Summary
The angular distributions of photofission fragments from uranium at X-ray maximum energies of 6.9, 8.1, 9.4, 15.5 and 20 MeV were measured using a 24 MeV betatron. The anisotropy was found to increase with decreasing X-ray energy and to be mainly consistent witha+b sin2 ϑ electric dipole photon absorption distribution. The quadrupole contribution is shown to be small. The ratio of the anisotropic dipole absorption to the isotropic fission yields at the first three superior energies are 2.80±0.44, 1.18±0.14 and 0.62±0.12. At 15.5 and 20 MeV the distributions are almost isotropic.
Riassunto
Usando un betatrone da 24 MeV si sono misurate le distribuzioni angolari dei frammenti di fotofissione dell’uranio ad energie massime dei raggi X di 6.9, 8.1, 9.4, 15.5 e 20 MeV. Si è riscontrato che l’anisotropia cresce al decrescere dell’energia dei raggi X e si accorda sostanzialmente con una distribuzione dell’assorbimento dei fotoni di dipolo elettrico secondo la leggea+b sin2 θ. Si mostra che il contributo di quadrupolo è piccolo. I rapporti fra l’assorbimento anisotropo di dipolo e le rese dalla fissione isotropa per i primi tre valori suddetti dell’energia sono 2.80±0.44, 1.18±0.14 e 0.62±0.12. A 15.5 e 20 MeV le distribuzioni sono pressochè isotrope.
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Presented to the 46-th National Conference of the Italian Physical Society, Naples, September 29, October 5th. This work is supported in part by funds provided by the Conselho Nacional de Pesquisas and by Comissão Nacional de Energia Nuclear (Brazil).
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de Carvalho, H.G., de Silva, A.G. & Goldemberg, J. Angular distribution of photofission fragments from uranium. Nuovo Cim 19, 1131–1141 (1961). https://doi.org/10.1007/BF02731389
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DOI: https://doi.org/10.1007/BF02731389