Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/00223131.2019.1593892

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Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

We have proposed a machine learning model for efficient gamma-ray spectrometry for environmental recovery from the Fukushima Daiichi Power Plant Accident. In the present study, we focus on a radioactive nuclide identification by the machine learning in a screening measurement. A simple deep neural network having two hidden layer is proposed, and the identification accuracy is achieved more than 95% for single gamma-ray spectra.

DOI： 10.1109/nss/mic42101.2019.9059618

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Language：Japanese   Publisher：The Japan Society of Applied Physics  

DOI： 10.11470/jsapmeeting.2019.1.0_530

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DOI： 10.1088/1674-4926/39/8/082001

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Charged particle activation analysis (CPAA) is a rapid method with high accuracy which can analyze multi-elements simultaneously. Since multiple gamma-ray detection method is expected to improve the detection efficiency and the signal-to-noise ratio, we study what design of the gamma-ray detector array is the most suitable for CPAA. We take up four design candidates and investigated the responses by the radiation simulation code Geant 4. From the results, we have deduced the best design with 5 germanium detectors in close geometry. By inspecting the sensitivity in CPAA, the method is proved to be useful and applicable to 116 nuclides.

DOI： 10.1007/s10967-017-5558-6

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Language：Japanese   Publisher：福島大学地域創造支援センター  

CiNii Article

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/2373566X.2016.1238721

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Journal of the Physical Society of Japan  

DOI： 10.7566/jpscp.11.070007

J-GLOBAL

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Publishing type：Research paper (scientific journal)  

© 2015 The Physical Society of Japan. We successfully measured muonic X-rays of cosmic-ray muons stopped in Al and Fe targets. In order to identify the events that incoming cosmic-ray muons were stopped in the targets, a coincidence and anticoincidence system of three plastic scintillators was used. The X-rays associated with the atomic muon captures were measured with germanium detectors. Measurements using the Al and Fe targets were carried out for 33 and 16 days, respectively. A sufficient number of muonic X-ray events for identifying the elemental compositions of the target materials were clearly observed. This technique provides a means of nondestructive elemental analysis that does not require the use of particle accelerators.

DOI： 10.7566/JPSJ.84.034301

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Language：Japanese   Publisher：新潟県医師会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Proton computed tomography (CT) is an imaging technique using a high-energy proton beam penetrating the human body and shows promise for improving the quality of cancer therapy with high-energy particle beams because more accurate electron density distribution measurements can be achieved with proton CT. The deterioration of the spatial resolution owing to multiple Coulomb scattering is, however, a crucial issue. The control of the radiation dose and the long exposure time are also problems to be solved. We have developed a prototype system for proton CT with a silicon strip detector and performed a beam test for imaging. The distribution of the electron density has been measured precisely. We also demonstrated an improvement in spatial resolution by reconstructing the proton trajectory. A spatial resolution of 045 mm is achieved for a 25-mm-thick polyethylene object. This will be a useful result for upgrading proton CT application for practical use. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nima.2013.09.051

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Proton computed tomography (CT) is an imaging technique using a high-energy proton beam penetrating the human body and shows promise for improving the quality of cancer therapy with high-energy particle beams because more accurate electron density distribution measurements and in-situ positioning can be achieved with proton CT. The deterioration of the spatial resolution owing to multiple Coulomb scattering is saved by reconstructing the proton trajectory. We have developed a prototype system for proton CT and demonstrate a precise measurement of electron density and an improvement in spatial resolution. In order to control of the radiation dose and reduce the exposure time for imaging, the precise position detector should work with very high rate (a few MHz). We have developed high speed tracker with large area silicon strip detector, Amplifier-Shaper-Discriminator LSI, which was developed for drift chamber readout at high energy physics experiment, and FPGA. We report the performance of the tracker evaluated with very high intensity proton beam for the cancer therapy.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Dynamic nuclear self-polarization (DYNASP) is a phenomenon observed in III-V semiconductors. When electrons of the valence band of a semiconductor are optically excited to the conduction band, a relaxation process of the conduction electrons induces a large nuclear polarization to suddenly occur below a critical temperature. This mechanism is useful for nuclear magnetic moment measurements of unstable nuclei implanted in semiconductors. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2013.07.042

