Proton Cross Sections ofBi209

The cross sections for the reactions ${\mathrm{Bi}}^{209}(p, 2n){\mathrm{Po}}^{208}$, ${\mathrm{Bi}}^{209}(p, n){\mathrm{Po}}^{209}$, and ${\mathrm{Bi}}^{209}(p, \gamma ){\mathrm{Po}}^{210}$ have been measured for proton energies up to 10.65 Mev. The threshold for the ($p, 2n$) reaction is 9.65 Mev (c.m.) which leads to a neutron binding energy for ${\mathrm{Bi}}^{210}$ of ≥ 4.59±0.14 Mev. The total cross section as a function of energy agrees with the theoretical calculations for a radius $R=1.5\mathrm{}{A}^{\frac{1}{3}}\times {10}^{-13\mathrm{}}$ cm. The energy dependence of the ratio of $\frac{{\sigma }_{\mathrm{}(p,2n)\mathrm{}}}{[{\sigma }_{\mathrm{}(p,n)\mathrm{}}+{\sigma }_{\mathrm{}(p,2n)\mathrm{}}]}$ corresponds to a nuclear temperature of 4 Mev for ${\mathrm{Po}}^{209}$.