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Type: Artigo de periódico
Title: Projected-length distributions of fission-fragment tracks from U and Th thin film sources in muscovite
Author: Guedes, S
Jonckheere, R
Iunes, PJ
Hadler, JC
Abstract: Thin films of natural uranium and thorium deposited on muscovite were used as sources of neutron-induced fission fragments. Fragment energy loss in thin-source geometry is negligible. In this way, the observed fragment range results from the interaction of the fragment with the detector material. This characteristic enables the investigation of asymmetric fission and etching, through measurements of projected track length distributions in muscovite micas coupled with thin films. The means and standard deviations of the etchable length distributions of the heavy and light fission-fragment tracks were estimated by fitting a theoretical equation to the experimental data. The light fission-fragment accounts for similar to 54% and the heavy fission-fragment for similar to 46% of the etchable length of a full fission track. This average partition is the same for tracks from thermal-neutron-induced fission of U-235 and fast-neutron-induced fission of Th-232. The mean etchable length of uranium fission tracks is similar to 2.5% longer than that of thorium fission tracks. This difference is at the resolution limit of these measurements but correlates with the difference in the mean combined initial kinetic energies of the fission fragments. The mean etchable length of uranium fission tracks in muscovite is similar to 5% shorter than their calculated latent track length, supporting earlier estimates of a length deficit of this magnitude. The length deficit and the standard deviation of the etchable length distribution of the light fission-fragment tracks are twice the equivalent values for the heavy fission-fragment tracks. This is interpreted in terms of a upsilon(t)-profile (track etch rate) that depends on the mass of the track-forming particle. (c) 2008 Elsevier B.V. All rights reserved.
Subject: Th-232
induced fission
fission tracks
Country: Holanda
Editor: Elsevier Science Bv
Rights: fechado
Identifier DOI: 10.1016/j.nimb.2008.01.014
Date Issue: 2008
Appears in Collections:Unicamp - Artigos e Outros Documentos

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