The structure of low-lying 1? states in 90,94Zr from (α,α′γ) and (p,p′γ) reactions
The structure of low-lying 1? states in 90,94Zr from (α,α′γ) and (p,p′γ) reactions
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(α,α′γ) 和 (p,p′γ) 反应中 90,94Zr 中低位 1? 态的结构
DOI：
10.1016/j.physletb.2021.136210
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发表时间：
2021
影响因子：
4.4
通讯作者：
Kobayashi N.
中科院分区：
文献类型：
--
作者：
Crespi F.C.L.;Bracco A.;Lanza E.G.;Tamii A.;Blasi N.;Camera F.;Wieland O.;Kobayashi N.
通过 80 MeV 下的 (p, p' γ) 和 130 MeV 下的 (α, α' γ) 研究了 90、94 Zr 核中的低位偶极子强度。 RCNP 进行的实验使用磁谱仪 Grand Raiden 测量散射粒子，并使用带有 HPGe 探测器的阵列 CAGRA 测量 γ 衰变。对于 94 Zr，这些是两个反应的第一个数据，对于 90 Zr，这些是带有 (p, p' γ) 的第一个数据和 (α, α' γ) 的第一个高分辨率数据。将两个原子核的当前结果与现有的（γ，γ'）数据进行比较表明，两种核探针产生的激发模式与电磁探针不同。 DWBA 计算是使用根据 RPA 计算从跃迁密度推导出的形状因子进行的，其特征是核表面存在强中子成分。首次对这两个反应进行了组合分析，以研究 90, 94 Zr 中 1− 态的等标量特征。 (p, p' γ) 横截面是使用从 (α, α' γ) 数据获得的等标量电偶极子能量加权和规则 (E1 ISEWSR) 的值计算的。发现 90 Zr 的等标量强度在高达 12 MeV 的能量范围内耗尽了 EWSR 的 20±2.5%。对于 94 Zr，在高达 8.5 MeV 的范围内发现 EWSR 的强度为 9±1.1%。尽管在所研究的能量区间中获得了总体的一般描述，但并非所有质子截面都可以使用 (α, α' γ) 的等标量强度很好地再现。这可能表明等标量和等矢量分量的混合，并且对于低于粒子结合能的所有 1− 态，这种混合和集体程度并不相同。
The low-lying dipole strength in the 90, 94 Zr nuclei was investigated via (p, p′ γ) at 80 MeV and (α, α′ γ) at 130 MeV. The experiments, made at RCNP, used the magnetic spectrometer Grand Raiden for the scattered particles and the array CAGRA with HPGe detectors for the γ-decay. For 94 Zr these are the first data for both reactions and for 90 Zr these are the first data with (p, p′ γ) and the first ones at high resolution for (α, α′ γ). The comparison of the present results for the two nuclei with existing (γ, γ′) data shows that both nuclear probes produce an excitation pattern different than that of the electromagnetic probes. DWBA calculations were made using form factors deduced from transition densities, based on RPA calculations, characterized by a strong neutron component at the nuclear surface. A combined analysis of the two reactions was performed for the first time to investigate the isoscalar character of the 1− states in 90, 94 Zr. The (p, p′ γ) cross section was calculated using values for the isoscalar electric dipole energy-weighted sum rule (E1 ISEWSR) obtained from the (α, α′ γ) data. The isoscalar strength for 90 Zr was found to exhaust 20±2.5% of the EWSR in the energy range up to 12 MeV. In case of 94 Zr, a strength of 9±1.1% of the EWSR was found in the range up to 8.5 MeV. Although an overall general description was obtained in the studied energy intervals, not all proton cross sections were well reproduced using the isoscalar strength from (α, α′ γ). This might suggest mixing of isoscalar and isovector components and that this mixing and the degree of collectivity are not the same for all the 1− states below the particle binding energy.