Resonance Detection of Neutron Energy Groups from theMn55(p, n)Fe55Reaction

The excitation energies of low-lying levels in ${\mathrm{Fe}}^{55}$ and the $Q$-value of the ${\mathrm{Mn}}^{55}(p, n){\mathrm{Fe}}^{55}$ reaction have been measured by determining the proton energies at which 257-kev neutrons are produced in this reaction. The ratio of the number of neutrons scattered by a ½-inch thick lithium slab to the number of neutrons transmitted was measured as the energy of a proton beam striking a thin manganese target was varied monotonically. Peaks in the ratio curve, indicating the presence of 257-kev (the energy for resonant neutron scattering from lithium) neutron groups from the reaction, occur at particular proton energies, and $Q$-values can readily be computed. A ground-state $Q$-value of (-1.011±0.005) Mev has been measured for the ${\mathrm{Mn}}^{55}(p, n){\mathrm{Fe}}^{55}$ reaction and states in ${\mathrm{Fe}}^{55}$ were located at exciatations of 437, 936, 1315, 1414, and 2156 kev. Advantages and limitations of the method are discussed.