Investigation of the ${}^{243}\mathrm{Am}+{}^{48}\mathrm{Ca}$ reaction products previously observed in the experiments on elements 113, 115, and 117

Free to Read

Investigation of the $^{243} Am +^{48} Ca$ reaction products previously observed in the experiments on elements 113, 115, and 117

Yu. Ts. Oganessian, F. Sh. Abdullin, S. N. Dmitriev, J. M. Gostic, J. H. Hamilton, R. A. Henderson, M. G. Itkis, K. J. Moody, A. N. Polyakov, A. V. Ramayya, J. B. Roberto, K. P. Rykaczewski, R. N. Sagaidak, D. A. Shaughnessy, I. V. Shirokovsky, M. A. Stoyer, N. J. Stoyer, V. G. Subbotin, A. M. Sukhov, Yu. S. Tsyganov, V. K. Utyonkov, A. A. Voinov, and G. K. Vostokin

Phys. Rev. C 87, 014302 – Published 3 January 2013

An article within the collection: Transuranium Elements and the Physical Review

Abstract

Results from the production and decay properties of element 115 nuclei observed using the reaction $^{243} Am +^{48} Ca$ at various beam energies between November 1, 2010, and February 26, 2012, at the Dubna Gas Filled Recoil Separator are presented. This long-running experiment with a total beam dose of $3.3 \times 10^{19}$ and carried out in the excitation energy range $E^{*} = 31$ –47 MeV of the $^{291}$ 115 compound nucleus resulted in observation of three isotopes of element 115 with masses 287, 288, and 289. The 28 detected decay chains of $^{288}$ 115 show that this isotope is produced with the maximum probability at $E^{*} = 34.0$ –38.3 MeV with a corresponding cross section of $σ_{3 n} = 8 . 5_{- 3.7}^{+ 6.4}$ pb. The four events attributed to the isotope $^{289}$ 115 that decays via a short $α \to α \to SF$ chain could be detected only at the lowest excitation energy $E^{*} = 31$ –36 MeV, in accordance with what could be expected for the 2 $n$ -evaporation channel of the reaction. The decay characteristics of this nuclide were established earlier (2010) and more recently (2012) in the reaction $^{249}$ Bk( $^{48}$ Ca,4 $n$ ) $^{293}$ 117 and following $α$ decay to $^{289}$ 115. At the energy $E^{*} = 44.8 \pm 2.3$ MeV we observed only a single long chain of the isotope $^{287}$ 115. The decay properties of nuclei starting at $^{288}$ 115 and $^{287}$ 115 isotopes obtained in the present work reproduce in full the results of the first experiment of 2003 that reported the discovery of elements 115 and 113. The excitation functions of the production of the isotopes of element 115 and observation of the isotope $^{289}$ 115 in cross-bombardment reactions with the targets of $^{243}$ Am and $^{249}$ Bk provide additional evidence of the identification of the nuclei of elements 115 and 113. The experiments were carried out using the $^{48}$ Ca beam of the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions, JINR.

Received 9 September 2012

DOI:https://doi.org/10.1103/PhysRevC.87.014302

Collections

This article appears in the following collection:

Transuranium Elements and the Physical Review

This collection marks the 150th anniversary of Dmitri Mendeleev’s discovery of the Periodic Table of Elements.

Authors & Affiliations

Yu. Ts. Oganessian^1,*, F. Sh. Abdullin¹, S. N. Dmitriev¹, J. M. Gostic², J. H. Hamilton³, R. A. Henderson², M. G. Itkis¹, K. J. Moody², A. N. Polyakov¹, A. V. Ramayya³, J. B. Roberto⁴, K. P. Rykaczewski⁴, R. N. Sagaidak¹, D. A. Shaughnessy², I. V. Shirokovsky¹, M. A. Stoyer², N. J. Stoyer², V. G. Subbotin¹, A. M. Sukhov¹, Yu. S. Tsyganov¹, V. K. Utyonkov¹, A. A. Voinov¹, and G. K. Vostokin¹

¹Joint Institute for Nuclear Research, RU-141980 Dubna, Russian Federation
²Lawrence Livermore National Laboratory, Livermore, California 94551, USA
³Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA
⁴Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

