SPIN2006 @ 京都

1. 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 1/13 Y. Seki et al.

2. Neutron Interferometer and Phase path 1 V1 l V2 path 2 L Large dimensional cold-neutron interferometers are more sensitive to small interactions than conventional ones. phase difference m : neutron mass l : neutron wavelengthh : Planck constant L : interaction path lengthDV = V1 – V2 small DVg enlarge land L cold-neutron interferometerusing multilayer mirrors conventional neutron interferometer(Si crystal, thermal neutron) • ～ 2Å < 6ÅL ～ 10cm l～ 10-100ÅL～ 1m DV ～ 1feV SPIN2006 @ 京都 2 Y. Seki et al.

3. Aharonov-Casher Effect B e‐ m E AC effect AB effect Our neutron interferometers with completely spatially separated two paths are suitable to measure topological AC effect. past experiments • Si neutron interferometer(A.Cimmino etal., 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.) The observed phase is nearly 2s above the theoretical value. SPIN2006 @ 京都 3 Y. Seki et al.

4. Development of Large Dimensional Cold-Neutron Interferometer gap multilayer mirror + etalon → “BSE” Jamin-type cold-neutron spin interferometerwith 10mm gapped BSEs → interference fringes of 60% contrast pilot experiment of nontopological Aharonov-Casher phase ～5mrad Enlargement of the spatial separation between two paths Investigation of phase resolution of neutron spin interferometry past measurement of small phase shift induced by the magnetic field of a helmholtz coil →51.9±1.7mrad now development ofJamin-type cold-neutron spin interferometerwith 200mm gapped BSEs How precise can we determine the phase shift? Why do we want to enlarge the gap? future precision measurement of small interactionex. topological AC phase, gravitationally induced phase… SPIN2006 @ 京都 4 Y. Seki et al.

5. Development of Large Dimensional Cold-Neutron Interferometer past gap multilayer mirror + etalon → “BSE” Jamin-type cold-neutron spin interferometerwith 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 now development ofJamin-type cold-neutron spin interferometerwith 200mm gapped BSEs How precise can we determine the phase shift? Why do we want to enlarge the gap? pilot experiment of nontopological Aharonov-Casher phase ～5mrad future precision measurement of small interactionex. topological AC phase, gravitationally induced phase… Enlargement of the spatial separation between two paths Investigation of phase resolution of neutron spin interferometry SPIN2006 @ 京都 4 Y. Seki et al.

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

7. Data and Analysis E2 E1 E1E2 We obtained the phase shifts from the interference fringes. counts / 40sec parameter of phase shifter To determine initial phase f0 of fringes, sin function was fitted. precision of each phase ～7.4mrad． (initial) phase [rad] SPIN2006 @ 京都 6 run number

8. Analysis on = 3.5±2.1mrad off ～±1/3000cycle E1E2 = 5.46mrad phase shift [rad] We could detected the small phase shift ～5mrad with 38% precision in 1 week on MINE2 beamline. (initial) phase [rad] run number Null experiment(E1 = E2 = 0) on off total countson : 2.0×106noff : 1.6×106nin 1 week SPIN2006 @ 京都 7 Y. Seki et al. phase shift [rad] phase shift [rad]

9. Development of Large Dimensional Cold-Neutron Interferometer past gap multilayer mirror + etalon → “BSE” Jamin-type cold-neutron spin interferometerwith 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 now development ofJamin-type cold-neutron spin interferometerwith 200mm gapped BSEs How precise can we determine the phase shift? Why do we want to enlarge the gap? pilot experiment of nontopological Aharonov-Casher phase ～5mrad future precision measurement of small interactionex. topological AC phase, gravitationally induced phase… Enlargement of the spatial separation between two paths Investigation of phase resolution of neutron spin interferometry SPIN2006 @ 京都 Y. Seki et al.

10. Multilayer Neutron Mirror Multilayer mirrors are artificial one-dimensional lattice which can Bragg reflect cold neutrons. normal multilayer mirror two materials with different optical potential potential 50～200Å m: neutron massn: average number densityb: neutron scattering length of nucleus magnetic multilayer mirror selective reflection about spin potential to up-spin ferro-magnetic potential to down-spin Ｂ SPIN2006 @ 京都 8

11. Requirements for mirror arrangement degree of freedom of mirrors recombination of the two subbeam two mirrors coherence length crossing angle g dx coherencevolume 2μm detectable region (horizontal) q moire fringe g < 8.4mrad dx < 1.4mm 17nm a pair of two mirrors 50nm α (vertical) q < 4mrad a < 40mrad 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. SPIN2006 @ 京都 9

12. Beam Splitting Etalon (BSE) up-spin parallel parallel down-spin 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 = 633nmroughness (RMS) less than 2Å magneticmirror space length normalmirror BSE SPIN2006 @ 京都 10 Y. Seki et al.

13. Jamin-type Neutron Spin Interferometer (NSI) B_guide BSE polarizer phase shifter coil up-spin B pspinflipper p/2spin flipper p/2spinflipper BSE analyzer down-spin We 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% SPIN2006 @ 京都 11 Y. Seki et al.