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

The gamma-radiation has been investigated for Ni-63 produced by cold neutron capture in an enriched Ni-62 sample. The 315 gamma-rays produced were placed in a Ni-63 level scheme, in which 272 placements are new. We determined the excitation energies with 0.2-0.8 keV error and the branching ratios of 62 bound levels in Ni-63, including 30 new levels. The Q-value of the Ni-62(n, gamma)Ni-63 reaction amounts to 6837.75 +/- 0.18 keV. A large-scale shell-model calculation was performed that included the four single-particle orbits of 0f(7/2), 1p(3/2), 0f(5/2), and 1p(1/2), assuming an inert Ca-40 core for negative-parity states, and those of 1p(3/2), 0f(5/2), 1p(1/2), and 0g(9/2), assuming a Ni-56 core for positive-parity states. The energies of the low-lying Ni-63 states were successfully reproduced. A mean-field statistical-model calculation was also performed by using a self-consistent interaction between the Hartree-Fock + Bardeen-Cooper-Schrieffer method and the statistical calculation. The calculation result is consistent with the experimental level density of Ni-63.

DOI： 10.1143/JPSJ.81.084201

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Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/GHTC.2012.18

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN PHYSICAL SOC  

A 4 pi LaBr3(Ce) spectrometer was designed for the measurements of neutron capture cross sections using a prompt gamma-ray spectroscopic method with a time-of-flight technique. An optimum configuration for the 4 pi LaBr3(Ce) spectrometer was chosen from four possible configurations based on comparison of simulated performance and cost of construction. Further simulations were performed to demonstrate performance of the 4 pi LaBr3(Ce) spectrometer.

DOI： 10.3938/jkps.59.1585

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN PHYSICAL SOC  

The 4 pi Ge spectrometer composed of 22-30 Ge detectors was developed, and it has been used to study neutron capture reactions with a neutron time-of-flight (TOF) technique. Since the distances between the sample position and the Ge detectors are variable, it can be used as a multifunctional spectrometer. At first, it was used as a sum energy spectrometer, and resonances in (nat)Ag were identified as those of (107)Ag or (109)Ag. In second, it was used to deduce gamma-ray intensity distribution for each resonance, and the results for (238)U were presented. In third, it was used to measure neutron capture cross sections of minor actinides and fission products at the electron linear accerelator facility of KURRI and at the accurate neutron-nucleus reaction measurement instrument (ANNRI) in MLF of J-PARC. The preliminary results are discussed mainly based on measurements of neutron capture cross section for (241)Am, together with related techniques.

DOI： 10.3938/jkps.59.1547

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

Lattice nuclei of III-V type semiconductors can be self-polarized through the contact hyperfine interaction with artificially excited conduction electrons at extremely low temperatures. In the self-polarization process, a positive feedback between the nuclear magnetization and the expansion of the energy splitting of the conduction electron states due to this nuclear magnetization takes an essential role. Extending the original theoretical work on the self-polarization with linearly polarized (LP) light by Dyakonov and Perel,(1) we examined the effect of the circularly polarized (CP) light on the phenomenon of the nuclear self-polarization. While no polarization is obtained with LP light above the critical temperature, the nuclear polarization is enhanced also above the critical temperatures with CP light. More important finding in the application of CP light is that the direction of the nuclear polarization can be controlled by the orientation of the excited conduction-electron polarization, which is easily manipulated by changing the degree of polarization of the excitation light. Related to this polarization change, it is also remarked that the nuclear polarization shows a hysteresis phenomenon below the critical temperature when the degree of the electron polarization is swept up and down. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3602118]

DOI： 10.1063/1.3602118

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

Medium-spin states of Ge-70 have been studied via the Ni-60(C-12,2p gamma)Ge-70 reaction at 45 MeV. The ground-state band and the second 0(+) band have been extended to the 12(+) and 8(+) states, respectively. Two negative-parity bands, one of which has a coupled structure and the other has a decoupled structure, have been observed additionally. Although the latter decoupled structure was known up to the (21(-)) state from a previous experiment, the part of the level scheme up to the 15(-) state has been largely modified by the present experiment. Backbendings observed in the positive- and negative-parity yrast bands have been compared with those of the neighboring even Ge isotopes. The experimental level structure has been compared with the shell-model calculations in the model space (2p(3/2), 1f(5/2), 2(p1/2), 1g(9/2)) employing two kinds of effective interactions, one of which is an extended P + QQ interaction with monopole interactions and the other is developed from a renormalized G matrix. Microscopic structures of the observed bands have been discussed with the help of the shell-model calculations.

