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B.A.R.C.-1074 V I I at < HI id GOVERNMENT OF INDIA ATOMIC ENERGY COMMISSION APPLICATIONS OF THERMOLUMINESCENCE OF QUARTZ by M. David and C. M. Sunta Health Physics Division BHABHA ATOMIC RESEARCH CENTRE BOMBAY, INDIA 1980 B.A.R.C.-1074 GOVERNMENT OF INDIA £ ATOMIC ENERGY COMMISSION o • U ffl APPLICATIONS OF THERMOLUMINESCENCE OF QUARTZ by M. David and C. M. Sunta Health Physics Division BHABHA ATOMIC RESEARCH CENTRE BOMBAY, INDIA 1980 IMIS Subject Category : B31 Des criptors : THERMOLUMINESCENCE QUARTZ DOSIMETRY ENVIRONMENT NATURAL RADIOACTIVITY PROSPECTING RADIOACTIVE MINERALS AGE ESTIMATION ARCHAEOLOGY TEMPERATURE MEASUREMENT GEOLOGIC DEPOSITS iPPLICATIONS OP THERMOLUMINBSCENCE OP QUARTZ SYNOPSIS Bventhough the TL mech-aiem is not well understood, it is perhaps one of those physical phenomenon which is more sucoeas- fully applied. Its application potential was first proposed by Daniels ' in 1953 and since then an awareness of its application in many diverse fields like, Radiation Dosimetry, Archaeology, Qeology, Radiation Physios, Solid State Physios, Forensic Sciences eto. is increased. This report describes an attempt to use TL of natural quarts in solving the following practical problems: (i) Radiation Dooimetryt The main basis in TL dosiaetry is that the TL output is direotly proportional to the radiation dose received by the phosphor and hence provides a means of estimating unknown irradiations. Also, TL can provide a picture of the integrated irradiation levels over an extended period. Thus it is used in finding out the environmental radiation level of an area from where a natural TL sample is collected and used as a TL phosphor. In the present case, quarts samples were oolleoted from the SJT coastal belt of India and the natural TL is used as an indicator of the environmental radiation level. Quarts sample* oolleoted from Chavars~Neendakara area and Medalam-Manavalakkuriohi area showed maximum TL output. Radiation measurement was done with other conventional methods and these are compared with the natural TL of quarts. There are some areas where minimum HTL was observed while other radiation measurements showed high radioactivity. It is concluded that these deposits are either young or seasonal. (10 Mineral Proapectingt Natural Thermoluminescence froji a mineral ie an indicator of the environmental radiation level. In the oase of quarts, the nineral itself contain negligible amount of radioactivity* Therefore the natural TI» of quarts indicates the presence of radio- activity in the surrounding minerals vhioh actually irradiated the quartz during its geological life* This is the theory behind the radioactive mineral prospecting. In the present study, two areas are studied* 1) The coastal belt of Kerala St«te where the aonasite mineral is found admixed with a variety of other heavy minerals* It is observed that the quarts colleoted showed maximum intensity in the following areaet («.) the area in between IRE factory and Indo-tforwagion Hospital near Chavara ( b) the area between the LULP School and Heendakara and( C )tbe area near and around Shaktilculangara Churob, The presenoe of high radiation level in these areas are confirmed with a scintillation surveymeter which means the presenoe of monasite. Therefore it can be concluded that these areas are the exact spots where the monasite concentration is maximum* The studies on the river banks oonoluded that the origin of the radioactive deposit is the Thenmtla Ponmudl Area of the Sahyadri Hills and the rivers Kallada and Ithtkka are responsible for the transport of these minerals to the sea and ultimately to the beaoh, 2) The Tuwe, river area of Gujarat State where Uranium movement is suspeoted through the geological faults in the rook system* Studies at these places show the usefulness of TL method in radioactive mineral prospecting. .It is observed that the movement of uranium is possible in two ways (i) Parrellel to the fault on the rock system and (ii) across the fault* The studies could relate the Eamkhund (hot spring) area with a radioactive dry nullah across the (fart river* -ui- (iii) Geological Studiesi In any geological specimen the accuau- 1atIon of oharge carriers at trapping centres and its drainage are usually assisted by many natural events duoh as earth makes, shearing, faulting, magmatic and valcanio outpours etc. These types of drainage(de-trapping) and subsequent storage(aecumulation) of charge carriers ia the lattice of tbe geologioal specimens can indicate the exact time of the past evdnt. In this report the sample collected from Pondioheri Beaoh is used to oaloulate tbe depositional rate of the beach* The natural event which helped in this calculation is the solar bleaching of the Tli from the mineral quarts which was on the surface and subsequently buried by another fresh layer of sand* It is calculated that the depositional rate of the pondieberi beach