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Abstract: Pulsed neutron imaging methods provide information on crystallographic structure, magnetic field, elemental composition, hydrogen bound state and other material features. Such methods have been expected to be a powerful complement to the traditional imaging method. Data analysis codes, detectors and new applications are being developed in Japan, and a new imaging beam line is being constructed at J-PARC. Here, recent progress in Japanese research on pulsed neutron imaging is presented, and a design for construction of the new imaging beam line is reported. [Copyright &y& Elsevier]

Abstract: We have performed various simulation calculations for a pulsed sextupole magnetic lens to look for the best condition of focusing experiments, assuming conditions of the pulse magnetic lens now under construction. Here, we placed a slit between the pulsed neutron moderator and the neutron lens, in order to see the focusing effect clearly. For the simulation, we used PHITS code to know influences of the position of the slit on the intensity of focused neutron beam, the focal point, and the broadening of the focal point. Increase of the distance of the slit from the source resulted in the decrease of the peak intensity of neutron beam at the focal point. Full-width at half-maximum of the neutron distribution along the incident beam direction around the focal point, broadened with increasing the distance, and the focal distance also became longer. The intensity ratios defined by (intensity with magnetic field)/(intensity without magnetic field) also increased with decreasing the distance. Therefore, it is better to set a slit near the moderator. [Copyright &y& Elsevier]

A sextupole magnetic field exerts focusing and defocusing effects on neutrons depending on the neutron-spin states. By combining both effects, we can realize a magnetic doublet which enables control of the neutron-beam size and divergence with high degrees of freedom. We constructed a magnetic doublet with two permanent sextupole magnets and a spin flipper, and experimentally investigated its function using pulsed neutrons. [ABSTRACT FROM AUTHOR]

Abstract: One of the most interesting applications of neutron imaging is that it enables the observation of magnetic field. Because the interaction between the neutron spin and the magnetic field depends on the neutron energy, it is important to study the neutron energy dependence of magnetic field imaging to quantitatively treat the characteristics of the magnetic field. In this study, we have performed a polarized pulsed neutron imaging experiment using a time-of-flight method at J-PARC and have analyzed the energy dependence of the obtained polarization image. We have also quantitatively analyzed the strength and the direction of the magnetic field relative to the quantized axis inside a solenoid coil. [Copyright &y& Elsevier]

Abstract: A pulsed sextupole electromagnetic lens with suitably controlled time-dependent magnetic field can in principle focus pulsed neutrons at the same focal point over a wide range of wavelength as the lens removes aberrations. However, in fact, it is difficult to focus neutrons over a wide range of wavelength because attenuation of a practical pulsed sextupole electromagnet is faster than an ideal case. We have devised a method of canceling the difference between the practical pulsed sextupole magnetic field and the ideal magnetic field with the use of a permanent sextupole magnet. We performed simulation calculations to investigate the feasibility of this method, and it was shown that focusing wavelength range spread compared with the case using a pulsed magnetic lens only. This result indicates the usefulness of the method. [Copyright &y& Elsevier]