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K Kossert - One of the best experts on this subject based on the ideXlab platform.
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improved activity standardization of 90sr 90y by means of liquid Scintillation Counting
Applied Radiation and Isotopes, 2021Co-Authors: K Kossert, X MougeotAbstract:Radioactive strontium isotopes play an important role in environmental radioactivity. Reliable activity standards are required in order to validate radioanalytical techniques and related measurements. In this paper, improved methods for the primary activity standardization of 90Sr/90Y based on liquid Scintillation Counting are presented. To this end, two methods were used: the CIEMAT/NIST efficiency tracing technique with 3H as a tracer and the triple-to-double coincidence ratio method. Non-negligible discrepancies between the two methods were found when applying existing analysis techniques. A detailed study was carried out to identify and eliminate the causes of these discrepancies. Eventually, excellent agreement between the two methods was obtained. This required advanced beta spectrum calculations which were carried out with a specific version of the BetaShape program taking the atomic exchange effect into account. In addition, it was found that the quench-indicating parameters determined in commercial liquid Scintillation counters are biased, which can cause significant problems for the CIEMAT/NIST efficiency tracing method. The effect depends on the Counting rate and can be explained by a superposition of the LS spectra generated by 90Sr/90Y and the external standard source.
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the importance of the beta spectrum calculation for accurate activity determination of 63ni by means of liquid Scintillation Counting
Applied Radiation and Isotopes, 2015Co-Authors: K Kossert, X MougeotAbstract:The activity concentration of a (63)Ni solution was determined by means of two liquid Scintillation Counting techniques: the TDCR method and the CIEMAT/NIST efficiency tracing technique. The results of both methods are in excellent agreement, provided that the (63)Ni beta spectrum calculation accounts for the atomic exchange effect. Thus, new beta spectrum calculations resolve a discrepancy that has been found in previous analyses. The influence of the computed beta spectrum on the final uncertainty of the activity concentration is discussed.
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activity determination of 227ac and 223ra by means of liquid Scintillation Counting and determination of nuclear decay data
Applied Radiation and Isotopes, 2015Co-Authors: K Kossert, Karen Bokeloh, Rainer Dersch, O NahleAbstract:The activity concentrations of solutions containing 227Ac and 223Ra in equilibrium with their progenies, respectively, were measured by means of liquid Scintillation Counting. The Counting efficiencies were determined with the aid of a free parameter model. The corresponding calculations comprise the computation of several alpha, beta and beta/gamma branches. For short-lived progenies like 215Po the Counting efficiency depends on the counter dead time. Measurements were made in custom-built triple-to-double coincidence ratio (TDCR) systems and various dead-time adjustments were used. In addition, two commercial counters were used to apply the CIEMAT/NIST efficiency tracing technique using 3H as a tracer. For the 227Ac solution, the overall relative standard uncertainty of the activity concentration was found to be 0.93%. The dominant uncertainty components are assigned to the efficiency computation of the low-energy beta transitions of 227Ac. We have identified a need for improved 227Ac decay data to achieve a significant reduction in the overall uncertainty. In the case of 223Ra, the activity concentrations were determined with relative standard uncertainties below 0.3%. Hence, PTB is prepared to provide calibration services for 223Ra, which is an isotope of increasing interest in nuclear medicine. The TDCR measurements were also used to determine the half-life of 223Ra. The decay was followed for about 58 days and a half-life T1/2=11.4362(50)d was obtained.
