Some characteristics of nuclear densities

We propose a simple expression for nuclear densities, which brings out the following important nuclear properties: (i) shell effects in proton and neutron central densities, (ii) approximate global constancy of neutron central densities, (iii) approximate constancy of RN^-1/3 and R_pZ^-1/3 where R is the nuclear half-density radius and R_p is the rms radius of the proton density, (iv) larger surface thickness and rms radius for neutron density as compared to those for proton density.