- Determination of the annual beta dose by meaming beta activity using the liquid scintillation technique. - This paper presents a method for measuring the gross alpha/beta radioactivity of ancient pottery by using the liquid scintillation technique, Tri - carb2770TR/SL in the alpha/beta discrimination counting mode.. - The beta radioactivity is converted to the annual dose, which can be applied in dating of pottery by thermoluminescence technique. - In comparision with the radiocarbon technique, the preliminary results shown that the liquid scintillation technique may be applied effectively for ancient ceramic dating in Vietnam.. - Pottery is one of the most important archaeological relics to study on ancient cultures and art histories. - One of the reliable methods to date archaeological pottery is the thermoluminescence method (TL), which is effectively applied in many countries all over the world [1,2].. - In the natural environment, the ionizing radiations from the radioactive elements contained in soils causing effects on the material’s properties of ancient pottery samples. - Natural ionising radiation consist of the alpha, beta and gamma irradiations.These irradiations cause the different effects on the thermoluminescence behaviour of the materials. - Hence, to date ancient pottery by the quartz inclusion technique, the determination of the beta annual dose plays a determining important role on the precision of method. - D β is annual beta dose (Gy/yr). - Presently, in the ancient pottery TL dating the following steps for the determination of annual dose rate are: (i) place the thermoluminiscnece dosimeter at the field. - (ii) determine the environmental radioactivity of a representative soil sample for the region concerned and (iii) determine the contents of radioactive elements, such as uranium, potassium and thorium in the soil sample. - Therefore, a new method (procedure), presented in this paper which allows quick and accurate avaluattion of the gamma and beta annual dose, will contribute to the significant improvement for the thermoluminescence pottery technique in Vietnam.. - A cylinder-shape detector NaJ(Tl) of the size 30mm x 30mm, allowing to measure the energy in range from 50keV to 3000keV. - In the practice, such stable and highly sensitive equipment was used to determinate the annual gamma dose in thermoluminesccence dating.. - In the consistency with the experimental results it was shown that the more accurate the beta dose evaluation is, the more reliable is the technique of. - the measurement of the gamma dose rate using the radiometer CΡΠ-68-01.. - This paper presents a new method to evaluate the annual beta dose (D β )by measuring the gross beta activity using the liquid scintillation analyzer Tri-carb 2770TR/SL.. - The scintillation measurement was carried out on a liquid scintillation analyzer, Packard Tri- carb 2770TR/SL (U s A), which is shown in Figure 3.. - The liquid scintillator used in the experiment was of the Ultima Gold AB series of DIN–based cocktails. - Measurement the total beta radioactivity by L s A Tri-carb 2770TR/ s L.. - The total alpha/beta activity in ancient pottery were measured with the Tri carb 2770TR/SL in the alpha/beta discrimination counting mode. - The high percentage of triplet states produced by alpha particles were translated into electronic pulses at the PMT anode which may be as much as 30 nsec longer than those derived from beta particles and gamma photons produced in the sample cocktail.. - In the Parkard Tri-carb 2770TR/SL the spillover percentage or misclassification percentage of Am-241 and Cl-36 samples is less than 0.5%.. - In this experiment, nine pottery samples collected from three archaeological sites at three different provinces were evaluated for the annual beta dose as the following: GoThap located in Tan Kieu commune (Thap Muoi district Dong Thap province). - At each site samples were chosen with the same identification, i.e. - Besides, for all pottery samples collected at each of the above locations, the regional gamma radioactivity from surrounding terrestrial environment and cosmic irradiation was predeterminated using the portable radiometer CPП-68-01. - The results as obtained are shown in the Table 1. - The measured results of the beta and gamma radioactivity Sites Beta specify activity * (C β ) Gamma dose rate (Iγ). - The annual dose of beta (mGy/yr) was evaluated from: D β C β and that of gamma (mGy/yr) from: D γ = 0.1752.I γ, where C β is the specify activity of beta (Bq/kg), and (I γ ) is gamma dose rate (µR/h).. - Water in the pore of pottery or in the soil absorbs some parts of the radiation that would otherwise reach the thermoluminescent grains. - think of the water as decreasing the radioactivity per unit mass compared to the dry situation.. - Consequently, if the dose-rates have been evaluated from measurement on the dry material, the corrected values to be used in the age-equation are given by [1,2]:. - With the values given as: W = 0.2. - W 1 = 0.2 and F =0.8, the corrected values were calculated for the annual gamma and beta dose of pottery in TL dating by quartz inclusion technique. - The annual dose in pottery for dating by quartz inclusion technique sites Annual beta dose rate (D β ) (mGy/yr) Annual gamma dose rate (D γ ) (mGy/yr). - The equivalent dose (Q) was evaluated applying the additive dose method: The thermoluminescence intensities of the samples were measured after the exposure to the radiation from radioisotope cobalt-60 source source at known dosages as: 1Gy, 2Gy and 3Gy. - The additive dose method for evaluation of the paleodose.. - The paleodose P that the sample has received during antiquity is usually greater than Q because of the pre-dose effects [1,2]. - A comparison between the obtained thermoluminescence ages and the radiocarbon ages is presented on the Figure 6.. - The results in Figure 6 indicate that, the TL ages of ancient pottery determined by the quartz inclusion technique were a good agreement with the radiocarbon ages as well as the approximate dates in archaeology, which were the early bronze period (BaiBen), and some AD begining centuries (GoThap), and from 8 th -11 th AD centuries for ThapBa [7].. - The procedure of sampling preparation and measurement for the total alpha/beta radioactivity in ancient pottery using the liquid scintillation technique using Tri-carb 2770TR/SL with cocktail Utima Gold AB is presented. - Based on the results obtained from the mesearement the annual beta dose rates were evaluated and applied in thermoluminisecence dating of ancient pottery samples collected from three archaeological sites. - The TL ages obtained are compared with the radiocarbon ones. - Preliminary results illustrate that the determination of the annual beta dose using the liquid scintillation technique Tri-carb 2770TR/SL can be considered as a high sensible and accurate method in archaeological sample dating. - This method is quite suitable for thermoluminescence dating of the ancient pottery in Viet Nam.. - Gordon, Cook, Handbook of Application the liquid scintillation counting in environment.. - [5] Nguyen Quang Mien, Dating the ancient pottery by radiocarbon. - Proceeding of the 14 th Conference, University of Mining and Geology, Hanoi, 17 th November (2004) 50.