Uncertainties in internal gas counting

Abstract

The uncertainties in internal gas counting will be broken down into counting uncertainties and gas handling uncertainties. Counting statistics, spectrum analysis, and electronic uncertainties will be discussed with respect to the actual counting of the activity. The effects of the gas handling and quantities of counting and sample gases on the uncertainty in the determination of the activity will be included when describing the uncertainties arising in the sample preparation.

Evidence against solar influence on nuclear decay constants

“…The measurement techniques employed are as follows: ionisation current measurements in a re-entrant ionisation chamber (IC) or a hospital calibrator (HIC) [31,32], net area analysis of full-energy γ-ray peaks (and integral spectrum counting) by γ-ray spectrometry with a HPGe detector (HPGe) [33], particle counting in a planar silicon detector in quasi-2πconfiguration (PIPS) [34], X-ray counting at a small defined solid angle with a gas-filled proportional counter (PC) [35,36], live-timed β–γ anti-coincidence counting (LTAC) [37], triple-to-double coincidence counting with a liquid scintillation vial and three photodetectors (TDCR) [38], liquid scintillation counting (LSC) [38], particle and photon counting in a sandwich CsI (Tl) spectrometer (CsI) [39], internal gas counting (IGC) [40], and α-particle counting at a small defined solid angle with a large planar silicon detector (αDSA) [35,36]. An overview of standardisation techniques and their sources of error can be found in the special issues 44(4) and 52(3) of Metrologia [41,42] and references in [25,28].…”

On decay constants and orbital distance to the Sun—part II: beta minus decay

“…Due to the low energy of the emitted beta particle and the absence of subsequent gamma-ray emission in the decay of 3 H, not many techniques are suitable for absolute activity measurements of this nuclide. Internal gas proportional counting [34] is a method applied at the NIST for the standardisation of 3 H in gas. The radioactive gas is mixed with counter gas and measured in a set of proportional counters of different length.…”

Comparison of tritiated-water standards by liquid scintillation for calibration of a new Standard Reference Material®

“…Lucas [1] previously summarized the sixteen different tritiated-water standards disseminated by the National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards (NBS), from 1954 to 1999. The most recent of these were standardized by length-compensated internal gas proportional counting [2][3][4]. 3 The procedure for the preparation of tritiated-water standards and the internal proportional gas counting method used at NIST has been described by Unterweger et al [7] and Unterweger and Lucas [8].…”

“…In addition, Zimmerman and Collé [11] in 1996 made a direct comparison between the then extant French and U.S. national standards for tritiated-water that were used as efficiency tracing monitors in liquid scintillation. The French standard from Laboratoire Primaire des Rayonnements Ionisants (LPRI), now known as Laboratoire National Henri Becquerel (LNHB), was certified with a reference date of 27 January 1994 [12]; whereas the US standard was a Standard Reference Material (SRM) 4 , 4927E, certified with reference date of 15 August 1995 [13]. The ratio of the massic activities for the two standards relative to the ratio of their certified values, as obtained from seven experimental trials of comparative LS measurements with quench matching under a wide variety of counting conditions, was 0.9963  0.0014, where the cited uncertainty is the standard deviation of the mean on the ratio.…”

“…The absence of an operable gas counting system at NIST at the time weighed heavily, along with other factors, in the NIST decision not to participate in the comparison. This paper reports on the preparation of a new standard 5 , SRM 4927G, and its calibration by comparison against two previous 1998 NIST SRMs (viz., SRM 4927F and 4926E), as well as to the 1994 LPRI standard (F1994) that was measured previously by Zimmerman and Collé [11] in 1996, and with 4 Standard Reference Material® (SRM), trademarked and disseminated by NIST, is a certified reference material that is issued with a certificate that provides the value of the specified property, its associated uncertainty, and a statement of metrological traceability. .…”