Comparison between neutron dosimetries utilized by the fission-track method (Au, Co and U)

• Grant number: 06/05618-9
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: August 01, 2008
• End date: July 31, 2010
• Field of knowledge: Physical Sciences and Mathematics - Physics - Nuclear Physics
• Principal Investigator: Julio Cesar Hadler Neto
• Grantee: Eduardo Augusto Campos Curvo
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

In general, minerals have some PPM of uranium as impurity. The most abundant uranium isotope, the 238U, decays by spontaneous fission and the two fission fragments departed from this process create a disorder in the mineral's crystalline structure, which is named latent track. The latent tracks are continuously produced into the mineral, with the flowing of the time. If properly chemically etched, these tracks are increased until the point of being observable through an optical microscope. Based upon an equation that relates the number of spontaneous tracks with the number of thermal neutron induced ones, both intersecting the mineral surface, it is possible to determine the mineral's age. Nevertheless, the density of induced tracks is a function of the neutrons fluence that the sample must face inside the nuclear reactor. There are two fundamental ways of determining inside the fission track method. One of them is performed through the use of metallic activation monitors (Au, Co). The other is achieved through the utilization of uranium thin films. Both absolute dosimetries are meant as accurate, however, there are few comparisons between them. The objective of this work is to compare these dosimetries. (AU)