基于双核模型对Z = 116~ 121 超重核产生截面的研究(英文)

Abstract

在双核模型的理论框架下系统研究了超重元素Z = 116 ~121 的蒸发剩余截面，计算过程中核子扩散由主方程描述，同时考虑了全熔合与准裂变的竞争。计算基本再现了利用热熔合反应48Ca+245Cm，48Ca+249Cf 和48Ca+249Bk 产生116~118 号同位素的合成截面。同样，分别以249Bk，249Cf 和243Am 为靶，以48Ca，50Ti 和58Fe 为炮弹，计算了Z = 119~ 121 号同位素的生成截面。结果表明，这些超重核的生成截面随着质子数的增大进一步变小。例如，利用58Fe+243Am 反应合成121 号同位素的最大蒸发剩余截面仅在fb 量级。基于对选择的几个反应系统的系统分析，发现双核系统在熔合蒸发过程中偶Z 奇N 和奇Z 偶N 复合核分别有强的3n 和4n 蒸发道。 The production cross sections of superheavy elements with Z = 116~121 have been investigated systematically within the dinuclear system (DNS) concept, where the master equation is solved numerically to obtain the fusion probability. The competition between complete fusion and quasifission, which can strongly affect the cross section of the compound nucleus formation, is taken into account. The evaporation residue cross sections ER calculated for the hot fusion actinide-based reactions (48Ca+245Cm, 48Ca+249Cf and 48Ca+249Bk) are basically in agreement with the known experimental data within one order of magnitude. Similar calculations for the synthesis of superheavy elements up to Z = 121 are performed using the available 249Bk, 249Cf and 243Am as targets and 48Ca, 50Ti and 58Fe as projectiles. Their production cross sections are relatively small,especially for the 58Fe+243Am→301121 reaction. A systematic analysis indicates that the 3n and 4n channels are respectively the most favorable fusion-evaporation channels in the synthesis of even- and odd-Z superheavy elements.