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Journal Articles

Study of charged particle activation analysis, 2; Determination of boron concentration in human blood samples

Ikebe, Yurie*; Oshima, Masumi*; Bamba, Shigeru*; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Toyoshima, Atsushi*; Bi, C.*; Seto, Hirofumi*; Amano, Hikaru*; et al.

Applied Radiation and Isotopes, 164, p.109106_1 - 109106_7, 2020/10

https://doi.org/10.1016/j.apradiso.2020.109106
 Times Cited Count：2 Percentile：17.88(Chemistry, Inorganic & Nuclear)

Boron Neutron Capture Therapy (BNCT) is a radiotherapy for the treatment of intractable cancer. In BNCT precise determination of $$^{10}$$B concentration in whole blood sample before neutron irradiation is crucial for control of the neutron irradiation time and the neutron dosimetry. We have applied the Charged Particle Activation Analysis (CPAA) to non-destructive and accurate determination of $$^{10}$$B concentration in whole blood sample. The experiment was performed at JAEA Tandem Accelerator using an 8 MeV proton beam. The 478 keV $$gamma$$ ray of $$^{7}$$Be produced in the $$^{10}$$B(p,$$alpha$$)$$^{7}$$Be reaction was used to quantify the $$^{10}$$B, and $$gamma$$ rays of $$^{56}$$Co originating from the reaction with Fe in blood was used to normalize the $$gamma$$-ray intensity. The results demonstrated that the present CPAA method can be applied to the determination of the $$^{10}$$B concentration in the blood sample.

Journal Articles

Ground-state configuration of the $$N=157$$ nucleus $$^{259}$$No

Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Haba, Hiromitsu*; Ichikawa, Takatoshi*; Ishii, Yasuo; Toyoshima, Atsushi; Ishii, Tetsuro; Nishinaka, Ichiro; Nagame, Yuichiro; et al.

Physical Review C, 87(1), p.014332_1 - 014332_6, 2013/01

https://doi.org/10.1103/PhysRevC.87.014332
 Times Cited Count：6 Percentile：41.96(Physics, Nuclear)

The spin-parity and neutron configuration of the ground state of $$^{259}$$No have been identified through $$alpha$$-decay spectroscopy. The $$^{259}$$No is the nucleus with the largest neutron number whose spin-parities and single-particle configurations have ever been identified. The neutron 9/2$$^{+}$$[615] configuration was assigned to the ground state of $$^{259}$$No as well as to the 231.4 keV level in $$^{255}$$Fm. This allowed us to establish energy spacings and order of the neutron single-particle orbitals in such heaviest nuclear region. The appearance of the 9/2$$^{+}$$[615] ground state at $$N$$=157 implies that the order of the neutron orbitals between the $$N$$=152 and 162 deformed shell gaps should change considerably with increasing neutron number.

Journal Articles

Time-evolution of thermal oxidation on high-index silicon surfaces; Real-time photoemission spectroscopic study with synchrotron radiation

Ono, Shinya*; Inoue, Kei*; Morimoto, Masahiro*; Arae, Sadanori*; Toyoshima, Hiroaki*; Yoshigoe, Akitaka; Teraoka, Yuden; Ogata, Shoichi*; Yasuda, Tetsuji*; Tanaka, Masatoshi*

Surface Science, 606(21-22), p.1685 - 1692, 2012/11

https://doi.org/10.1016/j.susc.2012.07.011
 Times Cited Count：9 Percentile：36.69(Chemistry, Physical)

Journal Articles

Analysis of bonding structure of ultrathin films of oligothiophene molecules grown on passivated silicon surfaces

Toyoshima, Hiroaki*; Hiraga, Kenta*; Ono, Shinya*; Tanaka, Masatoshi*; Ozawa, Kenichi*; Mase, Kazuhiko*; Hirao, Norie; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Baba, Yuji

Photon Factory Activity Report 2011, Part B, P. 102, 2012/00

The knowledge of the interaction between organic molecules and semiconductor surfaces plays an important role in adapting organic semiconductors into the semiconductor technology. In the present study, the process of $$alpha$$-sexithiophene ($$alpha$$-6T) thin layer formation on passivated silicon (Si) surfaces has been investigated in-situ by means of PES, angle-depended NEXAFS (near-edge X-ray absorption fine-structure), SDRS, and RDS. For water-adsorbed Si(001), it was found that the majority of $$alpha$$-6T molecules are standing on the substrate. Above 3 nm, most of molecules are standing and constitute well ordered islands or films. For ethylene adsorbed Si(001) on the contrary, some of $$alpha$$-6T molecules are flat-lying, resulting in less prominent orientation. Thus, the orientation of molecules depends on the method of passivation, which opens the possibility of controlling the molecular orientation by the surface modification.

