The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Jacqueline M Pates - One of the best experts on this subject based on the ideXlab platform.
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determination of 222rn in fresh water development of a robust method of analysis by α β separation liquid Scintillation Spectrometry
Applied Radiation and Isotopes, 2007Co-Authors: Jacqueline M Pates, Neil MullingerAbstract:Liquid Scintillation Spectrometry is used widely for determining 222Rn in natural waters; however, the benefits of α/β separation have not been fully explored. The extractants toluene and Ultima Gold F were compared, and both performed well for a range of extreme waters. A robust method for calibrating extraction and counting efficiencies has been developed. Detection limits are 20 mBq l−1 (toluene) and 16 mBq l−1 (UGF) for a 60 min count and 600-ml sample, halving the required sample volume.
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time efficient method for the determination of 210pb 210bi and 210po activities in seawater using liquid Scintillation Spectrometry
Analytical Chemistry, 2002Co-Authors: Colin D Biggin, Gordon Cook, And Angus B Mackenzie, Jacqueline M PatesAbstract:A novel method has been developed for determining the natural decay series radionuclides (NDS), 210 Pb, 210 Bi, and 210 Po, in seawater by way of state-of-the-art liquid Scintillation Spectrometry. For 210 Pb analysis, the method makes use of a 212 Pb yield tracer, prepared by ion exchange separation from aged Th(NO 3 ) 4 . 210 Bi recovery is determined using 207 Bi as the yield tracer, and 210 Po is determined using the conventional 208 Po yield tracer. The limits of detection for this method are 0.32, 0.34, and 0.004 mBq l -1 for 210 Pb, 210 Bi, and 210 Po, respectively. The analysis can be completed within 10 days, as compared with up to one year for traditional methods. Results are presented for a preliminary study of 210 Pb, 210 Bi, and 210 Po in the dissolved and particle-bound phases of Irish Sea water.
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implications of beta energy and quench level for alpha beta liquid Scintillation Spectrometry calibration
Analyst, 1998Co-Authors: Jacqueline M Pates, Gordon Cook, A B Mackenzie, Charles J PassoAbstract:Alpha/beta separation is achieved by the use of pulse shape discrimination (PSD), calibrated by quantifying event misclassification at any given setting for pure α and β emitters. Previous studies have shown that the degree of misclassification is affected by quenching, but with no attempt made to understand the causes for this phenomenon. This study examines the potential effects of β energy and quench on PSD calibration. PSD was shown to be energy dependent, with misclassification increasing with β event energy. Therefore, PSD calibration requires the use of a β emitter with the same energy distribution as is present in the sample, or a restricted region of interest should be employed. For gross α/gross β analysis of samples containing unknown β emitters, a stepwise calibration procedure is proposed for both PSD and efficiency calibration. Quenching by carbon tetrachloride, nitromethane and 9 M hydrochloric acid was shown to affect PSD by suppression of the delayed component of the Scintillation pulse, although to variable extents, and therefore having a range of effects on misclassification. Acetone quenching had little impact on PSD. Standard quench calibration procedures using either carbon tetrachloride or nitromethane are inappropriate for applications utilising α/β separation by PSD. Instead, a quench calibration procedure based on overspiking samples encompassing a range of quench conditions is recommended. The influence of oxygen quenching on PSD was investigated through purging samples with either oxygen or nitrogen. PSD was found to be unaffected by the small amounts of oxygen normally dissolved in the diisopropylnaphthalene based cocktail used in this study.
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determination of 234th in marine samples by liquid Scintillation Spectrometry
Analytical Chemistry, 1996Co-Authors: Jacqueline M Pates, Gordon Cook, A B Mackenzie, Robert F Anderson, Sarah J BuryAbstract:A liquid Scintillation Spectrometry method for the determination of 234Th in seawater with 230Th as the yield tracer has been developed and validated. 234Th is separated from the dissolved phase by an Fe(OH)3 precipitation and is then purified using ion exchange chromatography. The counting source is prepared by taking the sample to dryness in a vial, redissolving in acid, and mixing with a Scintillation cocktail. The instrument employed has a relatively low background (11 cpm) and the ability to separate α from β activity on the basis of pulse shapes. The 234Th + 234mPa counting efficiency is 50% over the counting window employed. The limit of detection, using the above parameters, a 20 L sample, and a 400 min count is found to be 0.04 dpm L-1. It was also demonstrated that less advanced instruments, without α/β separation, can also be used effectively.
