Ab initio calculation of the electron capture spectrum of 163Ho: Auger–Meitner decay into continuum states
Ab initio calculation of the electron capture spectrum of 163Ho: Auger–Meitner decay into continuum states
复制标题
163Ho 电子俘获谱的从头算：俄歇-迈特纳衰变成连续态
DOI：
10.1088/1367-2630/abac72
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发表时间：
2020
影响因子：
3.3
通讯作者：
M. Haverkort
中科院分区：
文献类型：
--
作者：
M. Braβ;M. Haverkort
通过163 Ho中的电子俘获来确定电子中微子质量依赖于对微分电子俘获核衰变率的准确理解，微分电子俘获核衰变率是中微子和电子激发之间总衰变能量分布的函数。由此产生的光谱是占主导地位的共振，由于本地原子多重态与核心空穴。电子之间的库仑散射通过Auger-Meitner衰变将离散的原子态耦合到具有自由电子的最终态。原子多重态高于自电离能，使得代表这些离散能级的δ函数变成洛伦兹、马汉和范诺等线形的叠加。我们提出了一个从头计算方法来计算由于这种过程的核衰变修改。它包括在局部原子轨道中与未结合的Auger-Meitner电子相互作用的多个相关空穴的状态。一个强大的能量依赖性，不对称的共振加宽与最近的实验结果吻合良好，我们提出了一个详细的分析的机制，确定最终的光谱线的形状，并讨论了不同的共振之间的Fano干扰，以及俄歇-迈特纳库仑矩阵元素的能量依赖。后一种机制被证明是占主导地位的通道负责的非对称线形的共振在电子捕获光谱的163 Ho。
Determining the electron neutrino mass by electron capture in 163Ho relies on an accurate understanding of the differential electron capture nuclear decay rate as a function of the distribution of the total decay energy between the neutrino and electronic excitations. The resulting spectrum is dominated by resonances due to local atomic multiplet states with core holes. Coulomb scattering between electrons couples the discrete atomic states, via Auger–Meitner decay, to final states with free electrons. The atomic multiplets are above the auto-ionisation energy, such that the delta functions representing these discrete levels turn into a superposition of Lorentzian, Mahan- and Fano-like line-shapes. We present an ab initio method to calculate nuclear decay modifications due to such processes. It includes states with multiple correlated holes in local atomic orbitals interacting with unbound Auger–Meitner electrons. A strong energy-dependent, asymmetric broadening of the resonances in good agreement with recent experiments is found. We present a detailed analysis of the mechanisms determining the final spectral line-shape and discuss both the Fano interference between different resonances, as well as the energy dependence of the Auger–Meitner Coulomb matrix elements. The latter mechanism is shown to be the dominant channel responsible for the asymmetric line-shape of the resonances in the electron capture spectrum of 163Ho.