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determination of the 10be half life by multicollector icp ms and liquid Scintillation Counting
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2010Co-Authors: Jerome Chmeleff, K Kossert, Friedhelm Von Blanckenburg, Dieter JakobAbstract:Abstract A new method was designed and used for determining the half-life of the isotope 10 Be. The method is based on (1) accurate 10 Be/ 9 Be measurements of 9 Be-spiked solutions of a 10 Be-rich master solution using multicollector ICP mass spectrometry (MC-ICP-MS) and (2) liquid Scintillation Counting (LSC) using the CIEMAT/NIST method for determining the activity concentrations of the solutions whose 10 Be concentrations were determined by mass spectrometry. Important requirements for the success of this approach (a) was the previous coating of glass ampoules filled for Counting experiments with 9 Be, thereby reducing the risk of the adsorptive loss of 10 Be; (b) the removal of Boron from solutions to be measured by MC-ICP-MS by cation chromatography without the introduction of mass fractionation and (c) the accurate determination of the mass bias of 10 Be/ 9 Be measurements by ICP-MS which are always affected by the space-charge effect. The mass bias factor was determined to be 1.1862 ± 0.071 for 10 Be/ 9 Be from careful fitting and error propagation of ratios of measured Li, B, Si, Cr, Fe, Cu, Sr, Nd, Hf, Tl and U standard solutions of known composition under the same measurement conditions. Employing this factor, an absolute 10 Be/ 9 Be ratio of 1.464 ± 0.014 was determined for a first dilution of the 10 Be-rich master solution. This solution is now available as an absolute Be ratio standard in AMS measurements. Finally, a half-life of (1.386 ± 0.016) My (standard uncertainty) was calculated. This value is much more precise than previous estimates and was derived from a fully independent set of experiments. In a parallel, fully independent study using the same master solution, Korschinek et al. [35] have determined a half-life of (1.388 ± 0.018) My. The combined half-life and uncertainty amounts to (1.387 ± 0.012) My. We suggest the use of this value in nuclear studies and in studies that make use of cosmogenic 10 Be in environmental and geologic samples.
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jstudy of a monte carlo rearrangement model for the activity determination of electron capture nuclides by means of liquid Scintillation Counting
Applied Radiation and Isotopes, 2008Co-Authors: K Kossert, Grau A CarlesAbstract:Abstract A new Monte Carlo approach for the computation of the electron spectra of electron-capture nuclides is applied to obtain efficiencies in liquid Scintillation Counting for CIEMAT/NIST applications. The new method is applied to the radionuclides 109 Cd and 125 I by using a stochastic atomic rearrangement model, taking into account rearrangement processes including L - , M-, and N-subshells. The Counting efficiencies were computed with the new code MICELLE which also comprises an approach for calculating the Counting efficiency of a radionuclide in a gel phase sample. The calculated Counting efficiencies are compared with experimental results.
Suresh K. Aggarwal - One of the best experts on this subject based on the ideXlab platform.
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determination of 235u 238u atom ratio in uranium samples using liquid Scintillation Counting lsc
Talanta, 2009Co-Authors: D. Alamelu, Suresh K. AggarwalAbstract:Abstract A correlation has been developed for the determination of 235U/238U atom ratio in uranium samples using liquid Scintillation Counting (LSC). The 235U/238U atom ratio determined by thermal ionization mass spectrometry (TIMS) was correlated to the ratio of (i) α-count rate and (ii) Cerenkov count rate due to 234mPa in the sample; both measured by LSC. This correlation is linear over the range of 235U/238U atom ratio encountered in the nuclear fuel samples, i.e. the low enriched uranium (LEU) samples with 235U
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determination of 241pu 239pu atom ratio in pressurised heavy water reactor phwr pu samples using liquid Scintillation Counting
Journal of Alloys and Compounds, 2007Co-Authors: D. Alamelu, Suresh K. AggarwalAbstract:The determination of 241 Pu is important in elucidating the isotopic composition of any Pu sample. The relatively short half-life (14.32 yr) of 241 Pu leads to inconsistency in the correlations involving this isotope unless the different Pu samples have either the same irradiation and cooling history or the exact cooling period is known to account for the decay of 241 Pu prior to using the data for developing isotope correlations. To overcome this limitation, a useful correlation based on the measurement of total β/total a activity of Pu sample using liquid Scintillation Counting method was developed. Total β/total a activity of the Pu sample is correlated to the 241 Pu/ 259 Pu atom ratio and thus does not depend upon the knowledge of the cooling period. For any unknown sample, the 241 Pn/ 259 Pu atom ratio can be determined by using the developed correlation and by measuring, using a liquid Scintillation counter, the total β/total a activity of purified Pu sample.
D Leong - One of the best experts on this subject based on the ideXlab platform.
