Atomic excitations during the nuclearβ−decay in light atoms

Abstract

Probabilities of various final states are determined numerically for β − -decaying He, Li, and Be atoms. In our evaluations of the final-state probabilities we have used the highly accurate atomic wave functions constructed for each few-electron atom or ion. We also discuss an experimental possibility to observe negatively charged ions which form during the nuclear β + decays. Corrections on direct interaction between atomic electrons and fast β electrons or positrons are considered. It is shown that for our results obtained for β ± decays in few-electron atoms with the use of the sudden approximation such corrections are very small (≈α 4 ) and can be neglected.

Generation of harmonics of laser radiation in plasmas

“…In his model, the third (recombination) stage of the three-step scenario is partitioned into two steps: the capture of a laser-accelerated electron into an autoionizing state of the parent ion followed by the radiative relaxation of this state to the ground state with emission of the harmonic photon. Although this four-step model provided reasonable estimates for the ratio of the enhanced harmonic intensity to the averaged intensity of neighboring harmonics comparable with those observed in experiment, authors of [56] point out that the suppression of harmonics preceding the resonant one remains a puzzle for the proposed theoretical model.…”

“…As it was mentioned above, some attempts in explanation of experimental observations of resonance-induced enhancement of single harmonic during plasma HHG have been reported in [43,45,49,[51][52][53][54][55][56][57]. In particular in [53], it has been shown that the influence of atomic autoionizing states on the phase matching of HHG may result in efficient selection of the single harmonic in calcium plasma.…”

“…Recent findings of the physical processes driving plasma HHG require systematic analysis of the results reported after previous reviews of this process [33][34][35][36][37]. Those include the harmonic generation in clusters using ablation of commercially available clusters [38,39], fullerenes [40][41][42][43][44][45], and carbon nanotubes [46], enhancement of harmonics from in-situ-produced nanoparticles [47], new resonance-enhanced features of plasma harmonics [48,49], application of high pulse repetition rate sources and ultrashort pulses for the HHG in plasma plumes [21], proposals for the quasi-phase matching of harmonics in plasmas [50], observation of quantum path signatures in harmonic spectra from various ablated targets [22], achievement of μJ level of harmonic energies [28,29], development of few theoretical approaches describing the observed peculiarities of resonance enhancement and fullerene-induced harmonics [43,45,49,[51][52][53][54][55][56][57], observation of extremely broadened high-order harmonics [58], emergence of a "second" plateau in harmonic distribution [59], destructive interference of harmonics in the mixtures of different harmonic emitters inside the plasma [60], measurements of plasma harmonic's pulse duration in the attosecond time scale [32], etc.…”

“…In their research [56], they showed that enhancements of single harmonics with harmonic energies near the energies of autoionizing states in atoms or ions, as well as the suppression of the preceding (or, in some cases, the Figure 3 (online color at www.lphys.org) Typical scheme for high-order harmonic generation in laser-produced plasma plumes. The rough image of harmonic spectra from the silver plasma is presented below the experimental setup succeeding) harmonics, may be interpreted in terms of the usual three-step HHG scenario [31,65,66], without any additional assumptions or extensions.…”

Accurate CI and Hylleraas-CI wave functions for the atomic effects in the whole-atom-nuclear β−-decay of the Li atom

“…In a previous paper [51] we have calculated the transition probabilities of the transitions from the 1 S ground state of He atom to the first ten low-lying 1 S ground and excited states of the Li + ion using the Hy-CI method, and with them the probability of ionization to the Li 2+ ion. The values of these probabilities have been also determined by the CI method using B-splines orbitals by Wauters and Vaeck [52] and by the full relativistic four-component Dirac-Kohn-Sham (DKS) method by Glushkov [43].…”