在CSR-RIBLL2外靶装置上开展14,15,16C反应截面的能量依赖性研究

Halo structure property is an important research subject in nuclear physics. Reaction cross section or interaction cross section measurements using intermediate to high energy radioactive beams have proved to be a powerful tool for probing nuclear halo property. More and more exotic nuclei with halo structure have been found or identified within this method recently. However, in some cases, there exists obvious discrepancy between the results extracted from intermediate data and those from high energy data. For example, the measurement with intermediate energy beams shows that the reaction cross section for 15C is much larger than that for neighboring 14,16C, indicating that 15C has an evident halo structure. On the other hand, high energy data shows that 15C does not clearly exhibit a halo structure. Even the newly developed theory also could not achieve consistent results between high energy and intermediate energy measurements. In this proposal, we aim to measure systematically the energy dependence of the 14,15,16C reaction cross sections using the CSR-RIBLL2 radioactive beam line and the External Target Faciltiy. The systematic results allow us to test and modify, in detail, the current Glauber theory. Results are essential to establish reliable theoretical framework for studying halo structure with both high energy and intermediate energy reaction cross section measurements.

晕结构是核物理领域的重要研究方向之一。基于中高能放射性束流的反应截面（或相互作用截面）测量是研究晕结构的重要手段之一。近年来，越来越多的晕核通过该手段被发现或确认。然而，经常出现高能束流数据和中能束流数据提取的结论不一致的情况。例如，中能束流测量结果显示15C反应截面较14,16C明显偏大，表明15C具有明显的晕结构，而高能束流结果却显示15C无明显晕结构。最近，新发展的利用反应截面提取晕结构信息的理论对于提取的15C高能和中能数据结果仍然相矛盾。基于此，本项目提出利用CSR-RIBLL2提供的中高能束流及外靶实验装置对14,15,16C反应截面进行系统的随能量变化的精确测量，以细致检验和促进完善现有Glauber模型，建立一套可靠的同时适用于中能和高能束流的提取晕结构信息的方法。

在中高能束流装置上开展相互作用截面(σI)和反应截面(σR)测量很早就被用来寻找和研究晕核。直到现在，通过测量σI和σR仍然被广泛的用于研究远离稳定线核的结构。人们利用测量反应截面对15C提取晕结构信息时发现，中能束流结果（83 MeV/u）和高能束流结果（700 MeV/u）出现了不一致的情况。中能束流测量结果显示15C反应截面较14,16C明显偏大，表明15C具有明显的晕结构，而高能束流结果却显示15C无明显晕结构。本工作利用CSR和RIBLL2产生了高品质的束流能量为240MeV/u的14,15,16C放射性束流，并利用外靶实验装置对14,15,16C在碳靶上的相互作用截面进行了测量，为14,15,16C反应截面束流能量依赖性细致研究提供了较好的实验数据基础。利用本实验提取的反应截面结合以往的低能和高能的实验数据，可以很好地检验Glauber理论在计算核反应截面能量依赖关系方面的可靠性，进而有助于改进和完善核反应模型。