Estimation of ( n , f ) cross sections by measuring reaction probability ratios

• Published in: Physical review. C, Nuclear physics Nuclear physics, 2005-05, Vol.71 (5), Article 051602
• Main Authors: Plettner, C., Ai, H., Beausang, C. W., Bernstein, L. A., Ahle, L., Amro, H., Babilon, M., Burke, J. T., Caggiano, J. A., Casten, R. F., Church, J. A., Cooper, J. R., Crider, B., Gürdal, G., Heinz, A., McCutchan, E. A., Moody, K., Punyon, J. A., Qian, J., Ressler, J. J., Schiller, A., Williams, E., Younes, W.
• Format: Article
• Language: English
• Subjects: COMPOUND NUCLEI; CROSS SECTIONS; DEUTERON REACTIONS; DEUTERONS; EXCITATION; FISSION; NEUTRON REACTIONS; NUCLEAR DECAY; NUCLEAR PHYSICS AND RADIATION PHYSICS; PROBABILITY; PROTONS; URANIUM 235; URANIUM 236; URANIUM 237; URANIUM 238
• ISSN: 0556-2813; 1089-490X
• DOI: 10.1103/PhysRevC.71.051602

Neutron-induced reaction cross sections on unstable nuclei are inherently difficult to measure due to target activity and the low intensity of neutron beams. In an alternative approach, named the 'surrogate' technique, one measures the decay probability of the same compound nucleus produced using a stable beam on a stable target to estimate the neutron-induced reaction cross section. As an extension of the surrogate method, in this paper we introduce a new technique of measuring the fission probabilities of two different compound nuclei as a ratio, which has the advantage of removing most of the systematic uncertainties. This method was benchmarked in this report by measuring the probability of deuteron-induced fission events in coincidence with protons, and forming the ratio P[{sup 236}U(d,pf)]/P[{sup 238}U(d,pf)], which serves as a surrogate for the known cross section ratio of {sup 236}U(n,f)/{sup 238}U(n,f). In addition, the P[{sup 238}U(d,d{sup '}f)]/P[{sup 236}U(d,d{sup '}f)] ratio as a surrogate for the {sup 237}U(n,f)/{sup 235}U(n,f) cross section ratio was measured for the first time in an unprecedented range of excitation energies.