"Radiochemical studies of the fission of thorium by 14 mev neutrons"

The relative yields of 14 mass chains* in the fission of thorium by 14 MeV neutrons have been measured radio- chemically. Fission-product sources were counted with an end-window β-proportional counter which was- absolutely calibrated for as many of the nuclides measured as was, practicable. The measured relative yields were corrected to total chain yields on application of the equal charge displacement hypothesis, and a mass-yield curve produced with two narrow peaks and a broad trough. Peak maxima occur at mass numbers 91 and 137.4, with a peak width at half-height of 12.5 mass units. The occurrence of a subsidiary maximum in the centre of the trough is considered, although insufficient evidence is, available to delineate this completely. The relative yields were converted to absolute yields on imposition of the condition that the sum of the yields of all the fission-products must be 200%. The value obtained, for the absolute yield of mass number 91 is 6.48 + 0.33?%. *Mass Numbers: 83, 84, 91, 93, 97, 99, 105, 111, 112, 113, 129, 132, 139, 143.