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Oral presentation

Simple determination method for $$^{99}$$Tc in radioactive waste arising from research facilities

Kameo, Yutaka; Ishimori, Kenichiro; Hoshi, Akiko; Watanabe, Koichi; Takahashi, Kuniaki

no journal, , 

no abstracts in English

Oral presentation

Fission fragment anisotropy in heavy-ion-induced fission of actinides

Nishinaka, Ichiro; Nishio, Katsuhisa; Tanikawa, Masashi*; Makii, Hiroyuki; Wakabayashi, Yasuo; Mitsuoka, Shinichi; Yokoyama, Akihiko*

no journal, , 

In order to study the effects of entrance channel mass asymmetry $$alpha$$=($$A_t$$-$$A_p$$)/($$A_t$$+$$A_p$$) on fission fragment anisotropy, we measured fission fragment angular distributions in the reactions of $$^{22}$$Ne+$$^{232}$$Th ($$alpha$$=0.827) and $$^{12}$$C+$$^{242}$$Pu ($$alpha$$=0.906), populating the same compound nucleus $$^{254}$$Fm. At the JAEA tandem accelerator fission fragments from the compound nucleus at excitation energies of 56.1, 52.5, 48.8 and 45.2 MeV were measured by position-sensitive parallel plate avalanch counters and silicon surface barrier detectors. The anisotropy for $$^{22}$$Ne+$$^{232}$$Th with smaller entrance channel mass asymmetry $$alpha$$=0.827 shows large values compared with those for $$^{12}$$C+$$^{242}$$Pu with $$alpha$$=0.906. This implies that entrance channel mass asymmetry plays a role for fission fragment anisotropy in the present systems.

Oral presentation

Improvement in precision of measurement of carbon isotope ratio by accelerator mass spectrometry

Kokubu, Yoko; Nishizawa, Akimitsu*; Suzuki, Mototaka*; Owaki, Yoshio*; Nishio, Tomohiro*; Matsubara, Akihiro; Ishimaru, Tsuneari

no journal, , 

no abstracts in English

Oral presentation

$$gamma$$-ray analysis and behavior of spallation products produced in mercury of the neutron source at J-PARC

Kai, Tetsuya; Kasugai, Yoshimi; Oi, Motoki; Wakui, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro; Hanano, Kohei

no journal, , 

The authors sampled mercury ($$sim$$120 g) and the adhesive substances (black powder) from a mercury circulation system in MLF/J-PARC. Twelve nuclides, $$^{203}$$Hg, $$^{188}$$Pt, $$^{189}$$Ir, $$^{188}$$Ir, $$^{185}$$Os, $$^{175}$$Hf, $$^{173}$$Lu, $$^{172}$$Lu, $$^{146}$$Eu, $$^{113}$$Sn, $$^{rm 110m}$$Ag, $$^{88}$$Y, were identified in the mercury specimen. The amounts of radioactivity were in the range between several to around hundred percents relative to calculation. Only $$^{rm 110m}$$Ag was not found in the adhesive substances. It is expected that other elements than mercury take important role to behavior of the spallation products since the content ratios of the elements were calculated to be in the order of ppb, and the elements (tin and europium) having higher solubility than silver were found in both specimens. For example, iron, which is expected to be a dominant impurity (caused by erosion of stainless steel pipes), dose not react with silver. On the other hand, iron reacts with tin.

Oral presentation

Selective electrocatalytic reduction of Np(V) to Np(IV) at a flow-through electrode

Kitatsuji, Yoshihiro; Kimura, Takaumi; Kihara, Sorin*

no journal, , 

Based on the electrocatalytic reduction, development of rapid and selective electrolytic reduction of Np(V) to Np(IV) is expected. A flow-through electrode of glassy carbon (GC) fiber platinized by electrodeposition was examined in the present study. Although Np(V) was reduced to Np(III) at the much negative potential at a flow-through electrode of normal GC, stepwise reductions of Np(V) to Np(IV) and Np(IV) to Np(III) were observed on the potential-current relation of electrolysis at platinized GC electrode. The overpotential of reduction of Np(V) to Np(IV) was decreased. This electrolysis method enables us to prepare Np(IV) rapidly without producing Np(III). Np(V) in the mixture solution of Np and U was also reduced to Np(IV) selectively, not accompanied with reduction of U(VI).

