SPIN2006 @ Y. Seki (Kyoto Univ. / RIKEN ) () K. Taketani (Kyoto Univ.) H. Funahashi (Osaka Electro-Communication Univ.) M. Kitaguchi, M. Hino (KURRI) Y. Otake (RIKEN) H. M. Shimizu (KEK)1/13Development of Cold Neutron Interferometer with Wide-Gapped BSEs for Precision MeasurementsY. Seki et al.

SPIN2006 @ Neutron Interferometer and Phasephase differencesmall DV g enlarge l and Lcold-neutron interferometer using multilayer mirrors conventional neutron interferometer (Si crystal, thermal neutron) 2 < 6 L 10cml 10-100 L 1mDV 1feV2Large dimensional cold-neutron interferometers are more sensitive to small interactions than conventional ones.m : neutron mass l : neutron wavelength h : Planck constant L : interaction path length DV = V1 V2Y. Seki et al.

SPIN2006 @ Aharonov-Casher Effectpast experiments Si neutron interferometer (A.Cimmino et al., Phys.Rev. Lett., 63 380 (1989)) topological but poor precision atom interferometer ( K.Zeiske et al., App.Phys. B60., 63 205 (1995)) high precision but nontopological (particles do not go around the charge density.)3Our neutron interferometers with completely spatially separated two paths are suitable to measure topological AC effect.The observed phase is nearly 2s above the theoretical value.Y. Seki et al.

SPIN2006 @ Development of Large Dimensional Cold-Neutron Interferometer 4pastnowmeasurement of small phase shift induced by the magnetic field of a helmholtz coil 51.91.7mrad development of Jamin-type cold-neutron spin interferometer with 200mm gapped BSEs futureprecision measurement of small interaction ex. topological AC phase, gravitationally induced phaseWhy do we want to enlarge the gap?How precise can we determine the phase shift? Investigation of phase resolution of neutron spin interferometryEnlargement of the spatial separation between two pathsY. Seki et al.

SPIN2006 @ 4Investigation of phase resolution of neutron spin interferometryEnlargement of the spatial separation between two pathsY. Seki et al.

SPIN2006 @ Pilot Experiment -Nontopological AC PhaseSetuppolarizerdetectoranalyzerp/2p/2pelectrodeelectrodeslitslitJRR-3M MINE2 beamline l = 8.8, Dl/l = 2.7% (FWHM) |E1| = |E2| = 33.5kV/cm (111.7 statV / cm) Phase difference generated between E1 and E2 was observed.5We measured the nontopological AC phase in atom interferometer like setup to demonstrate the phase detectability in our facility. NSI without BSEsE1E2 L = 20cm= 5.46mrad (theoretically)Y. Seki et al.DV = 4.04feV!

Data and AnalysisTo determine initial phase f0 of fringes, sin function was fitted.precision of each phase 7.4mrad6We obtained the phase shifts from the interference fringes.parameter of phase shifter counts / 40secSPIN2006 @ (initial) phase [rad] run number

Y. Seki et al.(initial) phase [rad] run numberAnalysis7phase shift [rad] Null experiment (E1 = E2 = 0)phase shift [rad] SPIN2006 @ total counts on : 2.0106n off : 1.6106n in 1 weekWe could detected the small phase shift 5mrad with 38% precision in 1 week on MINE2 beamline.onoff

SPIN2006 @ Investigation of phase resolution of neutron spin interferometryEnlargement of the spatial separation between two pathsY. Seki et al.

SPIN2006 @ Multilayer Neutron Mirrortwo materials with different optical potentialmagnetic multilayer mirrorferro-magnetic50200normal multilayer mirrorselective reflection about spinpotential8Multilayer mirrors are artificial one-dimensional lattice which can Bragg reflect cold neutrons.potential to up-spinpotential to down-spinm: neutron mass n: average number density b: neutron scattering length of nucleus

Requirements for mirror arrangementSPIN2006 @ 9In order to obtain the clear interference fringes we need to the recombine the two beam in the coherent volume without the large crossing angle.

SPIN2006 @ Beam Splitting Etalon (BSE)10specifications of etalon (within 32mm diameter)flatness (/ 100) parallelism / 100 at = 633nm roughness (RMS) less than 2magnetic mirrornormal mirrorspace lengthBSEBSEs 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.Y. Seki et al.

SPIN2006 @ Jamin-type Neutron Spin Interferometer (NSI)11We succeeded in constructing a Jamin-type interferometer using two BSEs with 10mm gap.M.Kitaguchi et al., Phys. Rev. A67, 033609 (2003)contrast of 60%Y. Seki et al.

