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(Al,Ga)
O
scintillator Compton camera mounted on an unmanned helicopterShikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.
Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12
Times Cited Count：24 Percentile：96.18(Nuclear Science & Technology)The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 4
4 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the 
-ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10
).
Isayama, Akihiko; Suzuki, Takahiro; Hayashi, Nobuhiko; Ide, Shunsuke; Hamamatsu, Kiyotaka; Fujita, Takaaki; Hosoyama, Hiroki; Kamada, Yutaka; Nagasaki, Kazunobu*; Oyama, Naoyuki; et al.
AIP Conference Proceedings 933, p.229 - 236, 2007/10
no abstracts in English
Nakamura, Hiroo; Tsuji, Shunji; ; Ozeki, Takahisa; Ishida, Shinichi; Azumi, Masafumi; Akiba, Masato; Ando, Toshiro; Fujii, Tsuneyuki; Fukuda, Takeshi; et al.
Nuclear Fusion, 30(2), p.235 - 250, 1990/02
Times Cited Count：15 Percentile：52.55(Physics, Fluids & Plasmas)no abstracts in English
Nakamura, Hiroo; Tsuji, Shunji; ; Ozeki, Takahisa; Ishida, Shinichi; Azumi, Masafumi; Akiba, Masato; Ando, Toshiro; Fujii, Tsuneyuki; Fukuda, Takeshi; et al.
JAERI-M 89-106, 52 Pages, 1989/08
no abstracts in English
Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Hosoyama, Hiroki; Suzuki, Takahiro; Fujita, Takaaki; Takenaga, Hidenobu; Ide, Shunsuke; Kamada, Yutaka
no journal, ,
no abstracts in English
Shikaze, Yoshiaki; Torii, Tatsuo; Shimazoe, Kenji*; Jiang, J.*; Takahashi, Hiroyuki*; Kurosawa, Shunsuke*; Kamada, Kei*; Yoshikawa, Akira*; Yoshino, Masao*; Ito, Shigeki*; et al.
no journal, ,
no abstracts in English
Shikaze, Yoshiaki; Torii, Tatsuo; Nishizawa, Yukiyasu; Yoshida, Mami*; Shimazoe, Kenji*; Jiang, J.*; Takahashi, Hiroyuki*; Kurosawa, Shunsuke*; Kamada, Kei*; Yoshikawa, Akira*; et al.
no journal, ,
no abstracts in English
Sato, Tetsuya; Kaneya, Yusuke*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Osa, Akihiko; Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; et al.
no journal, ,
The ground state electronic configuration of lawrencium (Lr, Z =103) is predicted to be [Rn]
, which is different from that of the lanthanide homolog Lu [Xe]
due to strong relativistic effects. According to semi-empirical considerations, volatility of Lr is expected to be higher than that of Lu. We have investigated adsorption behavior of 
Lr, which was produced in the reaction of 
Cf(
B, 4n), on a tantalum (Ta) metal surface using a surface ion-source installed into the isotope separator on-line (ISOL) at the JAEA tandem accelerator facility. The observed adsorption behavior of Lr was similar to those of Tb and Lu which have relatively higher adsorption enthalpy on Ta surface. It implies that Lr would have low volatility like such as Lu and Tb.
Sato, Tetsuya; Kaneya, Yusuke*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Osa, Akihiko; Makii, Hiroyuki; Hirose, Kentaro; Nagame, Yuichiro; et al.
no journal, ,
Our experimental results on the first ionization potential measurement of lawrencium (Lr, element 103) have strongly suggested that the Lr atom has a [Rn]
configuration as a result of the influence of strong relativistic effects. The configuration is different from that expected from the lanthanide homologue, lutetium (Lu). According to a semi-empirical consideration, it is expected that the change of the electronic configuration leads higher volatility of Lr than that of Lu. In this work, adsorption behaviors of Lr and various short-lived rare earth isotopes on a tantalum surface were investigated via observation of their surface ionization efficiencies. It was found that Lr would behave like low volatile rare earth elements such as Lu contrary to the semi-empirical expectation.
LrAsai, Masato; Kamada, Hiroki*; Shigekawa, Yudai*; Tsukada, Kazuaki; Sato, Tetsuya; Toyoshima, Atsushi; Mitsukai, Akina; Nagame, Yuichiro; Nishio, Katsuhisa; Hirose, Kentaro; et al.
no journal, ,
To clarify the fission mechanism of mass-symmetric spontaneous fissions observed around the neutron-rich Fm region, we have measured kinetic energies and mass distribution of spontaneous-fission fragments in this nuclear region precisely. The experiment was performed at the JAEA tandem accelerator facility using an on-line isotope separator (ISOL). The mass-separated Lr nuclei were implanted into thin foil, and two fragments of their spontaneous fission were coincidently measured with two Si detectors. The spontaneous fission of Lr was found to show a narrow symmetric mass distribution. On the other hand, their total kinetic energy TKE was found to be low, which is apparently different from the high-TKE symmetric fissions observed in the Fm isotopes. This indicates that the fission mechanisms of these two symmetric fissions are different.
