Thick target photon yields and angular distributions for the F-19(p,alpha gamma)O-16 source reaction at incident proton energies between 1.5 and 4.0 MeV

The absolute thick target yield of 6.129, 6.917 and 7.116 MeV gamma-rays pr oduced from the F-19(p,alpha gamma)O-16 source reaction has been measured f or incident proton energies bt tween 1.5 and 4.0 MeV. The angular distribut ions of the respective gamma-lines have been determined for incident proton energies of 2.0 and 3.0 MeV. The experiments were performed at the 4.5 MV Tandem Van der Graaff accelerator at the Ohio University Edwards Accelerato r Laboratory in Athens, Ohio, using a thick CaF2 target and a 7.62 cm x 7.6 2 cm Na(I) scintillation detector. The Monte Carlo code MCNP was used to ca lculate detector response functions for the three individual gamma-rays. A least-squares fit of these functions to a selected region in the pulse heig ht spectrum was carried out to determine the relative intensities of these gamma-rays. The uncertainty in the fluence determination is based on the ch i(2) Of the fit, the uncertainty in the response functions, the statistics of the data, and the uncertainty in the recording of the proton charge. A m aximum photon yield of 1.316 x 10(7) gamma/mu Csr (at 90 degrees) was deter mined for the sum of these three gamma-rays at the highest incident proton energy of 4.0 MeV. The contribution of the individual lines to the total ph oton yield depends strongly on the incident proton energy. The angular dist ributions are isotropic to within 15%. (C) 2000 Elsevier Science B.V, All r ights reserved.