Production and decay of the heaviest odd-Z nuclei in the 249Bk + 48Ca reaction. (9th February 2015)

• Record Type: Journal Article
• Authors: Oganessian, Yu Ts; Abdullin, F Sh; Alexander, C; Binder, J; Boll, R A; Dmitriev, S N; Ezold, J; Felker, K; Gostic, J M; Grzywacz, R K; Hamilton, J H; Henderson, R A; Itkis, M G; Miernik, K; Miller, D; Moody, K J; Polyakov, A N; Ramayya, A V; Roberto, J B; Ryabinin, M A; Rykaczewski, K P; Sagaidak, R N; Shaughnessy, D A; Shirokovsky, I V; Shumeiko, M V; Stoyer, M A; Stoyer, N J; Subbotin, V G; Sukhov, A M; Tsyganov, Yu S; Utyonkov, V K; Voinov, A A; Vostokin, G K;
• Is Part Of: Journal of physics. Number 580(2015)
• Page Start: 012038
• Publication Date: 2015-02-09
• Subjects: Physics -- Congresses; 530.5
• DOI: 10.1088/1742-6596/580/1/012038
• Languages: English
• ISSNs: 1742-6588

Abstract

Abstract: The reaction of 249 Bk with 48 Ca has been investigated with an aim of synthesizing and studying the decay properties of isotopes of the new element 117. The experiments were performed at five projectile energies (in two runs, in 2009-2010 and 2012) and with a total beam dose of 48 Ca ions of about 9x10 19 The experiments yielded data on a-decay characteristics and excitation functions of the produced nuclei that establish these to be 293 117 and 294 117 – the products of the 4 n - and 3 n -evaporation channels, respectively. In total, we have observed 20 decay chains of Z =117 nuclides. The cross sections were measured to be 1.1 pb for the 3 n and 2.4 pb for the 4 n -reaction channel. The new 289 115 events, populated by α decay of 117, demonstrate the same decay properties as those observed for 115 produced in the 243 Am( 48 Ca, 2 n ) reaction thus providing cross-bombardment evidence. In addition, a single decay of 294 118 was observed from the reaction with 249 Cf – a result of the in-growth of 249 Cf in the 249 Bk target. The observed decay chain of 294 118 is in good agreement with decay properties obtained in 2002-2005 in the experiments with the reaction 249 Cf( 48 Ca, 3 n ) 294 118. The energies and half-lives of the odd-Z isotopes observed in the 117 decay chains together with the results obtained for lower-Z superheavy nuclei demonstrate enhancement of nuclear stability with increasing neutron number towards the predicted new magic number N =184.