The Slow Neutron Cross Sections of Indium, Gold, Silver, Antimony, Lithium, and Mercury as Measured with a Neutron Beam Spectrometer
The variations of the slow neutron transmissions of In, Au, Ag, Sb, Li, and Hg have been investigated as a function of the time-of-flight of the incident neutrons for a 5.4-meter path by use of a neutron beam spectrometer. A method of analysis is developed for determining E0 and σ0Γ2 for resonances above 1 ev based on the experimental transmission curves and the Breit-Wigner theory. The positions of the levels located, listed in order of importance for each element, are: In, (1.44+/-0.04) ev; Au, (4.8+/-0.2) ev; Ag, (5.11+/-0.2) ev, (13.7+/-1) ev, and (43+/-5) ev; Sb, (6.3+/-0.5) ev, (19.2+/-1.0) ev, and indications of other unresolved levels in the region of 50 to 500 ev; Li, only a 1v cross section; Hg, a negative level at (-2.0+/-0.2 ev) and indications of unresolved positive levels above 25 ev. In the thermal region, the Ag, Sb and Li cross-section curves can be resolved into the sum of a constant term and a 1v term. If E is the neutron energy in ev, these are: Ag: [(9.05+/-0.10)E-12+(6.6+/-0.5)]×10- 24 cm2/atom; Sb: [(0.64+/-0.02)E-12+(4.2+/-0.3)]×10- 24 cm2/atom; Li: [(11.5+/-0.2)E-12+(1.7+/-0.2)]×10- 24 cm2/atom; LiF was used in the Li measurements and a value 2.5×10-24 cm2/atom has been deducted for the F. The Hg cross section below 5 ev was well matched by the relation (64+/-3)E-12(1+E2.0)-2×10-24 cm2/atom.