Photofission of 209Bi

The fragment yields of 91Sr, 92Sr, 92Y, 93Y, 97Zr, 99Mo, 105Ru, 109Pd, 112Pd, 111Ag and 113Ag were determined radiochemically for the photofission of 209Bi by bremsstrahlung produced from 28, 30, 32, 35, 36, and 40 MeV electrons impinging on a tungsten converter. A 65Cu(γ, n) 64Cu reaction on thin copper foils served to measure the integrated photon dose. A symmetric mass yield curve of about 19 mass units width was observed throughout the energy region studied. The total fission cross section increased from 1 × 10−8 barns at 28 MeV to 1 × 10−5 barns at 40 MeV.