Absolute Activation Cross Sections for Reactions of Bismuth, Copper, Titanium, and Aluminum with 14.8-Mev Neutrons
Absolute neutron activation cross sections at 14.8 Mev have been measured for bismuth, copper, titanium, and aluminum based on comparison with the Cu63(n, 2n)Cu62 reaction (556 millibarns) which served as a standard for monitoring the flux. The reactions studied, measured half-lives, and cross sections are: Bi209(n, α)Tl206, 4.29+/-0.05 min, 1.1+/-0.3 mb; Bi209(n, p)Pb209, 3.31+/-0.03 hours, 0.83+/-0.40 mb; Bi209(n, γ)Bi210, <=1.7 mb; Cu65(n, 2n)Cu64, 12.85+/-0.05 hours, 954+/-130 mb; Cu65(n, p)Ni65, 2.56+/-0.20 hours, 27+/-11 mb; Ti50(n, p)Sc50, 1.8+/-0.2 min, 27+/-6 mb; Ti50(n, p)Sc50, 22+/-3 min, 48+/-15 mb; Ti50(n, γ)Ti51, <=9 mb; Ti49(n, p)Sc49, 58+/-2 min, 29+/-5 mb; Ti48(n, p)Sc48, 44.0+/-0.9 hours, 58+/-8 mb; Ti47(n, p)Sc47, 3.45+/-0.06 days, 230+/-40 mb; Ti46(n, 2n)Ti45, 3.06+/-0.08 hours, 50.4+/-8.0 mb; Ti46(n, p)Sc46, 85+/-2 days, ~520 mb; Al27(n, α)Na24, 15.00+/-0.06 hours, 114+/-7 mb; Al27(n, p)Mg27, 9.46+/-0.02 min, 53+/-5 mb. Comparisons of the experimental cross sections with values estimated according to the continuum theory of the compound nucleus outlined by Blatt and Weisskopf are in agreement within an order of magnitude, except in the case of the bismuth results which exhibit large discrepancies. From irradiations of natural titanium and highly enriched Ti50, a new activity was observed having a half-life of 22+/-3 minutes. This activity is not produced from enriched Ti47 or Ti49 samples, and it is therefore assigned tentatively to an isomer of Sc50. Further work on this activity is in progress.