Neutron production in the interaction of 200-MeV deuterons with Li, Be, C, Al, Cu, Nb, In, Ta, and Au

Watanabe, Yukinobu*; Sadamatsu, Hiroki*; Araki, Shohei; Nakano, Keita; Kawase, Shoichiro*; Kin, Tadahiro*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; et al.

EPJ Web of Conferences, 284, p.01041_1 - 01041_4, 2023/05

https://doi.org/10.1051/epjconf/202328401041

Intensive fast neutron sources using deuteron accelerators have been proposed for the study of medical RI production, radiation damage for fusion reactor materials, nuclear transmutation of radioactive waste, and so on. Neutron production data from various materials bombarded by deuterons are required for the design of such neutron sources. In the present work, we have conducted a systematic measurement of double-differential neutron production cross sections (DDXs) for a wide atomic number range of targets (Li, Be, C, Al, Cu, Nb, In, Ta, and Au) at an incident energy of 200 MeV in the Research Center for Nuclear Physics (RCNP), Osaka University. A deuteron beam accelerated to 200 MeV was transported to the neutron experimental hall and focused on a thin target foil. Emitted neutrons from the target were detected by two different-size EJ301 liquid organic scintillators located at two distances of 7 m and 20 m, respectively. The neutron DDXs were measured at six angles from 0 to 25). The neutron energy was determined by a conventional time-of-flight (TOF) method. The measured DDXs were compared with theoretical model calculations by the DEUteron-induced Reaction Analysis Code System (DEURACS) and PHITS. The result indicated that the DEURACS calculation provides better agreement with the measured DDXs than the PHITS calculation.

Evaluation and mitigation of reactive ion etching-induced damage in AlGaN/GaN MOS structures fabricated by low-power inductively coupled plasma

Nozaki, Mikito*; Terashima, Daiki*; Yoshigoe, Akitaka; Hosoi, Takuji*; Shimura, Takayoshi*; Watanabe, Heiji*

Japanese Journal of Applied Physics, 59(SM), p.SMMA07_1 - SMMA07_7, 2020/07

https://doi.org/10.35848/1347-4065/ab8f0e

AlGaN/GaN metal-oxide-semiconductor (MOS) structures were fabricated by low-power inductively coupled plasma reactive ion etching and chemical vapor deposition of SiO dielectrics on the etched surfaces, and they were systematically investigated by physical and electrical characterizations in an effort to develop a low-damage recessed gate process. The comprehensive research demonstrates the significant advantages of the proposed low-damage recessed gate process for fabricating next-generation AlGaN/GaN MOS-HFET devices.

Neutron production in deuteron-induced reactions on Li, Be, and C at an incident energy of 102 MeV

Araki, Shohei*; Watanabe, Yukinobu*; Kitajima, Mizuki*; Sadamatsu, Hiroki*; Nakano, Keita*; Kin, Tadahiro*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; et al.

EPJ Web of Conferences, 146, p.11027_1 - 11027_4, 2017/09

https://doi.org/10.1051/epjconf/201714611027

In recently years, deuteron-induced reaction is considered to produce the neutron source for application fields such as radiation damage fusion materials and boron neutron capture therapy. However, as the experimental data are not sufficient at incident energies above 60 MeV, the theoretical models are not validated. Therefore, we measured the double differential cross sections (DDXs) for Li, Be and C at 100 MeV at the Research Center for Nuclear Physics in Osaka University. The DDXs were measured at 6 angles (025 and neutron energy was determined by a time of flight method. Three different-size NE213 liquid organic scintillators located at a distance of 7 m, 24 m and 74 m respectively were adopted as neutron detectors. In the measured DDXs, a broad peak due to deuteron breakup process was observed at approximately half of the deuteron incident energy. The DDXs calculated by PHITS did not reproduce the experimental ones due to lack of theoretical model.

Measurement of double differential (d,xn) cross sections for carbon at an incident energy of 100 MeV

Araki, Shohei*; Watanabe, Yukinobu*; Kitajima, Mizuki*; Sadamatsu, Hiroki*; Nakano, Keita*; Kin, Tadahiro*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; et al.

JAEA-Conf 2016-004, p.159 - 164, 2016/09

https://doi.org/10.11484/jaea-conf-2016-004

Neutron production data from materials such as Li, Be and C bombarded by deuteron are required for design such as the facility of radiation damage for fusion materials and boron neutron capture therapy. However, there is little measurement of double differential neutron production cross sections (DDXs). Therefore, we have planned a series of DDXs measurements at incident energies more than 100 MeV in the Research Center for Nuclear Physics, Osaka University. The experiment was carried out with a carbon target at the neutron Time of Flight (TOF) course in RCNP. Emitted neutrons were detected by three different-size NE213 liquid organic scintillators (5.08 cm, 12.7 cm and 25.4 cm in dimeter and thickness) located at a distance of 7 m, 24 m and 74 m respectively. The neutron detection efficiencies of the detectors were calculated by SCINFUL-QMD code. It turned out that the calculation data fr carbon does not reproduce the experimental data satisfactorily well.

