Liquid Scintillation Counting Efficiency Research Articles

Activity determination of 231Pa by means of liquid scintillation counting

Protactinium-231 decays through a chain of daughter nuclides to stable 207Pb, resulting in a number of alpha and beta transitions. A method based on liquid scintillation (LS) counting was developed to determine the activity concentration of 231Pa. For α emissions, the corresponding LS counting efficiency was assumed to be unity. A potential loss of the noble gas 219Rn was evaluated by an additional experiment. In the case of the short-lived 215Po, a dead-time-dependent correction factor was taken into account in the calculation. For beta emitters 227Ac, 223Fr, 211Pb and 207Tl, the counting efficiencies were determined by the CIEMAT/NIST efficiency tracing (CNET) method with 3H standard as a tracer. The impurities were checked and found that the possible impurity was 227Ac, with an initial activity ratio A(227Ac)/A (231Pa) between 0.5% and 0.8%. Finally, the activity concentration of the 231Pa solution was determined with a combined relative standard uncertainty of 0.39%.

Study on quench effects in liquid scintillation counting during tritium measurements

Quench effects can cause a serious reduction in counting efficiency for a given sample/cocktail mixture in liquid scintillation counting (LSC) experiments. This paper presents a simple experiment performed in order to test the influence of quenching on the LSC efficiency of 3H. The aim of this study was to investigate the behavior of several quench agents with different quench strengths (nitromethane, nitric acid, acetone, dimethyl-sulfoxide) added in different amounts to tritiated water in order to obtain standard sets for quench calibration curves. The OptiPhase HiSafe 2 and OptiPhase HiSafe 3 scintillation cocktails were used in this study in order to compare their quench resistance. Measurements were performed using a low-level LS counter (Wallac, Quantulus 1220).

Experimental half-life determination of 176Lu

The half-life of the naturally occurring long-lived rare earth isotope 176Lu was determined by a combination of highly sophisticated experimental procedures in order to further improve the reliability and the precision of literature data. The amount of lutetium in the samples was determined by inductively coupled plasma optical emission spectrometry (ICP-OES) using a NIST reference standard. The isotopic ratio N(176Lu)/N(Lu) in the samples was measured by means of inductively coupled plasma high resolution mass spectrometry (ICP-HRMS). The activity divided by the mass of Lu was determined by applying liquid scintillation (LS) counting. The LS counting efficiency of the beta/gamma emitter 176Lu was determined with the CIEMAT/NIST efficiency tracing technique with low uncertainty. The influences of colour quenching and background effects are discussed in this paper. The half-life was found to be 3.640(35)×1010y. The result is in good agreement with other evaluations and the relative standard uncertainty of 0.95% is among the lowest of previously published data.

Simulation of the relative damaging effects of Auger cascades with gel scintillators

Purpose: The aim of this work is to study the relative damaging effects of DNA-incorporated radionuclides by analyzing the behavior of the liquid-scintillation counting efficiency in volumes of nanometer size.Methods: A liquid scintillation counter can detect changes in the micelle size when different percentages of an aqueous solution containing an Auger-electron-emitting radionuclide are incorporated to a gel scintillator. The counting efficiency can be used as an indicator of the nature of the stochastic processes occurring within the micelle structure.Results: Because a large variation in the micelle size only perturbates the counting efficiency slightly, the accuracy of the method is poor. The application of tracing methods, which involve the calculation of the Auger cascades and the deposition of energy within nanometric spheres, can improve the accuracy of the results.Conclusions: Some steps in the complete simulation of the damaging efficiency can be obviated with the use of a tracer.

Quantification of 241Pu in aerosols released from nuclear power plants

A radiochemical method is described for the determination of 241Pu activity in gaseous effluents released to the environment from nuclear power plants. For the analysis of samples 236Pu isotope is used as an analytical tracer. A correlation factor between the gross alpha and the 236Pu activity measured by alpha-spectrometry was obtained and applied to the gross alpha, obtained by liquid scintillation counting (LSC). The minimum detectable activity (MDA) was 0.12 Bq/filter, for LSC efficiency of 25% and a recovery of 52%. The final calculation of the total propagated uncertainty on a real sample is presented.

