Frost formation on automobile heat exchanger

Kuroda, Rikuto*; Matsumoto, Ryosuke*; Oda, Yutaka*; Fukai, Ao*; Kida, Kenta*; Iikura, Hiroshi; Kurita, Keisuke

2022-Nendo Nihon Reito Kucho Gakkai Nenji Taikai Koen Rombunshu, 6 Pages, 2022/09

Frost formation causes the thermal resistance for the heat transfer performance on the heat exchanger. In this study, the frost distribution on the heat exchanger used in the automobile air conditioning system was evaluated by neutron radiography imaging. At the initial stage of the frost formation, the frost formed in the upstream side of the heat exchanger. The frost deposited in the downstream region of the heat exchanger as time proceeds.

High-temperature antiferromagnetism in Yb based heavy fermion systems proximate to a Kondo insulator

Suzuki, Shintaro*; Takubo, Ko*; Kuga, Kentaro*; Higemoto, Wataru; Ito, Takashi; Tomita, Takahiro*; Shimura, Yasumichi*; Matsumoto, Yosuke*; Bareille, C.*; Wadachi, Hiroki*; et al.

Physical Review Research (Internet), 3(2), p.023140_1 - 023140_12, 2021/05

https://doi.org/10.1103/PhysRevResearch.3.023140

We report our experimental discovery of the transition temperature reaching 20 K in a Yb-based compound at ambient pressure. The Mn substitution at the Al site in an intermediate valence state of -YbAlB not only induces antiferromagnetic transition at a record high temperature of 20 K but also transforms the heavy-fermion liquid state in -YbAlB into a highly resistive metallic state proximate to a Kondo insulator.

Numerical interpretation of hydrogen thermal desorption spectra for iron with hydrogen-enhanced strain-induced vacancies

Ebihara, Kenichi; Sugiyama, Yuri*; Matsumoto, Ryosuke*; Takai, Kenichi*; Suzudo, Tomoaki

Metallurgical and Materials Transactions A, 52(1), p.257 - 269, 2021/01

https://doi.org/10.1007/s11661-020-06075-7

We simulated the thermal desorption spectra of a small-size iron specimen to which was applied during charging with hydrogen atoms using a model incorporating the behavior of vacancies and vacancy clusters. The model considered up to vacancy clusters , which is composed of nine vacancies and employed the parameters based on atomistic calculations, including the H trapping energy of vacancies and vacancy clusters that we estimated using the molecular static calculation. As a result, we revealed that the model could, on the whole, reproduced the experimental spectra except two characteristic differences, and also the dependence of the spectra on the aging temperature. By examining the cause of the differences, the possibilities that the diffusion of clusters of and is slower than the model and that vacancy clusters are generated by applying strain and H charging concurrently were indicated.

Characterization of the PTW 34031 ionization chamber (PMI) at RCNP with high energy neutrons ranging from 100 - 392 MeV

Theis, C.*; Carbonez, P.*; Feldbaumer, E.*; Forkel-Wirth, D.*; Jaegerhofer, L.*; Pangallo, M.*; Perrin, D.*; Urscheler, C.*; Roesler, S.*; Vincke, H.*; et al.

EPJ Web of Conferences, 153, p.08018_1 - 08018_5, 2017/09

https://doi.org/10.1051/epjconf/201715308018

At CERN, gas-filled ionization chambers PTW-34031 (PMI) are commonly used in radiation fields including neutrons, protons and -rays. A response function for each particle is calculated by the radiation transport code FLUKA. To validate a response function to high energy neutrons, benchmark experiments with quasi mono-energetic neutrons have been carried out at RCNP, Osaka University. For neutron irradiation with energies below 200 MeV, very good agreement was found comparing the FLUKA simulations and the measurements. In addition it was found that at proton energies of 250 and 392 MeV, results calculated with neutron sources underestimate the experimental data due to a non-negligible gamma component originating from the target Li(p,n)Be reaction.

Neutron spectrometry and dosimetry in 100 and 300 MeV quasi-mono-energetic neutron field at RCNP, Osaka University, Japan

Mares, V.*; Trinkl, S.*; Iwamoto, Yosuke; Masuda, Akihiko*; Matsumoto, Tetsuro*; Hagiwara, Masayuki*; Satoh, Daiki; Yashima, Hiroshi*; Shima, Tatsushi*; Nakamura, Takashi*

EPJ Web of Conferences, 153, p.08020_1 - 08020_3, 2017/09

https://doi.org/10.1051/epjconf/201715308020

To validate response of an extended range Bonner Sphere Spectrometer (ERBSS) with He proportional counter, neutron energy spectra were measured using an ERBSS in the quasi-mono-energetic neutron field at the Research Center for Nuclear Physics (RCNP). Using 100 MeV and 296 MeV proton beams, neutron fields with nominal peak energies of 96 MeV and 293 MeV were generated via Li(p,n)Be reactions. The energy spectra were measured at a distance of 35 m from the target. To deduce the corresponding neutron spectra from thermal to the nominal maximum energy, the ERBSS data were unfolded using the MSANDB unfolding code. At high energies, the neutron spectra were also measured by means of the TOF method using NE213 organic liquid scintillators. The agreement between ERBSS and TOF neutron spectra above 5 MeV is very good. Comparison in terms of ambient dose equivalent, H(10) between ERBSS and TOF values for both proton energies shows very good agreement.

