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Title: Experiments on Synthesis of the Heaviest Element at RIKEN

Abstract

At the Institute of Physical and Chemical Research (RIKEN) a series of experiments studying the productions and their decays of the heaviest elements have been performed by using a gas-filled recoil ion separator GARIS. Results on the isotope of the 112th element, 277112, and on that of the 113th element, 278113, are reviewed. Tow decay chains which are assigned to be ones originating from the isotope 277112 were observed in the 208Pb(70Zn, n) reaction. Both chains consisted of four consecutive alpha decays followed by a spontaneous fission. The results provide a confirmation of the production and decay of the isotope 277112 reported by a research group at Gesellschaft fuer Schwerionenforschung (GSI), Germany, produced via the same reaction by using a velocity filter. Tow decay chains, both consisted of four consecutive alpha decays followed by a spontaneous fission, were observed also in the reaction 209Bi(70Zn, n). Those are assigned to be the convincing candidate events of the decays of the isotope of the 113th element, 278113, and its daughter nuclei, 274Rg, 270Mt, 266Bh, and 262Db.

Authors:
; ; ; ; ; ; ; ; ; ;  [1];  [1];  [2];  [3];  [4];  [5];  [6]; ;  [7];  [8] more »;  [2];  [9] « less
  1. Nishina Center for Accelerator Based Science, RIKEN, Wako, Saitama 315-0198 (Japan)
  2. (Japan)
  3. Center for Instrumental Analysis, Niigata University, Ikarashi, Niigata 950-2181 (Japan)
  4. Center for Nuclear Study, University of Tokyo Wako Branch, Wako, Saitama 351-0198 (Japan)
  5. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)
  6. Department of Chemistry, Niigata University, Ikarashi, Niigata 950-2181 (Japan)
  7. University of Tsukuba, Tsukuba, Ibaraki 305-8571 (Japan)
  8. Department of Physics, Tohoku University, Aoba-ku, Sendai 980-8578 Japan (Japan)
  9. Department of Physics, Yamagata University, Shirakawa, Yamagata 990-8560 (Japan) (and others)
Publication Date:
OSTI Identifier:
21056767
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 891; Journal Issue: 1; Conference: 6. Symposium on nuclear physics, Tours (France), 5-8 Sep 2006; Other Information: DOI: 10.1063/1.2713494; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ALPHA DECAY; BISMUTH 209 TARGET; BOHRIUM 266; DUBNIUM 262; ELEMENT 113 278; HEAVY ION FUSION REACTIONS; JAPANESE ORGANIZATIONS; LEAD 208 TARGET; MEITNERIUM 270; NEUTRONS; RECOILS; ROENTGENIUM 274; SPONTANEOUS FISSION; VELOCITY; ZINC 70 REACTIONS