MICELLE, the micelle size effect on the LS counting efficiency

This version extends the computation of the liquid-scintillation counting efficiency to electron-capture radionuclides of 30 ⩽ Z ⩽ 54 . The simplified deterministic models of previous versions are replaced by a complete stochastic model, which considers all possible subshells involved in the atomic rearrangement of the atom. The program can simulate samples in the gel phase, including the effects of the micelles on the counting efficiency. These effects have been found to be useful for building nanodosimeters based on gel scintillators. Program summary Title of program: MICELLE Catalogue identifier:ACPU_v3_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ACPU_v3_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing previsions: none Computers revisions: any IBM PC compatible with 80386 or higher Intel processors Operating systems under which the program has been tested: MS-DOS and higher systems Programming language used: FORTRAN 77 Memory required to execute with typical data: 235 kword No. of bits in a word: 16 No. of lines in distributed program, including test data, etc.: 16 653 No. of bytes in distributed program, including test data, etc.: 358 166 Distribution format: tar.gz Nature of the physical problem: Both β and electron-capture are decay processes characterized by a large variability in energy. In the first case, one single β-particle is emitted per decay following the Fermi distribution. In the second, several electrons (Auger and/or Coster–Kronig) of very different energies can be ejected simultaneously. The detailed simulation of these two electron release processes has practical interest in two situations: (1) to standardize radionuclides with a liquid-scintillation counter, (2) to compute the absorbed dose in the surroundings of a radiolabeled molecule. Method of solution: Although the application of simplified deterministic models is sufficiently accurate for pure β-ray emitters, the large stochastic variability of both electron-capture and internal conversion processes restricts the accuracy of the deterministic models KLM, KLMN and KL 1L 2L 3M to nuclides of low atomic numbers. To extend the applicability of the method to larger nuclei, both M i - and N j -subshells must be included into the model. However, the addition of these outer atom subshells to the deterministic model involves a huge number of atomic rearrangement pathways, requiring from simplifications which are frequently limited to certain nuclides. A more feasible method considers using random numbers to simulate step by step the rearrangement of the atom. Restrictions on the complexity of the problem: The program is restricted to radionuclides of atomic numbers within the interval 30 ⩽ Z ⩽ 54 . This version ignores the photoionization quench correction, which can be obviated for Z ⩾ 30 . On the other hand, the simulation of the mechanisms of multiple ionization require from more elaborated models for Z > 54 . Experiments with gases are only available for nuclides with atomic numbers larger than that of 131I, for which the emission of Auger electrons, and consequently the ionization of xenon ( Z = 54 ), stops for transitions outer than N 4O 2O 2.

EMI2, the counting efficiency for electron capture by a KL1L2L3M model

The program EMI2 computes the liquid-scintillation counting efficiency for pure electron capture, single isomeric and electron capture-gamma nuclides. In this second version, the atomic rearrangement process subsequent to electron capture is described in terms of a more sophisticated KL 1 L 2 L 3 M model of 264 different pathways. The addition of Coster–Kronig transitions improves the accuracy of the method, especially for nuclides of low atomic numbers. A Monte Carlo method is applied to simulatethe photoelectric and Compton interactions of X- and γ-photons with the scintillator inside the vial geometry.

125Sb to 125mTe branching ratio

The ratio of the 125Sb β-branch to the long-lived isomeric state 125mTe (57.4 days) has been measured by γ-spectrometry to be 0.231±0.010. Since the liquid scintillation counting efficiency is high for both 125Sb (90%) and 125mTe (100%), the determination of this branching ratio by liquid scintillation spectrometry requires one to apply a simultaneous standardization method to radioactive samples in which 125Sb and 125mTe are in full equilibrium.

CAPMULT, the counting efficiency for electron capture by a KLMN four-shell model

We present a new more advanced program to compute the liquid scintillation counting efficiency for pure electron capture nuclides. We consider a KLMN four-shell model with 262 different ways of atomic rearrangement, which permits one to improve the accuracy of the method for nuclides of large atomic numbers.

Determination of lead-210 in admixture with bismuth-210 and polonium-210 in quenched samples by liquid scintillation counting

An aqueous acidic mixture of /sup 210/Pb, /sup 210/Bi, /sup 210/Po, in secular equilibrium, was separated into its components by using a series of sequential complexometric extractions. A multi-channel pulse height analyzer was used to determine the effects of varying amounts of a chemical quenching agent on the liquid scintillation spectrum of each of the separated fractions. The /sup 210/Pb fraction was free of contaminating /sup 210/Bi. A mathematical algorithm was developed to predict the percent of /sup 210/Pb activity (0.61% of the initial /sup 210/Bi activity) in the bismuth fraction by using Cerenkov counting, which is specific for /sup 210/Bi. The approach taken was to relate the slope of the linear relationship between the logarithmically transformed theoretical decay curve for pure /sup 210/Bi and the transformed theoretical decay curve for /sup 210/Bi, /sup 210/Pb mixtures to the percent of contaminating /sup 210/Pb in the mixture. Equations were also developed (1) to predict the liquid scintillation counting efficiency of /sup 210/Pb (relative to an unquenched sample) by relating the level of quenching to a spectral quench parameter (SPQ-(E)) as determined by counting an external (/sup 226/Ra) and (2) to correct for the presence of /sup 210/Bi counts in the /supmore » 210/Pb window by relating the /sup 210/Bi count rate in the /sup 210/Pb window to the ratio of the count rate in a /sup 210/Bi interference free window over the SPQ(E). When combined, these expressions resulted in an algorithm that can be used to correct for variable amounts of chemical quenching and for the presence of variable amounts of /sup 210/Bi in the /sup 210/Pb-containing sample.« less

