Hiroshi Kira

A compact SEOP 3He neutron spin filter with AFP NMR

We developed AFP NMR in an aluminum container for polarized noble gas nuclei. The radio frequency magnetic field inside the aluminum container was designed from computer simulations. The polarization loss by the AFP spin flip of 3He was measured to be as low as 3.8×10−4. With this technique, a compact in-situ polarizing 3He neutron spin filter with AFP NMR is demonstrated.

Development and demonstration of in-situ SEOP 3He spin filter system for neutron spin analyzer on the SHARAKU polarized neutron reflectometer at J-PARC

A new neutron reflectometer, SHARAKU, with a vertical sample-plane geometry was installed at beam line 17 at J-PARC Materials and Life Science Facility. Although a polarizing supermirror was previously installed as a neutron spin analyzer on SHARAKU, a 3He spin filter is advantageous because it can cover a large solid angle. An in-situ SEOP 3He spin filter system using a new compact laser unit has been developed for the analyzer. In this paper, we report a successful off-specular measurement with the new compact in-situ SEOP analyzer at SHARAKU.

Developments of In-Situ SEOP Polarized 3He Neutron Spin Filter in Japan

We launched the polarized 3He neutron spin filters (NSF) project in order to provide neutron polarization for the pulsed neutron beams in Japan. We adopted the in-situ spin exchange optical pumping (SEOP) technique to polarize the nuclear spin of 3He atoms because it has some advantages for our applications. The overall system size is compact and it avoids the problem of the time decay of nuclear spin of 3He thus suppressing the costs of maintenance and providing other advantages [1, 2] with respect to data analysis and quality. In this paper, we performed pulsed neutron beam tests of our compact in-situ SEOP NSF system at the BL10 beamline in the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex (J-PARC). The polarization of the 3He gas reached was 73 % and a pump-up time constant of 9.5 h was observed. This paper is a status report about the development of in-situ SEOP NSF system for the pulsed beam at J-PARC.

Basic Concepts of Polarisation Analysis for Neutron Chopper Spectrometer POLANO at J-PARC

The basic concept underlying the use of neutron polarisers and analysers in a polarised neutron spectrometer which will be constructed in J-PARC/MLF is discussed. The spectrometer, named POLANO, is a compact chopper spectrometer for polarisation analysis in the energy region up to Ei ~200 meV. In the first stage of this project, a 3He spin filter polarised by the spin exchange optical pumping method will be used as the polariser. Based on the optimisations of the filter parameters, we confirm that the designed optimised 3He spin filters will be feasible for use up to 80 meV.

Concepts of Neutron Polarisation Analysis Devices for a New Neutron Chopper Spectrometer, POLANO, in J-PARC

The basic concept of polarisation analysers with bender type supermirrors on the polarised neutron spectrometer, POLANO, which is now under construction in J-PARC/MLF, is described.

Development of portable polarized 3He neutron spin filter and its application to magnetic field imaging at J-PARC

In order to expand the measurable neutron energy range up to the energy of epithermal neutrons in polarized neutron experiments, a portable polarized 3He neutron spin filter (NSF) was developed in the Materials and Life science experimental Facility (MLF) at J- PARC. After the generation of 3He polarization through a spin exchange optical pumping method, the NSF was used as a neutron spin polarizer and flipper in a beam line. We constructed a simple neutron spin analysis apparatus with two 3He NSFs and made a preliminary attempt to visualize magnetic fields generated by a coil. The results represented that our apparatus could function for neutron wavelengths between approximately 0.5-5 A through the use of a neutron time-of-flight method.

Polarisation Analysis Neutron Spectrometer, POLANO, at J-PARC - Concept and Magnetic Field Optimisation

The status of the polarised neutron spectrometer constructed at the Japan Proton Accelerator Research Complex through a collaboration between Tohoku University and KEK will be reported. In particular, the optimisation of magnetic fields to minimise neutron- beam depolarisation using the finite element method will be discussed on the basis of several simulations using the finite element method.

Improvement of 3 He Nuclear Polarization for Neutron Scattering

Nuclear-polarized 3 He gas has recently been widely used in neutron facilities around the world for polarized neutron scattering. The large neutron absorption cross-section of 3 He depends strongly on the 3 He-spin and the neutron-spin directions, and a polarized neutron beam can be easily obtained by passing the beam through polarized 3 He gas, thus constituting a neutron spin filter (NSF). The relationships between neutron polarization Pn, neutron transmission Tn, and 3 He polarization PHe are:

Development of polarized Xe gas target for neutron experiment at J-PARC

At the Materials and Life science experimental Facility (MLF) in J-PARC, an experiment of detecting a neutron polarizing ability caused by a neutron-nuclear spin correlation at a resonant peak of 129Xe is planned. We evaluated measurable quantities based on a neutron optical theorem, developed a polarized Xe gas system, and carried out a feasibility test of our apparatus.

Applications of 3He neutron spin filters on the small-angle neutron scattering spectrometer SANS-J-II

A polarized 3He neutron spin filter has been applied to polarization analysis on the small-angle neutron scattering spectrometer SANS-J-II at JRR-3. Measurements were taken on silver behenate, which has several coherent peaks in the small-angle region with a background of spin incoherent hydrogen scattering. Here we demonstrate that the coherent and spin incoherent scattering were successfully separated by the polarization analysis using the 3He spin filter on the instrument.