One- and two-neutron removal reactions from the most neutron-rich carbon isotopes
One- and two-neutron removal reactions from the most neutron-rich carbon isotopes
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DOI：
10.1103/physrevc.86.054604
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发表时间：
2011-11
影响因子：
3.1
通讯作者：
N. Kobayashi;T. Nakamura;J. Tostevin;Y. Kondo;N. Aoi;H. Baba;S. Deguchi;J. Gibelin;M. Ishihara;Y. Kawada;T. Kubo;T. Motobayashi;T. Ohnishi;N. Orr;H. Otsu;H. Sakurai;Y. Satou;E. Simpson;T. Sumikama;H. Takeda;M. Takechi;S. Takeuchi;K. Tanaka;N. Tanaka;Y. Togano;K. Yoneda
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文献类型：
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作者：
N. Kobayashi;T. Nakamura;J. Tostevin;Y. Kondo;N. Aoi;H. Baba;S. Deguchi;J. Gibelin;M. Ishihara;Y. Kawada;T. Kubo;T. Motobayashi;T. Ohnishi;N. Orr;H. Otsu;H. Sakurai;Y. Satou;E. Simpson;T. Sumikama;H. Takeda;M. Takechi;S. Takeuchi;K. Tanaka;N. Tanaka;Y. Togano;K. Yoneda
利用高能（约240 MeV/核子）单中子和双中子去除反应研究了19，20，22 C的结构。测量了带电剩余物的包容截面和动量分布。从19 C和20 C中去除一个中子和从22 C中去除两个中子观察到窄的动量分布。从20 C去除两个中子导致相对较宽的动量分布。与eikonal模型计算结合壳模型结构信息的结果进行了比较。中子去除截面和相关的动量分布的计算过渡到粒子束缚和粒子未绑定的最终状态。计算考虑了质量为A−1的反应残留物A−1C的布居数，以及在去除一个中子后发射一个中子后，质量为A−2的去除两个中子的残留物A−2C。直接去除两个中子的较小贡献，在一个步骤中填充A−2C残基，也被计算出来。数据和计算结果显示出良好的整体一致性，并与预测的壳模型基态构型和18− 21 C中低能级的单中子重叠相一致。这些结果表明，20 C和22 C中存在重要的νs1/22价中子组态。22 C的结果强烈支持了22 C是一个双中子晕核的观点，它具有占主导地位的νs1/22基态组态。
The structure of 19,20,22C has been investigated using high-energy (around 240 MeV/nucleon) one- and two-neutron removal reactions on a carbon target. Measurements were made of the inclusive cross sections and momentum distributions for the charged residues. Narrow momentum distributions were observed for one-neutron removal from 19C and 20C and two-neutron removal from 22C. Two-neutron removal from 20C resulted in a relatively broad momentum distribution. The results are compared with eikonal-model calculations combined with shell-model structure information. The neutron removal cross sections and associated momentum distributions are calculated for transitions to both the particle-bound and particle-unbound final states. The calculations take into account the population of the mass A−1 reaction residues A−1C and, following one-neutron emission after one-neutron removal, the mass A−2 two-neutron removal residues A−2C. The smaller contributions of direct two-neutron removal, that populate the A−2C residues in a single step, are also computed. The data and calculations are shown to be in good overall agreement and consistent with the predicted shell-model ground-state configurations and one-neutron overlaps with low-lying states in 18−21C. These suggest significant νs1/22 valence neutron configurations in both 20C and 22C. The results for 22C strongly support the picture of 22C as a two-neutron halo nucleus with a dominant νs1/22 ground-state configuration.