^*oganessian@jinr.ru

Article Text

Click to Expand

References

Click to Expand

Issue

Vol. 87, Iss. 1 — January 2013

Reuse & Permissions

Access Options

Article part of CHORUS

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
(a) Total energy spectra of beam-on $α$ -like signals and beam-off $α$ particles recorded during the 243-MeV $^{243} Am +^{48} Ca$ run. (b) Total fission-fragment energy spectrum. The arrows show the energies of events observed in correlated decay chains; see event numbers 20–25 in Table .Reuse & Permissions
Figure 2
(a) Relative position deviations of all events given in Tables (histogram) with a Gaussian fit ( $FWHM = 0.8$ mm, dashed line). (b) Energy spectrum of all ERs with $Z = 112$ –118 produced in $^{48}$ Ca-induced reactions [1, 2, 3, 4, 5, 6, 7, 8]. The energy distribution of $^{252}$ No implants measured in the calibration reaction $^{206} Pb +^{48} Ca$ is shown by the dashed line for comparison. Energies of $Z = 115$ ERs are shown by the gray histogram.Reuse & Permissions
Figure 3
$α$ -particle energy spectra registered by the focal-plane detector (left-hand panel) and decay-time distributions on a logarithmic scale (right-hand panel) for isotopes originating from $^{289}$ 115 and $^{288}$ 115. The events originating from $^{289}$ 115 observed in the reactions with $^{249}$ Bk in the first experiment [6, 7], in the second experiment [15], and in the reaction with $^{243}$ Am (Ref. [16] and this work) are shown in the histograms by red (top), green (middle), and blue (bottom) lines, respectively. The red lines for nuclei in the decay chains of $^{288}$ 115 show the energies and decay times of the three events obtained in the first experiment in 2003 [1, 2, 3, 4]. The smooth curves are the time spectra for exponential decays associated with the half-lives $T_{1 / 2}$ shown in the figures.Reuse & Permissions
Figure 4
Cross sections for the 2 $n$ , 3 $n$ , and 4 $n$ evaporation channels for the $^{243} Am +^{48} Ca$ reaction. Vertical error bars correspond to statistical uncertainties [21]. Horizontal error bars represent the range of excitation energies populated at one beam energy. Symbols with arrows show upper cross-section limits. Numbers of detected decay chains are given for each $^{48}$ Ca energy. The dashed line through the 3 $n$ data are drawn to guide the eye.Reuse & Permissions
Figure 5
Summary decay properties of the isotopes of elements 113, 115, and 117 observed for the first time among the products of $^{48}$ Ca beam and $^{237}$ Np, $^{243}$ Am, and $^{249}$ Bk target reactions. The number of the detected decay events of a given isotope is shown at the bottom of the chains. The energies of the emitted $α$ particles and half-lives are given for all 23 new $α$ emitters observed in these experiments. For five new spontaneously fissioning nuclei marked by gray squares, that is, the isotopes of Db and Rg that terminate the $α$ -decay sequences with SF, the half-lives are listed. The value for $^{268}$ Db was obtained combining the results of Refs. [1, 2, 3, 4, 10, 11, 16] and those of the present work.Reuse & Permissions

Physical Review C

covering nuclear physics

Investigation of the $^{243} Am +^{48} Ca$ reaction products previously observed in the experiments on elements 113, 115, and 117

Phys. Rev. C 87, 014302 – Published 3 January 2013

An article within the collection: Transuranium Elements and the Physical Review

Abstract

Collections

Transuranium Elements and the Physical Review

Authors & Affiliations

Article Text

References

Issue

Access Options

Physical Review C

covering nuclear physics

Investigation of the 243Am+48Ca reaction products previously observed in the experiments on elements 113, 115, and 117

Phys. Rev. C 87, 014302 – Published 3 January 2013

An article within the collection: Transuranium Elements and the Physical Review

Abstract

Collections

Transuranium Elements and the Physical Review

Authors & Affiliations

Article Text

References

Issue

Access Options

Authorization Required

Other Options

Download & Share

Images

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

Investigation of the $^{243} Am +^{48} Ca$ reaction products previously observed in the experiments on elements 113, 115, and 117