Constraints on neutron skin thickness in 208Pb and density-dependent symmetry energy

Accurate knowledge about the neutron skin thickness Delta R-np in Pb-208 has far-reaching implications for different communities of nuclear physics and astrophysics. Yet, the novel lead radius experiment (PREX) did not yield any stringent constraint on Delta R-np recently. We employ a more practicable strategy to probe the neutron skin thickness of Pb-208 based on a high linear correlation between the Delta R-np and J - a(sym), where J and a(sym) are the symmetry energy (coefficient) of nuclear matter at saturation density and of Pb-208. An accurate J - a(sym) thus places a strong constraint on the Delta R-np. Compared with the parity-violating asymmetry A(PV) in the PREX, the reliably experimental information on the J - a(sym) is much more easily available thanks to the wealth of measured data on nuclear masses and decay energies. The density dependence of the symmetry energy is also well constrained with the J -a(sym). Finally, with a "tomoscan" method, we find that one just needs to measure the nucleon densities in Pb-208 starting from R-m = 7.61 +/- 0.04 fm to obtain the Delta R-np in hadron scattering experiments, regardless of its interior profile being hampered by strong absorption.