Universal Proton Emission Systematics

We investigate proton systematics in terms of the barrier penetration and formation probability. To this purpose we approximate the realistic proton-core interaction by a parabolic dependence describing the nuclear part matched to a pure Coulomb potential. In this way we can use analytic semiclassical solutions to describe the proton dynamics inside the barrier. We then carefully investigate effects induced by the centrifugal barrier and quadrupole deformation. It turns out that the nuclear centrifugal and deformation effects are much smaller than their Coulomb counterparts. On the other hand, the Coulomb action defining the semi classical penetrability is larger by one order of magnitude than its nuclear counterpart. We evidence a dependence of the Coulomb action upon the Coulomb parameter in terms of two parallel lines separated by A = 145. Such a dependence was previously discovered for the logarithm of the experimental decay width corrected by the Coulomb centrifugal barrier. We also evidence an additional but smaller residual linear decrease of the proton formation probability versus A(1/3 )along two parallel lines separated by A = 145, induced by the internal proton wave function. Therefore, the dependence between the experimental decay width corrected by the centrifugal barrier and the Coulomb penetrability multiplied by the proton formation probability in the doubly logarithmic scale can be fitted within a factor of two by a universal straight line.