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

Boron Neutron Capture Therapy (BNCT) is a radiotherapy for the treatment of intractable cancer. In BNCT precise determination of 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 B concentration in whole blood sample. The experiment was performed at JAEA Tandem Accelerator using an 8 MeV proton beam. The 478 keV ray of Be produced in the B(p,)Be reaction was used to quantify the B, and rays of Co originating from the reaction with Fe in blood was used to normalize the -ray intensity. The results demonstrated that the present CPAA method can be applied to the determination of the B concentration in the blood sample.

First online operation of TRIGA-TRAP

Grund, J.*; Asai, Masato; Blaum, K.*; Block, M.*; Chenmarev, S.*; Dllmann, Ch. E.*; Eberhardt, K.*; Lohse, S.*; Nagame, Yuichiro*; Nagy, Sz.*; et al.

Nuclear Instruments and Methods in Physics Research A, 972, p.164013_1 - 164013_8, 2020/08

https://doi.org/10.1016/j.nima.2020.164013

We report on the successful coupling of the Penning-trap mass spectrometry setup TRIGA-TRAP to the research reactor TRIGA Mainz. This offers the possibility to perform direct high-precision mass measurements of short-lived nuclei produced in neutron-induced fission of a U target located near the reactor core. An aerosol-based gas-jet system is used for efficient transport of short-lived neutron-rich nuclei from the target chamber to a surface ion source. In conjunction with new ion optics and extended beam monitoring capabilities, the experimental setup has been fully commissioned. The design of the surface ion source, efficiency studies and first results are presented.

Sensitivity of charged particle activation analysis for long-lived radioactive nuclide determination

Oshima, Masumi*; Yamaguchi, Yurie*; Asai, Masato; Tsukada, Kazuaki; Goto, Jun*; Bamba, Shigeru*; Bi, C.*; Morimoto, Takao*

Journal of Nuclear Science and Technology, 56(9-10), p.866 - 872, 2019/09

https://doi.org/10.1080/00223131.2019.1593892

Sensitivity of charged particle activation analysis with 8 MeV proton beam was studied for determination of 35 long-lived radioactive nuclides. Reaction cross sections for those nuclides were estimated with ALICE-91 code and isomer yield ratios were estimated from those of neighboring isotopes by taking into account their spins and parities. It was found that the proposed charged particle activation analysis should show high sensitivity for the determination of several hardly measurable nuclides with long half-lives such as Cs, Pu, I, Sn, Mo, Pd, U, Cm, and Np.

Optimization of an isothermal gas-chromatographic setup for the chemical exploration of dubnium (Db, Z = 105) oxychlorides

Chiera, N. M.; Sato, Tetsuya; Tomitsuka, Tomohiro; Asai, Masato; Ito, Yuta; Shirai, Kaori*; Suzuki, Hayato; Tokoi, Katsuyuki; Toyoshima, Atsushi; Tsukada, Kazuaki; et al.

Journal of Radioanalytical and Nuclear Chemistry, 320(3), p.633 - 642, 2019/06

https://doi.org/10.1007/s10967-019-06505-w

An isothermal gas-chromatographic (IGC) device has been developed and tested for on-line gas phase studies of volatile oxychlorides of short-lived group-5 transition metals. Radioisotopes of niobium and tantalum, produced in nuclear fusion evaporation reactions, are directly flushed into the IGC setup by an inert gas-jet. Oxychloride compounds are formed by the addition of SOCl and O. Parameters influencing the formation and transport of NbOCl and TaOCl are investigated. For nuclides with half-lives () of about 30 s, an overall efficiency of 7% is obtained, rendering the IGC setup suitable for the chemical exploration of Db( = 34s).

Formation and thermochemical properties of oxychlorides of niobium (Nb) and tantalum (Ta); Towards the gas-phase investigation of dubnium (Db) oxychloride

Chiera, N. M.; Sato, Tetsuya; Tomitsuka, Tomohiro; Asai, Masato; Suzuki, Hayato*; Tokoi, Katsuyuki; Toyoshima, Atsushi; Tsukada, Kazuaki; Nagame, Yuichiro