is 4.9 Cm/1000 yrs. (IT) Archaeological Dating: Tbe starting of the *TL clock' is oonsiderad to be the time of firing of pottery specimen in the Kiln* Whatever TL had been stored in the material due to the internal and external irradiation over the geologioal times is considered to be erased during the kiln firing* Thus the age is arrived at by measuring the TIi accumulated sinoe the time of firing of the speoimenand' evaluating the annual dose rate received! ^ tne P°'t'tery specimen. In the present study, pottery samples colleoted from Daiaabad and Allahabad excavation sites were dated* The oultural period* of these sites are dated to be 5600-4200 B? for Allahabad sites and 3200-5100 BP for Dianabad sites* (v) Estimation of Kiln firing temperaturet The first peak sensiti- sation*4 ' depends upon the heat treatment given to the samples* la the case of an already fired snple, tbe aensitisation is observed to be much higher than that of the natural specimens. This sensiti- sation can be used as an indicator of the kiln firing temperature of arobaeologioal pottery sherds. In the present studies, four arobaeologloal samples were investigated for finding out the kiln firing tenperature. Xt is observed that the An«nabad potteries were well fired while that collected from Dainabad site were poorly fired. The evaluated values of firing temperatures are 800-900°C for Allahabad samples and around 7OO°C for Daiaabad samples. Thus the well established applioatione of TL will continue to gain the popularity in times to some and there is already sufficient ground for the start of using these quick end inexpensive methods as analytical tools in quality control of different industrial products like potteries, ceramic*, bricks etc The. auihoAA ant thankful to Shut. S.O.Sotnan, Head, Health fhijAixA Division and ShnJL, T,Subbanatnam, Head, 'Radiation. ftctftuuU CorvtAol Section {on. thein. constant tuppo/ut and tnaouAage* mania thnougkoui the wonh. The. ouihonA an& aJLso gnateftU to On* A.K»Qanguty., the. fonmen. Dinecton. of. Chemical Qnoup, B,AJt,C, {on. hid guidanat and encouAOQ&n&vU dwung. the. cowtte of. ihU wonh* We tahfi tkU oppontunlty. to thanh Stud. OJ.Khat*L, fan. maintaining, and jenvLcing. the eJLtcinonic inMnumetvU tued in. thate AiudJLtA, -v- CON"1 ^. Synopsis I Acknowledgements v Introduction 1 1. TL OF QUARTZ AS AN INDICATOR OF ENVIRONMENTAL EXPOSURE LEVEL 2 1. 1 Location of Survey 5 1. 2 Devices used for radiation monitoring 5 (i) TLDs 5 (ll) Scintillation Survey Meter 5 (lii) Alpha counter 5 1. 3 Radiation Level along the coast 6 1.4 Natural Thermoluminescence (NTL) of quartz 9 2. TL OF QUARTZ AS A TOOL FOR RADIOACTIVE MINERAL PROSPECTING 13 2. 1 Chavara-Neendakara area of Kerala Coast 14 (a) Dosimetry of River Banks 15 (b) Detailed study of Chavara Coast 15 (c) Vertical distribution of Radiation on the Beach 19 2.2 Khari River Area of Tuwa in Gujarat State 20 3 TL OF QUARTZ AS A METHOD FOR CALCULATING GEOLOGICAL DEPOSITIONAL RATE OF BEACHES 22 3. 1 Site Selection and Sample Collection 23 3.2 Sample preparation and TL evaluation 23 3. 3 NTL as a function of Depth 28 -vii- -vlii- Pae 4. TL OF QUARTZ FOR DATING OF ARCHAEOLOGICAL POTTERIES AND CERAMICS OBJECTS 30 4. 1 Dating of Allahabad and Daimabad Pottery Sherds 32 (i) Plateau test 36 (ii) Equivalent Gamma Dose (ED/ ) 36 (lii) Beta dosimetry of PotLery and Soil samples 36 (iv) Cosmic ray back ground 38 (v) Environmental Gamma Dose 38 4.2 Calculations for Dating 40 5. TL OF QUARTZ FOR ESTIMATION OF FIRING TEMPERATURE IN ANCIENT POTTERY SAMPLES 42 5. 1 Samples used 42 5. 2 Calculation of S/So and evaluation of firing temperature of pottery sherds 43 6. REFERENCES 46 APPLICATIONS OF THERMO LUMINESCENCE OF QUARTZ by M. David and CM. S unta INTRODUCTION Thermoluminescence is known to have been first observed by Robert Boyle in 1669. Ke reported to Royal Society of London about a feeble light emitted by a diamond piece when it was warned in dark* Much work was not done on the TL phenomenon or its applioations later. It is only during the last two decades that the progress in TL research (2 •>) and its applications has accelerated . Thermoluminescence(TL) can be defined as the thermally stimulated release of stored energy in the form of light from a pre-exoited material. It is exhibited by a hostof minerals, organic crystals, glasses, ceramics, organic compounds and bio—chemicals* The most widely studied materials for their TL characteristics are CaP2> hit, MggSiQ , LiB.0~, CaSO. ate. TL of minerals like quart*, ilgO Caleite, Zircon etc is studied because of its importance in arohaeologioal and geological applications. Quartz is a major constituent of the earths crust and is found almost everywhere in soil,sand and rooks. Its crystallography is very stable in the normal conditions of temperature and pressures It is observed that the TL of quarts is affected significantly by physioal treatment like heat, radiation, stress and polarisation.