21,881 research outputs found
An alternative understanding of mass formulas in terms of nuclear structure
A typical form of mass formula is re-explained in terms of nuclear structure.
For nuclei, we propose to start with the shell model picture
and to consider the T=0 (-like) correlations as the fundamental
concept, instead of the symmetry energy.
Subsequently, the symmetry energy is described on the basis of the
-like superfluidity caused by the T=0 correlations, in parallel
with the pairing energy described on the basis of the pairing superfluidity.
This re-explanation gives useful insight for understanding the nuclear mass
formula. The origin of the Wigner energy is also explained in an interacting
boson model for the Cooper pairs in the -like superfluid vacuum. Adding
a correction term due to the T=0 correlations, which determines the T=0
base level for nuclear masses, can improve the mass formulas in practice.Comment: to be published in Prog. Theor. Phys. Vol. 113, No.
Competition between isoscalar and isovector pairing correlations in N=Z nuclei
We study the isoscalar (T=0) and isovector (T=1) pairing correlations in N=Z
nuclei. They are estimated from the double difference of binding energies for
odd-odd N=Z nuclei and the odd-even mass difference for the neighboring
odd-mass nuclei, respectively. The empirical and BCS calculations based on a
T=0 and T=1 pairing model reproduce well the almost degeneracy of the lowest
T=0 and T=1 states over a wide range of even-even and odd-odd N=Z nuclei. It is
shown that this degeneracy is attributed to competition between the isoscalar
and isovector pairing correlations in N=Z nuclei. The calculations give an
interesting prediction that the odd-odd N=Z nucleus 82Nb has possibly the
ground state with T=0.Comment: 5 pages, 4 figures, to be published in Phys. Rev. C (R
Global features of proton-neutron interactions and symmetry energy
We study global features of proton-neutron (p-n) interactions and symmetry
energy over a wide range of nuclei, using a schematic model interaction with
four forces proposed recently.
Calculations are performed by the BCS approximation in N,Z=20-50 and
N,Z=50-82 regions. The experimental double differences of binding energies and
symmetry energy are reproduced quite well.
It is shown that the isoscalar p-n interactions with all J are indispensable
for explaining the binding energies of not only
but also N>Z nuclei in the A=40-160 region.Comment: 15 pages, 4 figures, submitted to Phys. Lett.
A possible mechanism to cause the quasi-biennial variability on the solar neutrino flux
It is suggested that the quasi-biennial change in the observed flux of the solar neutrinos is causally related to some non-linear process at the central core of the Sun, being associated with the charge in the central temperature. This process seems to be responsible for the physical adjustment of the internal structure of the Sun. Numerical simulation on this process is able to reproduce the quasi-biennial change in the flux of these neutrinos
- …