Journal Articles

Characterization of initial oxidation process on high-index silicon surfaces by real-time photoemission spectroscopy

Ono, Shinya*; Inoue, Kei*; Morimoto, Masahiro*; Arae, Sadanori*; Toyoshima, Hiroaki*; Yoshigoe, Akitaka; Teraoka, Yuden; Ogata, Shoichi*; Yasuda, Tetsuji*; Tanaka, Masatoshi*

Shingaku Giho, 111(114), p.23 - 27, 2011/07

https://cir.nii.ac.jp/crid/1571417127023066880

The initial oxidation on high-index silicon surfaces with (113) and (120) orientations at 820 K has been investigated by real-time X-ray photoemission spectroscopy (Si 2p and O 1s) using 687 eV photons. The time evolutions of the Si$$^{n+}$$ (n=1-4) components in the Si 2p spectrum indicate that the Si$$^{2+}$$ state is suppressed on high-index surfaces compared with Si(001). The O 1s state consists of two components, a low-binding-energy component (LBC) and a high-binding-energy component (HBC). It is suggested that the O atom in strained Si-O-Si contributes to the LBC component. The reaction rates are slower on high-index surfaces compared with that on Si(001).

Oral presentation

The Structure of $$alpha$$-sexithiophene ultra-thin films on passivated Si(001) surfaces

Hiraga, Kenta*; Toyoshima, Hiroaki*; Ono, Shinya*; Hirao, Norie; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Baba, Yuji; Mukai, Kozo*; Yoshinobu, Jun*; Tanaka, Masatoshi*

no journal, , 

It is important to control orientation structure and electric property at the interface between organic semiconductor molecule and surfaces of semiconductor substrates in order for the development of commercial base organic transistors and solar cells. In the present work, we have investigated the surface reflection spectroscopy (RDS, SRDS), S-1s angle resolved near-edge X-ray absorption fine-structure (NEXAFS), and UPS for $$alpha$$-sexithiophene ($$alpha$$-6T) ultra-thin films with a variety of thickness from 0.25 to 1.0 nm. The results of RDS and SDRS, and NEXAFS gave the information on orientation structure of the $$alpha$$-6T molecules. In contrast, UPS gave the uniformity of the thin films. We report on how orientation structures and condensed structures are changed depending on the method of passivation and the film thickness.

Oral presentation

$$alpha$$-$$gamma$$ spectroscopy of $$^{259}$$No

Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Ishii, Yasuo; Toyoshima, Atsushi; Ishii, Tetsuro; Nishinaka, Ichiro; Nagame, Yuichiro; Kasamatsu, Yoshitaka; Shibata, Michihiro*; et al.

no journal, , 

$$alpha$$-$$gamma$$ coincidence spectroscopy for the $$alpha$$ decay of $$^{259}$$No has been performed at the JAEA tandem accelerator facility to study nuclear shell structure of superheavy nuclei. The decay scheme of $$^{259}$$No has been established for the first time, and spin-parity and neutron single-particle configuration of the ground state of $$^{259}$$No have been identified. It was found that many theoretical calculations could not reproduce the ground-state configuration of the nuclei with 157 neutrons, which implies that the deformation of the nuclei with more than 157 neutrons would be substantially different from theoretical predictions.

