Measurement of neutron scattering cross section of nano-diamond with particle diameter of approximately 5 nm in energy range of 0.2 meV to 100 meV

Teshigawara, Makoto; Tsuchikawa, Yusuke*; Ichikawa, Go*; Takata, Shinichi; Mishima, Kenji*; Harada, Masahide; Oi, Motoki; Kawamura, Yukihiko*; Kai, Tetsuya; Kawamura, Seiko; et al.

Nuclear Instruments and Methods in Physics Research A, 929, p.113 - 120, 2019/06

https://doi.org/10.1016/j.nima.2019.03.038

A nano-diamond is an attractive neutron reflection material below cold neutron energy. The total neutron cross section of a nano-diamond was derived from a neutron transmission measurement over the neutron energy range of 0.2 meV to 100 meV because total neutron cross section data were not available. The total cross section of a nano-diamond with particle size of approximately 5 nm increased with a decrease in neutron energy to 0.2 meV. It was approximately two orders of magnitude larger than that of graphite at 0.2 meV. The contribution of inelastic scattering to the total cross section was to be shown negligible small at neutron energies of 1.2, 1.5, 1.9, 2.6, and 5.9 meV in the inelastic neutron scattering measurement. Moreover, small-angle neutron scattering measurements of the nano-diamond showed a large scattering cross section in the forward direction for low neutron energies.

First ionization potential of the heaviest actinide lawrencium, element 103

Sato, Tetsuya; Asai, Masato; Borschevsky, A.*; Stora, T.*; Sato, Nozomi*; Kaneya, Yusuke; Tsukada, Kazuaki; Dllmann, C. E.*; Eberhardt, K.*; Eliav, E.*; et al.

EPJ Web of Conferences, 131, p.05001_1 - 05001_6, 2016/12

https://doi.org/10.1051/epjconf/201613105001

Ionization efficiency in a surface ionization process depends on the first ionization potential of the atom. Based on the dependence, the ionization potential of the atom can be determined. We measured ionization efficiencies of fermium, einsteinium, mendelevium, and lawrencium by using a newly developed gas-jet coupled surface ion-source. The ionization potential of the elements have not been determined so far due to their low production rates and/or their short half-lives. Based on a relationship between the ionization efficiency and the ionization potential obtained via measurements of short-lived lanthanide isotopes, the ionization potentials of these actinide elements have been successfully determined.

Measurement of the first ionization potential of lawrencium, element 103

Sato, Tetsuya; Asai, Masato; Borschevsky, A.*; Stora, T.*; Sato, Nozomi; Kaneya, Yusuke; Tsukada, Kazuaki; Dllmann, Ch. E.*; Eberhardt, K.*; Eliav, E.*; et al.

Nature, 520(7546), p.209 - 211, 2015/04

https://doi.org/10.1038/nature14342

Ionization efficiency in a surface ionization process depends on the first ionization potential of the atom. Based on the dependence, the ionization potential of the atom can be determined. We successfully measured ionization efficiencies of lawrencium (Lr, =103) using a gas-jet coupled surface ion-source. The ionization potential of Lr has not been determined owing to its low production rate and its short half-life. Based on a relationship between the ionization efficiency and the ionization potential obtained via measurements of short-lived lanthanide isotopes, the ionization potential of Lr was determined.

Production of Lr in the Cf + B, Am + O, and Cm + N reactions

Sato, Nozomi; Sato, Tetsuya; Asai, Masato; Toyoshima, Atsushi; Tsukada, Kazuaki; Li, Z.*; Nishio, Katsuhisa; Nagame, Yuichiro; Schdel, M.; Haba, Hiromitsu*; et al.

Radiochimica Acta, 102(3), p.211 - 219, 2014/03

https://doi.org/10.1515/ract-2014-2142

Production cross-sections of the isotope Lr in the Cf + B, Am + O, and Cm + N reactions were measured using a He/KCl gas-jet transport system and a rotating wheel -particle detection apparatus. The -particle energy of Lr was distributed from 8.3 to 8.7 MeV and its half-life, , was measured to be s. The maximum cross sections in the Cf(B, 4)Lr and Am(O, 5)Lr reactions were determined to be nb at the beam energy of 63 MeV and nb at 96 MeV, respectively. In the Cm(N, 6)Lr reaction, the cross section was measured to be nb at 91 MeV.

Production of Lr in the Cm + N reaction

Sato, Nozomi; Sato, Tetsuya; Asai, Masato; Toyoshima, Atsushi; Tsukada, Kazuaki; Li, Z.*; Nishio, Katsuhisa; Nagame, Yuichiro; Schdel, M.; Haba, Hiromitsu*; et al.

RIKEN Accelerator Progress Report, Vol.46, P. 237, 2013/00

http://www.rarf.riken.jp/researcher/APR/Document/ProgressReport_vol_46.pdf

Due to the strong relativistic effects, the weakly-bound outermost electron results in a significantly low first ionization potential (IP) of Lr as compared with its neighboring heavy actinides. The isotope Lr, with a relatively long half-life of 27 s, is the suitable candidates for the IP measurement of Lr through the surface ionization method. In the present study, we measured the cross section of the Cm(N, 6)Lr reaction to evaluate the production rate of Lr. A Cm target with 960 60 g/cm thickness was bombarded with a N beam from the RIKEN AVF Cyclotron. The beam energy was 91 MeV in the middle of the target. The average beam intensity was 1.2 particle-A. Reaction products were transported to the rotating wheel -particle detection system with a He/KCl gas-jet system. The Lr cross section of 271 nb was calculated based on the -particle events between 8.3 and 8.7 MeV.