Characterization of high-energy quasi-monoenergetic neutron energy spectra and ambient dose equivalents of 80-389 MeV Li(p,n) reactions using a time-of-flight method

Iwamoto, Yosuke; Hagiwara, Masayuki*; Satoh, Daiki; Araki, Shohei*; Yashima, Hiroshi*; Sato, Tatsuhiko; Masuda, Akihiko*; Matsumoto, Tetsuro*; Nakao, Noriaki*; Shima, Tatsushi*; et al.

Nuclear Instruments and Methods in Physics Research A, 804, p.50 - 58, 2015/12

https://doi.org/10.1016/j.nima.2015.09.045

We have measured neutron energy spectra for the 80, 100 and 296 MeV proton incident reactions at the RCNP cyclotron facility using time-of-flight method. The neutron energy spectrum consisted of the peak and continuum parts and the peak intensity was 0.9-1.1 10 neutrons/sr/C. The ratio of peak intensity of the spectrum to the total intensity was between 0.38 and 0.48. To consider the correction required to derive a response in the peak region from the measured total response for neutron monitors, we proposed the subtraction method using energy spectra between 0 and 25. The normalizing factor k against the 25 neutron fluence that equalizes the 0 neutron fluence in the continuum region was from 0.74 to 1.02. With our previous results, we have obtained data for characterization of monoenergetic neutron field for the Li(p,n) reaction with 80389 MeV protons at the RCNP cyclotron facility.

Magnetic and electronic properties of URuSi revealed by comparison with nonmagnetic references ThRuSi and LaRuSi

Emi, Naoya*; Hamabata, Ryosuke*; Nakayama, Daisuke*; Miki, Toshihiro*; Koyama, Takehide*; Ueda, Koichi*; Mito, Takeshi*; Kohori, Yo*; Matsumoto, Yuji*; Haga, Yoshinori; et al.

Journal of the Physical Society of Japan, 84(6), p.063702_1 - 063702_4, 2015/06

https://doi.org/10.7566/JPSJ.84.063702

Characterization of quasi-monoenergetic neutron source using 137, 200, 246 and 389 MeV Li(p,n) reactions

Iwamoto, Yosuke; Hagiwara, Masayuki*; Iwase, Hiroshi*; Yashima, Hiroshi*; Satoh, Daiki; Matsumoto, Tetsuro*; Masuda, Akihiko*; Pioch, C.*; Mares, V.*; Shima, Tatsushi*; et al.

Progress in Nuclear Science and Technology (Internet), 4, p.657 - 660, 2014/04

https://doi.org/10.15669/pnst.4.657

The authors measured the neutron energy spectra of the proton incident reaction on the lithium target with 137, 200, 246 and 389 MeV protons at several angles (0, 2.5, 5, 10, 15, 20, 25 and 30), using a time-of-flight (TOF) method employing organic scintillators NE213 at the Research Center for Nuclear Physics (RCNP) of Osaka University. For the neutron energy spectrum at 0, the ratio of the peak neutron intensity to the total one varied between 0.4 and 0.5 depending on the incident energy. In order to consider the correction required to derive the response in the peak region from the measured total response for high-energy neutron detectors, the authors showed the subtractions of H*(10) obtained at larger angles from the 0 data in the continuum part. It was found that subtracting the dose equivalent at about 22 from the 0 data reduces the continuum component most efficiency.

Shielding benchmark experiment using hundreds of MeV quasi-monoenergetic neutron source by a large organic scintillator

Hagiwara, Masayuki*; Iwase, Hiroshi*; Iwamoto, Yosuke; Satoh, Daiki; Matsumoto, Tetsuro*; Masuda, Akihiko*; Yashima, Hiroshi*; Nakane, Yoshihiro; Nakashima, Hiroshi; Sakamoto, Yukio; et al.

Progress in Nuclear Science and Technology (Internet), 4, p.327 - 331, 2014/04

https://doi.org/10.15669/pnst.4.327

We have developed several hundreds of MeV p-Li quasi-monoenergetic neutron fields in the Research Center for Nuclear Physics (RCNP), Osaka University, Japan. In this study, we extended the measurements to higher energy with a p-Li quasi-monoenergetic neutron source, which was produced from a 1.0-cm-thick lithium target bombarded with 246 and 389 MeV protons, using a larger NE213 scintillator of 25.4-cm in diameter and 25.4-cm in thickness. The large NE213 have good energy resolution for high energy neutrons, because it can stop recoil protons up to 180 MeV. The measured data are compared with the Monte-Carlo codes (PHITS with JENDL-HE data library) in the energy spectra, time spectra and the attenuation length of the peak neutrons. This comparison shows good agreement between experiments and calculations. The attenuation length estimated from the well-fitted curves with single exponential form will be useful for the practical shielding design of high energy accelerator facilities.

Spin-nematic interaction in the multiferroic compound BaCoGeO

Soda, Minoru*; Matsumoto, Masashige*; Mnsson, M.*; Kawamura, Seiko; Nakajima, Kenji; Shiina, Ryosuke*; Masuda, Takatsugu*

Physical Review Letters, 112(12), p.127205_1 - 127205_5, 2014/03

https://doi.org/10.1103/PhysRevLett.112.127205

We demonstrate the existence of the spin-nematic interactions in an easy-plane type antiferromagnet BaCoGeO by exploring the magnetic anisotropy and spin dynamics. The combination of neutron scattering and magnetic susceptibility measurements reveals that the origin of the in-plane anisotropy is an antiferro-type interaction of the spin-nematic operator. The relation between the nematic operator and the electric polarization in the ligand symmetry of this compound is presented. The introduction of the spinnematic interaction is useful to understand the physics of spin and electric dipole in multiferroic compounds.