Study of liquid scintillation alpha spectral properties.

Alpha spectra were acquired with Quantulus 1220 liquid Scintillation Counter (LSC) and correlations among parameters, such as alpha particle energy, sample quenching, peak's centroid and resolution were established. The effect of quenching and factors such as types of counting vials, extractive reagents and composition of extractive scintillation cocktail on alpha spectral resolution, was experimentally studied.

Concentration of 3H in ground water and estimation of committed effective dose due to ground water ingestion in some places in the Maharashtra state, India.

The measurement of tritium in environmental samples requires highest possible sensitivity. In the present study, the authors have optimised the counting window for the analysis of (3)H in environmental samples using the recently installed Ultra Low Level Quantulus 1220 Liquid Scintillation Counting at BARC to improve the detection limit of the system. The optimised counting window corresponding to the highest figure of merit of 883.8 was found to be 20-162 channels. Different brands of packaged drinking waters were analysed to select a blank that would define the system background. The minimum detectable activity (MDA) achieved was 1.5 Bq l(-1) for a total counting time of 500 min. The concentration of tritium in well and bore well water samples collected from the villages of Pune, villages located at 1.8 km from Tarapur Atomic Power Station, Kolhapur and Ratnagiri, was analysed. The activity concentration ranged from 0.55 to 3.66 Bq l(-1). The associated age-dependant dose from water ingestion in the study area was estimated. The effective committed dose recorded for different age classes is negligible compared with World Health Organization and US Environmental Protection Agency dose guidelines.

Dosimetry and radiobiological studies of automated alpha-particle irradiator.

Understanding the effect of alpha radiation on biological systems is an important component of radiation risk assessment and associated health consequences. However, due to the short path length of alpha radiation in the atmosphere, in vitro radiobiological experiments cannot be performed with accuracy in terms of dose and specified exposure time. The present paper describes the design and dosimetry of an automated alpha-particle irradiator named 'BARC BioAlpha', which is suitable for in vitro radiobiological studies. Compared to alpha irradiators developed in other laboratories, BARC BioAlpha has integrated computer-controlled movement of the alpha-particle source, collimator, and electronic shutter. The diaphragm blades of the electronic shutter can control the area (diameter) of irradiation without any additional shielding, which is suitable for radiobiological bystander studies. To avoid irradiation with incorrect parameters, a software interlock is provided to prevent shutter opening, unless the user-specified speed of the source and collimator are achieved. The dosimetry of the alpha irradiator using CR-39 and silicon surface barrier detectors showed that ~4 MeV energy of the alpha particle reached the cells on the irradiation dish. The alpha irradiation was also demonstrated by the evaluation of DNA double-strand breaks in human cells. In conclusion, 'BARC BioAlpha' provides a user-friendly alpha irradiation system for radiobiological experiments with a novel automation mechanism for better accuracy of dose and exposure time.