Problem 6.273

The irradiation of lithium and beryllium targets by a monoergic stream of protons reveals that the reaction $\mathrm{Li}^{7}(p, n) \mathrm{Be}^{7}$ $-1.65 \mathrm{MeV}$ is initiated whereas the reaction $\mathrm{Be}^{9}(p, n) \mathrm{B}^{9}-1.85 \mathrm{MeV}$ does not take place. Find the possible values of kinetic energy of the protons.