Uncertainty determination for activity measurements by means of the TDCR method and the CIEMAT/NIST efficiency tracing technique

Kossert, Karsten; Broda, R.; Cassette, P.; Ratel, G; Zimmerman, Brian E.

doi:10.1088/0026-1394/52/3/s172

Cited by 43 publications

(29 citation statements)

References 61 publications

(7 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…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].…”

Section: Measurements and Analysismentioning

confidence: 99%

Evidence against solar influence on nuclear decay constants

et al. 2016

View full text Add to dashboard Cite

The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and are attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of alpha, beta-minus, electron capture, and beta-plus decaying sources set an upper limit of 0.0006% to 0.008% to the amplitude of annual oscillations in the decay rate. Oscillations in phase with Earth’s orbital distance to the Sun could not be observed within a 10−6 to 10−5 range of precision. There are also no apparent modulations over periods of weeks or months. Consequently, there is no indication of a natural impediment against sub-permille accuracy in half-life determinations, renormalisation of activity to a distant reference date, application of nuclear dating for archaeology, geo- and cosmochronology, nor in establishing the SI unit becquerel and seeking international equivalence of activity standards.

show abstract

Section: Measurements and Analysismentioning

confidence: 99%

Evidence against solar influence on nuclear decay constants

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Most of the counterevidence, on the other hand, was performed by experienced metrologists using superior detection techniques and showing awareness of the vulnerability of detector stability to external factors. This is witnessed by dedicated literature discussing factors contributing to the uncertainty budget for primary and secondary standardisation techniques [55][56][57][58][59][60][61][62].…”

Section: Introductionmentioning

confidence: 99%

On the recent claim of correlation between radioactive decay rates and space weather

Pommé

Pelczar

2020

Eur. Phys. J. C

View full text Add to dashboard Cite

In recent literature, several authors have challenged the validity of the exponential-decay law, based on observed variations in radioactive decay rate measurements beyond statistical accuracy. Tentative explanations have been sought in external interferences influencing the decay process, such as interactions of the nuclei with solar and cosmic neutrinos. Given the important implications of such statements on theoretical and practical level, one would expect that they are backed up with radionuclide metrology of the highest quality. In reality, they share the common traits of using poor metrology and incomplete uncertainty analysis with respect to the stability of the measurement technique. In this paper, new claims of correlations between decay rates and space weather are questioned.

show abstract

“…Uncertainties on determined DSs or, analogously, on the activities measured with them are typically mostly due to the uncertainty on the primary standard. Primary activity measurements are performed at NIST using a variety of techniques, among which coincidence counting [2,3] and liquid scintillation-based efficiency tracing or triple-to-double coincidence ratio (TDCR) counting [4,5] are most common. For radionuclides detected with high counting efficiency and relatively simple decay schemes, total combined uncertainties—determined using the methodology outlined by Taylor and Kuyatt [6]—on the order of 0.5 % are often achievable.…”

Section: Methodsmentioning

confidence: 99%