We are developing an active shield for the measurement of neutron electric dipole moment using ultracold neutron. The disturbing geomagnetism and environmental magnetic fields are cancelled by the active shield. We introduced proportional-integral-differential control to the feedback loop of the system to improve the performance of the active shield. A quadrupole-coil arrangement was adopted to control the diagonal components of the field gradient. The influence of magnetic shielding inside the active shield was studied. It was found that this effect caused no critical problems in the detection of zero-field conditions.

Automatic compensation system for the environmental magnetic field has been developed for the neutron electric dipole moment (n-EDM) measurement using ultra-cold neutrons (UCN). In the test experiment, a magnetic field of ~ 40 μT including geomagnetism with the field gradient of ~ − 9 μT/m was successfully suppressed. The suppression factors were consistent with the feed-back gains. Our goal is to achieve a suppression by a factor of 103, necessary for the n-EDM measurement of the order of 10−27 ecm.

A neutron EDM measurement by means of a He-II spallation UCN source is discussed.For an improvement in the statistical error, a proton beam power is increased up to 20 kW so that a UCN density in an EDM measurement cell becomes 800 UCN/cm 3 .The  heating in a He-II bottle is removed by using a 3 He cryostat.Polarized UCN are extracted from the He-II bottle through an aluminum window by using a superconducting magnet for Ramsey resonance in the EDM cell.For an improvement in the systematic error, 129 Xe nuclear spins are used for magnetic field monitoring in the EDM cell.A geometric phase effect is suppressed by a buffer gas effect.

A new superthermal UCN production in He-II, which is placed in a spallation neutron source, is discussed. In the new UCN source, the production rate is expected to be 200 UCN/cm3/s at a proton beam power of 500 MeV×40μA and the UCN maximum energy of Ec = 210 neV. The γ heating in the He-II can be removed by means of 3He pumping according to calculations. For an EDM measurement, UCN are extracted from a He-II bottle through an aluminum window by using a superconducting magnet. The possibility of a 129Xe magnetometer for the EDM measurement is also discussed.

A neutron EDM measurement with a comagnetometer is discussed. For magnetometry, polarized xenon atoms are injected into a cylindrical cell where a cylindrically symmetric magnetic field and an electric field are applied for the EDM measurement. The geometric phase effect (GPE), which originates from particle motion in a magnetic field gradient, is analyzed in terms of the Dyson series. The motion of the xenon atom is largely suppressed because of a small mean free path. The field gradient is controlled by means of NMR measurements, where the false effect of Earth's rotation is removed. As a result, the GPE is reduced below 10(-28)e cm. (C) 2012 Elsevier B.V. All rights reserved.

For the production of high-density ultracold neutrons (UCNs), we placed 0.8 K superfluid helium in a cold neutron moderator. We resolved previous heat-load problems in the spallation neutron source that were particularly serious below 1 K. With a proton-beam power of 400 MeV×1 μA, a UCN production rate of 4 UCN cm(-3) s(-1) at the maximum UCN energy of E(c)=210 neV and a storage lifetime of 81 s were obtained. A cryogenic test showed that the production rate can be increased by a factor of 10 with the same storage lifetime by increasing the proton-beam power as well as (3)He pumping speed.

The NPDGamma collaboration reports results from the first phase of a measurement of the parity violating up-down asymmetry A(gamma) with respect to the neutron spin direction of gamma rays emitted in the reaction (n) over right arrow + p -> d + gamma using the capture of polarized cold neutrons on the protons in a liquid parahydrogen target. One expects parity-odd effects in the hadronic weak interaction between nucleons to be induced by the weak interaction between quarks. A(gamma) in (n) over right arrow + p -> d + gamma is dominated by a Delta I = 1, S-3(1)-P-3(1) parity-odd transition amplitude in the n-p system. The first phase of the measurement was completed at the Los Alamos Neutron Science Center spallation source (LANSCE), with the result A(gamma) = [-1.2 +/- 2.1 (stat.) +/- 0.2 (sys.)] x 10(-7). We also report the first measurement of an upper limit for the parity-allowed left-right asymmetry in this reaction, with the result A(gamma,LR) = [-1.8 +/- 1.9 (stat.) +/- 0.2 (sys.)] x 10(-7). In this paper we give a detailed report on the theoretical background, experimental setup, measurements, extraction of parity-odd and parity-allowed asymmetries, analysis of potential systematic effects, and LANSCE results. The asymmetry has an estimated size of 5 x 10(-8) and the aim of the NPDGamma collaboration is to measure it to 1 x 10(-8). The second phase of the measurement will be performed at the Spallation Neutron Source at Oak Ridge National Laboratory.

