Production and decay of the heaviest odd-Z nuclei in the 249Bk + 48Ca reaction

11th International Spring Seminar on Nuclear Physics: Shell Model and Nuclear Structure – achievements of the past two decades

Oganessian, Yu Ts^1 ; Abdullin, F. Sh^1 ; Alexander, C.^2 ; Binder, J.^2 ; Boll, R.A.^2 ; Dmitriev, S.N.^1 ; Ezold, J.^2 ; Felker, K.^2 ; Gostic, J.M.^3 ; Grzywacz, R.K.^2,4 ; Hamilton, J.H.^5 ; Henderson, R.A.^3 ; Itkis, M.G.^1 ; Miernik, K.^2 ; Miller, D.^4 ; Moody, K.J.^3 ; Polyakov, A.N.^1 ; Ramayya, A.V.^5 ; Roberto, J.B.^2 ; Ryabinin, M.A.^6 ; Rykaczewski, K.P.^2 ; Sagaidak, R.N.^1 ; Shaughnessy, D.A.^3 ; Shirokovsky, I.V.^1 ; Shumeiko, M.V.^1 ; Stoyer, M.A.^3 ; Stoyer, N.J.^3 ; Subbotin, V.G.^1 ; Sukhov, A.M.^1 ; Tsyganov, Yu S^1 ; Utyonkov, V.K.^1 ; Voinov, A.A.^1 ; Vostokin, G.K.^1

Joint Institute for Nuclear Research, Dubna

RU-141980, Russia^1

Oak Ridge National Laboratory, Oak Ridge

TN

37831, United States^2

Lawrence Livermore National Laboratory, Livermore

CA

94551, United States^3

University of Tennessee, Knoxville

TN

37996, United States^4

Vanderbilt University, Nashville

TN

37235, United States^5

Research Institute of Atomic Reactors, Dimitrovgrad

RU-433510, Russia^6

关键词: Decay characteristics;    Decay properties;    Excitation function;    Magic numbers;    Neutron number;    Projectile energy;    Reaction channels;    Superheavy nuclei;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/580/1/012038/pdf
DOI  :  10.1088/1742-6596/580/1/012038

来源: IOP

【 摘 要 】

The reaction of249Bk with48Ca 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 of48Ca ions of about 9x1019The experiments yielded data on a-decay characteristics and excitation functions of the produced nuclei that establish these to be293117 and294117-the products of the 4n- and 3n-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 3n and 2.4 pb for the 4n-reaction channel. The new289115 events, populated by α decay of 117, demonstrate the same decay properties as those observed for 115 produced in the243Am(48Ca,2n) reaction thus providing cross-bombardment evidence. In addition, a single decay of294118 was observed from the reaction with249Cf-a result of the in-growth of249Cf in the249Bk target. The observed decay chain of294118 is in good agreement with decay properties obtained in 2002-2005 in the experiments with the reaction249Cf(48Ca,3n)294118. 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.