycle
total 56run
～6million coutns
current of phase shiter[A]
SPIN2006 @ 京都
Measurement of small phase shift
induced by magnetic field
phase [rad] / 2p
coil ON
RMS ～
1/530cycle
precision of
mean value
～ 1/3800cycle
precision of
1run ×√2
～1/750cycle
coil OFF
phase shift [rad] / 2p
run number
Phase shift of 51.9 ±1.7mrad was
detected.
phase
ON
OFF
run number
We need total 256million counts
for the measurement of
AC phase with 10% precision.
SPIN2006 @ 京都
Pilot Experiment -Nontopological AC Phase
neutron spin interferometer without BSEs
B_guide
polarizer
up-spin
Helmholtz
coil
phase shift
BSE
phase
shifter
51.9 ±
1.7mrad
detected
coil
B
p/2
Bp
p/2
BSE
analyzer
down-spin
SPIN2006 @ 京都
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Analysis
We approximated the phase drifts by a quadratic function.
phase [rad] / 2p
Approximation of phase drift
E1
E2
phase
E1
E2
run number
run number
Null
experiment
(E1 = E2 = 0)
phase shift [rad] / 2p
total
E1 : 608 runs
E2 : 612 runs
SPIN2006 @ 京都
phase shift [rad] / 2p