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[en] Radioactive 16N is generated in pure water (H2O) which has been exposed to D-T fusion neutrons with energies near 14 MeV. The principal neutron-activation reaction is 16O(n,p)16N. Decay by β emission (100%) of the 7.13±0.02 s 16N activity is accompanied by production of energetic gamma rays (most of them with energies >6 MeV) that are associated with the prompt radiative de-excitation of various elevated energy levels of 16O populated through the process 16N(β-)16O. The dominant gamma-ray emission branch energies (intensities) are 6.129 MeV (67.0±0.6%) and 7.115 MeV (4.9±0.4%). A particular given intensity refers to the percent of 16N decays that produce the indicated gamma ray. Both photons possess energies that are above the photo-fission threshold for the naturally occurring isotopes of uranium, namely, 234U, 235U, and 238U. This paper reports on an experiment that demonstrated 16N decay gamma-ray induced photo-fission in a commercial fission detector that contained 0.14 g of depleted uranium (predominantly 238U with a small trace of 235U). This detector was placed near a tubing system containing circulating water that had been activated by neutron bombardment as it passed near to the target of an intense D-T fusion neutron generator. The fission detector was situated in a shielded location remote from the source of primary D-T neutrons. Other possible mechanisms leading to the generation of the observed detector events were considered. Among these were natural background radiation (e.g., cosmic rays), delayed neutrons from the decay of 17N and 18N also produced in water by D-T neutrons, secondary neutrons from (γ,n) reactions in materials near the detector, and electronic noise or pulse pileup. (orig.)
[en] This is the final report on the various groups in Brazil working in the fields related to fission and photonuclear reactions involving: heavy ion fission, photonuclear reactions, theoretical models, applications. The state-of-the-art, as well as, new proposals for future work were made. (A.C.A.S.)
[pt]Este relatorio faz uma exposicao e um debate dos varios grupos no Brasil trabalhando na area de fissao e reacoes fotonucleares assim como propostas de trabalho futuro envolvendo fissao de nucleos pesados, reacoes fotonucleares, modelos teoricos, aplicacoes. (A.C.A.S.)
[en] This presentation discusses the capabilities at TRIUMF, Canada's national accelerator laboratory which has been involved with isotopes in physics and medicine for many years. The future program at TRIUMF capitalizes on next-generation accelerator technology with very high power beams. It is suggested that photo-fission is a candidate technology for isotopes even medical isotopes. However whichever technology is developed and deployed R and D in targets will be required.
[en] A calculation of the photon fission cross section in the Coulomb field of a nucleus reveals that the real part of the transition amplitude is the predominant contributor for photon energies up to 2 MeV. Since it is just this part that is associated with the fourth-order vacuum polarization process, it is suggested, given the present developmental state of laser technology, that coincidence experiments with photon fission might well afford a test of higher order quantum electrodynamics