Kaneya, Yusuke*; Tomitsuka, Tomohiro; Sato, Tetsuya; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina; Makii, Hiroyuki; Hirose, Kentaro; Osa, Akihiko; et al.
no journal, ,
Kaneya, Yusuke*; Asai, Masato; Sato, Tetsuya; Tomitsuka, Tomohiro; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina; Makii, Hiroyuki; Hirose, Kentaro; Osa, Akihiko; et al.
no journal, ,
To study the influence of the valence 7p
electronic orbital on chemical properties of lawrencium, a measurement of the adsorption enthalpy of lawrencium was carried out. A new method using a surface ionization technique coupled to an on-line isotope separator was developed, which enabled one to measure temperature dependence of lawrencium surface adsorption on a metallic tantalum surface at high temperature up to 2800 K. The temperature dependences of adsorption of lawrencium as well as various lanthanide elements were investigated with this method, and the adsorption enthalpy of lawrencium was successfully extracted.
Tomitsuka, Tomohiro; Tokoi, Katsuyuki*; Sato, Tetsuya; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Chiera, N. M.; Kamada, Hiroki; Nagame, Yuichiro; Goto, Shinichi*
no journal, ,
no abstracts in English
Sato, Tetsuya; Kaneya, Yusuke*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Osa, Akihiko; Makii, Hiroyuki; Hirose, Kentaro; Nagame, Yuichiro; et al.
no journal, ,
Our experimental results on the first ionization potential measurement of lawrencium (Lr, element 103) have strongly suggested that the Lr atom has a [Rn] configuration as a result of the influence of strong relativistic effects. The configuration is different from that expected from the lanthanide homologue, lutetium (Lu). According to a semi-empirical consideration, it is expected that the change of the electronic configuration leads higher volatility of Lr than that of Lu. In this work, adsorption behaviors of Lr and various short-lived rare earth isotopes on a tantalum surface were investigated via observation of their surface ionization efficiencies. It was found that Lr would behave like low volatile rare earth elements such as Lu contrary to the semi-empirical expectation.
Np isomerKamada, Hiroki*; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Toyoshima, Atsushi; Nagame, Yuichiro; Mitsukai, Akina; Tomitsuka, Tomohiro*; Andreyev, A. N.; Nishio, Katsuhisa; et al.
no journal, ,
Existence of the previously unknown isomer Np was discovered for the first time. Np was produced by using the JAEA tandem accelerator. Short-lived reaction products were mass-separated by the on-line isotope separator ISOL, and and X rays originating from the decay of Np were observed. The half-life of Np was determined to be approximately 9 min, and Np was found to decay via the EC decay as well as the isomeric transition. On the basis of the observed and X rays and the half-life value, we have evaluated level energy, spin-parity, and proton-neutron configuration of Np.
Es targetAsai, 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 Fm, 
Fm, and Lr have been measured using an 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 
Fm in multinucleon-transfer reactions with a Es target and 
O projectiles, and produced Lr in the 
Cm(
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 Fm, Fm, and Lr.
Es targetAsai, 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 Fm, Fm, and Lr have been measured at the JAEA Tandem accelerator facility. Fm and Fm were produced in a multinucleon transfer reaction with an O beam and an extremely rare 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 Fm and Fm, while the spontaneous fission of Lr was found to exhibit mixture of three different fission modes.
Kodama, Shohei*; Kurosawa, Shunsuke*; Morishita, Yuki; Usami, Hiroshi; Hayashi, Masateru*; Tanaka, Hiroki*; Yoshino, Masao*; Kamada, Kei*; Yoshikawa, Akira*; Torii, Tatsuo
no journal, ,
After Fukushima 1st Nuclear Plant accident, a large number of radioactive pollutants or nuclear debris with very high dose of more than a few Sv/h still have existed. To estimate the dose of such pollutants, a Japan Atomic Energy Agency research group has suggested a new technique to use a long optical fiber and a red-emitting scintillator, and the scintillation photons are read outside of high dose area. We tested the gamma-ray detection performance of a ruby (Cr:Al
O) and a newly developed CsHfI
scintillators as a scintillating probe coupled with an optical fiber in this study.
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 Es target and the O beam delivered by the JAEA tandem accelerator. The neutron-rich Lr isotope were produced with the Cm target and the 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.
Es targetAsai, 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 Fm and Fm and lawrencium isotope Lr were produced in the multinucleon transfer reaction on Es target with heavy-ion beam and in the heavy-ion fusion reaction on Cm target with 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 Fm was asymmetric, while that of Fm was sharp symmetric, which confirmed the previous experimental results. On the other hand, the SF of 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.