DOI： 10.1103/PhysRevC.81.024309

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DOI： 10.1103/PhysRevC.81.024309

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

High spin states of Dy-144 have been studied through in-beam gamma-ray spectroscopy by using the reaction Mo-92(Fe-56,2p2n). It has been found that the continuation of the ground-state band forks into three Delta I=2 bands above the 8(+) state. This forking has been attributed to the alignments of pi h(11/2)(2) or nu h(11/2)(-2) configurations with the help of the systematics in neighboring nuclei. Additionally a negative-parity sideband of Delta I=2 cascades has been observed to start from the 5((-)) state and continue to a dipole band above the (13(-)) state through another negative-parity sideband of Delta I=2 cascades in between. These structures have been discussed from the viewpoint of a competition between "Magnetic Rotation" and "Anti-magnetic Rotation" based on a classical particles-plus-rotor model.</p>.

DOI： 10.1103/PhysRevC.79.064321

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

The Zr isotopes between Zr-90 and Zr-96 are expected to be spherical based on the almost complete subsbell closures at Z=40 and N=50,56. On the other hand, they have low-lying 3(-) states and show the characteristics of low frequency octupole oscillation which arise as a superposition of particle-hole excitations. A 380 MeV Zr-94 beam from the tandem accelerator at the Japan Atomic Energy Agency (JAEA) was excited on a self-supporting Pb-nat target. The gamma-ray detector array GEMINI-II was used to detect deexcitation gamma rays. The scattered beam (Zr-94) was detected with a position-sensitive particle detector system. The gamma-ray intensities were used as an input to the least-squares search code GOSIA to determine the E3 matrix element of the first 3(-) excited state of Zr-94. The B(E3;0(+)-> 3(-)) value of 0.21(6) e(2)b(3) in Zr-94 has been obtained by Coulomb excitation experiment.

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Low-energy photons produced by the Compton scattering from hydrogen increase the background in the lower-energy region of the gamma-ray spectrum. This results in an increase in the detection limit for trace elements. In multiple photon detection prompt gamma-ray analysis (MPGA), only those elements that simultaneously emit two or more prompt gamma-rays, which have cascade relation and are emitted within a short interval, can be measured. Therefore, the influence of hydrogen can be reduced. In this study, standard polymer and food samples are measured. The hydrogen background is reduced in MPGA.

DOI： 10.1007/s10967-008-1505-x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

A neutron beam line for multiple prompt gamma-ray analysis was constructed at the Japan Atomic Energy Agency. A detector system for the MPGA was constructed at the C2-3-2 beam line in January 2005. It comprised eight (upgraded in March 2007) clover Ge detectors with a BGO Compton suppressor. High efficiency detector system provides an advantage in terms of the detection limit of MPGA when compared to the result of PGA. The supermirror neutron bender was improved and a supermirror neutron guide was installed upstream of the sample position.

DOI： 10.1007/s10967-008-1508-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN PHYSICAL SOC  

The excited states of the doubly odd nucleus I-118 have been studied by using in-beam gamma-ray spectroscopy with the Cd-110(C-12, p3n) reaction at E-lab = 80 MeV. We have established several multi-quasi particle states associated with different proton and neutron quasiparticle configurations. A I-pi = 14(-) level at 2561 keV was newly observed and found to be associated with the pi h(11/2)nu d(5/2) configuration coupled to a pair of protons in the g(7/2) orbital. TRS calculations for the 14(-) level indicated a favored oblate state based on the fully aligned four-quasiparticle pi[h(11/2)(g(7/2))(2)](23/2)-nu[d(5/2)](5/2+) configuration. Another energetically favored state I-pi = 24(-) at 6216 keV could be interpreted as a noncollective oblate state from the fully aligned six-quasiparicle pi[h(11/2)(g(7/2))(2)](23/2)-nu[d(5/2)(h(11/2))(2)](25/2+) configuration. No Delta = 1 side band of the same parity as the pi h(11/2)nu h(11/2) band was observed while a side band built on the pi g(9/2 nu)h(11/2) configuration was considered to be caused by the gamma vibration coupling.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：E D P SCIENCES  

A simulation study was performed to choose an optimal configuration of a gamma-ray spectrometer consisting of Ge and BGO detectors, which facilitates the identification of prompt gamma rays to ground states emitted following capture reactions of neutrons in the thermal energy region and determination of the reaction cross sections.

