Quantum physics of He near the double ionization threshold-quantum chaos and Wannier threshold law

这项研究包括三个主题。第一个主题是研究与量子混沌问题有关的He和其他原子的能级统计。二是研究了He在N=10-25阈值能区的光吸收光谱。到目前为止，对He的光吸收的理论和实验研究都局限在N=9的阈值附近。随着更强的光源，如来自自由电子XUV和软X射线激光的光源在几年内上线，这个能量区域将变得可访问。例如，光吸收光谱是否会在量子混沌区域中出现埃里克森涨落等问题将被研究。第三个主题是关于He在双电子逃逸阈值附近能量的绝对双光吸收截面。计算将从高于阈值的几个MeV开始进行，以测试Wannier阈值定律。到目前为止，还没有完整的ab inito计算能够探测到阈值以上约1 eV范围内的能区。

The proposed research includes three topics.The first is to study the level statistics of He and other atoms in relation to the questions of quantum chaos. The second is the study of the photoabsorption spectra of He in the energy region lying between the N=10-25 thresholds of He+. Until now both the theoretical and experimental investigations for the photoabsorption of He have been limited to about the N=9 threshold of He+. This energy region will become accessible as more intense light sources such as those from free electron XUV and soft-X-ray lasers come on line in a few years. Questions such as whether the photoabsorption spectra will exhibit Erickson fluctuations in the quantum chaos regime will be investigated. The third topic concerns the absolute double photoabsorption cross sections of He for energies near the double electron escape threshold. Calculations will be undertaken from about a few meV above the threshold to test the Wannier threshold law. No full ab inito calculations as yet have been able to probe the energy region within about 1 eV above the threshold.