Citation Formats

Morita, K., Morimoto, K., Kaji, D., Haba, H., Kanumgo, R., Katori, K., Kikunaga, H., Ohnishi, T., Suda, T., Yoneda, A., Yoshida, A., Akiyama, T., Department of Physics, Saitama University, Sakura-ku, Saitama 338-8570, Goto, S., Ideguchi, E., Koura, H., Kudo, H., Ozawa, A., Sueki, K., Sato, N., Nishina Center for Accelerator Based Science, RIKEN, Wako, Saitama 315-0198, and Tokanai, F. Experiments on Synthesis of the Heaviest Element at RIKEN. United States: N. p., 2007. Web. doi:10.1063/1.2713494.
Morita, K., Morimoto, K., Kaji, D., Haba, H., Kanumgo, R., Katori, K., Kikunaga, H., Ohnishi, T., Suda, T., Yoneda, A., Yoshida, A., Akiyama, T., Department of Physics, Saitama University, Sakura-ku, Saitama 338-8570, Goto, S., Ideguchi, E., Koura, H., Kudo, H., Ozawa, A., Sueki, K., Sato, N., Nishina Center for Accelerator Based Science, RIKEN, Wako, Saitama 315-0198, & Tokanai, F. Experiments on Synthesis of the Heaviest Element at RIKEN. United States. doi:10.1063/1.2713494.
Morita, K., Morimoto, K., Kaji, D., Haba, H., Kanumgo, R., Katori, K., Kikunaga, H., Ohnishi, T., Suda, T., Yoneda, A., Yoshida, A., Akiyama, T., Department of Physics, Saitama University, Sakura-ku, Saitama 338-8570, Goto, S., Ideguchi, E., Koura, H., Kudo, H., Ozawa, A., Sueki, K., Sato, N., Nishina Center for Accelerator Based Science, RIKEN, Wako, Saitama 315-0198, and Tokanai, F. Mon . "Experiments on Synthesis of the Heaviest Element at RIKEN". United States. doi:10.1063/1.2713494.
@article{osti_21056767,
title = {Experiments on Synthesis of the Heaviest Element at RIKEN},
author = {Morita, K. and Morimoto, K. and Kaji, D. and Haba, H. and Kanumgo, R. and Katori, K. and Kikunaga, H. and Ohnishi, T. and Suda, T. and Yoneda, A. and Yoshida, A. and Akiyama, T. and Department of Physics, Saitama University, Sakura-ku, Saitama 338-8570 and Goto, S. and Ideguchi, E. and Koura, H. and Kudo, H. and Ozawa, A. and Sueki, K. and Sato, N. and Nishina Center for Accelerator Based Science, RIKEN, Wako, Saitama 315-0198 and Tokanai, F.},
abstractNote = {At the Institute of Physical and Chemical Research (RIKEN) a series of experiments studying the productions and their decays of the heaviest elements have been performed by using a gas-filled recoil ion separator GARIS. Results on the isotope of the 112th element, 277112, and on that of the 113th element, 278113, are reviewed. Tow decay chains which are assigned to be ones originating from the isotope 277112 were observed in the 208Pb(70Zn, n) reaction. Both chains consisted of four consecutive alpha decays followed by a spontaneous fission. The results provide a confirmation of the production and decay of the isotope 277112 reported by a research group at Gesellschaft fuer Schwerionenforschung (GSI), Germany, produced via the same reaction by using a velocity filter. Tow decay chains, both consisted of four consecutive alpha decays followed by a spontaneous fission, were observed also in the reaction 209Bi(70Zn, n). Those are assigned to be the convincing candidate events of the decays of the isotope of the 113th element, 278113, and its daughter nuclei, 274Rg, 270Mt, 266Bh, and 262Db.},
doi = {10.1063/1.2713494},
journal = {AIP Conference Proceedings},
number = 1,
volume = 891,
place = {United States},
year = {Mon Feb 26 00:00:00 EST 2007},
month = {Mon Feb 26 00:00:00 EST 2007}
}
  • In the Institute of Physical and Chemical Research (RIKEN), using high intensity heavy ion beams from the RIKEN Linear Accelerator, productions and decays of isotopes of the heaviest elements have been investigated by using the gas-filled recoil separator, GARIS. The isotopes studied were 265Hs, 271Ds, 272Rg, 277112, and 278113, respectively. Based on the observed decay chains consisting of consecutive alpha decays connected to the previously known alpha decays or spontaneous fissions, assignments of the initially produced isotopes were done. Our data with the atomic number from 108 to 112, agree well with the data previously taken. The production cross sectionmore » of the isotope 278113 of the 113th element have reached around 32 fb which shows the simple decrease of the cross section with the increase of the atomic number. The isotopes were produced, for the first time in the 1n evaporation channel from heavy-ion induced fusion reaction.« less
  • The neutral muonic helium atom {sup 4}He{mu}, in which one of the electrons of He is replaced by a negative muon, may be effectively regarded as the heaviest isotope of the hydrogen atom, with a mass of 4.115 amu. We report details of the first muon spin rotation ({mu}SR) measurements of the chemical reaction rate constant of {sup 4}He{mu} with molecular hydrogen, {sup 4}He{mu} + H{sub 2} {yields} {sup 4}He{mu}H + H, at temperatures of 295.5, 405, and 500 K, as well as a {mu}SR measurement of the hyperfine coupling constant of muonic He at high pressures. The experimental ratemore » constants, k{sub He{mu}}, are compared with the predictions of accurate quantum mechanical (QM) dynamics calculations carried out on a well converged Born-Huang (BH) potential energy surface, based on complete configuration interaction calculations and including a Born-Oppenheimer diagonal correction. At the two highest measured temperatures the agreement between the quantum theory and experiment is good to excellent, well within experimental uncertainties that include an estimate of possible systematic error, but at 295.5 K the quantum calculations for k{sub He{mu}} are below the experimental value by 2.1 times the experimental uncertainty estimates. Possible reasons for this discrepancy are discussed. Variational transition state theory calculations with multidimensional tunneling have also been carried out for k{sub He{mu}} on the BH surface, and they agree with the accurate QM rate constants to within 30% over a wider temperature range of 200-1000 K. Comparisons between theory and experiment are also presented for the rate constants for both the D + H{sub 2} and Mu + H{sub 2} reactions in a novel study of kinetic isotope effects for the H + H{sub 2} reactions over a factor of 36.1 in isotopic mass of the atomic reactant.« less
  • No abstract prepared.
  • We have developed a new analytical system that consists of an electron cyclotron resonance ion source (RIKEN 18 GHz ECRIS) and a RIKEN heavy ion linear accelerator (RILAC). This system is called trace element analysis using electron cyclotron resonance ion source and RILAC (ECRIS-RILAC-TEA). ECRIS-RILAC-TEA has several advantages as described in the work of Kidera et al. [AIP Conf. Proc. 749, 85 (2005)]. However, many experimental results during the last several years revealed a few problems: (1) large background contamination in the ECRIS, particularly at the surface of the plasma chamber wall, (2) high counting of the ionization chamber andmore » the data taking system that is monitored by the direct beam from the accelerator, and (3) difficulty in the selection of the pilot sample and pilot beam production from the ECRIS for the purpose of normalization. In order to overcome these problems, we conducted several test experiments over the past year. In this article, we report the experimental results in detail and future plans for improving this system.« less