Near-threshold laser-modified proton emission in the nuclear photoeffect

Abstract

The change of the probability of proton emission in the nuclear photoeffect due to an intense coherent (laser) field is discussed near the threshold, where the hindering effect of the Coulomb field of the remainder nucleus is essential. The ratio of the laser-assisted and laser-free differential cross section is deduced and found to be independent of the polarization state of the γ field and the two types of initial nuclear state considered. The numerical values of this ratio are given at some characteristic parameters of the intense field. PACS numbers: 32.80.Wr,

Intense X-ray laser-induced proton emission from halo nuclei

“…For the initial wave function ψ i of the halo proton, there are two parameters E b and R rms . We would consider throughout the one-proton halo isotope 8 5 B as an example due to the very low proton separation energy of E b = 137 keV [55][56][57][58][59][60]. The value R rms ≈ 4.73 fm is used as the root-mean-square distance in the 7 4 Be-proton system [55][56][57][58][59][60].…”

“…We would consider throughout the one-proton halo isotope 8 5 B as an example due to the very low proton separation energy of E b = 137 keV [55][56][57][58][59][60]. The value R rms ≈ 4.73 fm is used as the root-mean-square distance in the 7 4 Be-proton system [55][56][57][58][59][60]. Moreover, we focus on the case of the vector potential A(t) linearly polarized along the +z axis, [ i.e., δ = 0 in Eq.…”

“…with the nuclear binding energy −E b [55][56][57]. Assuming that the halo proton is in an s state, the space-dependent part can be expressed approximately in Yukawa form [59] as…”

“…which is the square root of the so-called Coulomb factor (CF) [57]. Then, the final state of a particle can be approximated as…”

“…Recently, based on this approach, the two-photon and three-photon absorption processes of deuteron induced by the intense γ rays has been theoretically calculated [33]. Moreover, proton emission from halo nuclei via laser-assisted nuclear photoeffect (i.e., the combined a γ ray and low-frequency intense laser) has been investigated [55][56][57]. These studies have shown that rich sideband structures arise in the photo-proton energy spectra, and the total cross section of the photo-proton emission is not almost affected by the presence of the laser field [55][56][57].…”