Results 1 - 10 of 18
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[en] Very little is known about clustering in heavy nuclei and in particular the interaction between the correlated cluster nucleons and remaining core nucleons. Currently the phenomenological Saxon-Woods plus cubic Saxon-Woods core-cluster potential successfully predicts the alpha decay half-life and energy band spectra of a number of heavy nuclei. This model, however, lacks a microscopic understanding of clustering phenomenon in these heavy nuclear systems. A fully relativistic microscopic formalism is presented, which generates the core-cluster potential by means of the McNeil, Ray and Wallace based double folding procedure. The core and cluster baryon densities are calculated by using a relativistic mean field approach. The Lorentz covariant IA1 representation of the nucleon-nucleon interaction is folded with the core and cluster densities. Theoretical predictions of the ground-state decay half-life and positive parity energy band of 212Po are obtained with the relativistic mean field formalism and which are compared to the results from the phenomenological Saxon-Woods plus cubic Saxon-Wood core-cluster potential and microscopic M3Y interaction.
[en] The excitation energies of states belonging to the ground state bands of heavy even–even nuclei are analysed using recurrence relations. Excellent agreement with experimental data at the 10 keV level is obtained by taking into account strong correlations which emerge in the analysis. This implies that the excitation energies can be written as a polynomial of maximum degree 4 in the angular momentum. (paper)
[en] We investigate the cluster emission of Ne isotopes from the nuclei 232Th and 234U. Experiments are unable to distinguish between the isotopes 24Ne and 26Ne, but by establishing a method of determining the cluster, with associated preformation probability, and using a binary cluster formalism, we deduce that the most likely emitted cluster is 26Ne. (paper)
[en] We generate the core-cluster partitions of even-even nuclei in the rare-earth region using a form of the core-cluster interaction employed previously in an analysis of nuclei in the actinide region. The correlations between the core-cluster charge products thus obtained and various nuclear observables are found to display similar characteristics in the two mass regions
[en] It is known that coupling an intrinsic excitation of integer spin and positive parity I+ to a rotor having a degenerate set of states Lπ=0+,2+,4+,..., generates a series of K bands. A given value of I+ gives rise to several bands labeled by K+=0+,1+,2+,...,I+, that is, a total of (I+1) such bands, in the spectrum of the combined system. We discuss how a binary cluster model of an excited core orbited by a spinless cluster can approximate these conditions. A crucial point is that the radial wave functions of relative motion are very similar for low L, and their radial coupling integrals even more so, such that the wave functions play the model role of a common intrinsic state for the lowest excited states of the system. If the core has a 0+ ground state and a low-lying 2+ excited state, then lifting the degeneracy leads to a ground state K+=0+ band and low-lying excited K+=0+, 1+, and 2+ bands. Although these are all seen in light nuclei, the K+=1+ band is conspicuous by its apparent absence in heavy nuclei, and we urge experimental groups to reexamine their data for signs of it.
[en] We first give a brief review of our earlier empirical work on parameter-free difference equations for nuclear spectra and discuss some of the implications. Then we show that a simple quantum mechanical model is capable of explaining and improving our previously suggested recursion relations.
[en] We show that the ground-state band spectra of very many rare-earth and actinide nuclei appear to obey simple recurrence relations. Our initial empirical observation is then refined to suggest a new method for predicting higher lying members of a band from lower lying known members
[en] We describe the low-lying negative parity states of 238U in terms of a Pb-Ne cluster model. The Pb core is in an excited 3- state and the relative orbital motion has angular momentum values L = 0, 2, 4, .... The two bodies interact through central and second rank tensor potentials, leading to four bands loosely labelled by the rotational model notation of Kπ = 0-, 1-, 2-, 3-. However, the coupling between core and cluster is of intermediate strength, leading to an irregular pattern of energy differences, in particular inverted doublets in the Kπ = 1- band. Remarkably, the main features of the predicted spectrum are borne out by experiment
[en] In a binary cluster model the likely core-cluster decompositions of a nucleus involve especially stable cores and/or clusters. This criterion often gives rise to a number of preferred decompositions, each with different physical attributes. These differences are particularly acute for 212Po, and we examine the properties of the bands generated by the core-cluster decompositions of this nucleus into (208Pb+4He) and (132Te+80Ge)