Y. Seki et al.SPIN2006 @ Enlarging Gap of BSE12We have confirmed the beam separation with 200mm gapped BSEs.For experimental applications, we have to enlarge the gap of BSEs from 10mm to 200mm and separate the beam completely .

SPIN2006 @ Enlarging Gap of BSE12The requirement for the two BSEs arrangement is achivable enough .relative angletilting angleY. Seki et al.40130

SPIN2006 @ Summary and Future Plan13nowWe develop large-dimension interferometers for long-wavelength neutrons with wide gapped BSEs, which enable us to carry out precision measurements of small interactions.We have confirmed the complete beam separation.We have established the method to estimate alignment of two BSEs.We have demonstrated that small phase shifts 5mrad(DV4feV) is detectable with the precision of 1/3000 cycle in 1week on MINE2.near futureEstablishment of the interferogram of Jamin-type cold-neutron interferometer with 200mm gapped BSEs.Development of BSEs adapted to white beam with super mirrors. J-PARC spallation neutron source (beam intensity :10 100)Y. Seki et al.

polarizerBp/2 spin flipperBSEBSEphase shifteranalyzerp/2 spin flipperp spin flipperdetectorB_guideSPIN2006 @ Jamin-type Neutron Spin Interferometer (NSI)

multilayer mirrorSPIN2006 @ laminogram of multilayer mirror with transmission electron microscope

Specifications of Beam Splitting Etalonflatness : / 100 parallelism : / 100 at = 633nm (in clear aperture) = 54mmeffective diameter clear aperture: 32mm width : 12mm 2 gap 189mmanufactured by SLS Optics (UK)magnetic mirrornormal mirrorspacerNi / TiGe / PaNi / TiSPIN2006 @

MINE2 beamline on JRR-3M in JAEAwavelength = 0.88nmbandwidth2.7% in FWHMmeasurement of wavelength by TOFSPIN2006 @

Requirement for mirror arrangementdifference between two subbeamcoherence length2m17nm50nmcrossing anglecoherentcevolumedetectable regionmoire fingerelative angletilting angledegree of freedom of two mirrorsdegree of freedom of two BSEscause of difference(horizontal)(vertical) SPIN2006 @

120mm50mm220mmBeam Operation by SolenoidSPIN2006 @

Vertical Coherence LengthSPIN2006 @

Measurement of Relative Angle between Two BESsSPIN2006 @ polarizerdetector

Measurement of Tilting Angle between Two BSEslevel laserdL22= d / LThe tilt angle is adjusted with shims.SPIN2006 @

vertical shiftlongitudinal shiftrelative angletilting angle120mm50mm220mmrequirement for the arrangement of two BSEsSPIN2006 @ Adaptive Optical Devices (Quadrupole magnet, Solenoid)

112mm112mm50mmas adaptive optical deviceparallel shiftcorrectioncrossing anglecorrection135nrad at 3A300mm40.5nm at 3Adirection of magnetic gradientG = 0.471Gauss/mm at 3ABeam Operation with Quadrupole MagnetsSPIN2006 @

Precision Measurement of Gravitational Interaction beyond COW ExperimentCOW experimentneutron wavelengthA space enclosed by two pathstilting angle of interferometerS.A.Werner et al, Physica B 151(1988) 22K.C.Littrell et al, Phys.Rev.A 56(1997) 1767Result 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 @

Mach-Zehnder type Neutron Interferometer with BSEsBecause the space enclosed by the two paths is large (20cm2), this interferometer is suitable for measurement of gravitational interaction.BSE (solid etalon)rigid base500mm30mmBSEs are arranged on a precisely flat (l/20) rigid base.SPIN2006 @

Precedent Measurement of AC PhaseSi neutron interferometeratom interferometerA.Cimmino et al., Phys.Rev. Lett., 63 380 (1989)K.Zeiske et al., App.Phys. B60., 63 205 (1995)dynamical diffraction effectlarge dimengional cold-neutron interferometer with BSEsInteraction path length is longer (1m) , so more sensitive to the phase shiftsDynamical diffraction can be negligible.Path can be separated completely spatially (topological).SPIN2006 @ = 1.50mrad = 2.190.52mrad high precision but particle with a magnetic moment does not enclose the charge distribution (nontopological)

irror

Measurement of small phase shift induced by magnetic fieldpolarizer/2/2detectoranalyzerphase shifterHelmholtz coilsmall magnetic field 10.5mGauss0.03A: 34.6mrad1/180 cycle1run1cycle125sec 9points125mm125mm2counts / 125seccurrent of phase shiter[A]total 56run 6million coutnsoffon25kSPIN2006 @

