A5017402938- Radioactive Decay and Measurement Techniques
- Radioactivity and Radon Measurements
- Nuclear Physics and Applications
- Scientific Measurement and Uncertainty Evaluation
- Radioactive contamination and transfer
- Radiation Detection and Scintillator Technologies
- Nuclear reactor physics and engineering
- Nuclear physics research studies
- Atomic and Subatomic Physics Research
- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Radiopharmaceutical Chemistry and Applications
- Nuclear Materials and Properties
- Nuclear and radioactivity studies
- Medical Imaging Techniques and Applications
- Radiation Therapy and Dosimetry
- Neutrino Physics Research
- Pesticide Residue Analysis and Safety
- Particle accelerators and beam dynamics
- Particle Detector Development and Performance
- Astro and Planetary Science
- Chemical Thermodynamics and Molecular Structure
- Geophysical Methods and Applications
- X-ray Diffraction in Crystallography
- Advanced Statistical Process Monitoring
European Commission
2015-2024
Joint Research Center
1995-2016
New York State Department of Health
2010
Wadsworth Center
2010
European Union
2007
Belgian Nuclear Research Centre
1996-2002
Joint Research Centre
1996
Half-life measurements of radionuclides are undeservedly perceived as 'easy' and the experimental uncertainties commonly underestimated. Data evaluators, scanning literature, faced with bad documentation, lack traceability, incomplete uncertainty budgets discrepant results. Poor control has its implications for end-user community, varying from limitations to accuracy reliability nuclear-based analytical techniques fundamental question whether half-lives invariable or not. This paper...
A succinct overview is presented of primary standardization methods for activity. They have been subdivided into high-geometry (4π or 2π) methods, defined-solid-angle counting and coincidence methods. References are provided work explaining the basics as well papers describing recent developments applications.
A method is presented for calculating a key comparison reference value (KCRV) and its associated standard uncertainty. The allows technical scrutiny of data, correction or exclusion extreme but above all uses power-moderated mean that can calculate an efficient robust from any data set. For mutually consistent the approaches weighted mean, weights being reciprocals variances (squared uncertainties) with measured values. sets suspected inconsistency, weighting moderated by increasing...
Peak overlap is a recurrent issue in alpha-particle spectrometry, not only routine analyses but also the high-resolution spectra from which reference values for alpha emission probabilities are derived. In this work, improved peak shape formulae presented deconvolution of spectra. They have been implemented as fit functions spreadsheet application and optimum parameters were searched with built-in optimisation routines. Deconvolution results shown few challenging high statistical precision....
The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements mono-radionuclide sources were performed over periods from 200 days up four decades 14 laboratories across globe. Residuals exponential nuclear curves inspected for annual oscillations. Systematic deviations a purely curve differ one data set another are attributable instabilities in instrumentation measurement conditions. most stable...
Nuclear counting is affected by pulse pileup and system dead time, which induce rate-related count loss alter the statistical properties of process. Fundamental equations are presented to predict deviations from Poisson statistics due non-random in nuclear counters spectrometers. Throughput dispersion counts studied for systems with pileup, extending non-extending before also after compensation loss. Equations provided random fractions output events, applicable spectrometry applications....
Alpha-particle spectrometry is routinely performed with the aim of measuring absolute activities, activity ratios between different alpha-emitting nuclides or decay data such as branching factors, alpha emission probabilities and relative half-lives. It most commonly ion-implanted silicon detectors. Strong features technique are low background levels that can be achieved due to sensitivity other types radiation, intrinsic efficiency close 1 which reduces calculations a geometrical problem...
Specific uncertainty components of counting at a defined solid angle are discussed. It is potentially an extremely accurate technique for primary standardisation activity alpha emitters and low-energy x-ray emitters. Owing to its reproducibility, it very well suited half-life measurements. Considered sources 1) source–detector geometry, 2) solid-angle calculation, 3) energy loss self-absorption, 4) scattering, 5) detection efficiency. Other uncertainty, such as source weighing, counting,...
Claims that proximity to the Sun causes variation of decay constants at permille level have been investigated for alpha decaying nuclides. Repeated rate measurements 209Po, 226Ra, 228Th, 230U, and 241Am sources were performed over periods 200 d up two decades various nuclear metrology institutes around globe. Residuals from exponential curves inspected annual oscillations. Systematic deviations a purely curve differ in amplitude phase one data set another appear attributable instabilities...
The hypothesis that seasonal changes in proximity to the Sun cause variation of decay constants at permille level has been tested for radionuclides disintegrating through electron capture and beta plus decay. Activity measurements 22Na, 54Mn, 55Fe, 57Co, 65Zn, 82+85Sr, 90Sr, 109Cd, 124Sb, 133Ba, 152Eu, 207Bi sources were repeated over periods from 200 d up more than four decades 14 laboratories across globe. Residuals exponential nuclear curves inspected annual oscillations. Systematic...
It could be argued that activity measurements of radioactive substances should under statistical control, considering the measurand is unambiguously defined, decay processes are theoretically well understood and measurement function can derived from physical principles. However, comparisons invariably show a level discrepancy among standardisation results exceeds expectation uncertainty evaluations. Also characteristics radionuclides determined different experiments unexpected...
Claims that proximity to the Sun causes variations of decay constants at permille level have been investigated for beta-minus decaying nuclides. Repeated activity measurements 3H, 14C, 60Co, 85Kr, 90Sr, 124Sb, 134Cs, 137Cs, and 154Eu sources were performed over periods 259 d up 5 decades various nuclear metrology institutes. Residuals from exponential curves inspected annual oscillations. Systematic deviations a purely curve differ in amplitude phase one data set another appear attributable...
Some authors have raised doubt about the invariability of decay constants, which would invalidate exponential-decay law and foundation on common measurement system for radioactivity is based. Claims were made a new interaction - fifth force by neutrinos could affect thus predicting changes in rates correlation with variations solar neutrino flux. Their argument based observation permille-sized annual modulations particular rate measurements, as well transient oscillations at frequencies near...
Radon decay rate data from 2007–2011, measured in a closed canister with one gamma counter and two alpha detectors, were made available for analysis by the Geological Survey of Israel (GSI). Sturrock et al. have published several papers which they claim that variations can be associated solar rotation. They assert influences cosmic neutrinos on beta draw unsubstantiated conclusions about dynamics. This paper offers an alternative explanation relating daily annual patterns radon rates...
The half-life of 22Na has been determined through 523 activity measurements over 14.5 years with a re-entrant ionisation chamber in temperature-stabilised room. data were selected and aggregated from total 127 830 current reproducibility the order 0.065 % standard deviation. was collected an air capacitor measured as change voltage time, which warrants excellent linearity throughout experiment. residuals to exponential decay curve show distinct annual cycle 0.0055 (5) amplitude, reduces...
Claims were made by Sturrock et al. that radioactive decay can be induced interaction of the nucleus with solar neutrinos and cyclic modulations in rates are indicative dynamics interior. They analysed a series measurements gamma radiation associated emanation radon sealed container at Geological Survey Israel (GSI) laboratory. The integral count NaI detector showed strong variations time year day. From time-series analysis, claim presence small oscillations frequencies range between 7.4 a−1...
Abstract In recent literature, several authors have challenged the validity of exponential-decay law, based on observed variations in radioactive decay rate measurements beyond statistical accuracy. Tentative explanations been sought external interferences influencing process, such as interactions nuclei with solar and cosmic neutrinos. Given important implications statements theoretical practical level, one would expect that they are backed up radionuclide metrology highest quality....