Power laws for nuclear observables

Often mass-dependent nuclear observables are summarized by fits to a power law in the nuclear mass A, as proportional to A(alpha). In this work a simple justification of this usage is presented, also providing a simple expression for the exponent alpha, with one known parameter being the beam-nucleon total cross section and another parameter being a nuclear size r(0)A(1/3). Measured power-law exponents alpha for total and reaction cross sections are near this simple formulation using r(0) = 1.6 fm, whereas quasifree observables are near the simple expression using r(0) = 1.2 fm.