Phase shift of 51.9 1.7mrad was detected.ONOFFprecision of 1run 2 1/750cycleRMS1/530cycleprecision of mean value 1/3800cyclephase shift [rad] / 2pcoil ONcoil OFFphase [rad] / 2prun numberphaserun numberSPIN2006 @ We need total 256million counts for the measurement of AC phase with 10% precision.Measurement of small phase shift induced by magnetic field

neutron spin interferometer without BSEsSPIN2006 @ B_guidep9Pilot Experiment -Nontopological AC Phase phase shift 51.9 1.7mrad detected

AnalysisApproximation of phase drift We approximated the phase drifts by a quadratic function.E1E2phaserun numberNull experiment (E1 = E2 = 0)phase shift [rad] / 2pSPIN2006 @ total E1 : 608 runs E2 : 612 runs

Thank you, Mr. Chairman.I will be talking about "Development of Cold Neutron Interferometer with Wide-Gapped BSEs for Precision Measurements".This is a schematic diagram of a neutron interferometer.The phase difference which is detected by the neutron interferometer is proportional to lambda : the neutron wavelength and el : interaction path length,in other word, the dimension of the interferometer.

Therefore, if we measure a small interaction Delta V,we have to enlarge lambda and large el,increasing the sensitivity.

In the case of conventional neutron interferometers for thearmal neutrons,made of silicon crystal,lambda is the order of 2 angstrom, and less than about 6 angstrom that is, twice the lattice constant.

On the other hand,in the case ofour novel interferometers for cold neutrons, consisted of multilayer mirrors, neutrons of wavelength from 10 to 100 angstrom are available,in addition,el can be about ten times Si interferometer.Thus, the sensitivity is the order of 1 feV.One of the experimental target is measurement of the AC effect.

The Aharonov-Casher effect is a dual of the Aharonov-Bohm effect.When a neutral particle with a magnetic moment encloses charge density,the topological phase shift like this is induced.

Past experiments with Si neutron interferometers or atom interferometersdid not demonstrate topological nature of this effect precisely.

We have to develop a neutron interferometer with completely separated beambecause measurements of topological AC phase requires electrodes between the two paths.

This is an outline of our development process.There are two approaches.One is to enlarge the spatial separation between two waves in the interferometer withwide gapped BSEs.The other is to investigate the phase resolution of the neutron spin interferometry.

Until now we have succeeded in developing a interferometer with 10 \mu gapped BSEs and demonstrated the phase sensitivity on our experimantal environment up to about 50mrad.

Now,for the purpose of the practical use,we widen the gap of BSE up to 200 \mu m.I will report the status of this development explaining why we want to enlarge the gap.

Then I will also talk about a pilot measurement of nontopolotical Aharonov-Casher effectwhich demonstrate the higher phase sensitivity.

In this presentation first Im going to mention the right subject and then left oneshowing why we want to enlarge the gaphow precise we can determine the phase shifts.This is an outline of our development process.There are two approaches.One is to enlarge the spatial separation between two waves in the interferometer withwide gapped BSEs.The other is to investigate the phase resolution of the neutron spin interferometry.

Until now we have succeeded in developing a interferometer with 10 \mu gapped BSEs and demonstrated the phase sensitivity on our experimantal environment up to about 50mrad.

Now,for the purpose of the practical use,we widen the gap of BSE up to 200 \mu m.I will report the status of this development explaining why we want to enlarge the gap.

Then I will also talk about a pilot measurement of nontopolotical Aharonov-Casher effectwhich demonstrate the higher phase sensitivity.

In this presentation first Im going to mention the right subject and then left oneshowing why we want to enlarge the gaphow precise we can determine the phase shifts.Before precision measurements of the topological AC phasewe measured the nontopological AC phase in atom interferometer-like setup.in which the beam was not separated in the real-space but in the spin-space.

The aim of this pilot study is to demonstrate the sensitivity in our facility to very small phase shifts about 5mrad.

The experiment was carried out at cold-neutron beamline MINE2 on JRR-3M reactor in JAEA, The beam had a wavelength of 88nm and a bandwidth of 2.7% in FWHM.

Same two electrodes generating electric field of 33.5 kV/cm were installed in the interferometer.We could select the direction of electric field E_1 or E_2.which had the same magnitude.

Because the Aharonov-Casher phases depend on the direction of electric field,E_1 and E_2 cause the phase shift of opposite sign to each other.