We propose an access scheme for a synchronous dual-port (DP) SRAM that minimizes the 8T-DP-cell area and maintains cell stability. A priority row decoder circuit and shifted bit-line access scheme eliminates access conflict issues. Using 65 nm CMOS technology (hp90) with the proposed scheme, we fabricated 32 kB DP-SRAM macros. We obtained a 0.71 mu m(2) 8T-DP-cell for which the cell size is only 1.44 x larger than a 6T-single-port (SP)cell. The bit-density of the fabricated 32 kB DP-RAM macro is 667 kbit/mm(2), which is 25 % larger than a conventional 8T SRAM. The standby leakage is 27 % less because of the small drive-NMOS transistor of the proposed 8T-DP-cell.

Discussions in the taskforce meetings in the period of Jan.-Mar. 2009 on the technical possibility of the ultracold neutron (UCN) source at the Japan Proton Accelerator Research Complex (J-PARC) is summarized.

(Purpose and Background of the Research) Many theories beyond the standard model are proposed, since the standard model can't explain the baryon asymmetry in the universe, can't resolve the hierarchy problem and can't include gravity. The neutron electric dipole moment (n EDM) places a strict constraint on these theories. The early stage of SUSY was already excluded by the n EDM measurement. Recent SUSY predicts a n EDM of 10 -25 to 10 -28 e·cm. The most precise measurement was carried out at ILL, which showed the upper limit of 3×10-26 e·cm. The precision was limited by UCN counting statistics, namely UCN density in the EDM cell. We have been developing a new generation ultracold neutron (UCN) source for n EDM measurement.(1) We will increase the UCN density higher than 1×103 UCN/cm3, for the precision n EDM measurement.

An experiment on a Ramsey resonance for pulsed neutrons is discussed. The separated oscillatory fields for nuclear magnetic resonance were synchronized with a neutron pulse, and then the Ramsey resonance was observed as a function of the neutron velocity. The neutron spin was manipulated as a function of the neutron velocity. The phase of one of the oscillatory fields was modulated as a function of the neutron time of flight for a neutron velocity measurement.

A sapphire cell was used to obtain a high He3 nuclear polarization by means of spin-exchange optical pumping. The phase-shift difference between ordinary and extraordinary rays is well controlled using the thickness of the birefringent sapphire window so that a high circular polarization is obtained in the cell. Neutron transmission through the polarized He3 gas was measured as a function of neutron energy. A large He3 polarization of 63±1% was obtained at a He3 pressure of 3.1 atm. Neutron polarizations of 97 and 90 % were obtained with transmission rates of 15 and 22 % at 10 and 20 meV, respectively.

We report on progress of the development of neutron spin filters based on polarized gaseous 3He at KENS (Neutron Science Laboratory, KEK). 3He polarizer cells made of quartz glass and sapphire are prepared and tested. Quartz glass cells with spin relaxation times of more than 100 h are routinely produced. A 3He polarization of 63% has been achieved with a sapphire cell of a 3He pressure of 3 atm, and with this 3He cell, a neutron polarization of about 86% was obtained at thermal energy.

Ultra-cold neutrons (UCN) production in superfluid helium with spallation neutrons is discussed. A source is described, where superfluid helium is located in a cold moderator of deuterium at 20 K surrounded by a thermal moderator of heavy water at 300 K. A lead target is installed in the thermal moderator for neutron production via a medium energy proton induced spallation reaction. A Monte Carlo simulation showed that a UCN density of the order of 105 n/cm3 is achievable with an acceptable heat load for the helium cryostat.

The spin is a very useful probe for the space-time symmetry violation in fundamental interactions. Recent topics in this field are about the large enhancement (106) of the parity (P) violation in the neutron-nucleus interaction in the incident neutron-energy region of eV, where a large neutron-helicity dependence is found in the cross section [1, 2, 3, 4]. The large enhancement is also expected in the symmetry-violation effect under time reversal (T). A T-odd triple-correlation term between the neutron spin, nuclear spin and neutron momentum, which changes in sign under T, is measured in the T-violation test. The neutron spin is also used as a probe in condensed matter science. For example, the magnetic moment of the neutron and the neutron magnetic Bragg-scattering have been widely used for the study of the magnetism in condensed matter. In these studies, the neutron-spin polarization and analysis play a decisive role. 'He nuclear polarization has potentially the most preferable properties as a ...