Ratliff, H.; Matsuda, Norihiro; Abe, Shinichiro; Miura, Takamitsu*; Furuta, Takuya; Iwamoto, Yosuke; Sato, Tatsuhiko
Nuclear Instruments and Methods in Physics Research B, 484, p.29 - 41, 2020/12
Meleshenkovskii, I.*; Ogawa, Tatsuhiko; Sari, A.*; Carrel, F.*; Boudergui, K.*
Nuclear Instruments and Methods in Physics Research B, 483, p.5 - 14, 2020/11
For the purpose of fissile material detection, the technique to observe neutrons ejected from photo-fission induced by bremsstrahlung X-rays is being developed. This technique is advantageous in the sense that the machine can be compact compared to conventional neutron generators. However, photo-fission reaction cross sections are generally smaller than those of neutron-induced fission cross sections therefore optimization of the beam line is of high importance. In this study, we investigated the factors necessary to be optimized by using Monte-Carlo transport codes MCNP and PHITS. It was found that high-Z materials are advantageous to effectively produce bremsstrahlung X-rays but photons produce neutrons by secondary (,n) reactions resulting in mixing of prompt and delayed fission reactions. Moreover, secondary neutrons are produced not only inside the target but also in the materials surrounding the target. Therefore it is necessary to select elements whose neutron separation energy is high to suppress parasitic secondary neutrons.
Matsuda, Hiroki; Iwamoto, Hiroki; Meigo, Shinichiro; Takeshita, Hayato*; Maekawa, Fujio
Nuclear Instruments and Methods in Physics Research B, 483, p.33 - 40, 2020/11
A thick target neutron yield for a mercury target at an angle of 180 from the incident beam direction is measured with the time-of-flight method using a 3-GeV proton beam at the Japan Proton Accelerator Research Complex (J-PARC). Comparing the experimental result with a Monte Carlo particle transport simulation by the Particle and Heavy Ion Transport code System (PHITS) shows that there are apparent discrepancies. We find that this trend is consistent with an experimental result of neutron-induced re- action rates obtained using indium and niobium activation foils. Comparing proton-induced neutron-production double-differential cross-sections for a lead target at backward directions between the PHITS calculation and experimental data suggests that the dis- crepancies for our experiments would be linked to the neutron production calculation around 3 GeV by the PHITS spallation model and/or the calculation of nonelastic cross-sections around 3 GeV in the particle transport simulation.
Arai, Yoichi; Watanabe, So; Ono, Shimpei; Nomura, Kazunori; Nakamura, Fumiya*; Arai, Tsuyoshi*; Seko, Noriaki*; Hoshina, Hiroyuki*; Hagura, Naoto*; Kubota, Toshio*
Nuclear Instruments and Methods in Physics Research B, 477, p.54 - 59, 2020/08
Watanabe, So; Sano, Yuichi; Okada, Makoto*; Matsuura, Haruaki*; Hagura, Naoto*; Kada, Wataru*
Nuclear Instruments and Methods in Physics Research B, 477, p.60 - 65, 2020/08
IBIL and EXAFS analyses were applied on strucutral analysis of Eu complex formed in adsorbent developed for extraction chromatography. Those analyses revealed slight structural difference between adsorbent and solvent systems.
Chrysalidis, K.*; Barzakh, A. E.*; Ahmed, R.*; Andreyev, A. N.; Ballof, J.*; Cubiss, J. G.*; Fedorov, D. V.*; Fedosseev, V. N.*; Fraile, L. M.*; Harding, R. D.*; et al.
Nuclear Instruments and Methods in Physics Research B, 463, p.472 - 475, 2020/01
A number of radiogenically produced dysprosium isotopes have been studied by in-source laser spectroscopy at ISOLDE using the Resonance Ionization Laser Ion Source (RILIS). Isotope shifts were measured relative to Dy in the (gs) (418.8 nm )resonance transition. The electronic factor, F, and mass shift factor, M, were extracted and used for determining the changes in mean-squared charge radii for Dy and Dy for the first time.
Ogawa, Tatsuhiko; Ishikawa, Norito; Kai, Takeshi
Nuclear Instruments and Methods in Physics Research B, 461, p.272 - 275, 2019/12
Heavy ion irradiation, which deposits energy locally in materials, is widely used to study new material modification and radiation-induced damage. So far, radial distribution of energy deposition by heavy ions were well studied. By contrast, depth profile of energy deposition was usually assumed to be uniform but the energy deposition near the incident surface is likely suppressed because the delta-rays are pushed by the incident heavy ions. In this study, spatial distribution of energy deposition in the materials exposed to heavy ions is calculated by using a track structure simulation code RITRACKS. The result showed that energy deposition is suppressed in the first 2 nm of water and that beyond 2 nm is uniform. This result can be applied to the materials other than water by scaling with electron density. It is indicated that reactor fuel pins damaged by fission products and the materials modified by heavy ions receive less energy deposition and less radiation effect in the first 2 nm.