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comparison of the absorption of micronized daflon 500 mg and nonmicronized 14c diosmin tablets after oral administration to healthy volunteers by accelerator mass spectrometry and liquid Scintillation Counting
Journal of Pharmaceutical Sciences, 2002Co-Authors: R C Garner, J V Garner, S Gregory, M Whattam, A Calam, D LeongAbstract:Daflon 500 mg, is a micronized purified flavonoid fraction, containing 90% w/w diosmin and 10% w/w of flavonoids expressed as hesperidin, used clinically in the treatment of chronic venous insufficiency and hemorrhoidal disease. This study was designed to investigate the influence of particle size on the overall absorption of diosmin after oral administration of micronized (mean particle size = 1.79 microm, with 80% of particles having a size lower than 3.45 microm) and nonmicronized diosmin (mean particle size = 36.5 microm, with 80% of particles comprised between 19.9 and 159 microm). In a double blinded, cross-over study design, 500 mg tablets containing trace amounts (approximately 25 nCi) of (14)C-diosmin were administered to 12 healthy male volunteers as a single oral dose. Accelerator mass spectrometry and liquid Scintillation Counting were used for the measurement of (14)C-diosmin in urine and feces. Absorption of (14)C-diosmin from the gastrointestinal tract, measured by the urinary excretion of total radioactivity, was significantly improved with the micronized (57.9 +/- 20.2%) compared with the nonmicronized material (32.7 +/- 18.8%). Statistical comparison of the urinary excretion of the two pharmaceutical formulations showed this difference to be highly significant (p = 0.0004, analysis of variance). The overall excretion of the radiolabeled dose was 100% with mean +/- SD of 109 +/- 23% and 113 +/- 20% for the micronized and nonmicronized forms, respectively. The results of this study show: 1. the impact of a reduction of particle size on the extent of absorption of diosmin, giving a pharmacokinetic explanation to the better clinical efficacy observed with the micronized formulation, and 2. the use of accelerator mass spectrometry in conjunction with liquid Scintillation Counting in measurement of bioavailability in a human cross-over study comparing two drug formulations containing trace amounts of radioactivity.
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a validation study comparing accelerator ms and liquid Scintillation Counting for analysis of 14c labelled drugs in plasma urine and faecal extracts
Journal of Pharmaceutical and Biomedical Analysis, 2000Co-Authors: R C Garner, J V Garner, M Whattam, James Barker, C Flavell, G C Young, N Cussans, S Jezequel, D LeongAbstract:A comparison has been made between accelerator mass spectrometry (AMS) analysis and liquid Scintillation Counting (LSC) of plasma, urine and faecal samples containing 14C-labelled drugs. In an in vitro study in which human plasma was spiked (the term spiked is used in Section 2.6) with 14C-Fluconazole (14C-FL) over a concentration range of 0.1-2.5 dpm/ml, a correlation coefficient of 0.999 was determined for AMS analysis versus extrapolated LSC data. No significant day to day (or inter-day)variation was seen (P < 0.05 by ANOVA). Coefficients of variation for these analyses ranged from 2.68 to 6.50%. In vivo studies in which rats were given a high (11.5 microCi/kg) or low (18.1 nCi/kg) radioactive dose (to model an exposure of 0.9 microSievert to man) of 14C-Fluticasone propionate(14C-FP) showed that there was also a good correspondence between AMS and LSC data. A mass balance study in a single the faeces by 96 h; less than 1% of the administered dose was excreted in the urine. The limit of reliable measurement of drug related material, above background concentrations, by AMS analysis in this study was approximately 0.1 dpm/ml for plasma, 0.01 dpm/ml for urine without any sample extraction or concentration and 0.01 dpm/ml for faecal extracts. The data reported here demonstrate that AMS is an ultrasensitive and reliable method for analysing 14C-labelled drugs in human and animal body fluids.
G Sgorbati - One of the best experts on this subject based on the ideXlab platform.
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assessment of drinking water radioactivity content by liquid Scintillation Counting set up of high sensitivity and emergency procedures
Analytical and Bioanalytical Chemistry, 2004Co-Authors: R Rusconi, Arianna Azzellino, S Bellinzona, Maurizio Forte, R Gallini, G SgorbatiAbstract:In our institute, different procedures have been developed to measure the radioactivity content of drinking water both in normal and in emergency situations, such as those arising from accidental and terrorist events. A single radiometric technique, namely low level liquid Scintillation Counting (LSC), has been used. In emergency situations a gross activity screening is carried out without any sample treatment by a single and quick liquid Scintillation Counting. Alpha and beta activities can be measured in more than one hundred samples per day with sensitivities of a few Bq/L. Higher sensitivity gross alpha and beta, uranium and radium measurements can be performed on water samples after specific sample treatments. The sequential method proposed is designed in such a way that the same water sample can be used in all the stages, with slight modifications. This sequential procedure was applied in a survey of the Lombardia district. At first tap waters of the 13 largest towns were examined, then a more detailed monitoring was carried out in the surroundings of Milano and Lodi towns. The high sensitivity method for the determination of uranium isotopes was used to check the presence of depleted uranium in Lake Garda. Reduced equipment requirements and relative readiness of radiochemical procedures make LSC an attractive technique which can also be applied by laboratories lacking specific radiochemistry facilities and experience.