Lauri Kaihola - One of the best experts on this subject based on the ideXlab platform.
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surface and underground ultra low level liquid Scintillation Spectrometry
Radiocarbon, 2004Co-Authors: W Plastino, Lauri KaiholaAbstract:Cosmic background and its variation have been removed in the Gran Sasso National Laboratory (National Institute of Nuclear Physics) by its 1400-m rock overburden. Stable, high-performance liquid Scintillation counting conditions are obtained when any remaining variable components of the environmental background, such as radon, are eliminated. The ultra low-level liquid Scintillation spectrometer Quantulus (super TM) has an anti-Compton guard detector (guard for short) that allows monitoring of gamma radiation in the background. The guard detector efficiency in radiocarbon background reduction is 8% in the Gran Sasso National Laboratory, while 80% is observed in surface laboratories. Thus, atmospheric pressure variations in surface laboratories cause variation in cosmic radiation flux. The Quantulus anti-Compton detector is highly efficient in detecting cosmic radiation, and the sample count rate remains stable in long-term counting. Also, correlation of sample backgrounds with environmental gamma radiation in various laboratories is examined.
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cosmic background reduction in the radiocarbon measurements by liquid Scintillation Spectrometry at the underground laboratory of gran sasso
Radiocarbon, 2001Co-Authors: W Plastino, Lauri Kaihola, Paolo Bartolomei, Francesco BellaAbstract:Radiocarbon measurements by two 1220 Quantulus ultra low background liquid Scintillation spectrometers were performed at the underground laboratory of Gran Sasso and the Radiocarbon Laboratory of E.N.E.A.-Bologna to study the efficiency and background variations related to measurement sites. The same configuration setup, i.e. the same center of gravity of the 14 C spectrum (SQP(I) = 410 ± 1) was obtained in both instruments. Many different background and modern standards with pure analytical benzene were used and spectra for 40 one-hour periods were obtained. The data indicates a background reduction of approximately 65% between the surface and underground laboratories, with no differences in the efficiency. Recording similar efficiencies in both spectrometers is probably due to fairly identical photomultiplier characteristics. The cosmic noise reduction observed at the laboratory of Gran Sasso makes it possible to perform high precision 14 C measurements and to extend for these idealized samples the present maximum dating limit from 58,000 BP to 62,000 BP (5 mL, 3 days counting).
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ultra sensitive alpha particle detection in the presence of high beta activity by low level liquid Scintillation Spectrometry
1996Co-Authors: Lauri Kaihola, T Oikari, Jari SuontaustaAbstract:Liquid Scintillation (LS) Spectrometry offers several advantages in the detection of a radiation. These include
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cosmic particle spectrum as a quench monitor in low level liquid Scintillation Spectrometry
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 1994Co-Authors: Lauri KaiholaAbstract:Abstract Muons comprise a major component of the cosmic particle flux that reaches sea level. In standard liquid-Scintillation counters, the muons may not be separately identifiable among the resulting spectrum due to their low intensity. A Wallac Quantulus™ liquid-Scintillation spectrometer can be used to separate the muons and other external radiations from the sample spectrum with the aid of an anticoincidence guard counter. The muon peak is a well pronounced feature in this coincidence spectrum of rejected events, and is located beyond the Compton continuum. The feasibility of muon spectrum as a quench monitor in low-level liquid-Scintillation Spectrometry was investigated.
W Plastino - One of the best experts on this subject based on the ideXlab platform.