Kitamura, Akane; Yamaki, Tetsuya*; Yuri, Yosuke*; Koshikawa, Hiroshi*; Sawada, Shinichi*; Yuyama, Takahiro*; Usui, Aya; Chiba, Atsuya*
Nuclear Instruments and Methods in Physics Research B, 460, p.254 - 258, 2019/12
Poly(vinylidene-fluoride) (PVDF) film is suitable for investigation of the size of etchable ion tracks because we can clearly judge the finish of the track etching and the surrounding bulk area remains due to the high chemical stability. Thereby we can measure the radius of ion tracks of each ion. In this study, we focused on two irradiation conditions for controlling the size of etchable ion tracks of PVDF films. One was irradiation in an oxygen atmosphere and the other was a fullerene (C) cluster beam irradiation. SEM observation showed that the size of pores became larger by irradiation in an oxygen atmosphere. It was found that the oxidation of ion tracks widened the size of etchable ion tracks. The C irradiation caused larger etchable tracks on the PVDF surface. The result could represent the effect of local and simultaneous collisions by the swift aggregated ions.
Kitamura, Akane; Ishikawa, Norito; Kondo, Keietsu; Yamamoto, Shunya*; Yamaki, Tetsuya*
Nuclear Instruments and Methods in Physics Research B, 460, p.175 - 179, 2019/12
Irradiation at grazing incidence formed chains of multiple hillocks on the surface of strontium titanate (SrTiO) and titanium oxide (TiO). They were observed with an atomic force microscope (AFM), however, the AFM measurement gives resolution errors in a nanometer order due to the curvature of the probe tip. To prevent these errors, a field emission scanning electron microscope (FE-SEM) would be a better option for observation. In this study, we performed SEM observations for the chains of the multiple hillocks. Single crystals of SrTiO and TiO were irradiated with 200 MeV Xe in the tandem accelerator at JAEA-Tokai. It was revealed that a lot of isolated hillocks were formed in a line on these surface. The diameter and the interval of those hillocks are discussed in comparison to AFM observation.
Ha, Yoosung; Takamizawa, Hisashi; Katsuyama, Jinya; Hanawa, Satoshi; Nishiyama, Yutaka
Nuclear Instruments and Methods in Physics Research B, 461, p.276 - 282, 2019/12
Kokubu, Yoko; Fujita, Natsuko; Miyake, Masayasu; Watanabe, Takahiro; Ishizaka, Chika; Okabe, Nobuaki; Ishimaru, Tsuneari; Matsubara, Akihiro*; Nishizawa, Akimitsu*; Nishio, Tomohiro*; et al.
Nuclear Instruments and Methods in Physics Research B, 456, p.271 - 275, 2019/10
JAEA-AMS-TONO has been in operation at the Tono Geoscience Center, Japan Atomic Energy Agency since 1998 and 20 years have passed from the beginning of its utilization. The AMS system is a versatile system based on a 5 MV tandem Pelletron type accelerator. The system has been used to measure carbon-14 (C), beryllium-10 (Be) and aluminium-26 (Al). In addition, the development of measurement of iodine-129 (I) has been started. The main use is measurement of C in geological samples for dating studies in neotectonics and hydrogeology. In order to increase the speed of sample preparation, we introduced the automated graphitization equipment and made a gas-strip line to collect dissolved inorganic carbon in groundwater samples. Measurement of Be and Al has been used for geoscience studies and the detection limit in the measurement of Be was improved by Be-counting suppression. Recently tuning of measurement condition of I has been progressed.
Watanabe, So; Katai, Yuya*; Matsuura, Haruaki*; Kada, Wataru*; Koka, Masashi*; Sato, Takahiro*; Arai, Tsuyoshi*
Nuclear Instruments and Methods in Physics Research B, 450, p.61 - 65, 2019/07
Tsai, P.-E.; Heilbronn, L. H.*; Lai, B.-L.*; Iwata, Yoshiyuki*; Murakami, Takeshi*; Sheu, R.-J.*
Nuclear Instruments and Methods in Physics Research B, 449, p.62 - 70, 2019/06
The secondary neutrons produced from 100- and 230-MeV/nucleon He ions, respectively, stopping in the thick iron, PMMA and water targets are measured by the time of flight method combined with the pulse shape discrimination of liquid scintillators. The experimental data show that the secondary neutrons were contributed from breakup of projectiles, emission from overlap regions of projectile nuclei and target nuclei, and evaporation of projectiles and target nuclei. The measured double-differential thick target neutron yields, angular distributions, and total neutron yields per ion, were benchmarked by the PHITS, FLUKA, and MCNP model calculations. The default models in these codes agree the experimental data well at intermediate-to-large angles in the low-to-intermediate energy range. However, the physics models implemented in PHITS need further improvement for some particular nuclear interaction mechanisms, and this work can be an importance reference for future model development.
Sasajima, Yasushi*; Ajima, Naoki*; Kaminaga, Ryuichi*; Ishikawa, Norito; Iwase, Akihiro*
Nuclear Instruments and Methods in Physics Research B, 440, p.118 - 125, 2019/02
In the present paper, we have extensively analyzed the atomic structures generated by supplying a thermal spike to the single crystal CeO. Our analysis results were compared with the atomic structures obtained by the microscope experiments. Our simulation reproduced the distribution of the numbers of oxygen atoms obtained from the analysis of microscope images. We found that the number of vacancies was increased abruptly immediately after the thermal spike, and the number subsequently dropped through a relaxation process within 3 ps.