VIASKL: A computer program to evaluate the liquid scintillation counting efficiency and its associated uncertainty for K-L-atomic shell electron-capture nuclides

VIASKL: A computer program to evaluate the liquid scintillation counting efficiency and its associated uncertainty for K-L-atomic shell electron-capture nuclides

Standardization of isomeric-transition radionuclides by liquid-scintillation efficiency tracing with hydrogen-3: Application to technetium-99m

A method is described for computing the liquid-scintillation counting efficiency for isomeric-transition radionuclides. The counter efficiency is traced using standards of the low-energy β-particle emitter 3H. The method is applied to the standardization of 6-h 99mTc. The two-phototube coincidence counting efficiency is computed as 0.28, with an uncertainty (one standard deviation) of 3.4%. A simple and accurate secondary-standardization technique is also demonstrated, which is based on measurements of a full-energy peak at 119–140 keV. The computed detection efficiency for this full-energy peak is 0.109, which compares well with measured values of 0.110 and 0.112 for two commercial spectrometers. Effects due to γ-ray interactions in the scintillators and ionization quenching for low-energy electrons are also discussed.

Liquid-scintillation counting efficiency as a function of the figure of merit for pure beta-particle emitters

Liquid-scintillation counting efficiency as a function of the figure of merit for pure beta-particle emitters

Some empirical observations concerning the liquid scintillation counting of coloured solutions

The colour quenching capabilities of nine dyes have been examined, and compared with the visible absorption spectra of the dyes in toluene solution. From these data an empirical relationship is derived, from which the liquid scintillation counting efficiency is estimated simply from the λmax (wavelength of maximum absorption) of the dye and its absorption, A, at that wavelength. For the particular instrument, window settings, and scintillator solutions used in this work the relationship was[Formula: see text]Colour quenching agents are classified as severe (λmax 380–480 nm), moderate (λmax 480–520 nm), light (λmax 520–560 nm), or zero (λmax > 560 nm).The normal external standard channels ratio method for obtaining counting efficiency of chemically quenched samples has been applied to samples that contain colour quenchers and various combinations of colour and chemical quench. The results are in excellent agreement with the actual counting efficiencies; this result is in direct contrast to current views on the matter. It appears, therefore, that the counting of samples quenched both chemically and by colour may not always be impossible and the user is well advised to investigate his own System to evaluate whether results within acceptable error may be obtained.

Internal standard with identical system properties for determination of liquid scintillation counting efficiency.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInternal standard with identical system properties for determination of liquid scintillation counting efficiencyArsalan A. Moghissi and Melvin Whitehead. CarterCite this: Anal. Chem. 1968, 40, 4, 812–814Publication Date (Print):April 1, 1968Publication History Published online1 May 2002Published inissue 1 April 1968https://doi.org/10.1021/ac60260a007RIGHTS & PERMISSIONSArticle Views47Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (345 KB) Get e-Alerts Get e-Alerts

Determination of liquid scintillation counting efficiency by pulse-height shift.

A method was developed by which liquid scintillation counting efficiency can be determined simultaneously with the count. The two scalers of a liquid scintillation spectrometer are set to count simultaneously different parts of the spectrum. The ratio between the counts on the two scalers can be used as an accurate index of the counting efficiency on one of them. This method saves considerable time compared with the conventional internal standard method and appears to be of equal or greater accuracy. (auth)

Determination of liquid scintillation counting efficiency by pulse height shift

A method has been developed by which liquid scintillation counting efficiency can be determined simultaneously with the count. The two scalers of a liquid scintillation spectrometer are set to count simultaneously different parts of the spectrum. The ratio between the counts on the two scalers can be used as an accurate index of the counting efficiency on one of them. This method saves considerable time compared with the conventional internal standard method and appears to be of equal or greater accuracy.