Magnetic dipole excitations of 50 Cr
Magnetic dipole excitations of 50 Cr
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DOI：
10.1103/physrevc.93.014318
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发表时间：
2016-01
影响因子：
3.1
通讯作者：
H. Pai;T. Beck;J. Beller;R. Beyer;M. Bhike;V. Derya;U. Gayer;J. Isaak;Krishichayan;J. Kvasil;B. Löher;V. Nesterenko;N. Pietralla;G. Martínez-Pinedo;L. Mertes;V. Ponomarev;P. Reinhard;A. Repko;P. Ries;C. Romig;D. Savran;R. Schwengner;W. Tornow;V. Werner;J. Wilhelmy;A. Zilges;M. Zweidinger
中科院分区：
文献类型：
--
作者：
H. Pai;T. Beck;J. Beller;R. Beyer;M. Bhike;V. Derya;U. Gayer;J. Isaak;Krishichayan;J. Kvasil;B. Löher;V. Nesterenko;N. Pietralla;G. Martínez-Pinedo;L. Mertes;V. Ponomarev;P. Reinhard;A. Repko;P. Ries;C. Romig;D. Savran;R. Schwengner;W. Tornow;V. Werner;J. Wilhelmy;A. Zilges;M. Zweidinger
开壳核 $^{50}$Cr 的低位 $M1$ 强度已通过高达 9.7 MeV 的核共振荧光方法进行了研究，使用超导达姆施塔特线性电子加速器 S-DALINAC 的轫致辐射和高强度 $\gamma$ 射线源 (HI$\gamma$S) 设施的康普顿背散射光子，在 6 至 9.7 MeV 之间初始光子能量。在 3.6 到 9.7 MeV 之间观察到了 15 个 $1^{+}$ 状态。根据我们的分析，3.6 MeV 处的最低 $1^{+}$ 状态可以被视为具有一些自旋混合的等矢量轨道模式。获得的结果通常与剪刀模式的典型估计和趋势相匹配。 Skyrme 准粒子随机相位近似方法和大型壳模型中的详细计算证明了我们的结论。计算出的最低 $1^{+}$ 状态的轨道电流分布表明了 Lipparini 和 Stringari 的示意图（刚性表面内的等矢量旋转振荡），而不是 Lo Iudice 和 Palumbo 的剪刀状图。自旋 M1 共振主要是由 $fp$ 壳层轨道之间的自旋翻转跃迁产生的。
The low-lying $M1$-strength of the open-shell nucleus $^{50}$Cr has been studied with the method of nuclear resonance fluorescence up to 9.7 MeV, using bremsstrahlung at the superconducting Darmstadt linear electron accelerator S-DALINAC and Compton backscattered photons at the High Intensity $\gamma$-ray Source (HI$\gamma$S) facility between 6 and 9.7 MeV of the initial photon energy. Fifteen $1^{+}$ states have been observed between 3.6 and 9.7 MeV. Following our analysis, the lowest $1^{+}$ state at 3.6 MeV can be considered as an isovector orbital mode with some spin admixture. The obtained results generally match the estimations and trends typical for the scissors-like mode. Detailed calculations within the Skyrme Quasiparticle Random-Phase-Approximation method and the Large-Scale Shell Model justify our conclusions. The calculated distributions of the orbital current for the lowest $1^{+}$-state suggest the schematic view of Lipparini and Stringari (isovector rotation-like oscillations inside the rigid surface) rather than the scissors-like picture of Lo Iudice and Palumbo. The spin M1 resonance is shown to be mainly generated by spin-flip transitions between the orbitals of the $fp$-shell.