Lifetime measurements for the first 2 states in Gd populated by the decay of Eu

Nagae, Daisuke*; Ishii, Tetsuro; Takahashi, Ryuta*; Asai, Masato; Makii, Hiroyuki; Osa, Akihiko; Sato, Tetsuya; Ichikawa, Shinichi; Shimizu, Yoshifumi*; Shoji, Takuya*

AIP Conference Proceedings 1224, p.156 - 160, 2010/04

https://doi.org/10.1063/1.3431410

Decay properties of Bh and Db produced in the Cm + Na reaction

Morita, Kosuke*; Morimoto, Koji*; Kaji, Daiya*; Haba, Hiromitsu*; Ozeki, Kazutaka*; Kudo, Yuki*; Sato, Nozomi*; Sumita, Takayuki*; Yoneda, Akira*; Ichikawa, Takatoshi*; et al.

Journal of the Physical Society of Japan, 78(6), p.064201_1 - 064201_6, 2009/06

https://doi.org/10.1143/JPSJ.78.064201

Decay properties of an isotope Bh and its daughter nucleus Db produced by the Cm(Na,5) reaction were studied by using a gas-filled recoil separator coupled with a position-sensitive semiconductor detector. Bh was clearly identified from the correlation of the known nuclide, Db. The obtained decay properties of Bh and Db are consistent with those observed in the 113 chain, which provided further confirmation of the discovery of 113.

Adsorption of Db and its homologues Nb and Ta, and the pseudo-homologue Pa on anion-exchange resin in HF solution

Tsukada, Kazuaki; Haba, Hiromitsu*; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko*; Kasamatsu, Yoshitaka; Nishinaka, Ichiro; Ichikawa, Shinichi; Yasuda, Kenichiro; Miyamoto, Yutaka; et al.

Radiochimica Acta, 97(2), p.83 - 89, 2009/02

https://doi.org/10.1524/ract.2009.1577

Anion-exchange chromatography of element 105, dubnium (Db), produced in the Cm(F, 5n)Db reaction is investigated together with the homologues Nb and Ta, and the pseudo-homologue Pa in 13.9 M hydrofluoric acid (HF) solution. The distribution coefficient (K) of Db on an anion-exchange resin is successfully determined by running cycles of the 1702 chromatographic column separations. The result clearly indicates that the adsorption of Db on the resin is significantly different from that of the homologues and that the adsorption of anionic fluoro complexes of these elements decreases in the sequence of Ta Nb Db Pa.

On-line diffusion tracing in Li ionic conductors by the short-lived radioactive beam of Li

Jeong, S.-C.*; Katayama, Ichiro*; Kawakami, Hirokane*; Watanabe, Yutaka*; Ishiyama, Hironobu*; Imai, Nobuaki*; Hirayama, Yoshikazu*; Miyatake, Hiroari; Sataka, Masao; Sugai, Hiroyuki; et al.

Japanese Journal of Applied Physics, 47(8), p.6413 - 6415, 2008/08

https://doi.org/10.1143/JJAP.47.6413

A non-destructive and on-line diffusion tracing in Li ionic conductors has been demonstrated. As a tracer, pulsed beam of Li was implanted into LiGa. By analyzing the time dependent yield of the -particles decaying from Li, diffusion coefficients were extracted with a high accuracy. The ordering of Li vacancies in the Li-deficient phase of LiGa was observed for the first time in terms of the Li diffusion.

Direct measurement of Li+d reactions of astrophysical interest

Hashimoto, Takashi; Ishiyama, Hironobu*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Miyatake, Hiroari; Jeong, S. C.*; Tanaka, Masahiko*; Yoshikawa, Nobuharu*; Nomura, Toru*; et al.

AIP Conference Proceedings 1016, p.313 - 318, 2008/05

https://doi.org/10.1063/1.2943592

Nuclear reactions involving Li are thought to be key reactions to synthesize heavier elements in the early universe and supernovae because of filling a gap of mass number=8. Direct cross-section measurement of Li(d,x), (x = t,p,) reactions was performed in the energy region of astrophysical interest, covering the Gamow peaks of T=1-3. The Li beam at 7 different energies from E=0.3 to 1.2 MeV was provided by Tokai Radioactive Ion Accelerator Complex (TRIAC). The experiment was carried out using a CD target and large-area position sensitive silicon detectors. This measurement provides the first data of cross sections in the low-energy region below E=1.5 MeV. The analysis of the Li(d,t)Li reaction measurement has been completed. An enhancement on the excitation function was observed at around E = 0.8 MeV and its energy corresponds to the excitation energy of E=22.4 MeV in Be, where an excited state was previously reported. The new astrophysical nuclear reaction rate will be presented and the contribution to the r-process nucleosynthesis will be discussed. Also, the preliminary result of the Li(d,p)Li reaction will be presented.