Matsunaka, Tetsuya*; Sasa, Kimikazu*; Takahashi, Tsutomu*; Hosoya, Seiji*; Matsumura, Masumi*; Satou, Yukihiko; Shen, H.*; Sueki, Keisuke*
Nuclear Instruments and Methods in Physics Research B, 439, p.64 - 69, 2019/01
no abstracts in English
Matsubara, Akihiro*; Fujita, Natsuko; Ishii, Kunikazu*
Nuclear Instruments and Methods in Physics Research B, 437, p.81 - 86, 2018/12
no abstracts in English
Okubo, Nariaki; Okuno, Yasuki; Kitamura, Akane; Taguchi, Tomitsugu*
Nuclear Instruments and Methods in Physics Research B, 435, p.198 - 202, 2018/11
Accelerator driven system (ADS) adopts the lead-bismuth eutectic (LBE) as both coolant and spallation target. The oxygen concentration control is one of the most important technical developments. Estimation of durability under gamma-ray irradiation for the oxygen sensor is necessary for the integrity evaluation of ADS components. The Zirconia added by Yttria (YSZ) is the main element in oxygen sensor. Effect of gamma-ray irradiation on the mechanical property and structural change for three types of YSZ with 3, 6, 8 mol% Yttria was evaluated by using 4 points bend test, XRD, SEM and Raman spectroscope. The gamma-ray irradiations were conducted at 1 and 2 kGy/h, which corresponded to the LBE activity after 1 year ADS operation. In the cases of 8Y and 6Y, degradation of strength was not measured and the fracture surface did not change the morphology. In the case of 3Y, however, the strength did not change but phase transformation from tetragonal to monoclinic crystal structure was observed in XRD results, depending on the irradiation dose. This implies that the gamma-ray irradiation causes the phase transformation in 3Y-YSZ.
Yamaki, Tetsuya*; Nuryanthi, N.*; Kitamura, Akane; Koshikawa, Hiroshi*; Sawada, Shinichi*; Voss, K.-O.*; Severin, D.*; Tautmann, C.*
Nuclear Instruments and Methods in Physics Research B, 435, p.162 - 168, 2018/11
We used individual single-ion tracks in fluoropolymers with diameters of tens to hundreds of nanometers; chemical etching and ion-track grafting enabled us to develop ion-track and proton-conductive membranes, respectively. In the ion-track membranes of PVDF, strongly-LET-dependent etching was found, so the pore shape as well as the size was exclusively controlled by the track structures. We performed the ion-track grafting of styrene into ETFE to develop nanostructure-controlled proton exchange membranes (PEMs) for applications in PEM fuel cells. Our ion beam technology to develop fluoropolymer-based nanostructures has the potential to apply in the field of filtration processes and fuel cell devices. This would make it possible to provide new microfiltration technology for water treatment, sterilization, petroleum refining and dairy processing.
Nuclear Instruments and Methods in Physics Research B, 419, p.32 - 37, 2018/03
In this study, the Monte Carlo displacement damage calculation method in the Particle and Heavy-Ion Transport code System (PHITS) was improved to calculate displacements per atom (DPA) due to irradiation by electrons and rays. For the damage due to electrons and rays, PHITS simulates electromagnetic cascades using the EGS5 algorithm and calculates DPA values using the recoil energies. A comparison of DPA values calculated by PHITS and the Monte Carlo assisted Classical Method (MCCM) reveals that they were in good agreement for -ray irradiations of silicon and iron at energies that were less than 10 MeV. Above 10 MeV, PHITS can calculate DPA values not only for electrons but also for charged particles produced by photonuclear reactions. For irradiation of 90-cm-thick carbon by protons with energies of more than 30 GeV, the ratio of the secondary electron DPA values to the total DPA values is more than 10% and increases with an increase in incident energy.
Tsai, P.-E.; Lai, B.-L.*; Heilbronn, L. H.*; Sheu, R.-J.*
Nuclear Instruments and Methods in Physics Research B, 416, p.16 - 29, 2018/02
Fifteen thin target experiments were selected for this benchmark study of the neutron production cross sections. The studied cases include a mix combination of C, Ne Ar, Kr, and Xe ions bombarding Li, C, Al, Cu, and Pb target with projectile energies between 135 and 600 MeV/nucleon. The experimental data were compared to the model calculations performed by (1) PHITS version 2.73 with JQMD and GEM model, (2) PHITS version 2.82 with revised JQMD 2.0 and GEM model, (3) FLUKA version 2011.2c with RQMD 2.4 and FLUKA's own de-excitation model, and (4) MCNP6 version 1.0 with LAQGSM 03.03 and GEM2 model. This study provides useful information not only for code users but also for model developers, and it will lead to future improvements of the PHITS - JQMD model for heavy-ion induced reactions, which is important for accelerator facilities, heavy-ion radiotherapy, and space radiation.