论文标题
来自$^{137 \ mathrm {m}} $ ba的竞争性$γγ/γ$ -Decay的电磁特征
Electromagnetic character of the competitive $γγ/γ$-decay from $^{137\mathrm{m}}$Ba
论文作者
论文摘要
物理学的二阶过程是一个研究主题，重点是全球几个领域的关注，例如，具有高功率激光器的非线性量子电动力学，中微子双元 - $β$衰减以及刺激原子的两光子过渡。对于电磁核相互作用，从$^{137 \ Mathrm {M}} $ BA对竞争性双$γ$衰减的观察已经打开了核结构领域，以详细研究通过表现出偏高的核极极性的表现来详细研究二阶过程。在这里，我们以$8.7σ$的意义确认此观察结果，双光子与单光子分支比率的提高值为$ 2.62 \ times10^{ - 6}（30）$。然而，我们的结果与原始实验的结论相矛盾，在原始实验中，衰减被解释为由四极核分量组成。在这里，我们发现与主导的八极 - 偶极特征一致的能量分布和衰减中相当小的四极质元素元件一致，这是由于内部核结构的演变而受到阻碍。在$^{{137 \ Mathrm {M}} $ BA中，隐含的双光子分支的强烈阻碍，可以使双光子分支作为可行的工具，用于对核中核核结构研究的可行工具，而这种核中不存在这种障碍的核极化性。
Second-order processes in physics is a research topic focusing attention from several fields worldwide including, for example, non-linear quantum electrodynamics with high-power lasers, neutrinoless double-$β$ decay, and stimulated atomic two-photon transitions. For the electromagnetic nuclear interaction, the observation of the competitive double-$γ$ decay from $^{137\mathrm{m}}$Ba has opened up the nuclear structure field for detailed investigation of second-order processes through the manifestation of off-diagonal nuclear polarizability. Here we confirm this observation with an $8.7σ$ significance, and an improved value on the double-photon versus single-photon branching ratio as $2.62\times10^{-6}(30)$. Our results, however, contradict the conclusions from the original experiment, where the decay was interpreted to be dominated by a quadrupole-quadrupole component. Here, we find a substantial enhancement in the energy distribution consistent with a dominating octupole-dipole character and a rather small quadrupole-quadrupole element in the decay, hindered due to an evolution of the internal nuclear structure. The implied strongly hindered double-photon branching in $^{137\mathrm{m}}$Ba opens up the possibility of the double-photon branching as a feasible tool for nuclear-structure studies on off-diagonal polarizability in nuclei where this hindrance is not present.
