Failure of Standard Optical Models to Reproduce Neutron Total Cross Section Differences in the W Isotopes

• Published in: Journal of nuclear science and technology Vol. 39; no. sup2; pp. 822 - 825
• Main Authors: Anderson, J.D., Bauer, R.W., Dietrich, F.S., Grimes, S.M., Finlay, R.W., Abfalterer, W.P., Bateman, F.B., Haight, R.C., Morgan, G.L., Bauge, E., Delaroche, J.-P., Romain, P.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 01.08.2002
• Subjects: coupled-channds optical model; microscopic folding models; neutron total cross sections; Ramsauer model; spherical optical model
• ISSN: 0022-3131; 1881-1248
• DOI: 10.1080/00223131.2002.10875225

Recently cross section differences among the isotopes 182, 184, 186 W have been measured as part of a study of total cross sections in the 5-560 MeV energy range. 1) These measurements show oscillations up to 150 mb between 5 and 100 MeV. Spherical and deformed phenomenological optical potentials with typical radial and isospin dependences show very small oscillations, in disagreement with the data. In a simple Ramsauer model, 2-4) this discrepancy can be traced to a cancellation between radial and isospin effects. Understanding this problem requires a more detailed model that incorporates a realistic description of the neutron and proton density distributions. This has been done with results of Hartree-Fock-Bogolyubov calculations using the Gogny force, together with a microscopic folding model employing a modification 5,6) of the JLM potential as an effective interaction. This treatment yields a satisfactory interpretation of the observed total cross section differences.