Oral presentation

Stability constants of minor actinides and lanthanides with dithiocarbamate

Miyashita, Sunao; Kitatsuji, Yoshihiro; Kimura, Takaumi

no journal, , 

The stability constants of trivalent minor actinides (An$$^{3+}$$; $$^{241}$$Am and $$^{244}$$Cm) and lanthanides (Ln$$^{3+}$$; Eu) with Ammonium pyrrolidinedithiocarbamate (APDC) in aqueous solution were investigated. The stability constants were obtained by back-extraction technique using di(2-ethylhexyl)phosphoric acid (HDEHP) as follows. Aqueous phase was acetic buffer solution from 0.02 to 0.10 mol/cm$$^3$$ containing various concentrations of APDC. Organic phase was toluene or benzene solution containing HDEHP and trace amounts of the extracted radionuclide such as $$^{241}$$Am or $$^{244}$$Cm. Eqvolumes of the aqueous phase and the organic phase were mixed in vial and were shaken 30 minutes at 298 ${it K}$. The results show that minor actinides strongly interacted with dithiocarbamate. From those results, the obtained stability constants ($$ beta_n$$, ${it n}$ = 1, 2) for Am are log$$ beta_1$$(Am) = 2.5 $$pm$$ 0.3, log$$ beta_2$$(Am) = 4.3 $$pm$$ 0.2 at 298 ${it K}$.

Oral presentation

Measurements of mercury and gold concentrations in samples from tailing dams which contaminated by Small Scale Mining, using PGAA and INAA

Hatsukawa, Yuichi; Osawa, Takahito; Appel, P. W. U.*; Arcilla, C.*; Perez, E.*

no journal, , 

Small scale gold mining is widely seen in many places in the world. During gold extract processing, large amount of mercury was released in the environment. Extrapolated to the whole country 200 to 500 tons of mercury is released to the environment every year. Most of the mercury will end in the mangrove swamps fringing the coast line. The mangrove swamps serve as hatching grounds for fish and shellfish the main source of proteins for the Filipinos. Very high concentrations of mercury have been found in water which was used for watering rice paddies. In this study, we developed determination of mercury and gold in the crushed rock mines nondestructively using PGAA and INAA. Also based on the concentration of gold and mercury in tailings, we will optimize conditions of the state battery method. Observed mercury and gold concentrations in tailings are 2.5-393 ppm, 1-3.9 ppm, respectively. Based on these results, we will optimize the conditions of the state battery method for mercury clean up project.

Oral presentation

Optimization of automated sequential anion-exchange separation of ultra-trace elements

Miyamoto, Yutaka; Yasuda, Kenichiro; Magara, Masaaki; Kimura, Takaumi

no journal, , 

The sequential separation technique of trace U, Th, Pb and lanthanides with a single anion-exchange column has been developed. The pressurized sequential separation system with compressed air was examined to make up an automated separation system. The separation was optimized for some parameters including the flow rate of eluents and the composition of eluents. This pressurized separation system improved the resolution of separation peaks and reduced the separation time compared with the previous gravity flow separation.

Oral presentation

Separation of U/Pu/Am for safeguards environmental samples

Miyamoto, Yutaka; Esaka, Fumitaka; Magara, Masaaki; Kimura, Takaumi

no journal, , 

For accurate analyses of Pu in a Pu oxide/MOX particle, the sample should be chemically separated from Am and U. These interferences lead to systematic error in the quantitative and isotopic analyses of Pu. Two types of chemical separation technique of U, Pu, and Am were examined. One is an anion-exchange separation, and the other is an extraction separation with the TRU resin. Plutonium, U, and Nd which is analogous to Am in the chemical behaviors were successfully separated with the both an anion-exchange column and a TRU extraction column.

Oral presentation

Sulfate complexation of element 104, Rf, in H$$_{2}$$SO$$_{4}$$/HNO$$_{3}$$ mixed solution ([H$$^{+}$$] = 1.0 M)

Li, Z.; Toyoshima, Atsushi; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Sato, Nozomi; Kikuchi, Takahiro; Sch$"a$del, M.*; Nagame, Yuichiro; Liang, X. H.*; et al.

no journal, , 

Cation-exchange behavior of $$^{261}$$Rf (T$$_{1/2}$$ = 78 s) produced in the $$^{248}$$Cm($$^{18}$$O, 5n) reaction was studied on a "one-atom-at-a-time" scale in H$$_{2}$$SO$$_{4}$$ (0.15-0.69 M)/HNO$$_{3}$$ mixed solutions ([H$$^{+}$$] = 1.0 M) using an automated ion-exchange separation apparatus coupled with the detection system for alpha-spectroscopy. It was found that adsorption probability (%ads) of $$^{261}$$Rf on cation-exchange resin decreases with increasing [HSO$$_{4}$$$$^{-}$$], showing a successive formation of its sulfate complexes. Rf exhibited much weaker formation of the complexes than the lighter homologues Zr and Hf, which is qualitatively in good agreement with theoretical calculations including relativistic effects.

