Papers by victor velazquez
Physical Review Letters, 2002
Due to the time reversal invariance of the angular momentum operator J 2 , the average energies a... more Due to the time reversal invariance of the angular momentum operator J 2 , the average energies and variances at fixed J for random two-body Hamiltonians exhibit odd-even-J staggering, that may be especially strong for J = 0. It is shown that upon ensemble averaging over random runs, this behaviour is reflected in the yrast states. Displaced (attractive) random ensembles lead to rotational spectra with strongly enhanced BE2 transitions for a certain class of model spaces. It is explained how to generalize these results to other forms of collectivity.
The Projected Shell Model is a shell model theory built up over a deformed BCS mean field. Ground... more The Projected Shell Model is a shell model theory built up over a deformed BCS mean field. Ground state and excited bands in eveneven nuclei are obtained through diagonalization of a pairing plus quadrupole Hamiltonian in an angular momentum projected 0-, 2-, and 4-quasiparticle basis. The residual quadrupole-quadrupole interaction strength is fixed self-consistently with the deformed mean field and the pairing constants are the same used in constructing the quasiparticle basis. Taking 160 Dy as an example, we calculate low-lying states and compare them with experimental data. We exhibit the effect of changing the residual interaction strengths on the spectra. It is clearly seen that there are many J π = 0 + , 1 + , 4 + bandheads whose energies can only be reproduced using the self-consistent strengths. It is thus concluded that the Projected Shell Model is a model essentially with no free parameters.
A systematic study of correlations in the chart of nuclear masses calculated using the Finite Ran... more A systematic study of correlations in the chart of nuclear masses calculated using the Finite Range Droplet Model of Möller et al. is presented. It is shown that the differences between the calculated and measured masses have a well defined oscillatory component as function of the proton and neutron numbers, which can be removed with an appropriate fit, reducing significantly the error width, and concentrating the error distribution on a single peak around zero. The presence of this regular residual correlations suggests that the Strutinsky method of including microscopic fluctuations in nuclear masses could be improved.
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Papers by victor velazquez