A) study and measurements of TL-residual. B) Application in dating in the Paranaguá Barrier

• Grant number: 17/25828-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2018
• End date: February 28, 2019
• Field of knowledge: Physical Sciences and Mathematics - Physics - Nuclear Physics
• Principal Investigator: Shigueo Watanabe
• Grantee: Luiz Felipe de Faria Pereira
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 14/03085-0 - Quaternary geochronology of Southeastern and Southern coast of Brazil, AP.TEM

Abstract

This Project is divided in two parts. In the part A, study and measurement will be carried on of the so called Residual TL, TLr. when any sediment is exposed to solar radiation its TL decreases with time as long as 10 to 12 hours, however, never this TL becomes zero, meaning after long exposure to solar radiation the sediment presents a residual TL, TLr. In dating using TL method one has to measure TLr of the sample to be dated, for a due correction. However, an experiment of measurement of TLr, exposing the sediment to solar radiation, seems very simple, but in practice the wind, rain and clouds very often interfere with experiment and what should be one or two week work, it is possible to take one up to two months. We are, therefore, trying to use fluorescent lamp that has 220, 365 and 420 nm UV band and, since, solar radiation has only 365 and 420 UV component, we will use an optical filter that absorb 220 nm UV light. An alternative is to use Xe lamp which has spectrum that shows UV light increasing from 200 nm up to about 560 nm, where starts visible light spectrum. The Hg fluorescent lamp has a spectrum with strong 220 nm band and then up to 500 nm has a large UV component to which two bands, one at 365 and the other at 400 nm superposes. In the part B, a dating of Paranaguá Barrier in the state of Paraná will be carried out. This Barrier being a sand sediment, the first part of measurement is to determine TLr. And then we will complete with measurement of accumulated dose, Dac, by TL method. To obtain the expected age of Barrier U(238), Th(232) and K(40) content will be measured to obtain the annual dose rate, Dan, so that finally we will have: Age=Dac/Dan (AU)