Oral presentation

$$alpha$$-HiB complexation and ion-exchange behavior of the group-4 elements as homologues of Rf

Kikuchi, Takahiro; Toyoshima, Atsushi; Li, Z.; Tsukada, Kazuaki; Asai, Masato; Sato, Tetsuya; Sato, Nozomi; Nagame, Yuichiro; Kasamatsu, Yoshitaka*; Fan, F.*

no journal, , 

We studied complexation of the group-4 elements Zr and Hf as well as the pseudo group-4 element Th with $$alpha$$-hydroxyisobutyric acid ($$alpha$$-HiB) as homologues of Element 104, rutherfordium (Rf). The isotopes of $$^{88}$$Zr and $$^{175}$$Hf were produced at the JAEA tandem accelerator while $$^{234}$$Th was separated from $$^{238}$$U. These radiotracers stocked in $$alpha$$-HiB/HNO$$_{3}$$ were mixed with cation-exchange resin. After shaking the sample for a certain time, an aliquot of the aqueous phase was precisely taken, which were subjected to $$gamma$$-spectrometry. The complex formation of Zr and Hf reached to chemical equlibria at 180 min. Distribution coefficients of Zr and Hf were decreased with an increase of the concentration of $$alpha$$-HiB, indicating the consecutive complexation of these ions with $$alpha$$-HiB. On the other hand, Th was adsorbed on the cation-exchange resin under the given conditions, showing clearly different behavior of Th from that of Zr and Hf.

Oral presentation

Observation of new neutron-deficient actinide isotopes of $$^{234}$$Bk and $$^{230}$$Am

Kaji, Daiya*; Haba, Hiromitsu*; Kasamatsu, Yoshitaka*; Kudo, Yuki*; Morimoto, Koji*; Morita, Kosuke*; Ozeki, Kazutaka*; Sumita, Takayuki*; Yoneda, Akira*; Koura, Hiroyuki; et al.

no journal, , 

no abstracts in English

Oral presentation

Solvent extraction of heavy actinides (III) with HDEHP

Takayama, Reona*; Oe, Kazuhiro*; Komori, Yukiko*; Fujisawa, Hiroyuki*; Kuriyama, Ai*; Kikutani, Yuki*; Kikunaga, Hidetoshi*; Kasamatsu, Yoshitaka*; Yoshimura, Takashi*; Takahashi, Naruto*; et al.

no journal, , 

The extraction behavior of trivalent actinides (Am, Cm, Cf, Es, and Fm) into di(2-ethylhexyl)phosphoric acid, HDEHP, in benzene from HNO$$_{3}$$ was studied together with lanthanides. The extraction constants, $$it K$$$$_{ex}$$ values, of lanthanides, Am, Cm, Cf, and Es were determined by a batch method using stable lanthanide isotopes and radiotracers of $$^{241}$$Am, $$^{243}$$Cm, $$^{249}$$Cf, and $$^{253}$$Es, respectively, while that of Fm was measured with $$^{250}$$Fm which was produced in the $$^{238}$$U($$^{16}$$O,4n) reaction and was on-line supplied by a gas-jet method at the AVF cyclotron of RCNP, Osaka University. The $$it K$$$$_{ex}$$ values were determined by the slope analysis for the variation of the distribution ratio as a function of the concentration of HDEHP. We found that the $$it K$$$$_{ex}$$of Fm is smaller than that of Dy in spite of the similar ionic radii while those of other actinides are almost the same as those of each lanthanide with a similar ionic radius.

Oral presentation

Production of no-carrier-added $$^{177}$$Lu for radioimmunotherapy

Hashimoto, Kazuyuki; Watanabe, Satoshi; Ishioka, Noriko

no journal, , 

no abstracts in English

Oral presentation

Synthesis of $$^{186,188}$$Re-MAG3 and $$^{186,188}$$Re-[(CO)$$_{3}$$(H$$_{2}$$O)$$_{3}$$]$$^{+}$$

Kurihara, Yuichi*; Nogawa, Norio*; Hashimoto, Kazuyuki; Koike, Yuya*; Morikawa, Naotake*; Ijiri, Kenichi*

no journal, , 

no abstracts in English

Oral presentation

Study of the $$^{188}$$W-$$^{188}$$Re generator using PZC

Kurihara, Yuichi*; Nogawa, Norio*; Hashimoto, Kazuyuki; Koike, Yuya*; Morikawa, Naotake*; Ijiri, Kenichi*

no journal, , 

no abstracts in English

Oral presentation

Anion-exchange behavior of the group-6 elements in HF/HNO$$_{3}$$ mixed solutions; Towards the study of ion-exchange behavior of $$^{106}$$Sg

