Relative Yields of Nuclear Isomers ofBr80Produced by a (γ, n) Reaction

The yield ratio, $\frac{{\mathrm{Be}}^{81}(\gamma , n){\mathrm{Br}}^{80}}{{\mathrm{Br}}^{81}(\gamma , n){\mathrm{Br}}^{80m}}$, was determined at several energies between 15 Mev and 70 Mev, using bremsstrahlung produced by the Iowa State 70-Mev synchrotron. It was concluded that the yield ratio does not change significantly above 25 Mev, and, consequently, that the corresponding cross section ratio is also constant.