Isovector quadrupole excitations in the valence shell of the vibrator nucleus 136 Ba: Evidence from photon scattering experiments
Isovector quadrupole excitations in the valence shell of the vibrator nucleus 136 Ba: Evidence from photon scattering experiments
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振子核 136 Ba 价壳中的等矢量四极激发：来自光子散射实验的证据
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
I. Wiedenhöver
中科院分区：
文献类型：
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作者：
N. Pietralla;D. Belic;P. Brentano;C. Fransen;R. Herzberg;U. Kneissl;H. Maser;P. Matschinsky;A. Nord;T. Otsuka;H. Pitz;V. Werner;I. Wiedenhöver
在${}^{136}$Ba核上进行了光子散射实验，光子能量为${E}_{ensuremath{gamma}}l~4.1$ MeV和${E}_{ensuremath{gamma}}l~2.8$ MeV。在2.1 MeV时，已经发现了${2}_{mathm {ms}}^{+}$状态的明确证据。从测量的寿命中，我们提取了价层中等矢量四极激发的特征：弱集体$E2$衰变到基态，强$M1$衰变到${2}_{1}^{+}$态。由于轫致辐射下的共振光子散射是一个完全反应，我们可以得出结论：2129 keV处的${2}^{+}$态是一个较纯的$ bbb_1 _{mathm {ms}}^{+}$态，几乎没有碎裂。这与${1}^{+}$ scissors状态相反。并与IBM-2计算方法进行了比较。
Photon scattering experiments have been performed on the nucleus ${}^{136}$Ba with photon energies of ${E}_{ensuremath{gamma}}l~4.1$ MeV and ${E}_{ensuremath{gamma}}l~2.8$ MeV. At 2.1 MeV clear evidence for the ${2}_{mathrm{ms}}^{+}$ state has been found. From the measured lifetime we extract signatures for the isovector quadrupole excitation in the valence shell: a weakly collective $E2$ decay to the ground state and a strong $M1$ decay to the ${2}_{1}^{+}$ state. As the resonant photon scattering with bremsstrahlung is a complete reaction, we can conclude that the ${2}^{+}$ state at 2129 keV is a rather pure ${2}_{mathrm{ms}}^{+}$ state with little fragmentation. This is in contrast to the ${1}^{+}$ scissors state. A comparison with an IBM-2 calculation is given.