Measurement of activity yields for 12C(gamma, n)11C, 14N(gamma, n)13N, and 16O(gamma, n)15O reactions as a function of electron beam energy and angle from the electron beam using thick target produced bremsstrahlung.

The calculation of activity yields from practical photonuclear target systems designed to produce short-lived positron emitting radionuclides for nuclear medicine purposes requires certain basic information. These include a knowledge of the photon source (bremsstrahlung energy spectrum and intensity as a function of angle from the electron beam) and the gamma, n activation cross section of the secondary target element. A lack of adequate information concerning these parameters motivated the present study in which activity yields for the reactions 12C(gamma, n)11C, 14N(gamma, n)13N, and 16O(gamma, n)15O were measured as a function of energy of and angle from the electron beam between 16 and 30 MeV and 0 degree and 30.5 degrees, respectively. The data indicate highly complex relationships between the activity yield and the experimental variables. Also indicated are possible applications of the data to indicate the energy of an electron beam producing a given bremsstrahlung field in which activation measurements are made.