DOI： 10.1051/ndata:07399

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：E D P SCIENCES  

We have evaluated the performance of our new data acquisition system (DAQ), which utilizes digital signal processing techniques and was developed for a 4 pi Ge spectrometer. The total energy resolution of this system was 2.5 keV in FWHM for 1.33-MeV gamma rays and 16.4 keV in FWHM for 10.83-MeV prompt gamma rays. The time resolution of timing signals, which are used for the measurements of coincident gamma rays, was 120 ns in FWHM. Those values fulfilled our requirements for the DAQ. A method of dead time correction with this system was also developed.

DOI： 10.1051/ndata:07400

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：E D P SCIENCES  

Neutron capture cross sections on minor actinides are important in the design work for innovative nuclear reactor systems. In order to improve data accuracy, a 4 pi Ge spectrometer system surrounded with large BGO detectors for Compton suppression has been developed. Capture cross sections of Np-237 were obtained and resonance analyses using the code SAMMY were performed for several low energy resonances. Measurements were carried out at the electron Linac of KURRI (Kyoto University Research Reactor Institute) with an electron energy of 30 MeV.

DOI： 10.1051/ndata:07463

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：E D P SCIENCES  

Neutron capture cross sections of minor actinides and long-lived fission products are important for the R&D of innovative nuclear reactors. However, those data are rather poor both in quality and in quantity at present. Thus, we have started projects for neutron cross section measurements. We have constructed an 4 pi Ge spectrometer consisting of Ge crystals and BGO shields. The neutron cross section measurements have been done at KURRI electron linac and JAEA JRR-3 facilities, which will be extended at the high-intensity neutron source at J-PARC.

DOI： 10.1051/ndata:07552

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

In order to improve the sensitivity for the quantification of trace elements, we propose the combination of prompt gamma-ray analysis (PGA) and a multiple gamma-ray detection method. A new Ge detector system for multiple prompt gamma-ray analysis (MPGA) was constructed at the neutron guide-hall of the JRR-3M reactor of the Japan Atomic Energy Agency (JAEA). The first demonstration of this system was given with a plastic sample containing traces of cadmium. The quantification limit of cadmium in a plastic sample was found to be about 0.1 ppm.

DOI： 10.1007/s10967-007-0520-7

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Recycled steel products demands a new technique for determining tramp elements in steel. In this paper, As and Sb in iron certified reference materials were determined by neutron activation analysis with the multiple gamma-ray detection method. The determined values are in good agreement with certified and reference values. The lower determination limits (LDL) for As and Sb in high purity iron are 0.012 and 0.0025 ppm, respectively. As the demanded LDL for As and Sb is 0.1 ppm, the method described in this work is suitable for determining As and Sb in recycled steel.

DOI： 10.1007/s10967-007-0211-4

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Language：Japanese   Publisher：Atomic Energy Society of Japan  

DOI： 10.11561/aesj.2007s.0.84.0

CiNii Article

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The Cd concentration in food is a public concern related to the human health. In order to remove Cd-polluted food, the development and validation of a rapid and sensitive method of Cd analysis is required. By applying the multiple gamma-ray detection method to prompt gamma-ray analysis (PGA). the influence from nuclei which emit only one prompt gamma-ray at a time at every neutron capture reaction can be reduced. therefore the quantification limit of Cd is improved significantly. The limit of Cd contained in rice in the case of MPGA was evaluated. and under our proposed experimental conditions, it may be possible to quantify Cd content in rice to within 0.2 ppm in 10 min. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.apradiso.2006.02.087

