论文标题
$^{54} $ ca超过$^{55} $ k，$^{55} $ ca和$^{57} $ CA
A First Glimpse at the Shell Structure beyond $^{54}$Ca: Spectroscopy of $^{55}$K, $^{55}$Ca, and $^{57}$Ca
论文作者
论文摘要
$ n = 35 $和37同位素中的状态$^{55,57} $ ca已由$^{56,58} $ SC和$^{56} $ ca beams的直接质子诱导的核去除反应填充。此外，研究了$^{56} $ ca的$（P，2P）$无准单蛋白去除反应。 $^{55} $ k，$^{55} $ ca中的激发状态和$^{57} $ ca首次通过束内$γ$ -Ray spectroscopy建立。质子和中子去除反应的结果是从$^{56} $ ca到$^{55} $ K和$^{55} $ ca的状态，用于水平能量，激发的状态寿命和独家跨段与使用不同方法的最新理论计算很好地一致。在$^{57} $ CA中对短暂状态的观察表明，同位素同位素从单粒子主导的状态$ n = 35 $ to $ n = 37 $的集体激发。
States in the $N=35$ and 37 isotopes $^{55,57}$Ca have been populated by direct proton-induced nucleon removal reactions from $^{56,58}$Sc and $^{56}$Ca beams at the RIBF. In addition, the $(p,2p)$ quasi-free single-proton removal reaction from $^{56}$Ca was studied. Excited states in $^{55}$K, $^{55}$Ca, and $^{57}$Ca were established for the first time via in-beam $γ$-ray spectroscopy. Results for the proton and neutron removal reactions from $^{56}$Ca to states in $^{55}$K and $^{55}$Ca for the level energies, excited state lifetimes, and exclusive cross sections agree well with state-of-the-art theoretical calculations using different approaches. The observation of a short-lived state in $^{57}$Ca suggests a transition in the calcium isotopic chain from single-particle dominated states at $N=35$ to collective excitations at $N=37$.
