Coupled-channels study of fine structure in theαdecay of platinum isotopes

Abstract

The fine structure observed in the α decay of deformed platinum isotopes is investigated using the recently developed five-channel formalism, based on the coupled-channel Schrödinger equation with outgoing wave boundary conditions. The internal effect of daughter states is taken into account in dealing with the interaction matrix and the α-cluster formation. The available experimental data concerning α-decay half-lives and fine structures are reproduced. Some predictions are made especially for the α decay of neutron-rich isotopes, which could guide future experiments.Alpha decay is one of the oldest subjects of study in nuclear physics, and continual attention has been paid to its importance from both experimental and theoretical sides. The half-lives of α emitters provide information on the stability of nuclides, especially for superheavy nuclei, while the decay energies pose a tough test for nuclear-mass models and provide direct information on the excitation energy of final daughter states. Theoretically, the main focus of recent investigations has been on the fine structure observed in α decay, where the decay proceeds from the ground states of the parent nucleus to various members of the regular ground-state rotational band in the daughter system. The available theoretical approaches for deformed systems can be divided into two groups, namely, semiclassical and coupledchannels. Some semiclassical methods, based on the onedimensional Wentzel-Kramers-Brillouin (WKB) semiclassical approximation, have been extended from the spherical picture to a deformed case in a phenomenological manner, such as the simple WKB barrier penetration approach [1], the generalized liquid drop model (GLDM) [2], and the unified model for α decay and α capture (UMADAC) [3]. The other group uses the stationary coupled-channels approach [4][5][6][7][8], where the three-dimensional Schrödinger equation is exactly solved with outgoing wave boundary conditions. The second approach is less documented than the semiclassical calculation. Recently, within the coupled-channels framework, we have employed two different techniques to deal with the coupling interaction matrix between channels. We have performed separate four-channel and five-channel calculations for well-deformed rotational α emitters [7,8]. The theoretical results reproduced well the available experimental data concerning α-decay halflives and fine structures. It was also found that semiclassical calculations have a tendency to overrate branching ratios for excited 4 + states by one order of magnitude, while the coupled-channels analysis gives a satisfactory description because of the inclusion of the coupling effect between channels. * From the experimental side, besides considerable progress in the synthesis of new superheavy elements [9,10], improvements have been made for long-living rare α emitters [11][12][13]. Along with the enhancement of experimental sensitivity, some new data have been measured with improved accuracy and some have even been observed for the first time,...

Half-life of sphericalαemitters and intrinsic properties of nuclei

“…Among these, various models incorporating parent and daughter ground-state (GS) deformations are developed, such as the unified model for α decay and α capture [8], generalized density-dependent cluster model [9], and Coulomb and proximity potential model for deformed nuclei [10,11], which show the reduction of barrier height due to quadrupole deformation. In fact, in the case of a deformed parent, there are a lot of accessible ground states and low-lying excited states in the daughter nucleus [8,9], so there is the possibility of coupling of these states during tunneling process through the potential barrier, and a realistic coupled channel treatment can be used to address these effects [12][13][14].…”

Alpha-Decay Studies of Rf, Sg, and Hs Isotopes within the Multi-Channel Cluster Model

“…16), 17). The previous systematic calculations of 35 deformed α emitters 17) have shown that the experimental branching ratios to various states and total α-decay half-lives can be well reproduced with the same factor P α = 0.36 and the same BD c = 2.38 MeV −1 . §3.…”

“…18) The Q α formula for superheavy nuclei was proposed by Dong and Ren, 19) where the macroscopic terms are based on the well-known Weizsäcker-Bethe mass formula and the shell corrections are simulated by the Mexican hat wavelet functions. Additionally, the predictive power of the MCCM has been checked for a wide range of deformed α emitters including the newly measured neutron-rich Pt isotopes, 17) where the five-channels microscopic calculations well reproduced the available experimental data concerning α-decay half-lives and fine structures. Encouraged by these successes, in this work we intend to perform a detailed study of the fine structure in the α decay of Rf to Hs isotopes within the MCCM.…”

“…The generalized density-dependent cluster model (GDDCM) 16) suggested that in addition to nuclear deformations the excitation spectrum of daughter nuclei also plays an important role in describing the fine structure. And further studies of the multi-channel cluster model (MCCM) 17) showed that the α transition to highspin states is an important and sensitive tool to probe the energy spectrum and deformation of daughter nuclei.…”

Phenomenological potential calculations for cluster decays

“…After Gamow wrote a closed formula between the logarithmic values of half-lives and the Q-values, this relation and formula were also obtained by Geiger and Nuttall [6]. In recent years studies considering deformations on the α -decay of heavy and super heavy nuclei have become interesting and popular research avenues [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25].…”