14. Enlarging Gap of BSE BSE BSE B_guide BSE 300±30mm (incident angle 1.05) polarizer phase shifter coil up-spin B 500mm counts / 500sec p/2 p p/2 200mm BSE 10mm analyzer down-spin scanning position [mm] BSE BSE We 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 @ 京都 12 Y. Seki et al.

15. Enlarging Gap of BSE BSE BSE 500mm a b The requirement for the two BSEs arrangement is achivable enough . tilting angle relative angle 40 130 SPIN2006 @ 京都 12 Y. Seki et al.

16. Summary and Future Plan past multilayer neutron mirror + etalon → “BSE” Jamin-type cold-neutron spin interferometerwith 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 development ofJamin-type cold-neutron spin interferometerwith 200mm gapped BSEs pilot experiment of nontopological Aharonov-Casher phase ～5mrad future precision measurement of small interactionex. topological AC phase, gravitationally induced phase… We 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(DV～4feV) is detectable with the precision of ～1/3000 cycle in 1week on MINE2. now near future • Establishment 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) SPIN2006 @ 京都 13 Y. Seki et al.

18. B = + Ｉ ΔΦ Jamin-type Neutron Spin Interferometer (NSI) B_guide BSE polarizer phase shifter p/2 spin flipper B p spin flipper p/2 spin flipper detector BSE analyzer SPIN2006 @ 京都

19. multilayer mirror laminogram of multilayer mirrorwith transmission electron microscope SPIN2006 @ 京都

20. gap Specifications of Beam Splitting Etalon Ge / Pa Ni / Ti Φ = 54mm Ni / Ti effective diameter（clear aperture）: 32mmwidth : 12mm ×2gap ： 189μm magneticmirror normal mirror flatness : λ/ 100parallelism : λ/ 100 at λ = 633nm(in clear aperture) spacer manufactured by SLS Optics (UK) SPIN2006 @ 京都

21. MINE2 beamline on JRR-3M in JAEA measurement of wavelength by TOF wavelengthλ = 0.88nm， bandwidth2.7% in FWHM SPIN2006 @ 京都

22. x z y y x z y z x Requirement for mirror arrangement difference between two subbeam cause of difference degree of freedom of two mirrors crossing angle coherence length coherentcevolume detectable region 2μm (horizontal) moire finge → 17nm degree of freedom of two BSEs 50nm α (vertical) β tilting angle relative angle SPIN2006 @ 京都

23. Beam Operation by Solenoid 220mm 50mm 120mm SPIN2006 @ 京都

24. Vertical Coherence Length SPIN2006 @ 京都

25. Measurement of Relative Angle between Two BESs polarizer detector SPIN2006 @ 京都

26. Measurement of Tilting Angle between Two BSEs BSE θ d level laser 2θ L 2θ= d / L The tilt angle is adjusted with shims. SPIN2006 @ 京都

27. Adaptive Optical Devices (Quadrupole magnet, Solenoid) α Q x Q y z y x x z z y S 112mm N N S 50mm 112mm relative angle ↓ longitudinal shift 220mm 50mm β 120mm tilting angle requirement for the arrangement of two BSEs ↓ vertical shift SPIN2006 @ 京都

28. S N N S Beam Operation with Quadrupole Magnets direction of magnetic gradient（G = 0.471Gauss/mm at 3A） 40.5nm at 3A 300mm 135nrad at 3A as adaptive optical device… correction 112mm correction parallel shift crossing angle 50mm SPIN2006 @ 京都 112mm

29. 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

30. 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

31. Precedent Measurement of AC Phase Si neutron interferometer atom interferometer K.Zeiske et al., App.Phys. B60., 63 205 (1995) A.Cimmino et al., Phys.Rev. Lett., 63 380 (1989) 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

32. Ｓｕｐｅｒ　Ｍirror

33. Measurement of small phase shift induced by magnetic field small magnetic field～10.5mGauss polarizer π/2 detector phase shifter π/2 analyzer Helmholtz coil off on 1run：　1cycle125sec ×9points 2巻 25k total 56run～6million coutns counts / 125sec 125mm 125mm 0.03A: 34.6mrad～1/180 cycle current of phase shiter[A] SPIN2006 @ 京都

34. Measurement of small phase shift induced by magnetic field precision of mean value～ 1/3800cycle coil ON RMS　～1/530cycle phase [rad] / 2p precision of 1run ×√2～1/750cycle coil OFF phase shift [rad] / 2p run number ON Phase shift of 51.9 ±1.7mrad was detected. phase We need total 256million counts for the measurement ofAC phase with 10% precision. OFF run number SPIN2006 @ 京都

35. Pilot Experiment -Nontopological AC Phase BSE polarizer phase shifter coil up-spin Helmholtzcoil B p/2 B p/2 BSE analyzer down-spin neutron spin interferometer without BSEs B_guide phase shift51.9 ± 1.7mrad detected p SPIN2006 @ 京都 9

36. Analysis phase [rad] / 2p E1E2 run number phase shift [rad] / 2p We approximated the phase drifts by a quadratic function. Approximation of phase drift E1 phase E2 run number Null experiment(E1 = E2 = 0) totalE1 : 608 runsE2 : 612 runs SPIN2006 @ 京都 phase shift [rad] / 2p