FERNANDO, WKPK2011-02-142011-02-1420002000FERNANDO, WKPK, Gamma spectroscopy measurements for estimating the thermoluminescence dates of a terracotta site at Rajanganaya, University of Colombo UC(SCI), 2000: p.http://imsear.searo.who.int/handle/123456789/129621Dissertation: M.Sc. , University of Colombo: UC(SCI), 2000.Terracotta and pottery samples collected from an ancient site at Rajanganaya were dated by thermoluminescence in this study. The natural radioactivity of these objects and of their surrounding was measured using insitu and laboratory gamma spectrometry. With gamma apectrometry the comparison of 238U (deduced from 234Th gamma emission) and that of 226Ra (deduced from 214Pb and 214Bi gamma emissions in equilibrium with 222Rn) shows a significant disequilibrium of the U series. The activity ratio 238U/226Ra, which is greater than unity in the present study is interpreted as a result of either uranium enrichment orradium impoverishment which had occurred before the burial of the terracotta. The effects of the changes in radiochemical composition on the annual dose are discussed and various determinations of the annual dose are analysed according to different hypothesis of disequilibrium which could be due to either a permanent state or occurrence. The Thermoliminescence age estimates 1292+73, 1257+59 obtained for thepottery and terracotta respectivily are consistent with the radiocarbon dates obtained from charcola collected at the same location which are 1215+125, 1135+105, 1175+105 AD. Except for the age estimates obtained for terracotta (sample No544) which indicates an older age to this cultural phase. Radiocarbon dating is considered stoll to be one of the best methods....en-USUniversity of Colombo, UC(SCI): Sri Lanka HELLIS NetworkSpectrometry, gammaSpectrometry, Gamma-methodsThesis