Gamma-Neutron Cross Sections

Abstract

A method is outlined for determining the total number of photons at each energy for a given irradiation from a betatron, assuming the bremsstrahlung photon distribution to be represented by an equation of Schiff and the response of an r-meter to be proportional to the absorption cross section for photons in the wall material.The resulting activities produced by gamma-neutron reactions in Cu 63 , Cu 65 , Sb 121 , Sb 123 , and Ta 181 have been measured as functions of the maximum photon energy of the betatron. In each case the activity was normalized to saturation per gram for 100 roentgens of radiation.A method is also outlined whereby these activation curves may be analyzed to give the photo-neutron cross section as a function of energy. The cross section for Cu 63 obtained by this method has its maximum at 17.5 Mev with a resonance half-width of 6 Mev and an integrated area of 0.7 Mev-barn. Maxima for the other nuclides are at somewhat lower energies and have essentially the same half-width.

Angular Distribution of Photoprotons from Nitrogen

“…The most general feature of photodisintegration experiments is the existence of the so-called" giant resonance" (Baldwin and Klaiber 1948;Johns et al 1950). This resonance occurs in the cross section v. energy curve of every photonuclear reaction.…”

Effective photoexcitation cross section of115In(γ,γ′)115mIn from photoactivation data

“…[7] presents a maximum value at 4.4 mb positioned at 9 MeV with a width at half maximum of 9 MeV. The authors mention that the uncertainty associated with their method of extraction of the cross section from the activation data can be up to 50% [27]. Authors from Ref.…”

Resolution of Bremsstrahlung Experiments

“…, p, and thus in general has a unique solution and any exact method to solve (2) will give the same unique solution. Existing methods are the total spectrum method (Johns et al 1950), the photon difference method (Katz and Cameron 1951), and the modified total spectrum method of Penfold and IJeiss (1958). An iteration method is used by Carver and Lokan (1957).…”