We measured the phase difference between E_1 and E_2which was theoretically 5.46mrad, about a tenth of the magnetic induced phase.

We measured the phase shift from the shift of interference fringes, that is, the shift of intial phases.First We observed a interference fringe of the beam passing through E_1 by operating the phase shifter.Next we observed a fringe of the beam passing through E_2 and repeated this procedure alternating the electric field.Then,we had the phase of these fringes by fitting sin function to them.These phases were filled in a histogram and fitted by a Gaussian.We decided the mean value.

We also carried out a null experiment in which electrodes were off,and similarly decided the mean value.

In total,608 runs of E_1 and 612runs of E_2 were obtaind in 1 week.

From the difference between two mean values,we obtained the nontopological AC phase of 3.5 \pm 2.1mrad.This is an outline of our development process.There are two approaches.One is to enlarge the spatial separation between two waves in the interferometer withwide gapped BSEs.The other is to investigate the phase resolution of the neutron spin interferometry.

Until now we have succeeded in developing a interferometer with 10 \mu gapped BSEs and demonstrated the phase sensitivity on our experimantal environment up to about 50mrad.

Now,for the purpose of the practical use,we widen the gap of BSE up to 200 \mu m.I will report the status of this development explaining why we want to enlarge the gap.

Then I will also talk about a pilot measurement of nontopolotical Aharonov-Casher effectwhich demonstrate the higher phase sensitivity.

In this presentation first Im going to mention the right subject and then left oneshowing why we want to enlarge the gaphow precise we can determine the phase shifts.Now,I will be explaining the multilayer neutron mirrors.

The Multilayer is the very useful and basic device in the cold neutron optics.Because its two materials have different optical potentials for neutronsand are layered alternately,it can reflect neutrons by Bragg reflection as one-dimensional crystal .

Furthermore,when one of the two materials is ferromagneticin the magnetic field,the mirror can reflect neutrons selectively as to the spin direction.It is called magnetic multilayer mirror.And then,these mirrors are coated on parallel planes of an elalon, as shown here.We call this neutron optical device Beam Spilitting Etalon, for short, "BSE".The etalon is an optical device, usually used in laser optics.It provides us precisely paralell, flat and smooth planes, as listed here.

In our case,the normal mirror is coated on one plane,and the magnetic mirror on the other plane.Therefore,the BSE divides neutron beam spatially into two spin components,and ensure that the two beam are also parallel to each other.By using two BSEs,We can construct a Jamin-type neutron spin interferometer like this.In particular, by using 10 \mu m gapped BSEs we have observed the interference fringes with the contrast of 60%.

However,considering the beam width,the two beam are almost overlapped actually.

From a practical viewpoint,we have to enlarge the gap of the BSE to 200 \mu m and separate the beam completely spatially.With the large separation, we can insert some devices between paths of the interferometer.

We have already confirmed the beam separation with the 200 \mu m gapped BSEs byscanning the beam profile between the two BSEs.And now we adjust the alignment of the BSEs.However,considering the beam width,the two beam are almost overlapped actually.

From a practical viewpoint,we have to enlarge the gap of the BSE to 200 \mu m and separate the beam completely spatially.With the large separation, we can insert some devices between paths of the interferometer.

We have already confirmed the beam separation with the 200 \mu m gapped BSEs byscanning the beam profile between the two BSEs.And now we adjust the alignment of the BSEs.Now, let me summarize my talk.We have confirmed the complete beam separation.We have established the method to estimate alignment of two BSEs.We have demonstrated that small phase shifts 5mrad is detectable in 1week on MINE2.

However,for more precise measurements,high beam intensity is necessary.

So,We are developing new BSEs adapted to white beam with super mirrorson the assumption that they are used in high intensity beamline on J-PARC.

Of course,we also have to establish the cold-neutron interferometry with large gapped BSEs.

Thank you.

"without BSEs" means thatthe beam was not separated in the real-space but in the spin-space.

With this interferomter We already demonstrated that phase shifts of about 50mrad induced by small magnetic field of helmholtz coilcould be determined with 3% precision.Then we had to determine the phase differences between E_1 and E_2.However,as you see,observed phases drifted with time.

For the purpose of decreasing the effect of the drift,we approximated the drift of three successive phases on the same electric field by a quadratic function,that is,we obtained the phases difference between the estimated phase from a quadradratic curve and its counterpart.

These phases were filled in a histogram and fitted by a Gaussian.We decided the mean value.

We also carried out a null experiment in which electrodes were off,and similarly decided the mean value.

In total,608 runs of E_1 and 612runs of E_2 were obtaind in 1 week.