Oral presentation

Real-time photoemission spectroscopy measurements of high-index Si surfaces

Ono, Shinya*; Inoue, Kei*; Morimoto, Masahiro*; Arae, Sadanori*; Toyoshima, Hiroaki*; Yoshigoe, Akitaka; Teraoka, Yuden; Ogata, Shoichi*; Yasuda, Tetsuji*; Tanaka, Masatoshi*

no journal, , 

A 3$$times$$2 reconstruction surface is made at the Si(113) surface. The oxidation processes by O$$_{2}$$ molecules were observed by real-time photoelectron spectroscopy. All experiments were conducted using the JAEA surface chemistry experimental station at BL23SU in the SPring-8. Time evolution of Si2p and O1s photoelectron spectra were observed. A suboxide Si$$^{3+}$$ component ratio increased during oxidation as the Si(110) surface case. Both of Si(110) and (113) surfaces have a pentagon structure on the reconstruction surface. The increase of Si$$^{3+}$$ component in the oxidation of the Si(11n) surface can be understood as competing formation of an SiO$$_{2}$$/Si(001) type interface and an SiO$$_{2}$$/Si(111) type interface.

Oral presentation

Structure of $$alpha$$-sexithiophene thin films grown on semiconductor surface studied by near-edge X-ray absorption fine structure

Hiraga, Kenta*; Toyoshima, Hiroaki*; Nakajima, Junki*; Tanaka, Hiroya*; Ono, Shinya*; Tanaka, Masatoshi*; Sekiguchi, Tetsuhiro; Hirao, Norie; Shimoyama, Iwao; Baba, Yuji

no journal, , 

It is important to investigate structure of organic thin films grown on semiconductor surfaces for fabrication of the organic semiconductors.

Oral presentation

Spontaneous fission measurements for neutron-rich Fm isotopes using an $$^{254}$$Es target

Asai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi; Tomitsuka, Tomohiro; Chiera, N. M.; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro; Nishio, Katsuhisa; et al.

no journal, , 

Spontaneous fissions of neutron-rich heavy actinide isotopes $$^{256}$$Fm, $$^{258}$$Fm, and $$^{259}$$Lr have been measured at the JAEA Tandem accelerator facility. $$^{256}$$Fm and $$^{258}$$Fm were produced in a multinucleon transfer reaction with an $$^{18}$$O beam and an extremely rare $$^{254}$$Es target with a half-life of 276 days. Reaction products were mass-separated with an on-line isotope separator (ISOL). A transition between the typical asymmetric mass distribution and a very sharp symmetric one was clearly observed between $$^{256}$$Fm and $$^{258}$$Fm, while the spontaneous fission of $$^{259}$$Lr was found to exhibit mixture of three different fission modes.

Oral presentation

Alpha-$$gamma$$ spectroscopy of N = 155 and 157 nuclei using a gas-jet transport technique

Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Ishii, Yasuo; Toyoshima, Atsushi; Ishii, Tetsuro; Nishinaka, Ichiro; Nagame, Yuichiro; Kasamatsu, Yoshitaka; Haba, Hiromitsu*; et al.

no journal, , 

Alpha-$$gamma$$ spectroscopy of $$^{257,259}$$No and $$^{261}$$Rf nuclei with the neutron number N=155 and 157 have been performed for the first time at the JAEA tandem accelerator using a gas-jet transport technique. Spin-parities and neutron single-particle configurations of ground states of these nuclei as well as excited states in their daughter nuclei have been identified. On the basis of these experimental results, energy spacings and order of neutron single-particle orbitals between N=153 and 161 were evaluated. The result implies that the order of the neutron orbitals between N=153 and 161 should be inverted between lighter nuclei around $$^{253}$$Fm and heavier ones around $$^{269}$$Hs.

Oral presentation

Spontaneous fission measurements for neutron-rich Fm and Lr isotopes using $$^{254}$$Es target

Asai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi*; Tomitsuka, Tomohiro*; Chiera, N. M.*; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro*; Nishio, Katsuhisa; et al.

no journal, , 

Neutron-rich fermium isotopes $$^{256}$$Fm and $$^{258}$$Fm and lawrencium isotope $$^{259}$$Lr were produced in the multinucleon transfer reaction on $$^{254}$$Es target with heavy-ion beam and in the heavy-ion fusion reaction on $$^{248}$$Cm target with $$^{15}$$N beam, respectively. Reaction products were mass-separated with an on-line isotope separator (ISOL), and spontaneous fission (SF) of these isotopes were measured. It was found that the mass distribution of the SF of $$^{256}$$Fm was asymmetric, while that of $$^{258}$$Fm was sharp symmetric, which confirmed the previous experimental results. On the other hand, the SF of $$^{259}$$Lr seemed to contain both symmetric and asymmetric mass distributions. On the basis of the present results of the mass and total kinetic energy distributions, we discussed the mechanism of fission for these isotopes.

