Emission ofBe7and Competition Processes at 30 to 42 MeV

A study has been made of cross sections for the reactions ${\mathrm{Al}}^{27}(p, {\mathrm{Be}}^7)$ at 30 to 39 MeV; ${\mathrm{V}}^{51}(p, {\mathrm{Be}}^7)$ at 33 to 39 MeV; ${\mathrm{V}}^{51}$ (${\mathrm{He}}^4$, ${\mathrm{Be}}^7$) and ${\mathrm{V}}^{51}$ (He, ${\mathrm{He}}^4$ ${\mathrm{He}}^3$) at 40 MeV; ${\mathrm{Co}}^{59}$ (${\mathrm{He}}^4$, ${\mathrm{Be}}^7$) and ${\mathrm{Co}}^{59}$ (${\mathrm{He}}^4$, ${\mathrm{He}}^4$ ${\mathrm{He}}^3$) at 36 to 41 MeV and Ni (${\mathrm{He}}^4$, ${\mathrm{Be}}^7$) at 33 to 41 MeV. The cross sections for the competing modes of ${\mathrm{Be}}^7$ and ${\mathrm{He}}^4$+${\mathrm{He}}^3$ emission are found to be of the same order of magnitude in ${\mathrm{V}}^{51}$ at bombarding energies where these modes alone can compete in the emission of 7 amu. Significantly different results were obtained with the ${\mathrm{Co}}^{59}$ target where ${\mathrm{He}}^4$+${\mathrm{He}}^3$ emission is favored by a factor of 6 or 7 over ${\mathrm{Be}}^7$ emission. He-ion- and proton-induced reactions leading to the same compound nucleus with subsequent emission of ${\mathrm{Be}}^7$ show that the (${\mathrm{He}}^4$, ${\mathrm{Be}}^7$) reaction has a somewhat higher cross section at equivalent excitations of the compound nuclei. Cross sections for other He-ion-induced reactions with ${\mathrm{V}}^{51}$ and ${\mathrm{Co}}^{59}$ involving multicluster alpha emission are reported.