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

In order to measure the neutron capture cross-section of minor actinides, we have proposed the use of a 4 pi Ge spectrometer. A time-of-flight neutron beam line for the experiment has been constructed at the electron LINAC of Kyoto University Research Reactor Institute. The assembling of the 4 pi Ge spectrometer is in progress. We are also developing a new data acquisition system based on a digital processing technique. (c) 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nima.2006.02.051

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

We are developing a 4 pi Ge-spectrometer for the measurement of neutron capture cross sections of minor actinides. The 4 pi Ge-spectrometer consists of Ge detectors that cover a large solid angle of a sample; the spectrometer has high efficiency and good energy resolution for gamma-ray detection. This feature enables us to discriminate desired events from backgrounds based on the measurement of total excitation energy following the neutron capture reaction. In this work, we determined an optimal configuration and evaluated performances of 4 pi Ge-spectrometer using a Geant4 simulation. From comparison of performances, two configurations that have uniform count rates or a high efficiency were determined. Therefore one of the two configurations is used properly to reduce an experimental error for the neutron capture cross section. Further simulations were made with a full geometry including BGO shields; absolute efficiency for the high-efficiency configuration was estimated to be 15% for a 1-MeV gamma ray.

DOI： 10.1063/1.1945125

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

High-spin yrast states in Sc-43 were investigated by using in-beam gamma-ray technique with the Al-27(F-19,p2n) reaction at 50 MeV. The positive-parity rotational band built on the 152-keV J(pi) = 3/2(+) state has been extended up to the terminating J pi = (27/2(+)) state. Several fast transitions feeding to the oblate-deformed J(pi) = 19/2(-) isomer have been also identified. Character of observed levels and transition rates were discussed in comparison with the shell-model calculations.

DOI： 10.1088/1742-6596/20/1/041

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

Most of nuclei emit two or more prompt gamma rays in the neutron capture reaction. In multiple prompt gamma-ray analysis (MPGA), the gamma rays are simultaneously measured by two or more sets of gamma-ray detectors; these gamma rays are reduced to a pair of two prompt gamma rays, and it is added to the two-dimensional spectrum, which sets two energy axes. A gamma-ray peak corresponding to the pair of gamma rays that are emitted simultaneously will appear on the two-dimensional spectrum. By analyzing this two-dimensional peak, resolution can be raised by leaps and bounds. MPGA needs not only the knowledge of energies of capture gamma rays, but also nuclear level structure data. While the energies are usually accurate, many of the excited level structures are poorly known. Complete sets of these nuclear data are of great importance. A new MPGA system will be constructed at the guide-hall of JRR-3M in Japan Atomic Energy Research Institute. This system consists of three clover Ge detectors with anti-Compton suppressors. The absolute efficiency of the system is about 10% for a 1.3-MeV gamma ray. It will be widely used in the fields of agriculture, engineering, geosciences, environmental science, and measurement of neutron capture cross sections of minor actinides.

DOI： 10.1063/1.1945328

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

To measure neutron cross-section data of the minor actinides, we construct a 4-pi Ge-spectrometer utilizing a multiple gamma-ray detection method. This spectrometer consists of 30 Ge crystals and BGO anti-Compton shields. Generally, a data acquisition system for such a large Ge spectrometer consists of many NIM modules; it requires a large space and huge cost. To overcome these problems, we developed a new data acquisition system with digital signal processing techniques. This system is mounted in a 19-in. VME sub-rack, and the cost of this system is less than 2000 US dollars per one Ge detector channel.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ATOMIC ENERGY SOC JAPAN  

A compact 4pi Ge spectrometer was designed for the measurement of neutron capture cross sections of minor actinides. It consists of two EUROBALL clusters and four clover detectors with BGO shields surrounding a sample as close as possible so as to absorb a few gamma-rays of high energy emitted after the neutron capture reaction with reasonable efficiency. This feature opens up the possibility to discriminate the desired nuclide from other impurities based on the measurement of excitation energy and determine the cross section accurately.: Overall performances such as total detection efficiencies for 3 cascade gamma-rays as well as monochromatic gamma-rays were simulated using Geant4. It turned out we could achieve the peak detection efficiency as large as 0.9% for 3 cascade gamma-rays, which is almost an order of magnitude larger than the value of the Gammasphere.

