Record Details

A STUDY OF DISEQUILIBRIUM BETWEEN Rn-220 AND Po-216 FOR Rn-220 MEASUREMENTS USING A FLOW-THROUGH LUCAS SCINTILLATION CELL

DSpace at IIT Bombay

View Archive Info
 
 
Field Value
 
Title A STUDY OF DISEQUILIBRIUM BETWEEN Rn-220 AND Po-216 FOR Rn-220 MEASUREMENTS USING A FLOW-THROUGH LUCAS SCINTILLATION CELL
 
Creator SATHYABAMA, N
DATTA, D
GAWARE, JJ
MAYYA, YS
TRIPATHI, RM
 
Subject THORON
CALIBRATION
RADON
 
Description Lucas-type scintillation cells (LSCs) are commonly used for rapid measurements of Rn-220 concentrations in flow-through mode in field and for calibration experiments in laboratories. However, in those measurements, equilibrium between Rn-220 and Po-216 is generally assumed and two alpha particles are considered to be emitted per Rn-220 decay due to very short half-life of Po-216. In this paper, a small, yet significant disequilibrium existing between Rn-220 and Po-216 has been examined and shown that less than two alpha particles are actually emitted per Rn-220 decay in the cell when flow is maintained. A theoretical formula has been derived for the first time for a correction factor (CF) to be applied to this measured concentration to account for the disequilibrium. The existence of this disequilibrium has been verified experimentally and is found to increase with the increase in the ratio of flow rate to cell volume. The reason for the disequilibrium is attributed to the flushing out of Po-216 formed in the cell before its decay due to the flow. Uncertainties in measured concentrations have been estimated and the estimated CF values have been found to be significant for the flow rates considered above 5 dm(3) min(-1) for a cell of volume 0.125 dm(3). The calculated values of the CF are about 1.055 to 1.178 in the flow rate range of 4 to 15 dm(3) min(-1) for the cell of volume 0.125 dm(3), while the corresponding experimental values are 1.023 to 1.264. This is a systematic error introduced in Rn-220 measurements using a flow-through LSC, which can be removed either by correct formulation or by proper design of a measurement set-up.
 
Publisher OXFORD UNIV PRESS
 
Date 2014-12-28T14:54:53Z
2014-12-28T14:54:53Z
2014
 
Type Article
 
Identifier RADIATION PROTECTION DOSIMETRY, 158(2)187-194
0144-8420
1742-3406
http://dx.doi.org/10.1093/rpd/nct203
http://dspace.library.iitb.ac.in/jspui/handle/100/16806
 
Language English