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natural radionuclides measurements in drinking water by liquid Scintillation Counting methods and results
2003Co-Authors: Peter Warwick, R Rusconi, S Bellinzona, Maurizio Forte, Elisabetta Di Caprio, G SgorbatiAbstract:Concern about total radionuclides content in water intended for human consumption has been brought to public attention by the recent Council Directive 98/83/EC, subsequently enforced through an Italian law. Parameter values have been fixed for Tritium content (100 mBq/l) and total indicative dose (0,1 mSv/year): the Directive points out that the total indicative dose must be evaluated excluding Tritium, K, C, Radon and its decay products, but including all other natural series radionuclides. Maximum concentration values for Radon are separately proposed in Commission Recommendation 2001/928/Euratom. Tritium determination follows a well established procedure, standardized by International Standard Organization. On the contrary, total indicative dose evaluation requires more specific and cumbersome procedures for the measurement of radioactivity content, with special regard to natural series radionuclides. The large number of possibly involved radionuclides and the good sensitivities required make the application of traditional analytical techniques unsuitable in view of a large scale monitoring program. World Health Organization guidelines for drinking water suggest performing an indirect evaluation of committed dose by measuring alpha and beta gross radioactivity and checking compliance to derived limit values; the proposed limit values are 0,1 Bq/l for gross alpha and 1 Bq/l for gross beta radioactivity. Nevertheless, it is desirable to identify single radionuclides contribution to alpha and beta activity in order to perform more accurate measurements of committed dose. Ultra-low level liquid Scintillation Counting coupled to extractive techniques and alphabeta discrimination allows rapid and simple determination of all radiometric parameters relevant to dose evaluation, namely gross alpha and beta activity, uranium and radium isotopes content. For tritium and radon determination well established procedures, based on LSC, can also be used. These techniques were applied to a preliminary monitoring program of tap waters in Lombardia; up to now, total alpha and beta activity and uranium isotope concentration have been measured. A Quantulus-Wallac Scintillation counter has been used in this work. Some brands of bottled water were examined too, both for testing methods and because of the widespread use of mineral water by the Italian population. Mineral water brands are not reported here. 2 METHODS AND RESULTS
D. Alamelu - One of the best experts on this subject based on the ideXlab platform.
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determination of 235u 238u atom ratio in uranium samples using liquid Scintillation Counting lsc
Talanta, 2009Co-Authors: D. Alamelu, Suresh K. AggarwalAbstract:Abstract A correlation has been developed for the determination of 235U/238U atom ratio in uranium samples using liquid Scintillation Counting (LSC). The 235U/238U atom ratio determined by thermal ionization mass spectrometry (TIMS) was correlated to the ratio of (i) α-count rate and (ii) Cerenkov count rate due to 234mPa in the sample; both measured by LSC. This correlation is linear over the range of 235U/238U atom ratio encountered in the nuclear fuel samples, i.e. the low enriched uranium (LEU) samples with 235U
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determination of 241pu 239pu atom ratio in pressurised heavy water reactor phwr pu samples using liquid Scintillation Counting
Journal of Alloys and Compounds, 2007Co-Authors: D. Alamelu, Suresh K. AggarwalAbstract:The determination of 241 Pu is important in elucidating the isotopic composition of any Pu sample. The relatively short half-life (14.32 yr) of 241 Pu leads to inconsistency in the correlations involving this isotope unless the different Pu samples have either the same irradiation and cooling history or the exact cooling period is known to account for the decay of 241 Pu prior to using the data for developing isotope correlations. To overcome this limitation, a useful correlation based on the measurement of total β/total a activity of Pu sample using liquid Scintillation Counting method was developed. Total β/total a activity of the Pu sample is correlated to the 241 Pu/ 259 Pu atom ratio and thus does not depend upon the knowledge of the cooling period. For any unknown sample, the 241 Pn/ 259 Pu atom ratio can be determined by using the developed correlation and by measuring, using a liquid Scintillation counter, the total β/total a activity of purified Pu sample.
