An algorithm for the solid angle calculation applied in alpha-particle counting

Pommé, S.; Johansson, Lena; Sibbens, G.; Denecke, B.

doi:10.1016/s0168-9002(03)01070-2

Cited by 48 publications

(23 citation statements)

References 8 publications

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“…in which N 243 ∕m and A tot ∕m are the number of 243 Am atoms and the 241 Am + 243 Am activity per gram of solution, respectively. The activity at the reference date, A tot (t ref ) (Bq), is obtained by counting alpha particles under a small but well-defined solid angle, using the equation in which C tot ∕t m is the number of counts per system livetime, which is adequately corrected for count loss through pileup and system dead time by imposing a well-known dead time for each registered pulse [47,48]; Ω is the solid angle in steradian [41,[43][44][45]; f tail is a correction factor for the extrapolation of the spectrum below the imposed low-energy threshold [36]; and f d is a weighted decay correction factor (Eq. 2) for both Am isotopes, based on the activity ratio derived from alpha spectrometry.…”

Section: Specific Activity Methodsmentioning

confidence: 99%

“…By measuring a small fraction of alpha-particles emitted perpendicularly from the source plane, loss of particles by absorption in the source material at low emission angles is avoided. The detection efficiency practically equals the geometrical efficiency, which can be calculated from solid-angle formulas [43][44][45]. The accuracy of the method depends particularly on the reproducibility and accurate knowledge of the geometrical conditions.…”

Section: Activity By Alpha Countingmentioning

confidence: 99%

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Absolute and relative measurement of the 243Am half-life

Marouli

Pommé

Jobbágy

et al. 2020

J Radioanal Nucl Chem

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The half-life of 243Am has been measured by an absolute and a relative method, i.e. by determining the specific activity of 243Am and the specific activity ratio with 241Am. A mixed 241,243Am reference material was produced and certified for its americium mass content and its isotope amount ratios. The characterisation of the mass content of 243Am was established by isotope dilution mass spectrometry using an 241Am spike, produced from highly enriched 241Pu material. The isotope amount ratios n(241Am)/n(243Am) and n(242mAm)/n(243Am) were measured by thermal ionisation mass spectrometry. Activity measurements were performed by alpha-particle counting at a defined solid angle, as well as high-resolution alpha-particle spectrometry. From the 243Am/241Am activity and isotopic amount ratios, a value of 16.988 (24) was derived for the 243Am/241Am half-life ratio. Using a value of 432.6 (6) a for the 241Am half-life, the corresponding 243Am half-life value, 7349 (15) a, is in good agreement with the result obtained from the absolute method, 7342 (14) a. The mean value, 7345 (14) a, agrees well with data from literature and lowers the relative standard uncertainty to 0.2%.

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Section: Specific Activity Methodsmentioning

confidence: 99%

Section: Activity By Alpha Countingmentioning

confidence: 99%

Absolute and relative measurement of the 243Am half-life

Marouli

Pommé

Jobbágy

et al. 2020

J Radioanal Nucl Chem

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“…Variations in geometrical efficiency can be realised by replacing diaphragms and distance tubes. Accurate measurements of the distance between source and diaphragm as well as the diaphragm radius were performed by optical techniques [37,38], which have later been replaced by a 3D-coordinate measuring machine [39]. The solid angle subtended by the detector can be addressed with exact mathematical algorithms for circular and elliptical configurations [40,41], however the method gains significant robustness by taking into account the source activity distribution [36,42,43].…”

Section: α-Counting At a Defined Solid Anglementioning

confidence: 99%

Standardisation of 241Am activity for a key comparison

Pommé

Altzitzoglou

Ammel

et al. 2021

J Radioanal Nucl Chem

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The JRC applied six measurement techniques to standardise the activity of an 241Am solution in the frame of the 2003 key comparison CCRI(II)-K2.Am-241. The methods used were alpha-particle counting at a defined small solid angle, high-efficiency particle and photon counting with a windowless 4π CsI(Tl) sandwich spectrometer, 4π alpha counting with a pressurised proportional counter, alpha-gamma coincidence counting and sum counting with a small pressurised proportional counter and a NaI(Tl) well detector, and 4π counting with a liquid scintillation counter. All results were consistent and an unusually low measurement uncertainty of 0.054% was achieved. An overview is presented of the outcome of the key comparison exercise, which demonstrates international equivalence.

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“…Frequently, both the detector and sample are of circular shapes having cylindrical symmetries [20]. The exact efficiency can be calculated by integrating over all angles imposed by the dimensions of the detector and sample, or by a Monte Carlo simulation (Pomme´et al [21], and references therein). These methods, however, do not provide formulas which could be easily fitted to the data.…”

Section: Detector Edge Effectsmentioning

confidence: 99%