E2 strengths and transition radii difference of one-phonon 2 + states of 92 Zr from electron scattering at low momentum transfer
E2 strengths and transition radii difference of one-phonon 2 + states of 92 Zr from electron scattering at low momentum transfer
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低动量转移时电子散射的 92 Zr 单声子 2 态 E2 强度和跃迁半径差异
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
C. Walz
中科院分区：
文献类型：
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作者：
A. S. Obeid;O. Burda;M. Chernykh;A. Krugmann;P. Neumann;N. Pietralla;I. Poltoratska;V. Ponomarev;C. Walz
背景：振动核中混合对称2 +态的特征是相对于完全对称2 +态，主要质子和中子价壳组分之间的符号变化。该符号可以通过结合非弹性电子和强子散射对质子和中子跃迁半径的分解来测量[C]。Walz et al.，物理学。[j].科学通报，2011,(6)。对于92zr，中子组分在实验上存在差异，而质子跃迁半径大致相等。目的：测定混合对称2 +态的基态跃迁强度，并验证92zr中单声子2 +态之间质子跃迁半径差的预期消失。方法：用S-DALINAC （e, e）反应在动量传递范围q 0.3‐0测量了92zr中单声子2 +态和3−态激发的微分截面。6f m−1。结果：将实验截面与准粒子-声子模型（QPM）计算结果进行比较，确定了过渡强度B(E2;2 +→0 +)= 6.18(23)，B(E2;2 +→0 +)= 3.31(10)，B(E3;3−→0 +)= 18.4(1.1)Weisskopf单位。结果表明，不依赖于模型的平面波玻恩近似（PWBA）分析可以确定B（E2）跃迁强度与2 +，2态的比值，精度约为1%。此外，该方法还可以提取它们的质子跃迁半径差。现在/
Background: Mixed-symmetry 2 + states in vibrational nuclei are characterized by a sign change between dominant proton and neutron valence-shell components with respect to the fully symmetric 2 + state. The sign can be measured by a decomposition of proton and neutron transition radii with a combination of inelastic electron and hadron scattering [C. Walz et al., Phys. Rev. Lett. 106, 062501 (2011)]. For the case of 92 Zr, a difference could be experimentally established for the neutron components, while about equal proton transition radii were indicated by the data. Purpose: Determination of the ground-state (g.s.) transition strength of the mixed-symmetry 2 + state and verification of the expected vanishing of the proton transition radii difference between the one-phonon 2 + states in 92 Zr. Method:Differential cross sections for the excitation of one-phonon 2 + and 3 − states in 92 Zr have been measured with the (e, e � ) reaction at the S-DALINAC in a momentum transfer range q � 0.3‐0. 6f m −1 . Results: Transition strengths B(E2;2 + → 0 + ) = 6.18(23), B(E2;2 + → 0 + ) = 3.31(10), and B(E3;3 − → 0 + ) = 18.4(1.1) Weisskopf units are determined from a comparison of the experimental cross sections to quasiparticle-phonon model (QPM) calculations. It is shown that a model-independent plane wave Born approximation (PWBA) analysis can fix the ratio of B(E2) transition strengths to the 2 +,2 states with a precision of about 1%. The method furthermore allows to extract their proton transition radii difference. With the present /