Cross section measurements of $^{9}\mbox{Be}(\alpha, \mbox{n})^{12}\mbox{C}$

The $^{9}\mbox{Be}(\alpha, \mbox{n})^{12}\mbox{C}$ reaction has a large cross section and hence is useful in applications as a neutron source. This reaction is also a key step in the formation of $^{12}\mbox{C}$ in neutron-rich environments, such as the ejecta of type-II supernovae. Using the 4.5-MV tandem accelerator at Ohio University, the differential cross section of $^{9}\mbox{Be}(\alpha, \mbox{n})^{12}\mbox{C} $ has been measured for an incident energy of $E_{\alpha}$ = 4.5 MeV. The time-of-flight method was used with a flight path of 30 m. A 15-$\mu \mbox{m}$-thick target of $^{9}\mbox{Be}$ was used. This thickness yielded broad peaks in the neutron energy spectra which allowed the energy dependence of the cross section to be inferred for $2 \leq E_{\alpha} \leq 4.5$ MeV. Using a beam swinger apparatus, neutrons were detected at laboratory angles of $0^{\circ}$, $15^{\circ}$, $35^{\circ}$, $40^{\circ}$, $60^{\circ}$, $88^{\circ}$, $110^{\circ}$, $120^{\circ}$, $130^ {\circ}$, and $145^{\circ}$. Neutrons associated with the ground state and the first two excited states of $^{12}\mbox{C}$ were measured. I will present the cross section data and discuss its implications.