2007 International Nuclear Atlantic Conference - INAC 2007 Santos, SP, Brazil, September 30 to October 5, 2007 ASSOCIA˙ˆO BRASILEIRA DE ENERGIA NUCLEAR - ABEN ISBN: 978-85-99141-02-1 THERMOLUMINESCENT CHARACTERISTICS OF JASPER SAMPLES Maria InŒs Teixeira 1, 2 and Linda V.E. Caldas 1 1 Instituto de Pesquisas EnergØticas e Nucleares (IPEN / CNEN - SP) Av. Professor Lineu Prestes 2242 05508-000 Sªo Paulo, SP miteixei@ipen.br ; lcaldas@ipen.br 2 Associaªo Educacional Nove de Julho (UNINOVE - SP) R. Diamantina, 302 02117-010 Sªo Paulo, SP ABSTRACT Different jasper samples proceeding from Brazilian mines were powdered and mixed with teflon (composites jasper-teflon TM ). This paper describes a preliminary study of thermoluminescent method (TL) to verify the possibility of their use as high dose dosimeters or irradiation indicators in industrial areas. The TL emission curves of samples exposed to gamma doses of 50 Gy up to 20 kGy presented two peaks at 130 ”C and 190 ”C. Calibration curves were obtained for the jasper samples between 50 Gy and 20 kGy. All five tested jasper samples showed their usefulness as irradiation indicators and as high dose dosimeters. 1. INTRODUCTION Radiation processing using high doses has been presenting various advantages in the areas of sterilisation of pharmaceutical products, food preservation and treatment of several materials. The dosimeter characteristics of silicates samples were studied for application in dosimetry. The silicates are abundant and represent 92% of the volume of minerals of the terrestrial crust. Glass silicates [1-4], quartz [5-6], amethyst [7], jasper [8], topaz [9] and recently the bioglass [10] were tested for the possibility of their use in gamma dosimetry, using the technique of thermoluminescence (TL). In this work preliminary studies of the dosimetric properties of the jasper samples are presented. Chalcedony is a group name for the compact varieties of silica composed by minute crystals of quartz with submicroscopic pores. Their color and texture vary considerably according to the impurities present, but in general such materials may be sub-divided into chalcedony (sometimes called jasper) and agate. Jasper color is fairly uniform (green, red, brown, ocean and striped), and agate color is arranged in bands or concentric zones. The results suggested that some kinds of jasper can be employed as TL dosimetric materials.