On the 209Po half-life error and its confirmation: an answer to the critique

Pommé, S.; Benedik, Ljudmila

doi:10.1007/s10967-015-4646-8

Cited by 3 publications

(4 citation statements)

References 12 publications

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“…Pommé and Benedik [76] published an improved half-life value for 209 Po based on the continuous measurement of emitted alpha particles from two drop-deposited sources in close geometry with a planar silicon detector (PIPS © ). The decay curve of source #1 is presented in figure 40 (and of source #2 in [76]). The residuals are purely of statistical nature, and therefore the annual oscillations in figure 41 (A = 0.006 (5)%, a = 6 d) are insignificant.…”

Section: Po @Jrcmentioning

confidence: 99%

On decay constants and orbital distance to the Sun—part I: alpha decay

et al. 2016

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Claims that proximity to the Sun causes variation of decay constants at permille level have been investigated for alpha decaying nuclides. Repeated decay rate measurements of 209 Po, 226 Ra, 228 Th, 230 U, and 241 Am sources were performed over periods of 200 d up to two decades at various nuclear metrology institutes around the globe. Residuals from the exponential decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ in amplitude and phase from one data set to another and appear attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of α decaying sources set an upper limit between 0.0006% and 0.006% to the amplitude of annual oscillations in the decay rate. There are no apparent indications for systematic oscillations at a level of weeks or months. Oscillations in phase with Earth's orbital distance to the sun could not be observed within 10 −5 -10 −6 range precision.

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Section: Po @Jrcmentioning

confidence: 99%

On decay constants and orbital distance to the Sun—part I: alpha decay

et al. 2016

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“…Although these data sets are less elaborate, they also exhibit a humidity effect. Extensive decay rate series of two 209 Po sources measured with Si detectors show no significant correlation with humidity [34,35]. The same conclusion applies to repeated activity measurements of 3 H and 14 C in a liquid scintillation detector (LSC) [9], 55 Fe in an x-ray counter with defined solid angle using a gas counter [54] and a large pressurised gas proportional counter [55], as well as a combination of 230 U decay rates taken with a CsI sandwich spectrometer, LSC, pressurised proportional counter, and planar Si detectors [56].…”

Section: Other Nuclidesmentioning

confidence: 97%

“…The repeatability requirement of half-life experiments exceeds that of absolute measurements by one or more orders of magnitude. For example, better than 0.02% mediumterm stability was demonstrated in alpha decay with planar Si detectors [33,34] and repeatability in an ionisation chamber (IC) is of the order of 0.04% [35]. That explains why half-life measurements are a magnifying glass for underlying metrological imperfections and why their uncertainties have often been underestimated in the literature [32,[36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Ambient humidity, the overlooked influencer of radioactivity measurements

Pommé,

Stroh,

Altzitzoglou

et al. 2023

Metrologia

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When verifying the validity of the exponential-decay law through 137 precise decay rate measurement series at various nuclear laboratories, minor violations have been observed in the shape of annual cycles in the residuals with different amplitudes and phase shifts. The timing and amplitude of these deviations have been compared with local weather data and it appears that ambient humidity is highly correlated with the observed instabilities in these radioactivity measurements. In fact, when compensating the residuals for a linear relationship with absolute humidity in air, most of the annual cycles are no longer statistically significant. As a result, the validity of the exponential-decay law can now be demonstrated with even higher fidelity.

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“…With the enhanced rigor in experimental execution and data analysis, the metrological community is currently achieving better consistency at a higher level of accuracy than in the past. Examples of recently achieved convergence are the improved half-life values for 55 Fe [7,8], 109 Cd [9][10][11], 177 Lu [12][13][14][15][16], 209 Po [17][18][19], 225 Ac [20,21], 223 Ra [22,23], and 227 Th [24,25].…”

Section: Introductionmentioning

confidence: 99%

Empirical decomposition and error propagation of medium-term instabilities in half-life determinations

Pommé

Pelczar

2021

Metrologia

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A least-squares fit of exponential functions to a measured radioactive decay rate curve provides an estimate of the half-life and its statistical uncertainty in the assumption that all deviations from the theoretical curve are purely of a random nature. The result may be biased and the error underestimated as soon as the experiment suffers instabilities that exceed the duration of individual measurements. Contrary to long-term systematic errors, medium-frequency cyclic perturbations may be observable as autocorrelated structures in the residuals. In this work, an empirical decomposition algorithm is used to separate medium-frequency effects from the random statistical component in the fit residuals, such that custom error propagation factors can be calculated. A theoretical study of error propagation is made for sine and square wave perturbations. The empirical decomposition method is demonstrated on a synthetic spectrum, a time series of solar neutrino detection rates, and two experimental decay curves of 134Cs measured in an ionisation chamber.

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On the 209Po half-life error and its confirmation: an answer to the critique

Cited by 3 publications

References 12 publications

On decay constants and orbital distance to the Sun—part I: alpha decay

On decay constants and orbital distance to the Sun—part I: alpha decay

Ambient humidity, the overlooked influencer of radioactivity measurements

Empirical decomposition and error propagation of medium-term instabilities in half-life determinations

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