Deducing the 237U(n,f) Cross Section Using the Surrogate Ratio Method

We have deduced the cross section for 237 U(n, f) over an equivalent neutron energy range from 0 to 20 MeV using the surrogate ratio method. A 55 MeV 4 He beam from the 88 inch cyclotron at Lawrence Berkeley National Laboratory was used to induce fission in the following reactions: 238 U(α, α f) and 236 U(α, α f). The 238 U reaction was a surrogate for 237 U(n, f), and the 236 U reaction was used as a surrogate for 235 U(n, f). Scattered α particles were detected in a fully depleted segmented silicon telescope array over an angle range of 35 • to 60 • with respect to the beam axis. The fission fragments were detected in a third independent silicon detector located at backward angles between 106 • and 131 • .