Photonuclear Activation by 20.5-Mev Gamma Rays

Abstract

The photonuclear activation cross section of elements whose (y,n) cross sections lead to a suitable positron activity has been measured using monochromatic gamma rays from the T 3 (^,7)He 4 reaction. The gamma rays were monitored by a 3-in. diam by 4-in. long sodium iodide crystal and calibrated with a 4f X6 in. crystal whose response curve to the y rays was determined. The absorption coefficient of these photons in Nal was determined by a good geometry transmission experiment. The positron activity was determined by a coincidence detector, consisting of two 5-in. diam by 2-in. long Nal crystals set on the annihilation radiation photopeaks. This detector was calibrated against a F 18 positron source standardized in a 2T flow counter.The C n (y,n)C^ and F 19 (7,w)F 18 reactions were investigated over the range from 20.1 to 21.2 Mev. Structure, although reported by other experimenters, was not observed. The (y,n) activation cross section was measured at 20.5 Mev for O 16 ,

Photoneutron Cross Sections ofPr141andI127from Threshold to 33

“…The energy dependence of the cross section for photon absorption is predicted by the hydrodynamic model of Steinwedel and Jensen 1 and by extended hydrodynamic models 2,3 which include deformation and vibrationrotation effects. The shell model has been applied to photon absorption in medium-heavy nuclei, 4 but exact life of Fm 258 might be 10 days, as reported by Gatti et alP More recent efforts 30 with larger amounts of Fm 257 target and higher neutron fluxes have failed to produce observable amounts of Fm 258 , with even lower limits being set on the half-life of Fm 258 . 29 R. C. Gatti, R. Brandt, L. Phillips, and S. G. Thompson, J. Inorg.…”

“…25, 1089 (1963). 30 E. K. Hulet, R. W. Lougheed, and B. J. Qualheim, University of California, Lawrence Radiation Laboratory, Livermore, Report No. UCRL-14499- T, 1965 (unpublished).…”

Measurement of neutron energy spectra for Eg=23.1 and 26.6 MeV mono-energetic photon induced reaction on natC using laser electron photon beam at NewSUBARU

“…11 C reaction at Eg = 23.1 and 26.6 MeV in comparison with other experimental data [1,[14][15][16][17][18] and the simulation results of the PHITS code with monoenergetic photon. The produced 11 C nuclei in the target were counted in the simulation.…”

Evaluation of Photonuclear Data of Mo, Zn, S and CI for Medical and Accelerator Applications

“…The measured data of photoneutron cross sections in the incident photon energy region from the threshold to 24 MeV were first performed by Goryachev (7,8) and Coote et al (9) are in agreement with Goryachev's data.…”