First experiment at the Super Heavy Element Factory: High cross section of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Mc</mml:mi><mml:mprescripts/><mml:none/><mml:mn>288</mml:mn></mml:mmultiscripts></mml:math> in the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mmultiscripts><mml:mi>Am</mml:mi><mml:mprescripts/><mml:none/><mml:mn>243</mml:mn></mml:mmultiscripts><mml:mo>+</mml:mo><mml:mmultiscripts><mml:mi>Ca</mml:mi><mml:mprescripts/><mml:none/><mml:mn>48</mml:mn></mml:mmultiscripts></mml:mrow></mml:math> reaction and identification of the new isotope <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Lr</mml:mi><mml:mprescripts/><mml:none/><mml:mn>264</mml:mn></mml:mmultiscripts></mml:math>
Yu. Ts. Oganessian, V. K. Utyonkov, N. D. Kovrizhnykh, F. Sh. Abdullin, S. N. Dmitriev, D. Ibadullayev, М. Г. Иткис, D. A. Kuznetsov, O. V. Petrushkin, A. V. Podshibiakin, А. N. Polyakov, A. G. Popeko, R. N. Sagaidak, L. Schlattauer, I. V. Shirokovski, V. D. Shubin, M. V. Shumeiko, D. I. Solovyev, Yu. S. Tsyganov, A. A. Voinov, V. G. Subbotin, A. Yu. Bodrov, A. V. Sabelnikov, A. V. Khalkin, В. Б. Злоказов, K. P. Rykaczewski, T. King, J. B. Roberto, N. T. Brewer, R. Grzywacz, Z. G. Gan, Z. Y. Zhang, M. H. Huang, H. B. Yang
Abstract
Here, we present results of the first experiment aimed at the synthesis of Mc isotopes in the <sup>243</sup>Am+<sup>48</sup>Ca reaction performed at the new gas-filled separator DGFRS-2 online to the new cyclotron DC280 at the Super Heavy Element Factory at JINR. Fifty-five new decay chains of <sup>288</sup>Mc and six chains assigned to <sup>289</sup>Mc were detected. The α decay of <sup>268</sup>Db with an energy of 7.6–8.0 MeV, half-life of 16$^{+6}_{-4}$h, and a branch of 55$^{+20}_{-15}$% was registered for the first time, and a new spontaneously fissioning isotope <sup>264</sup>Lr with a half-life of 4.9$^{+2.1}_{-1.3}$h was identified. The cross section for the <sup>243</sup>Am(<sup>48</sup>Ca,3n)<sup>288</sup>Mc reaction was measured to be 17.1$^{+6.3}_{-4.7}$ pb, which is the largest value for the known superheavy nuclei at the island of stability.