Neutron Radiative Capture Cross Sections for ${\mathrm{Na}}^{23}$, ${\mathrm{Mn}}^{55}$, ${\mathrm{In}}^{115}$, and ${\mathrm{Ho}}^{165}$ in the Energy Range 1.0 to 19.4 MeV

Activation cross sections for the ${\mathrm{Na}}^{23}(n,\gamma ){\mathrm{Na}}^{24}$, ${\mathrm{Mn}}^{55}(n,\gamma ){\mathrm{Mn}}^{56}$, ${\mathrm{In}}^{115}(n,\gamma ){\mathrm{In}}^{116m}$, and ${\mathrm{Ho}}^{165}(n,\gamma ){\mathrm{Ho}}^{166}$ reactions have been measured at 17 neutron energies between approximately 1.0 and 19.4 MeV. Neutrons were produced by means of the $\mathrm{T}\mathrm{}(p,n)\mathrm{}{\mathrm{He}}^3$, $\mathrm{D}\mathrm{}(d,n)\mathrm{}{\mathrm{He}}^3$, ${\mathrm{Be}}^9(\alpha ,n){\mathrm{C}}^{12}$, and $\mathrm{T}\mathrm{}(d,n)\mathrm{}{\mathrm{He}}^4$ reactions using a 3.5-MV Van de Graaff accelerator. The measurements were made relative to the fission cross section of ${\mathrm{U}}^{235}$ for fast neutrons. Thermal irradiations were made in order to obtain cross sections normalized to the thermal-activation cross sections of the irradiated samples and the thermal-fission cross section of ${\mathrm{U}}^{235}$. The experimental cross-section data for all the isotopes investigated show evidence of a peak in the vicinity of 14 MeV. The measured capture cross sections have been compared with the cross sections predicted by the "direct-capture" reaction theory of Lane and Lynn and by the "semidirect" reaction theory of Brown.