RESUMEN
Electron spin resonance (ESR) dating was carried out on laterite samples collected from Ban Tha Ta Suea, the original deposit of the laterite used in the construction of Muang Sing Historical Park. Ban Tha Ta Suea is about 6 km east of Muang Sing Historical Park in Kanchanaburi province (181 km far from Bangkok). The dose response of the g=2.0028 ESR signal was found to be suitable for age determination. An exponential saturation function was fitted to the ESR signal growth on additional γ-irradiation. Extrapolation of this function resulted in the accumulated dose 144±5 Gy. Gamma spectroscopy and neutron activation analysis (NAA) were used to determine concentrations of (238)U, (232)Th and (40)K in the samples from which the annual dose rate 16±2 mGy was calculated. In addition, the dose rate of cosmic rays was taken into account. The ESR age of laterite samples was found to be 9.0±0.9 ka. This age falls within the Holocene epoch of the Quaternary on the geological time scale. Samples from Muang Sing Historical Park were assigned to the same epoch. Both results agree with the geological map.
RESUMEN
The scintillation response of a plastic scintillator (NE102) has been characterized using compton coincidence technique. The coincidence technique allowed detection of nearly monoenergetic internal electrons resulting from the scattering of incident 662keV gamma-rays within a primary NE102 detector. Scattered gamma-rays were detected using a secondary NaI(Tl) detector in a coincidence mode. The electron response nonproportionality of NE102 plastic scintillator was measured using this technique for electron energies ranging from 28 to 436keV, by varying the scattering angle. The NE102 showed a good proportionality of light yield within 3% at energies between 90 and 436keV. Below 90keV, the light yield decreases by about 20% upon lowering the electron energy to 28keV. The electron energy resolution of NE102 was also measured using this technique in the energy range from 68 to 436keV. It has been found that the energy resolution varies from 25.2% at 68keV to 11.8% at 436keV.