论文标题
对中等质量核的$Δ$激发的研究，并具有外周重离子电荷 - 交换反应
Study of $Δ$ excitations in medium-mass nuclei with peripheral heavy ion charge-exchange reactions
论文作者
论文摘要
等速单一电荷 - 交换反应，将核电荷通过一个单位改变，但使群众不受影响，这是首次通过$^{112} $ sn ions的外围碰撞进行调查，最多可加速GSI设施的GEV {A} GEV。 FRS光谱仪的高分辨率能力使我们能够获得$（p，n）$ - 类型的同余电荷 - 交换横截面，不确定性为$ 3.5 \％$，并在弹出器缺失的能量光谱中分离Quasi弹性和非弹性组件。非弹性成分与$δ$（1232）的异荷拉共振的激发以及靶标和弹丸核中S波中亲质的发射有关，而准弹性贡献与核子 - 孔励激发的核自旋 - 异种反应有关。当比较从测量值与质子和碳靶标的缺失能源光谱时，观察到$Δ$ resonance峰的明显变化。用理论模型对反应进行的详细分析表明，该观察结果可以简单地解释为在目标中和弹丸中共振的激发的贡献之间的相对幅度变化。
Isobaric single charge-exchange reactions, changing nuclear charges by one unit but leaving the mass partitions unaffected, have been for the first time investigated by peripheral collisions of $^{112}$Sn ions accelerated up to 1\textit{A} GeV at the GSI facilities. The high-resolving power of the FRS spectrometer allows us to obtain $(p, n)$-type isobaric charge-exchange cross sections with an uncertainty of $3.5\%$ and to separate quasi-elastic and inelastic components in the missing-energy spectra of the ejectiles. The inelastic component is associated to the excitation of the $Δ$(1232) isobar resonance and the emission of pions in s-wave both in the target and projectile nucleus, while the quasi-elastic contribution is associated to the nuclear spin-isospin response of nucleon-hole excitations. An apparent shift of the $Δ$-resonance peak of $\sim$63 MeV is observed when comparing the missing-energy spectra obtained from the measurements with proton and carbon targets. A detailed analysis, performed with a theoretical model for the reactions, indicates that this observation can be simply interpreted as a change in the relative magnitude between the contribution of the excitation of the resonance in the target and in the projectile.
