Development of odd-Z-projectile reactions for transactinide element synthesis
Development of odd-Z-projectile reactions for transactinide element synthesis
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DOI：
10.2172/843003
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发表时间：
2004-11
期刊：
影响因子：
--
通讯作者：
Folden;C. Marvin
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作者：
Folden;C. Marvin
介绍了产生超锕系元素的奇Z射弹反应的发展。在劳伦斯伯克利国家实验室的88英寸回旋加速器中，使用伯克利充气分离器在两种新的能量下测量了208Pb（64Ni，n）271Ds的偶Z射弹反应截面。总共观察到7条271Ds衰变链。这些数据，结合以前的结果，建立了一个激发函数的生产271 Ds。利用271Ds的实验数据，采用Swiatecki，Siwek-Wilczynska和Wilczynski提出的扩散聚变理论，估算了新的奇Z射弹208Pb（65Cu，n）272 - 111反应的最佳束流能量。第一次测量了该反应的横截面，在实验室框架中的目标能量中心为321.1 MeV。在靶中心形成的复合核的激发能为13.2MeV。观察到一条衰变链，测得的截面为1.7 + 3.9 - 1.4 pb。这条衰变链与以前发表的272 - 111的衰变数据符合得很好。在三种不同的射弹能量下研究了新的奇Z射弹208Pb（55Mn，n）262Bh反应，观察到33条262Bh的衰变链。证实了先前报道的这种核素中存在α衰变同分异构态。在所有三种束能量下，基态的生产是优选的。在靶心能量为264.0MeV时，最大截面为540 + 180 - 150pb。这个截面比之前报道的偶数Z射弹209Bi（54Cr，n）262Bh反应的截面大得多，这可能是因为在后一反应中54Cr射弹能量太高，不能最佳地产生1n产物。在靶中心的最高射弹能量为268.0 MeV时，观察到208Pb（55Mn，2n）反应产生的两条261Bh衰变链。总之，这项工作表明，奇数Z-射弹反应可以有类似的偶数Z-射弹反应的横截面，并且可以简单地估计1n反应的最大横截面的能量。
The development of new odd-Z-projectile reactions leading to the production of transactinide elements is described. The cross section of the even-Z-projectile 208Pb(64Ni, n)271Ds reaction was measured at two new energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, seven decay chains attributable to 271Ds were observed. These data, combined with previous results, establish an excitation function for the production of 271Ds. The maximum cross section was 20 +15 -11 pb at a center-of-target energy of 311.5 MeV in the laboratory frame.The data from the 271Ds experiments were used to estimate the optimum beam energy for the new odd-Z-projectile 208Pb(65Cu, n)272-111 reaction using the Fusion by Diffusion theory proposed by Swiatecki, Siwek-Wilczynska, and Wilczynski. A cross section for this reaction was measured for the first time, at a center-of-target energy of 321.1 MeV in the laboratory frame. The excitation energy f or compound nuclei formed at the target center was 13.2 MeV. One decay chain was observed, resulting in a measured cross section of 1.7 +3.9 -1.4 pb. This decay chain is in good agreement with previously published data on the decay of 272-111.The new odd-Z-projectile 208Pb(55Mn, n)262Bh reaction was studied at three different projectile energies, and 33 decay chains of 262Bh were observed. The existence of a previously reported alpha-decaying isomeric state in this nuclide was confirmed. Production of the ground state was preferred at all three beam energies. The maximum cross section was 540 +180 -150 pb at a projectile center-of-target energy of 264.0 MeV. This cross section is much larger than that previously reported for the even-Z-projectile 209Bi(54Cr, n)262Bh reaction, which may be because the 54Cr projectile energies in the latter reaction were too high for optimum production of the 1n product. At the highest projectile energy of 268.0 MeV in the target center, two decay chains from 261Bh were observed as a result of the 208Pb(55Mn, 2n) reaction. In summary, this work shows that odd-Z-projectile reactions can have cross sections comparable to analogous even-Z-projectile reactions, and that the energy of the maximum cross section for 1n reactions can be estimated simply.