20 research outputs found
Why does the recently proposed simple empirical formula for the lowest excitation energies work so well?
It has recently been shown that a simple empirical formula, in terms of the
mass number and the valence nucleon numbers, is able to describe the main
trends of the lowest excitation energies of the natural parity even multipole
states up to in even-even nuclei throughout the entire periodic table.
In an effort to understand why such a simple formula is so capable, we
investigate the possibility of associating each term of the empirical formula
with the specific part of the measured excitation energy graph.Comment: 9 pages, 3 figure
Spin-dependent empirical formula for the lowest excitation energies of the natural parity states in even-even nuclei
We present an empirical expression which holds for the lowest excitation
energy of the natural parity states in even-even nuclei throughout the entire
periodic table. This formula contains spin-dependent factors so that it is
applied to different multipole states with the same model parameters in
contrast to the recently proposed empirical expression where the model
parameters had to be fitted for each multipole separately.Comment: 9 pages, 5 figure
Origin of Excitation Energy Dependence on Valence Nucleon Numbers
It has been shown recently that a simple formula in terms of the valence
nucleon numbers and the mass number can describe the essential trends of
excitation energies of the first states in even-even nuclei. By
evaluating the first order energy shift due to the zero-range residual
interaction, we find that the factor which reflects the effective particle
number participating in the interaction from the Fermi orbit governs the main
dependence of the first excitation energy on the valence nucleon numbers.Comment: 9 pages, 5 figure
Universal Expression for the Lowest Excitation Energy of Natural Parity Even Multipole States
We present a new expression for the energy of the lowest collective states in
even-even nuclei throughout the entire periodic table. Our empirical formula is
extremely valid and holds universally for all of the natural parity even
multipole states. This formula depends only on the mass number and the valence
nucleon numbers with six parameters. These parameters are determined easily and
unambiguously from the data for each multipole state. We discuss the validity
of our empirical formula by comparing our results with those of other studies
and also by estimating the average and the dispersion of the logarithmic errors
of the calculated excitation energies with respect to the measured ones.Comment: 10 pages, 5 figure
scheme and the valence proton-neutron interaction
We examine the common belief that the scheme is manifested as a
direct consequence of the valence proton-neutron interaction which has proven
to be a dominant factor in developing collectivity in nuclei. We show that the
simplification of the -plot of the lowest excitation energy is
introduced merely because the excitation energy always decreases when the
valence nucleon number becomes larger.Comment: 10 pages, 6 figure