We calculate the cross section of the inverse beta decay process, e+n ! p+eÀ€€ inrncurved spacetime in the presence of strong magnetic eld and.Using exact solutionsrnof the Dirac equation in a curved space-time and Spinors of the Dirac Equationrnand its solution In Robertson-Walker Spacetime, we nd the cross section forrnarbitrary polarization of the initial neutrons.The magnetic eld might provide arnnet polarization of the neutrons, which we take into account