Standardization of xenon-127 and measurement of photon emission intensities

Abstract

Xenon-127 was standardized by internal gas counting using three proportional counters in a differential arrangement to eliminate edge effects. The detection efficiency of the proportional counters was calculated by considering the cascade of events following the electron capture and associated gamma transitions. Activity per unit volume was measured with 0.7% relative standard uncertainty. Gamma-ray spectrometry was performed and absolute photon emission intensities were derived. This study shows that (127)Xe could be a surrogate for (133)Xe for the calibration of remote radio-xenon monitoring stations.

Measurement of charge and light yields for Xe127 L -shell electron captures in liquid xenon

“…Roughly 2% of all 127 Xe decays result in an L-shell vacancy with no other visible energy deposition, primarily from the two bold entries in the table. Data taken from [14,[20][21][22].…”

Radioxenon standards used in laboratory inter-comparisons

“…Xe-127 was standardized at LNE-LNHB, the National Metrology Institute of France for ionizing radiations, by internal gas counting (Lansiart et al, 1993) using three proportional detectors with different lengths. The calibration method is described by (Rodrigues et al, 2014).…”

Uncertainties in internal gas counting

“…Laboratoire National Henri Becquerel (LNHB) [11][12][13] For beta emitters, the counting efficiency is close to 1. But two additional counting corrections have to be considered.…”

“…Under the trigger threshold channel N 0 , the area of the spectra difference is null, and just above the level the difference forms a plateau at a constant level c 1,l-s , c 1,l-m , c 1,m-s The plateau level is extrapolated under the threshold to estimate the number of undetected low energy beta particles (c 0 ): c 0,l-s = N 0 × c 1,l-s . Then from analytical demonstration, the number of undetected non-ionizing particles is given by [12,13] When measuring a radioactive gas decaying by gamma transition (Xe-131m, Xe-133m) or electron capture (Xe-127), the counting efficiency is lower than unity, the efficiency has to be calculated using the decay scheme and the successive atomic desexcitation processes [13]. In these cases, a decaymodel uncertainty term must be also considered depending on the evaluated atomic and nuclear fundamental parameter uncertainties.…”