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A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h(-1) to 500 nGy h(-1). The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h(-1). This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h(-1) (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Natural background gamma radiation and radioactivity concentrations were investigated from 2003 to 2005 in Kinta District, Perak, Malaysia. Sample locations were distant from any 'amang' processing plants. The external gamma dose rates ranged from 39 to 1039 nGy h(-1). The mean external gamma dose rate was 222+/-191 nG yh(-1). Small areas of relatively enhanced activity were located having external gamma dose rates of up to 1039+/-104 nGy h(-1). The activity concentrations of (238)U, (232)Th and (40)K were analyzed by using a high-resolution co-axial HPGe detector system. The activity concentration ranges were 12-426 Bq kg(-1) for (238)U, 19-1377 Bq kg(-1) for (232)Th and <19-2204 Bq kg(-1) for (40)K. Based on the radioactivity levels determined, the gamma-absorbed dose rates in air at 1m above the ground were calculated. The calculated dose rates and measured dose rates had a good correlation coefficient, R of 0.94. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the gamma-absorbed dose rate and the mean population weighted dose rate were calculated. An isodose map for the Kinta District was also produced.

Environmental terrestrial gamma radiation dose rates were measured throughout Melaka, Malaysia, over a period of two years, with the objective of establishing baseline data on the background radiation level. Results obtained are shown in tabular, graphic and cartographic form. The values of terrestrial gamma radiation dose rate vary significantly over different soil types and for different underlying geological characteristics present in the study area. The values ranged from 54 +/- 5 to 378 +/- 38 nGy h(-1). The highest terrestrial gamma dose rates were measured over soil types of granitic origin and in areas with underlying geological characteristics of an acid intrusive (undifferentiated) type. An isodose map of terrestrial gamma dose rate in Melaka was drawn by using the GIS application 'Arc View'. This was based on data collected using a NaI(Tl) scintillation detector survey meter. The measurements were taken at 542 locations. Three small 'hot spots' were found where the dose rates were more than 350 nGy h(-1). The mean dose rates in the main population areas in the mukims (parishes) of Bukit Katil, Sungai Udang, Batu Berendam, Bukit Baru and Bandar Melaka were 154 +/- 15, 161 +/- 16, 160 +/- 16, 175 +/- 18 and 176 +/- 18 nGy h(-1), respectively. The population-weighted mean dose rate throughout Melaka state is 172 +/- 17 nGy h(-1). This is lower than the geographical mean dose rate of 183 +/- 54 nGy h(-1). The lower value arises from the fact that most of the population lives in the central area of the state where the lithology is dominated by sedimentary rocks consisting of shale, mudstone, phyllite, slate, hornfels, sandstone and schist of Devonian origin which have lower associated dose rates. The mean annual effective dose to the population from outdoor terrestrial gamma radiation was estimated to be 0.21 mSv. This value is higher than the world average of 0.07 mSv.

This article reports the characteristics of thermoluminescence (TL) dosimeter of dysprosium doped strontium borate glass for NaO, Li2O, and CaO modifiers imposed by 10–90 Gy dose of 60Co gamma ray irradiation. The different elements are (70.0 – x) B2O3–20SrO–10NaO–xDy2O3, 10Li2O–20SrO–(70 – x)B2O3–(x)Dy2O3 and 10CaO–20SrO–(70.0 – x)B2O3–(x)Dy2O3 (x = 0, 0.10, 0.30, 0.50, 0.70 mol %). The glass was formed by melt quenching method and the ranges of Dy2O3 were 0.0 to 0.7 mol %. Calcium strontium borate doped with 0.3 mol % Dy2O3 shows very good linearity on dose response and gives an excellent sensitivity at 50 Gy dose of 60Co gamma ray irradiation. The samples N1, L1, C3 were completely amorphous. The optimums anneal temperature, time, concentration of Dy2O3 and heating rate were investigated for glass samples N1, L1, C3. The systematic characteristics of glow curve, TL intensity, reproducibility, sensitivity, kinetic parameters and effective atomic number were studied for three selected samples. All samples show the maximum peak from 154–200°C temperatures. [ABSTRACT FROM AUTHOR]

A thermoluminescence (TL) analysis was carried out to study the sensitivity and dose responses of Yb-Tb-doped SiO optical fiber subjected to 1.25 MeV gamma radiation. The results are compared with the commercially available standard LiF:Mg, Ti (TLD-100) chip. The Yb-Tb-doped SiO optical fiber and TLD-100 chips were placed inside Perspex and irradiated with 1.25 MeV gamma photons with doses ranging from 1.0 to 10.00 Gy. The results clearly show the superiority of TLD-100 chips in terms of response and sensitivity. The sensitivity of Yb-Tb-doped optical fiber and TLD-100 chips is 45.25 and 768.85 nc/(mg × Gy) respectively. [ABSTRACT FROM AUTHOR]

TL characteristics of powder form of Al 2 O 3 doped with 0.1 mol% carbon and co-doped with different magnesium concentrations of 0.1 mol% and 0.2 mol% exposed to Cobalt-60 gamma ray at doses ranging from 5 Gy to 70 Gy were investigated. The recorded glow curves consist a dominant peak at 180 °C for a heating rate of 1 °C s −1 . The TL sample with 0.2 mol% Mg concentration have higher response compared to the sample with 0.1 mol% Mg concentration for a delivered dose of 5 Gy. The TL response has linear relationship with delivered dose for both samples. The TL sensitivity was found as 277.9 nC mg −1 Gy −1 for the sample with Mg concentration 0.2 mol% and 128.2 nC mg −1 Gy −1 for 0.1 mol% Mg. However, the sample with 0.1 mol% Mg concentration has better fading properties compared to the sample with 0.2 mol% Mg concentration. Both samples show good reproducibility with value less than 13%. The experimental value of effective atomic number, Z eff is 9.21 and 9.44 for the sample with Mg concentration 0.1% mol and 0.2% mol, respectively, which are near to Z eff of bone with a value of about 11.6. [ABSTRACT FROM AUTHOR]

The aim of this study is to prepare and investigate the thermoluminescence characteristics for the un-doped and Cu 2 O doped calcium lithium borate glass upon adding various Cu 2 O concentrations of 0.005% to 0.1 mol%. The glasses were prepared by melt quenching method and irradiated with 60 CO gamma-ray having different doses in the range of (0.5–4) Gy, (5–10) Gy, and (20–100) Gy. The amorphous phases were identified for optimization glass samples, effect of heating rate, glowing curves, linearity, sensitivity, fading, reproducibility of response and minimum detectable dose are also studied. The TL sample with 0.02 mol% Cu 2 O concentration has higher response compared to the other samples concentration for a delivered dose of 50 Gy, The recorded glow curves consist a dominant peak at 187 °C for a heating rate of 5 °C s −1 . However, the value of effective atomic number Z eff is 8.84 for 0.02Cu 2 O doped which are near to the atomic number of soft tissue. [ABSTRACT FROM AUTHOR]