Excitation Functions to 100 Mev

A method is described for obtaining excitation functions using the stacked foil technique with an internal cyclotron beam. The method, which utilizes multiple Coulomb scattering for deflection and 180\ifmmode^\circ\else\textdegree\fi{} focusing for energy separation, has the advantages of good energy resolution, high intensity, and low background. Equations are presented for the particle orbits from which are derived the energy resolution and efficiency attainable. Absolute excitation curves are given for the reactions, ${\mathrm{C}}^{12}(p,pn){\mathrm{C}}^{11}$; ${\mathrm{Na}}^{24}$, ${\mathrm{Na}}^{22}$, and ${\mathrm{F}}^{18}$ from ${\mathrm{Al}}^{27}$; ${\mathrm{B}}^{11}(p,n){\mathrm{C}}^{11}$; and ${\mathrm{S}}^{34}(p,n){\mathrm{Cl}}^{34}$. Absolute cross sections are determined using the monitor reaction, ${\mathrm{C}}^{12}(p,pn){\mathrm{C}}^{11}$, and the ratio of the $\ensuremath{\beta}$-counting rates. Various corrections to the relative and absolute excitation curves are discussed. A brief interpretation of the results is given in which it is argued that they are consistent with present ideas about high energy nuclear reactions.