Liang, X.; Li, Z.; Tsukada, Kazuaki; Toyoshima, Atsushi; Asai, Masato; Sato, Tetsuya; Sato, Nozomi; Kikuchi, Takahiro; Kaneya, Yusuke; Nagame, Yuichiro

no journal, , 

Anion-exchange behavior of the group-6 elements, W and Mo, in HF and HNO$$_{3}$$ mixed solutions has been studied by a batch method using the carrier-free radiotracers $$^{rm 181}$$W and $$^{rm 93m}$$Mo. The long-lived isotope $$^{181}$$W and the short-lived isotope $$^{rm 93m}$$Mo were produced in the $$^{181}$$Ta(p,n) and the $$^{93}$$Nb(p,n) reaction at the JAEA tandem accelerator, respectively. The solutions containing $$^{rm 181}$$W or $$^{rm 93m}$$Mo were mixed with anion exchange resin. Radioactivities of the solution were assayed for $$gamma$$-ray spectrometry, and then distribution coefficients (K$$_{d}$$s) of these elements were determined. It was found that the K$$_{d}$$ values of W depend strongly on the concentration of HF, while those of Mo are almost constant as a function of [HF] under the given conditions.

Oral presentation

Study on the adsorption rate of Zr and Hf as homologues of element 104, Rutherfordium, on the cation-exchange resin in H$$_{2}$$SO$$_{4}$$ solutions

Ikarashi, Satoshi*; Sueki, Keisuke*; Tsukada, Kazuaki; Nagame, Yuichiro

no journal, , 

The adsorption rates of Zr and Hf on the cation-exchange resin in H$$_{2}$$SO$$_{4}$$ solutions were investigated in order to lead to the quantitative discussion of the chromatography. It was obtained the adsorption rates of $$^{88}$$Zr and $$^{175}$$Hf on the cation-exchange resin in 0.1 M H$$_{2}$$SO$$_{4}$$ at 15, 25 and 45$$^{circ}$$C as functions of the shaking times. The results showed that the equilibrium of cation-exchange was reached at 70$$sim$$80 seconds and that the adsorption rates on the cation-exchange resin were not changed between 15$$sim$$45$$^{circ}$$C in the present condition. In H$$_{2}$$SO$$_{4}$$/HNO$$_{3}$$ mixed solution ([H$$^{+}$$]$$_{eq}$$ = 1.0 M), the adsorption rate was similar to those of $$^{88}$$Zr and $$^{175}$$Hf on the cation-exchange resin in H$$_{2}$$SO$$_{4}$$ solution.

Oral presentation

Development of a surface ionizer coupled to a gas-jet transport system for the measurement of the first ionization potential of Lr

Sato, Nozomi; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Toyoshima, Atsushi; Li, Z.; Kikuchi, Takahiro; Kaneya, Yusuke*; Ichikawa, Shinichi; Nagame, Yuichiro; et al.

no journal, , 

It is important to determine the first ionization potentials (IPs) of the heaviest elements with atomic number Z $$>$$ 100 to understand their valence electronic structure affected by relativistic effects. Due to low production rates and short half-lives of the heaviest nuclides, IPs of these elements have not been so far determined. We are developing a surface-ionization-type ion source coupled to a gas-jet transport system in the Isotope Separator On-Line (ISOL) at the JAEA tandem accelerator facility to measure the IP of the heaviest actinide, lawrencium (Lr, Z = 103). In the symposium, we report the present status of the development of the apparatus. Production yield measurements of $$^{256}$$Lr (half-life 27 s), that is suitable for this study, will be also presented.

Oral presentation

Production of $$^{265}$$Sg via the $$^{248}$$Cm($$^{22}$$Ne,5$$n$$)$$^{265}$$Sg reaction

Haba, Hiromitsu*; Oe, Kazuhiro*; Ozeki, Kazutaka*; Kasamatsu, Yoshitaka*; Kaji, Daiya*; Kikunaga, Hidetoshi*; Kudo, Hisaaki*; Kudo, Yuki*; Komori, Yukiko*; Sato, Nozomi; et al.

no journal, , 

RIKEN group has investigated the performance of the system using an isotope of element 106, $$^{265}$$Sg, produced in the $$^{248}$$Cm($$^{22}$$Ne,5$$n$$) reaction. Alpha-particles of $$^{265}$$Sg separated with a GAs-filled Recoil Ion Separator (GARIS) and extracted to a chemistry laboratory were successfully identified with a rotating wheel system for $$alpha$$-spectrometry under low background conditions. As a result, two isomeric states in $$^{265}$$Sg, $$^{265a}$$Sg ($$alpha$$-particle energy $$E_{alpha} = 8.84$$ MeV, half-life $$T_{1/2} = 6.7$$ s) and $$^{265b}$$Sg ($$E_{alpha} = 8.69$$ MeV, $$T_{1/2} = 15$$ s), were identified. The cross sections for the $$^{248}$$Cm($$^{22}$$Ne,5$$n$$) reactions at 118 MeV were roughly evaluated to be 200 pb for $$^{265a}$$Sg and 170 pb for $$^{265b}$$Sg.

25 (Records 1-20 displayed on this page)