DOI： 10.3327/jnst.41.1129

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

High-spin states in Sc-43 have been investigated by using the in-beam gamma-ray technique with the Al-27(F-19,p2n) reaction at 50 MeV. The J(pi)=(17/2(-)) level at 4382 keV, the J(pi)=(17/2(-),21/2(-)) level at 4633 keV, and some higher-lying levels were newly identified above the J(pi)=19/2(-) high-spin isomer, while the quasirotational structure built on the J(pi)=3/2(+) state has been extended up to the terminating J(pi)=(27/2(+)) state. The energy levels of the observed positive-parity quasirotational band were consistent with the prediction of the shell-model calculation in {0d(3/2),0f(7/2), 1p(3/2)} model space, while the J(pi)=(17/2(-),21/2(-)) level at 4633 keV could not be reproduced by the calculation in {0f1p} model space.

DOI： 10.1103/PhysRevC.70.054323

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Nuclear magnetic resonance on oriented nuclei was carried out using a sample of dilute Y-91 and Y-91m in iron prepared by ion implantation of radioactive precursor Rb isotopes. For (YFe)-Y-91, the beta-ray asymmetry was utilized to measure the magnetic hyperfine interaction frequency, nu(0)=73.566(22) MHz, which led to the magnetic hyperfine field, B-HF=-29.4(2)T, by using the known nuclear g-factor. The field shift of the resonant frequency, dnu(0)/dB(0)=-2.501(17) MHz/T for (YFe)-Y-91, implies a Knight shift value, K=0.0(8)%. The interaction frequency and the field shift of (YFe)-Y-91m obtained via the gamma-ray detection confirmed the previously reported results. A ratio of the measured nu(0) and dnu(0)/dB(0) values for both (YFe)-Y-91 and (YFe)-Y-91m gave rise to the hyperfine anomaly, (91)Delta(91m)=-4.2(8)%, which can explain discrepancies in the B-HF values of YFe as determined by various experiments.

DOI： 10.1103/PhysRevB.70.132405

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Nuclear magnetic resonance on oriented nuclei was carried out using a sample of dilute 91Y and 91mY in iron prepared by ion implantation of radioactive precursor Rb isotopes. For 91YFe, the beta-ray asymmetry was utilized to measure the magnetic hyperfine interaction frequency, ν0=73.566(22) MHz, which led to the magnetic hyperfine field, BHF=-29.4(2)T, by using the known nuclear g-factor. The field shift of the resonant frequency, dν0/dB0=-2.501(17) MHz/T for 91YFe, implies a Knight shift value, K=0.0(8)%. The interaction frequency and the field shift of 91mYFe obtained via the gamma-ray detection confirmed the previously reported results. A ratio of the measured ν0 and dν0/dB0 values for both 91YFe and 91mYFe gave rise to the hyperfine anomaly, 91Δ91m=-4.2(8)%, which can explain discrepancies in the BHF values of YFe as determined by various experiments.

DOI： 10.1103/PhysRevB.70.132405

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We develop a 4 pi Ge spectrometer consisting of large-volume Ge detectors and BGO scintillators for capture cross section measurement of minor actinides such as Am-241,Am-243 and (237)Ap. By using this spectrometer we can extract summed gamma-ray energy, which corresponds to excitation energy of the residual nucleus after neutron capture reaction. The high energy resolution achieved by Ge crystals will enable us to distinguish between the nucleus of interest and impurity nucleus; we can eliminate the contribution from the impurity nucleus in the cross section measurements, enabling us to derive accurate cross section data In this paper we win describe detailed design study of the spectrometer and its performance based on the Monte-Carlo simulation code GEANT 4.5.0.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

To measure neutron cross-section data of the minor actinides, we construct a 4-pi Ge-spectrometer utilizing multiple gamma-ray detection method. This spectrometer consists of 30 Ge crystals and BGO anti-Compton shields. Generally, a data acquisition system for such a big Ge spectrometer consists of many NIM modules; it requires large space and huge cost. To overcome these problems, we developed a new data acquisition system with digital signal processing techniques. This system is mounted in a 19 inches VME sub-rack, and the cost of this system is greatly reduced.

