A vacuum-tube type neutron image intensifier (NII), composed of Gd or 10B neutron convertor, is considered to have better spatial resolution and better detection efficiency compared with a ...traditional neutron scintilator. However, quantitative evaluation of difference in sensitivity among these imagers and difference in characteristics of the images between two NIIs has not been done since it needs measurements under the same irradiation condition. In this study we carried out radiography experiments at Hokkaido University Neutron Source (HUNS). Firstly, neutron radiography images were obtained by Gd-type NII, 10B-type NII, and the traditional neutron scintillator; NE426 (ZnS:Ag/6LiF). Next, we evaluated the brightness values from these images. We also evaluated the contrast and the image quality from two NIIs. The brightness of Gd-type NII is 8.8 times and the 10B-type is 12.9 times higher than the NE426. There is contrast little difference between the two types of NII. The image quality of Gd-type is better than 10B-type when exposure time is short.
Japanese swords are peculiar ones forged by a unique method developed in Japan. The forging methods are different each other, depending on age and area. Therefore, the crystalline structure of a ...Japanese sword depends on the age and the area. In this study, we obtained crystallographic information of Japanese swords and investigated the difference in texture and crystallite size from Japanese swords by using the pulsed neutron transmission spectroscopy. The neutron transmission experiment was carried out at HUNS (Hokkaido University Neutron Source). The samples were two types of Japanese swords. We analyzed the position-dependent neutron transmission spectra and obtained quantitative microstructural information in two-dimensional real space. We found that there were differences of the microstructure between edge and back of each Japanese sword and the microstructure was different between two Japanese swords.
We measured two-dimensional transmission spectra of pulsed neutron beams for a Japanese sword sample. Atom density, crystalline size, and preferred orientation of crystals were obtained using the ...RITS code. The position dependence of the atomic density is consistent with the shape of the sample. The crystalline size is very small and shows position dependence, which is understood by the unique structure of Japanese swords. The preferred orientation has strong position dependence. Our study shows the usefulness of the pulsed neutron transmission method for cultural metal artifacts.
A nano-diamond is an attractive neutron reflection material below cold neutron energy. The total neutron cross section of a nano-diamond produced using the detonation explosive technique was derived ...from a neutron transmission measurement over the neutron energy range of 0.2 meV to 100 meV because total neutron cross section data were not available. The total cross section of a nano-diamond with particle size of approximately 5 nm increased as the neutron energy decreased to 0.2 meV. It was approximately two orders of magnitude larger than that of carbon at 0.2 meV. The contribution of inelastic scattering to the total cross section was shown to be negligibly small at neutron energies of 1.2, 1.5, 1.9, 2.6, and 5.9 meV in inelastic neutron scattering measurements. Moreover, small-angle neutron scattering measurements of the nano-diamond showed a large scattering cross section in the forward direction at low neutron energies.
•Nano-diamond is attractive neutron reflection material below cold neutron energy.•Total cross section increased as the neutron energy decreased to 0.2 meV.•Approximately two orders of magnitude larger than that of carbon at 0.2 meV.•Contribution of inelastic neutron scattering was negligible small.•Large scattering in forward direction from small-angle neutron scattering measurement.
A fast data acquisition method based on pulse width analysis was developed for γ-ray spectroscopy with an NaI(Tl) detector. The new method was tested in experiments with standard γ-ray sources and ...pulsed neutron beam from a spallation neutron source. Pulse height spectra were successfully reconstructed from pulse width distribution by use of an energy calibration curve. The 197Au(n, γ)198Au cross section was measured by this method to test the viability. The obtained experimental cross section showed a good agreement with a calculation using the resonance parameters of JENDL-4.0.
Imaging using polarized neutrons is one of the most attractive techniques in the neutron imaging field, because of its capability to visualize magnetic field inside materials or spaces by analyzing ...neutron polarization. An advanced method, which can quantify the magnetic field by combining the time-of-flight method with a polarization analysis of pulsed neutrons, has been developed at J-PARC. To introduce this method to the compact accelerator-driven neutron source, we have started the magnetic imaging experiments at Hokkaido University Neutron Source (HUNS). Using an experimental system consisting of a pair of magnetic super-mirrors as a polarizer and an analyzer, a spin flipper, and a two-dimensional neutron detector, we obtained the polarization of 90% at the wavelength over 6Å. The first demonstration experiments were performed for coil samples. As a result, an oscillatory behaviour of polarization depending on the wavelength due to the neutron spin's Larmor precession was clearly observed.
The neutron focusing effect of a superconducting sextupole magnet has been investigated using unpolarized and polarized cold neutrons. The feasibility on the application of the magnetic lens to ...small-angle neutron scattering experiments are discussed.
The measurements of the neutron-capture cross sections were performed for the radioactive 107Pd and stable 105,108Pd nuclei by the time-of flight method using an apparatus called “Accurate ...Neutron–Nucleus Reaction measurement Instrument (ANNRI)” installed at the neutron Beam Line No.4 of the Materials and Life science experimental Facility (MLF) in the J-PARC. The neutron-capture cross sections of 107Pd and 105,108Pd have been measured in the low energy region from the thermal to a few hundreds eV. From the measurements, new information was obtained for some resonances of these Pd nuclei.
The cross section of the 237Np(n,γ) reaction has been measured at the Japan Proton Accelerator Research Complex (J-PARC). The NaI(Tl) spectrometer installed in the accurate neutron-nucleus reaction ...measurement instrument (ANNRI) was used for the measurement. The relative cross section was obtained using the neutron spectrum measured by the 10B(n,α1) reaction. The absolute value of the cross section was deduced by normalizing the relative cross section to the evaluated value in JENDL-4.0 at the first resonance.
Neutron resonance capture γ-ray measurements on 74Se and 77Se were performed with a 4π Ge spectrometer in the Accurate Neutron–Nucleus Reaction measurement Instrument (ANNRI) at the Japan Proton ...Accelerator Research Complex (J-PARC). The relative intensities of primary transitions were derived for the 27-eV resonance of 74Se and the 113-, 212-, 291-, 342-, 690- and 864-eV resonances of 77Se, respectively. For the 27-eV resonance of 74Se, a strong transition to the 293-keV state was observed. Moreover, new resonances of 74Se were found at 6, 123, 436 and 640 eV. It was confirmed that those resonances had originated in the neutron capture reaction of 74Se by obtaining the TOF spectrum corresponding to the strong 287-keV ground-state transition γ ray. As for 77Se, differences of the decay pattern were found between the resonances.
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