Oral presentation

Real-time photoemission spectroscopy measurements of initial oxidation process of high-index Si surfaces

Ono, Shinya*; Inoue, Kei*; Morimoto, Masahiro*; Arae, Sadanori*; Toyoshima, Hiroaki*; Yoshigoe, Akitaka; Teraoka, Yuden; Ogata, Shoichi*; Yasuda, Tetsuji*; Tanaka, Masatoshi*

no journal, , 

no abstracts in English

Oral presentation

Spontaneous fission measurements for nuclei around neutron-rich Fm region produced by using an $$^{254}$$Es target

Asai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi; Tomitsuka, Tomohiro; Chiera, N. M.; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro; Nishio, Katsuhisa; et al.

no journal, , 

Spontaneous fissions of $$^{256}$$Fm, $$^{258}$$Fm, and $$^{259}$$Lr have been measured using an $$^{254}$$Es target at the JAEA Tandem Accelerator Facility. These three nuclei show different fission properties: the asymmetric fission, the high total-kinetic-energy (TKE) symmetric fission, and the low TKE symmetric fission, and the mechanisms of these three fissions should be very different. It is of great interest to elucidate how these differences occur. We have produced $$^{256,258}$$Fm in multinucleon-transfer reactions with a $$^{254}$$Es target and $$^{18}$$O projectiles, and produced $$^{259}$$Lr in the $$^{248}$$Cm($$^{15}$$N,4n) fusion-evaporation reaction. The reaction products were mass-separated with a gas-jet-coupled on-line isotope separator, and were delivered into a rotating wheel alpha- and fission-fragment detection system. By comparing the mass and TKE distributions deduced from the present experimental data, we will discuss the differences in fission mechanism among $$^{256}$$Fm, $$^{258}$$Fm, and $$^{259}$$Lr.

Oral presentation

Spontaneous fission studies for neutron-rich Fm and Lr isotopes

Asai, Masato; Tsukada, Kazuaki; Hirose, Kentaro; Toyoshima, Atsushi*; Tomitsuka, Tomohiro*; Chiera, N. M.*; Ito, Yuta; Makii, Hiroyuki; Nagame, Yuichiro*; Nishio, Katsuhisa; et al.

no journal, , 

We have studied spontaneous fission of neutron-rich Fm and Lr isotopes. The neutron-rich Fm isotopes were produced with the $$^{254}$$Es target and the $$^{18}$$O beam delivered by the JAEA tandem accelerator. The neutron-rich Lr isotope were produced with the $$^{248}$$Cm target and the $$^{15}$$N beam. Reaction products were mass-separated with an on-line isotope separator (ISOL), which enabled us to obtain non-contaminated samples and to measure fission fragments precisely. From the deduced fission-fragment mass and total kinetic energy distributions, we have obtained a new insight into the competition between the symmetric and asymmetric fission which is characteristic in this neutron-rich region.

Oral presentation

$$gamma$$-ray spectroscopy of the heaviest nuclei at JAEA tandem accelerator

Asai, Masato; Tsukada, Kazuaki; Sakama, Minoru*; Ishii, Yasuo; Toyoshima, Atsushi; Ishii, Tetsuro; Nishinaka, Ichiro; Nagame, Yuichiro; Kasamatsu, Yoshitaka; Haba, Hiromitsu*; et al.

no journal, , 

Recent results on the $$gamma$$-ray spectroscopic studies of the heaviest nuclei at the JAEA tandem accelerator are reviewed. The nuclei $$^{257}$$No, $$^{259}$$No, and $$^{261}$$Rf studied in the present work are the heaviest and the most neutron-rich nuclei that $$gamma$$-ray spectroscopic studies have ever been performed for. Excited-state energies, spin-parities, and single-particle configurations of those nuclei and their daughters have been established by means of $$alpha$$-$$gamma$$ coincidence spectroscopy. The deduced energy spacings and order of neutron single-particle orbitals suggest that the higher-order deformations play an important role in level structure of the superheavy nuclei in this region.

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