11Be+208Pb破裂反应机制研究

The effect on the fusion process of the breakup of weakly bound light nuclei is a subject of current experimental and theoretical investigations. This is due to the recent availability of beams of unstable nuclei with weakly bound nucleons. An understanding of breakup and fusion is directly relevant to producing nuclei near the drip lines, and possibly super-heavy nuclei...Until recently, there were two opposing theoretical points of view, one which predicted the enhancement of fusion cross sections due to couplings to the low lying unbound or continuum states of the weakly bound light nuclei, and the other which predicted reduction in fusion due to break up of the nuclei. However, it was shown that complete fusion cross sections are enhanced at energies below the barrier but reduced at above-barrier energies. Since then this result has been supported by other theoretical calculations. Thus, the question of enhancement versus suppression is resolved as far as theoretical predictions are concerned. ..The high precision excitation functions will be measured using a large-area high-resolution detector array for the breakup of 11Be with 208Pb reactions, at energies near the Coulomb barrier. The relative energy of the breakup fragments will reveal the full dynamics of the breakup mechanism, identifying all physical processes that lead to the breakup of the projectile-like nucleus. The role of break-up processes in the fusion of the 11Be+208Pb system will be studied.

随着次级放射性核束流线的发展，破裂反应道对熔合反应作用逐渐成为一个研究热点。这方面已经有了大量的的实验和理论研究，但也随之产生了一些相互矛盾的结论。在多年进行弱束缚稳定核破裂反应研究的基础上，本申请计划利用兰州近代物理研究所的RIBLL1装置所提供的放射性核素，配合大立体角双面硅条探测器的组合，高精度测量11Be+208Pb的破裂反应和熔合反应激发函数，考察破裂反应道对于熔合反应的影响，为相关的理论和实验研究提供素材，同时也是熔合反应机制研究的重要部分。

随着次级放射性核束流线的发展，弱束缚核的破裂逐渐成为一个研究热点。这方面已经有了大量的的实验和理论研究，但也随之产生了一些相互矛盾的结论。在多年进行弱束缚稳定核破裂反应研究的基础上，本课题建立了一套针对于这类实验的大立体角硅条探测器的阵列，并且利用这套探测器阵列进行了稳定束实验以作为测试，取得了不错的实验结果。进一步，我们将利用兰州近代物理研究所的RIBLL1装置所提供的放射性束流，高精度测量11Be+208Pb的破裂反应。为相关的理论和实验研究提供素材，同时也这方面的进一步工作打下良好的基础。