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.

Monopole-driven shell evolution below the doubly magic nucleus Sn explored with the long-lived isomer in Pd

Watanabe, H.*; Lorusso, G.*; Nishimura, Shunji*; Otsuka, T.*; Ogawa, K.*; Xu, Z. Y.*; Sumikama, Toshiyuki*; Sderstrm, P.-A.*; Doornenbal, P.*; Li, Z.*; et al.

Physical Review Letters, 113(4), p.042502_1 - 042502_6, 2014/07

https://doi.org/10.1103/PhysRevLett.113.042502

SiO desorption kinetics of Si(111) surface oxidation studied by real-time photoelectron spectroscopy

Tang, J.*; Nishimoto, Kiwamu*; Ogawa, Shuichi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; Watanabe, Daiki*; Teraoka, Yuden; Takakuwa, Yuji*

e-Journal of Surface Science and Nanotechnology (Internet), 11, p.116 - 121, 2013/11

https://doi.org/10.1380/ejssnt.2013.116

Observation of graphene-on-diamond formation studied by real-time photoelectron spectroscopy

Ogawa, Shuichi*; Yamada, Takatoshi*; Ishizuka, Shinji*; Watanabe, Daiki*; Yoshigoe, Akitaka; Hasegawa, Masataka*; Teraoka, Yuden; Takakuwa, Yuji*

Hyomen Kagaku, 33(8), p.449 - 454, 2012/08

https://doi.org/10.1380/jsssj.33.449

Graphene-on-insulator structures are required for fabrication of the graphene transistor. Diamond has been attracted as the substrate for graphene growth because it has a larger band gap and break down voltage compared with SiC. The detail of graphitization on a diamond surface has not been clarified yet because the nondestructive evaluation for graphene-on-diamond (GOD) structure was hard. In this study, we have developed an evaluation method of GOD based on the photoemission spectroscopy using synchrotron radiation focusing the shift of photoelectron spectra due to band bending. We can clearly determine the graphitization temperature on the diamond C(111) surface as approximately 1120 K, which is lower than that on an SiC substrate. It is also confirmed from C 1s photoelectron spectra, there is the buffer layer at the interface between the grapheme layer and the diamond substrate.

Upgrades of DARWIN; A Dose and spectrum monitoring system applicable to various types of radiation over wide energy ranges

Sato, Tatsuhiko; Satoh, Daiki; Endo, Akira; Shigyo, Nobuhiro*; Watanabe, Fusao*; Sakurai, Hiroki*; Arai, Yoichi*

Nuclear Instruments and Methods in Physics Research A, 637(1), p.149 - 157, 2011/05

https://doi.org/10.1016/j.nima.2011.02.027

A dose and spectrum monitoring system applicable to neutrons, photons and muons over wide ranges of energy, designated as DARWIN, has been developed for radiological protection in high-energy accelerator facilities. The performance of the upgraded DARWIN was examined in various radiation fields, including an operational field in J-PARC. The experiments revealed that the dose rates and spectra measured by the upgraded DARWIN are quite reasonable, even in radiation fields with peak structures in terms of both spectrum and time variation. These results clearly demonstrate the usefulness of DARWIN for improving radiation safety in high-energy accelerator facilities.

Radiation tolerance linked to anhydrobiosis in

Nakahara, Yuichi*; Watanabe, Masahiko*; Kikawada, Takahiro*; Fujita, Akihiko*; Horikawa, Daiki*; Okuda, Takashi*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Wada, Seiichi*; et al.

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 113, 2008/03

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2007-060.pdf

We have shown that anhydrobiotic larvae of have higher tolerance against both high linear energy transfer (LET) radiation than hydrated larvae. We therefore examined effects of high-LET radiation on four kinds of larvae: (1) normal hydrated (intact) larva, (2) intermediates between the anhydrobiotic and normal hydrated state, (3) almost completely dehydrated (anhydrobiotic) larvae, and (4) immediately rehydrated larvae that are assumed to have a similar molecular profile to anhydrobiotic larvae. The intermediates and immediately rehydrated larvae survived longer after high-LET radiation than intact larvae, indicating that radiation tolerance could be enhanced even in hydrated larvae. Physiological changes toward anhydrobiosis, e.g. accumulation of protectants or increasing damage repair capacity, correlate with improved radiation tolerance in hydrated larvae.