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surface and underground ultra low level liquid Scintillation Spectrometry
Radiocarbon, 2004Co-Authors: W Plastino, Lauri KaiholaAbstract:Cosmic background and its variation have been removed in the Gran Sasso National Laboratory (National Institute of Nuclear Physics) by its 1400-m rock overburden. Stable, high-performance liquid Scintillation counting conditions are obtained when any remaining variable components of the environmental background, such as radon, are eliminated. The ultra low-level liquid Scintillation spectrometer Quantulus (super TM) has an anti-Compton guard detector (guard for short) that allows monitoring of gamma radiation in the background. The guard detector efficiency in radiocarbon background reduction is 8% in the Gran Sasso National Laboratory, while 80% is observed in surface laboratories. Thus, atmospheric pressure variations in surface laboratories cause variation in cosmic radiation flux. The Quantulus anti-Compton detector is highly efficient in detecting cosmic radiation, and the sample count rate remains stable in long-term counting. Also, correlation of sample backgrounds with environmental gamma radiation in various laboratories is examined.
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cosmic background reduction in the radiocarbon measurements by liquid Scintillation Spectrometry at the underground laboratory of gran sasso
Radiocarbon, 2001Co-Authors: W Plastino, Lauri Kaihola, Paolo Bartolomei, Francesco BellaAbstract:Radiocarbon measurements by two 1220 Quantulus ultra low background liquid Scintillation spectrometers were performed at the underground laboratory of Gran Sasso and the Radiocarbon Laboratory of E.N.E.A.-Bologna to study the efficiency and background variations related to measurement sites. The same configuration setup, i.e. the same center of gravity of the 14 C spectrum (SQP(I) = 410 ± 1) was obtained in both instruments. Many different background and modern standards with pure analytical benzene were used and spectra for 40 one-hour periods were obtained. The data indicates a background reduction of approximately 65% between the surface and underground laboratories, with no differences in the efficiency. Recording similar efficiencies in both spectrometers is probably due to fairly identical photomultiplier characteristics. The cosmic noise reduction observed at the laboratory of Gran Sasso makes it possible to perform high precision 14 C measurements and to extend for these idealized samples the present maximum dating limit from 58,000 BP to 62,000 BP (5 mL, 3 days counting).
G A Badun - One of the best experts on this subject based on the ideXlab platform.
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liquid Scintillation Spectrometry of tritium in studying lysozyme behavior in aqueous organic liquid systems the influence of the organic phase
Langmuir, 2011Co-Authors: M G Chernysheva, G A BadunAbstract:Liquid Scintillation Spectrometry of tritium in the application of the Scintillation phase method was used for studying the adsorption of lysozyme at the liquid/liquid interface and its distribution in the bulk of the system. The goal of this research was to reveal the influence of the nature of the organic phase on the distribution and adsorption ability of the protein when it is placed in a system containing two immiscible liquids. Based on the radiochemical assay distribution coefficients and adsorption isotherms obtained for aqueous/octane, aqueous/p-xylene and aqueous/octanol systems, it was concluded that the interaction of the protein with the interface plays a dominant role in protein behavior in aqueous/organic liquid systems.
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liquid Scintillation Spectrometry of tritium in the investigation of compound adsorption at a water nonpolar liquid interface
Moscow University Chemistry Bulletin, 2009Co-Authors: G A Badun, M G Chernysheva, Z A Tyasto, V M FedoseevAbstract:We examine the application of the Scintillation phase method as a radiochemical assay for studying the behavior of surfactants in liquid/liquid systems. The theoretical background of the technique is described. Results of our investigation of cationic and nonionic surfactants in a water/organic liquid system (arenes, alkanes, alcohols) are summarized.
Franz Schonhofer - One of the best experts on this subject based on the ideXlab platform.
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liquid Scintillation Spectrometry in environmental measurements
Science of The Total Environment, 1995Co-Authors: Franz SchonhoferAbstract:The power of liquid Scintillation Spectrometry for low-level measurements of radionuclides in the environment is demonstrated by some successful applications for the determination of tritium, α-emitters, Kr-85, Sr-90 and excretion analysis. The advantages of this technique are discussed as well as some limitations and difficulties which have to be considered.