A measurement of the n-p 180/90 degree cross section ratio at 65 and 50 MeV

A measurement of the 1800 to 900 n-p differential cross section ratio is of interest because recent data from Louvain in the range 45 to 65 MeV showed a larger ratio than earlier data from Harwell and U.C. Davis. Here large area scintillation detectors are used to cover the range 50 to 300 (lab) and 400 to 460. A ΔE -ΔE telescope covers the 00 to 20 range. Position sensitive wire chambers cover the angular range of all three detectors, allowing a range of cross sections to be measured at the same time. The experimental arrangements, analysis and partial results to date are presented. (author)