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arXiv 1409.7209nucl-exnucl-th
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重离子近垒弹性散射中的强耦合效应

Strong coupling effects in near-barrier heavy-ion elastic scattering

N. Keeley, K. W. Kemper, K. Rusek

摘要:

精确的弹性散射角分布数据测量的轰击能量刚好高于库仑势垒的形状,可以显着不同或相同的预期的经典菲涅耳散射图案取决于结构的弹丸,目标或两者。例如18 O +184 W和16 O + 148,152 Sm,其中由于库仑核干涉而引起的卢瑟福散射的预期上升通过耦合到目标激发态而被阻尼,以及11 Li散射的极端情况,其中耦合到9 Li + n + n连续谱导致不能由任何标准光学模型参数集再现的弹性散射形状。最近获得的高质量的6He,11Li和11Be数据提供了耦合效应对弹性散射的影响的进一步例子。提出了强弹靶耦合效应的条件,特别强调了束靶装药组合足够大以产生强耦合效应的重要性。提出了几个测量,可以导致进一步了解强耦合效应的非弹性激发和核子转移近垒弹性散射。最后一个关于8B弹性散射的异常性质的说明,因为它具有或多或少的正常菲涅耳散射形状,而由于8B的非常低的破裂阈值,人们不会先验地期望这一点。11锂的特殊性质,因为它是预测,无论多远以上的库仑势垒的弹性散射测量,它的形状不会出现菲涅尔像而所有其他松散的结合核的弹性散射研究到目前为止,最终应该这样做,随着入射能量的增加,使8B和11锂真正的“异国情调”。

英文摘要:

Accurate elastic scattering angular distribution data measured at bombarding energies just above the Coulomb barrier have shapes that can markedly differ from or be the same as the expected classical Fresnel scattering pattern depending on the structure of the projectile, the target or both. Examples are given such as 18O + 184W and 16O + 148,152Sm where the expected rise above Rutherford scattering due to Coulomb-nuclear interference is damped by coupling to the target excited states, and the extreme case of 11Li scattering, where coupling to the 9Li + n + n continuum leads to an elastic scattering shape that cannot be reproduced by any standard optical model parameter set. The recent availability of high quality 6He, 11Li and 11Be data provides further examples of the influence that coupling effects can have on elastic scattering. Conditions for strong projectile-target coupling effects are presented with special emphasis on the importance of the beam-target charge combination being large enough to bring about the strong coupling effects. Several measurements are proposed that can lead to further understanding of strong coupling effects by both inelastic excitation and nucleon transfer on near-barrier elastic scattering. A final note on the anomalous nature of 8B elastic scattering is presented as it possesses a more or less normal Fresnel scattering shape whereas one would a priori not expect this due to the very low breakup threshold of 8B. The special nature of 11Li is presented as it is predicted that no matter how far above the Coulomb barrier the elastic scattering is measured, its shape will not appear as Fresnel like whereas the elastic scattering of all other loosely bound nuclei studied to date should eventually do so as the incident energy is increased, making both 8B and 11Li truly "exotic".

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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