Coupled channels description of theα-decay fine structure

Abstract

We review the coupled channels approach of α transitions to excited states. The α-decaying states are identified as narrow outgoing Gamow resonances in an α-daughter potential. The real part of the eigenvalue corresponds to the Qvalue, while the imaginary part determines the half of the total α-decay width. We first review the calculations describing transitions to rotational states treated by the rigid rotator model, in even-even, odd-mass and odd-odd nuclei. It is found that the semiclassical method overestimates the branching ratios to excited 4 + for some even-even α-emitters and fails in explaining the unexpected inversion of branching ratios of some odd-mass nuclei, while the coupled-channels results show good agreement with the experimental data. Then, we review the coupled channels method for α-transitions to 2 + vibrational and transitional states. We present the results of the Coherent State Model that describes in a unified way the spectra of vibrational, transitional and rotational nuclei. We evidence general features of the α-decay fine structure, namely the linear dependence between α-intensities and excitation energy, the linear correlation between the strength of the α-core interaction and spectroscopic factor, and the inverse correlation between the nuclear collectivity, given by electromagnetic transitions, and α-clustering.

Charged particle emissions in high-frequency alternative electric fields

“…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].…”

Microscopic description of α-decay as super-asymmetric fission

“…The ↵ emission is usually explained as the formation of a cluster on the surface of the daughter nucleus followed by a penetrability of an external barrier at an energy close to the Q-value [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. The probability to form such a combination is given by a square overlap of the convolution of the wave functions of the parent nucleus and that of the system at the touching configuration.…”

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.…”