Low-lying dipole strength of the open-shell nucleus 94 Mo
Low-lying dipole strength of the open-shell nucleus 94 Mo
复制标题
开壳核 94 Mo 的低位偶极子强度
DOI：
10.1103/physrevc.88.044331
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发表时间：
2013
影响因子：
3.1
通讯作者：
M. Zweidinger
中科院分区：
文献类型：
--
作者：
C. Romig;J. Beller;J. Glorius;J. Isaak;J. H. Kelley;E. Kwan;N. Pietralla;V. Y. Ponomarev;A. Sauerwein;D. Savran;M. Scheck;L. Schnorrenberger;K. Sonnabend;A. P. Tonchev;W. Tornow;H. R. Weller;A. Zilges;M. Zweidinger
通过超导达姆施塔特电子线性加速器 (S-DALINAC) 轫致辐射设施中高达 8.7 MeV 激发能量的核共振荧光技术以及高强度射线源 (HIS) 设施中的康普顿背散射光子，研究了开壳核 Mo 的低位偶极子强度。总共确定了 83 个激发态。利用 HIS 中的偏振准单能光子，奇偶量子数被分配给由偶极跃迁激发的 41 个状态。确定了高达 8.7 MeV 的电偶极子强度分布，并与准粒子声子模型内的微观计算进行了比较。计算结果和实验数据对于破碎度以及综合强度非常一致。利用五种能量设置下的 HIS 测量结果研究了激发态的平均衰减模式。从准单能光子的测量中提取基态和第一激发态的平均分支比，并与统计模型内的级联模拟进行比较。实验推导的平均支化比在 6.4 MeV 处表现出类似共振的最大值，这无法在统计模型中重现。这表明能量范围在 5.5 至 7.5 MeV 之间的非统计结构。
The low-lying dipole strength of the open-shell nucleusMo was studied via the nuclear resonance fluorescence technique up to 8.7 MeV excitation energy at the bremsstrahlung facility at the Superconducting Darmstadt Electron Linear Accelerator (S-DALINAC), and with Compton backscattered photons at the High Intensity-ray Source (HIS) facility. In total, 83 excited states were identified. Exploiting polarized quasi-monoenergetic photons at HIS, parity quantum numbers were assigned to 41 states excited by dipole transitions. The electric dipole-strength distribution was determined up to 8.7 MeV and compared to microscopic calculations within the quasiparticle phonon model. Calculations and experimental data are in good agreement for the fragmentation, as well as for the integrated strength. The average decay pattern of the excited states was investigated exploiting the HIS measurements at five energy settings. Mean branching ratios to the ground state and first excitedstate were extracted from the measurements with quasi-monoenergetic photons and compared to-cascade simulations within the statistical model. The experimentally deduced mean branching ratios exhibit a resonance-like maximum at 6.4 MeV which cannot be reproduced within the statistical model. This indicates a nonstatistical structure in the energy range between 5.5 and 7.5 MeV.