标题： 在四体反应模型中从$^{9}$拆散反应确定$S_{18}$ 显示英文标题

标题： Determination of $S_{18}$ from $^{9}$C breakup reaction within a four-body reaction model

摘要： 天体物理因子 $S_{18}$ 对于 $^{8}$ B($p$, $\gamma$) $^{9}$ C 已经通过从 $^9$ C 的质子去除反应、重靶上 $^9$ C 的弹性裂变反应以及转移反应间接测量得到。 最近，弹性破裂截面数据使用连续离散耦合通道方法（CDCC）重新进行了分析，假设了$p+{\rm ^{8}B}$二体模型用于$^9$C，并且$S_{18}$被修改了。然而，将$^8$B 视为惰性核并不合理，因为它的质子分离能仅为 137 keV。 我们通过四体CDCC方法重新考察了$^9$C 的弹性裂变，并采用$p+p+{\rm ^{7}Be}$的三体模型来描述$^9$C，评估了$S_{18}$。 为了实现这一点，我们首次提出了一种方法，用于在四体CDCC计算中分离$p+{\rm ^{8}B}+{\rm ^{208}Pb}$的三体通道。 我们计算了在65 MeV/核子能量下，$^9$C 对$^{208}$Pb 靶的弹性裂变截面。 所得的破裂截面通过使用复尺度Lippmann--Schwinger方程的解被分解为$p+{\rm ^{8}B}+{\rm ^{208}Pb}$和$p+p+{\rm ^{7}Be}+{\rm ^{208}Pb}$通道的贡献。 $p+{\rm ^{8}B}+{\rm ^{208}Pb}$通道的破裂截面很好地再现了低破裂能区的实验数据形状，这对于确定$S_{18}$至关重要。 通过对理论结果与实验数据的拟合，得到了$^9$C 在$p+{\rm ^{8}B}$配置下的渐近归一化系数，并获得了$S_{18}=38.4\pm1.1$eVb。 该结果比之前用三体CDCC获得的结果小约45%。 因此，我们的新结果表明有必要考虑$^{8}$B 在$^{9}$C 解离过程中脆弱性的因素。 显示英文摘要

摘要： The astrophysical factor $S_{18}$ for the $^{8}$B($p$,$\gamma$)$^{9}$C has indirectly been measured with the proton removal reactions from $^9$C, elastic breakup of $^9$C off a heavy target, and transfer reactions. Quite recently, the elastic breakup cross section data were reanalyzed with the continuum-discretized coupled channels method (CDCC) assuming a $p+{\rm ^{8}B}$ two-body model for $^9$C and the $S_{18}$ was modified. It was not well justified, however, to treat $^8$B as an inert nucleus given its proton separation energy is only 137~keV. We reexamine the elastic breakup of $^9$C by the four-body CDCC with a $p+p+{\rm ^{7}Be}$ three-body model for $^9$C and evaluate $S_{18}$. To achieve this, we propose a method to disentangle the $p+{\rm ^{8}B}+{\rm ^{208}Pb}$ three-body channel in the four-body CDCC calculation, for the first time. We calculate the elastic breakup cross section of $^9$C off a $^{208}$Pb target at 65~MeV/nucleon. The obtained breakup cross sections are decomposed into the contributions of the $p+{\rm ^{8}B}+{\rm ^{208}Pb}$ and $p+p+{\rm ^{7}Be}+{\rm ^{208}Pb}$ channels by using the solution of the complex-scaled Lippmann--Schwinger equation. The breakup cross section to the $p+{\rm ^{8}B}+{\rm ^{208}Pb}$ channel reproduces well the shape of the experimental data in the low breakup energy region, which is important for determining $S_{18}$. By fitting the theoretical result to the experimental data, the asymptotic normalization coefficient of $^9$C for the $p+{\rm ^{8}B}$ configuration is determined and we obtain $S_{18}=38.4\pm1.1$ eVb. This result is smaller than the previous value obtained with the three-body CDCC by about 45\%. Thus, our new results suggest the necessity of taking into account the fragile nature of $^{8}$B in the $^{9}$C breakup.