Applying the Surrogate Technique to Stockpile Stewardship

Recent work has focused on developing the absolute probability and external ratio surrogate techniques for use in determining neutron-induced cross sections on unstable nuclei. In this talk we will present a new ``internal'' ratio method where a ratio of different exit channel probabilities for the same compound nucleus can be used to determine the cross section for an unknown exit channel when a cross for a different exit channel (e.g. determining (n,$\gamma )$ when (n,f)) is known. This technique can be used in combination with an ``external'' ratio method measurement to ``bootstrap'' several surrogate (n,x) cross section from a single surrogate measurement. We will present results from two experiments using STARS+LIBERACE at the 88-Inch cyclotron at LBNL to determine the $^{237}$U(n,$\gamma )$ and $^{237}$U(n,2n) cross sections using this ``internal'' ratio method. This work was sponsored by UC-LLNL under Contract No. W-7405-Eng-48 and Grant Nos. DE-FG-05NA25929, DE-FG52-06NA26206, and DE-FG02-05ER41379.