Inorganica Chimica Acta, 486, p.361 - 366, 2019/02

https://doi.org/10.1016/j.ica.2018.10.032

The formation of NbOCl and TaOCl and their adsorption behavior on quartz surfaces was explored by applying an isothermal gas-chromatographic method. Trace amounts of short-lived Nb and Ta isotopes were used. Adsorption enthalpy values () at zero surface coverage of -(NbOCl) = 102 4 kJ/mol and -(TaOCl) = 128 5 kJ/mol were determined by analyzing the chromatographic behavior of the Nb andTa complexes with a Monte-Carlo simulation method based on an adsorption-desorption kinetic model.By applying an empirical correlation, the experimental values were successively related to the macroscopic standard sublimation enthalpy, , as a measure of the volatility of each substance. The inferred sublimation enthalpies are in agreement with tabulated thermochemical values. Thus, the linear empirical correlation between and for metal-oxychlorides was updated with the inclusion of the present data. According to the predicted (DbOCl), a (DbOCl) value of 135 2 kJ/mol was extrapolated. The future accomplishment of comparative studies with DbOCl under the same experimental conditions will provide valuable information on the volatility trend in Group-5 elements, together with an indication on the magnitude of relativistic effects on the electronic structure of dubnium.

Online chemical adsorption studies of Hg, Tl, and Pb on SiO and Au surfaces in preparation for chemical investigations on Cn, Nh, and Fl at TASCA

Lens, L.*; Yakushev, A.*; Dllmann, Ch. E.*; Asai, Masato; Ballof, J.*; Block, M.*; David, H. M.*; Despotopulos, J.*; Di Nitto, A.*; Eberhardt, K.*; et al.

Radiochimica Acta, 106(12), p.949 - 962, 2018/12

https://doi.org/10.1515/ract-2017-2914

Online gas-solid adsorption studies with single atom quantities of Hg, Tl, and Pb on SiO and Au surfaces were carried out using short-lived radioisotopes with half-lives in the range of 4-49 s. This is a model study to measure adsorption enthalpies of superheavy elements Cn, Nh, and Fl. The short-lived isotopes were produced and separated by the gas-filled recoil separator TASCA at GSI. The products were stopped in He gas, and flushed into gas chromatography columns made of Si detectors whose surfaces were covered by SiO or Au. The short-lived Tl and Pb were successfully measured by the Si detectors with the SiO surface at room temperature. On the other hand, the Hg did not adsorb on the SiO surface, but adsorbed on the Au surface. The results demonstrated that the adsorption properties of short-lived Hg, Tl, and Pb could be studied with this setup, and that this method is applicable to the experiment for Cn, Nh, and Fl.

Science of heavy and superheavy elements (nuclear physics); Experimental studies on shell structure of superheavy nuclei

Asai, Masato

Radioisotopes, 67(6), p.291 - 298, 2018/06

https://doi.org/10.3769/radioisotopes.67.291

Stability and limit of existence essentially depend on nuclear shell structure. It is theoretically predicted that stable doubly-closed-shell spherical superheavy nuclei should exist around the region of the proton number 114 to 126 and the neutron number 172 to 184, although their locations and degree of stability have not been established because of large variety of theoretical predictions. On the other hand, recent advances on experimental techniques have made it possible to accumulate experimental data concerning the shell structure of superheavy nuclei, such as half-lives and nuclear masses. In addition, some pioneering experiments have been performed to directly establish the level structure of superheavy nuclei through spectroscopic methods. This paper introduces the current status of experimental studies on nuclear shell structure of superheavy nuclei.

Study of fission using multi-nucleon transfer reactions

Nishio, Katsuhisa; Hirose, Kentaro; Vermeulen, M. J.; Makii, Hiroyuki; Orlandi, R.; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Sato, Tetsuya; Nagame, Yuichiro; et al.

EPJ Web of Conferences, 163, p.00041_1 - 00041_6, 2017/11

https://doi.org/10.1051/epjconf/201716300041

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.

Complex chemistry with complex compounds

Eichler, R.*; Asai, Masato; Brand, H.*; Chiera, N. M.*; Di Nitto, A.*; Dressler, R.*; Dllmann, Ch. E.*; Even, J.*; Fangli, F.*; Goetz, M.*; et al.

EPJ Web of Conferences, 131, p.07005_1 - 07005_7, 2016/12

https://doi.org/10.1051/epjconf/201613107005

In recent years gas-phase chemical studies assisted by physical pre-separation allowed for the productions and investigations of fragile single molecular species of superheavy elements. The latest highlight is the formation of very volatile hexacarbonyl compound of element 106, Sg(CO). Following this success, second-generation experiments were performed to measure the first bond dissociation energy between the central metal atom and the surrounding ligand. The method using a tubular decomposition reactor was developed and successfully applied to short-lived Mo(CO), W(CO), and Sg(CO).