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Recent studies of hyperfine fields B-HF of Sr and Y in Fe are briefly reviewed. The B-HF value of Y in Ni is given by NMRON of (YNi)-Y-91m. The nuclear mangetic moment of the ground state of Y-93 is extracted from the beta-ray detected NMRON of Y-93 Fe.

DOI： 10.1007/s10751-005-9106-3

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：WORLD SCIENTIFIC PUBL CO PTE LTD  

Nuclear magnetic resonance on oriented nuclei for (YFe)-Y-91 experiments have been performed. Comparing the external field dependence of resonance frequencies with (YFe)-Y-91 and (YFe)-Y-91m, the hyperfine anomaly in Fe was determined as (91m)Delta(91) = +4.2(8)%. The measured hyperfine anomaly was interpreted in terms of a microscopic theory including core polarization and meson exchange currents.

DOI： 10.1142/9789812702401_0045

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Language：English   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER PHYSICAL SOC  

Nuclear magnetic resonance on oriented nuclei was used in combination with beta-ray detection and ion implantation, leading to the successful observation of the resonance of (SrFe)-Sr-91. The magnetic hyperfine field (B-HF) was deduced as B-HF(SrFe)=-23.83(7) T using the known nuclear g factor. This result explains the existing problem of disagreement in B-HF values for SrFe between theory and experiment. An experimental nuclear spin-lattice relaxation rate was obtained and is briefly discussed in comparison with a theoretical estimate.

DOI： 10.1103/PhysRevB.68.012403

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PHYSICAL SOC JAPAN  

Nuclear magnetic resonance on oriented nuclei (NMR-ON) of La existing as a dilute impurity in Fe was observed for the first time. NMR-ON experiments were performed by detecting the 1596 keV gamma rays from the beta decay of La-140 in external magnetic fields of 0.1, 0.1 0.4 and 0.6 T. From the external magnetic-field dependence of the resonance frequency. the magnetic hyperfine field and the Knight shift were deduced to be B-hf = -47 +/- 1 T and K = -4.0 +/- 3.4% respectively. The effective relaxation time of (LaFe)-La-140 at 8 mK in an external magnetic field of 0.2 T was determined to be 8.8 +/- 1.5 min using a single-exponential fit. The present value of the magnetic hyperfine field agrees with that deduced from a two-site model by the low-temperature nuclear orientation method.

DOI： 10.1143/JPSJ.72.723

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN INST METALS  

A La-140(I-pi = 3(-), T-1/2 = 40.3h)-doped layer has been produced in CaB6 by means of radioactive isotope (RI) beam technique: Cs-140(I-pi = 1(-), T-1/2 = 63.7 s) was implanted into CaB6 and the radioactive equilibrium of Ba-140-La-140 was achieved. The concentration of La in CaB6 was La/Ca similar to 0.001 and similar to0.005. Obtained TDPAC spectra of the 2083keV level of Ce-140 (I-pi = 4+, T-1 /2 = 3.4ns, mu = +4.35+/-0.10mu(N)) followed by the beta decay of La-140 showed the existence of hyperfine magnetic fields: B-hyp = -15.0+/-0.5T and -1.00+/-0.15T for La/Ca similar to 0.001 and Bhyp = -1.51+/-0.12T for La/Ca similar to 0.005.

DOI： 10.2320/matertrans.43.1502

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMERICAN PHYSICAL SOC  

The nuclear magnetic moment of the Ce-143 ground state (T-1/2 = 33.0 h, I-pi = 3/2(-)) has been measured with the technique of nuclear magnetic resonance on oriented nuclei (NMR-ON) at low temperature. A sample ((CeFe)-Ce-143) was prepared by implanting into an Fe foil nuclei of mass number 143, which were separated from fission products with an on-line isotope separator. The NMR-ON spectra were obtained by detecting specific beta and gamma rays, and the resonance frequency was thereby determined to be 84.3(1) MHz. Using the reported value of the hyperfine magnetic field at other Ce nuclei in Fe, the nuclear magnetic moment of the Ce-143 ground state was determined to be \mu\ = 0.43(1) mu(N). This value is discussed based on a systematics of the magnetic moments of other N = 85 nuclei.

