We report on the first in-beam γ-ray spectroscopy of the proton-dripline nucleus 40Sc using two-nucleon pickup onto an intermediate-energy rare-isotope beam of 38Ca. The 9Be(38Ca,40Sc+γ)X reaction at 60.9 MeV/nucleon mid-target energy selectively populates states in 40Sc for which the transferred proton and neutron couple to high orbital angular momentum. In turn, due to angular-momentum selection rules in proton emission and the nuclear structure and energetics of 39Ca, such states in 40Sc then exhibit γ-decay branches although they are well above the proton separation energy. This work uniquely complements results from particle spectroscopy following charge-exchange reactions on 40Ca as well as 40Ti EC/β decay which both display very different selectivities. The population and γ-ray decay of the previously known first (5−) state at 892 keV and the observation of a new level at 2744 keV are discussed in comparison to the mirror nucleus and shell-model calculations. On the experimental side, this work shows that high-resolution in-beam γ-ray spectroscopy is possible with new generation Ge arrays for reactions induced by rare-isotope beams on the level of a few μb of cross section.

中文翻译：

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质子滴管处的光束内 γ 射线光谱：40Sc

我们报告了质子-滴落线核 40Sc 的第一个射束内 γ 射线光谱，使用双核子拾取到 38Ca 的中能稀有同位素束。9Be(38Ca,40Sc+γ)X 反应在 60.9 MeV/核子中间目标能量下选择性地填充 40Sc 中的状态，其中转移的质子和中子与高轨道角动量耦合。反过来，由于质子发射中的角动量选择规则以及 39Ca 的核结构和能量学，40Sc 中的这种状态然后表现出 γ 衰变分支，尽管它们远高于质子分离能。这项工作独特地补充了粒子光谱学在 40Ca 和 40Ti EC/β 上发生电荷交换反应后的结果，两者都显示出非常不同的选择性。与镜核和壳模型计算相比，讨论了先前已知的 892 keV 第一 (5-) 态的布居和 γ 射线衰变以及在 2744 keV 处观察到的新能级。在实验方面，这项工作表明，使用新一代 Ge 阵列可以实现高分辨率射束内 γ 射线光谱，用于由几μb 横截面水平的稀有同位素束引起的反应。