Charged particle emissions in high-frequency alternative electric fields

Abstract

Proton emission, α decay, and cluster radioactivity play an important role in nuclear physics.We show that high-frequency alternative electric fields could deform Coulomb barriers that trap the charged particle, and raise the possibility of speeding up charged particle emissions. They could also cause anisotropic effects in charged particle emissions, and introduce additional terms in the Geiger-Nuttall laws. Our study may further suggest that, for proton emitters like 166 Ir, when the electric field is strong, the dominant decay mode could be changed from α decay to proton emission. As high-frequency alternative electric fields correspond to high-frequency laser fields in the dipole approximation, our study could be viewed as a benchmark for future theoretical studies of charged particle emissions in realistic laser fields.Recent years witness great progress in studying proton emission, α decay, and cluster radioactivity [1][2][3][4]. Historically, modern theoretical nuclear physics originates from the explanation of α decay by Gamow, Gurney and Condon in 1928 [5, 6]. Interests in alpha decay persist after that, and lots of interesting results have been obtained . Later discoveries of proton emission in the 1960s [37,38] and cluster radioactivity in the 1980s [39,40] also make important contributions to deepening our understanding of nuclei lying near the border of nuclear stability. Recently, it is pointed out by Ref. [41][42][43][44][45][46][47] that, α decay, proton emission, and cluster radioactivity could be described systematically using unified decay rules. For a pedagogic introduction to charged particle emissions, we would like to recommend Ref. [1]. In the last few years, several works [50][51][52][53][54][55][56] are devoted to α decay in strong electromagnetic fields, partially inspired by the upcoming powerful laser facilities in the near future [48, 49]. These studies provide some preliminary hints that strong laser fields could speed up α decays. This is not only interesting from the pure academic viewpoint, but also might be helpful for decontaminating α-radioactive nuclear wastes. In this note, we study charged particle emissions in high-frequency alternative electric fields, treating α decay, proton emission, cluster radioactivity in a unified approach inspired by Ref. [41][42][43][44][45][46][47].By high-frequency alternative electric fields, we refer to alternative electric fields with frequencies (photon energies ω) much higher than the Q values of charged particle emissions, which means ω Q α ∼ 10 MeV, Q p ∼ 1 MeV, Q c ∼ 50 MeV for α decay, proton emission, and cluster radioactivity, respectively. High-frequency alternative electric fields correspond 1/3 d and R c0 = 1.2A 1/3 c are their radii. β 2d and β 2c are the corresponding deformation parameters. The spherical Coulomb potential could be restored by setting β λ = 0.

Can extreme electromagnetic fields accelerate the $α$ decay of nuclei?

“…In a striking contrast to these estimates, several recent theoretical works have predicted a strong effect of laser radiation on α decay even at currently achievable intensities [11][12][13][14][15]. These spectacular claims brought super-intense lasers in discussions about practical applications for recycling of nuclear waste [30].…”

“…We address the controversy with results of Refs. [13][14][15] and conclude that the gross enhancements in α decay rates predicted there are most likely due to the misuse of an approximation.…”

“…[7][8][9] and references therein. Within this new field, several theoretical proposals to consider the effect of laser radiation on nuclear processes and in particular on α decay have been recently reported [10][11][12][13][14][15][16].…”

Phase-dependent cross sections of deuteron-triton fusion in dichromatic intense fields with high-frequency limit

“…It is found that intense lasers can induce resonance internal conversion, i.e., F. F. Karpeshin considered mechanisms of isomer pumping via a laser-radiation-induced resonance conversion and of isomer energy triggering in a resonance laser radiation field [7]. And intense lasers can accelerate nuclear fission processes [8,9], especially in the aspect of increasing α-decay rates [10][11][12] by modifying the Coulomb potential barrier. However, there is no conclusive result on whether laser-induced enhancement of the decay rate is considerable or not because there is no successful experiment to prove these theories [13,14].…”

Cluster-daughter overlap as a new probe of alpha-cluster formation in medium-mass and heavy even–even nuclei

“…The study of alpha-cluster formation in heavy/superheavy nuclei could date back to Rutherford's discovery of alpha decay more than one hundred years ago [18]. Till today, alpha decay is still an important direction being continuously developed [6,[19][20][21][22][23], from which we gain lots of information on alpha-cluster formation in heavy/superheavy nuclei [20,[24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Especially, it is found that alpha-cluster formation probabilities change significantly at magic numbers N = 126 and Z = 82.…”