Page 20 - IEAR1_60y_Book_of_Abstracts_UPD

8 Invited Talks

with bioaccumulating native trees and bromeliads, river and lake sediments, and litho-
logical discontinuities in soils. Food safety and quality started with Brazilian coffee
produced in conventional, organic and sustainable agroforestry systems, discrimina-
tion of organic and conventional produces (tomatoes, orange, potatoes), impact of
rare earth elements on the citrus agribusiness, essential and toxic elements in bovine
milk, honey of meliponines, arsenic in rice, and beef traceability. Development and
production of reference materials in the context of the CCDA (Collaborative Center
for Agricultural Defense) and organization of proficiency testing in the NIT-Agro
(Nucleus for Technological Innovation –Metrology and Quality in Agriculture) both
funded by CNPq.

THE NEUTRON ACTIVATION ANALYSIS APPLIED TO THE DATING OF
ARCHAEOLOGICAL CERAMICS AND SEDIMENTS BY CRYSTAL
30 Nov LUMINESCENCEPRESENTATION
3:00pm
S.H. Tatumi a
a
sonia.tatumi@gmail.com
Marine Science Department, Federal University of São Paulo, Brazil

Neutron activation analysis technique has been a great partner in the physico-
chemical characterization, as in the dating archaeological and geological sites. This
is due to its high precision as well as low detection limit of trace elements, necessary
for the determination of the annual dose rate (AD), which is essential for the calcu-
lation of age by Thermoluminescence (TL) and Optically Stimulated Luminescence
(OSL). In addition, it is a technique considered non-destructive because it uses a
few milligrams of samples in the measurements. Therefore, it is a technique capable
of providing point values. Often necessary in the research of samples which present
great heterogeneity, or samples with very small size. Age can be calculated according
to the equation:
D e
Age =
AD
+ 0:9AD + AD Cosmic
r ay
where D e is the equivalent dose (Gy), amount of energy deposited by ionizing ra-
diation in the crystal divided by the AD (Gy/year) incident on the crystal, due to
gamma-rays, beta particles and cosmic ray radiation. The D e is determined by the
TL or OSL techniques and the AD is determined through the U, Th and K-40 lev-
els in natural samples, such as sediments, soil and archaeological ceramics. These
quantities do not exceed a few ppm, in this way, a technique with great accuracy is
required for the determination of these radioactive contents. Therefore, the NAA is
widely used because of its high accuracy.