Experimental Determination of One- and Two-Neutron Separation Energies for Neutron-Rich Copper Isotopes

A method is proposed to determine the one-neutron $S_n$ or two-neutron $S_{2n}$ separation energy of neutron-rich isotopes. Relationships between $S_n$ ($S_{2n}$) and isotopic cross sections have been deduced from an empirical formula, i.e., the cross section of an isotope exponentially depends on the average binding energy per nucleon $B/A$. The proposed relationships have been verified using the neutron-rich copper isotopes measured in the 64$A$ MeV $^{86}$Kr + $^{9}$Be reaction. $S_n$, $S_{2n}$, and $B/A$ for the very neutron-rich $^{77, 78, 79}$Cu isotopes are determined from the proposed correlations. It is also proposed that the correlations between $S_n$, $S_{2n}$ and isotopic cross sections can be used to find the location of neutron drip line isotopes.