DOI： 10.1003/PhysRevC.65.017301

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Brute-force nuclear magnetic resonance on oriented nuclei (BF-NMRON) experiments have been performed with 12 T maximum field and at 10 mK. The resonances for (TcNb)-Tc-95,96, (AgAg)-Ag-106-Ag-m, and 110Ag(m)Ag have been observed. The magnetic moment of Ag-106(m) was determined to be 3.705(4) mu (N). Comparing the resonance frequencies of BF-NMRON and those of the known NMR-ON results in Fe, the hyperfine anomalies in Fe were determined: (95)Delta (96)(Tc) = -0.026(17)%. (106m)Delta 110(m)(Ag) = 0. 10(6)%. The measured hyperfine anomalies are interpreted in terms of a microscopic theory including core polarization and exchange current effects.

DOI： 10.1103/PhysRevC.63.044314

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

Brute-force nuclear magnetic resonance on oriented nuclei (BF-NMRON) experiments have been performed for (NbCu)-Nb-90, (RhCu)-Rh-101m and (AgAg)-Ag-110m at about 10 mK. Narrow resonance spectra were detected. Using the known values of the g-factors, the Knight shift has been deduced: K((NbCu)-Nb-90) = 0.62(24)%, K((RhCu)-Rh-101m) = 0.87(27)%. The effective spin-lattice relaxation times were also measured.

DOI： 10.1023/A:1012213519149

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

Low-temperature nuclear orientation (LTNO) experiments were performed on Pm-151 implanted into iron and Nd-147 implanted into nickel. The gamma-ray anisotropy measurements yielded values of the magnetic hyperfine field and the substitutional fractions of these ions in the host metals. An observed discrepancy between the substitutional fractions obtained from the 91 keV and 531 keV data on Nd-147 (Ni) under bar is briefly discussed.

DOI： 10.1023/A:1020583010083

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

A La-140(I-pi = 3(-), T-1/2 = 40 3 h)-doped layer has been produced in CaB6 by means of radioactive isotope (RI) beam technique: Cs-140(I-pi = 1(-), T-1/2 = 63.7 s) was implanted into CaB6 and the radioactive equilibrium of Ba-140-La-140 was achieved. The concentration of La in CaB6 was La/Ca similar to 0.001. Obtained TDPAC spectra of the 2083 keV level of Ce-140 (I-pi = 4(+), T-1/2 = 3.4 ns, mu = + 4.35 +/- 0.10 mu(N)) followed by the beta decay of La-140 showed the existence of hyperfine magnetic fields: B-hyp = 15.0 +/- 0.5 T and -1.00 +/- 0.15 T.

DOI： 10.1023/A:1020598028120

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

We have measured the polarization of unstable nuclei produced by the technique of ion beam surface interaction at grazing incidence (IBSIGI). A 60 keV Cs-124 beam from the on-line mass separator was used. The NMR technique was employed for the observation of the nuclear polarization. A small polarization of 0.22(13)% was observed. The small value was interpreted in terms of the velocity dependence of nuclear polarization, comparing with the results observed with stable nuclei.

DOI： 10.1023/A:1017044211496

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Language：Japanese   Publisher：新潟大学災害・復興科学研究所  

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-25870243/

Language：Japanese   Publisher：新潟大学災害・復興科学研究所  

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DOI： 10.11561/aesj.2012s.0.48.0

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DOI： 10.11561/aesj.2011f.0.54.0

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原子力機構の研究炉JRR-3及び放射線標準施設で発生させた高エネルギーガンマ線、及び標準ガンマ線源を用いて、次世代の検出器として期待されるLaBr3（Ce)検出器の基礎特性試験を実施した。得られた性能を従来のNaI（Tl）検出器と比較し、LaBr3（Ce)検出器の優位性を、広範囲のガンマ線エネルギー領域について示した。

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DOI： 10.11561/aesj.2007f.0.72.0

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DOI： 10.11561/aesj.2007f.0.68.0

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DOI： 10.11561/aesj.2007s.0.42.0

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DOI： 10.11561/aesj.2006f.0.57.0

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DOI： 10.11561/aesj.2006s.0.36.0

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DOI： 10.11561/aesj.2003f.0.058.0

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Venue：Uji Obaku Plaza, Kyoto University  

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Venue：新潟大学五十嵐キャンパス  

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Venue：Shizuoka University Shizuoka Campus  

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