Application Of Liquid Scintillation Counting Research Articles

MEASUREMENTS OF AIRBORNE CONCENTRATIONS OF RADON AND THORON DECAY PRODUCTS.

Liquid scintillation counting (LSC) is a measuring technique, broadly applied in environmental monitoring of radionuclides. One of the possible applications of LSC is the measurement of radon and thoron decay products. But this method is suitable only for grab sampling. For long-term measurements a different technique can be applied-monitors of potential alpha energy concentration (PAEC) with thermoluminescent detectors (TLD). In these devices, called Alfa-2000 sampling probe, TL detectors (CaSO4:Dy) are applied for alpha particles counting. Three independent heads are placed over the membrane filter in a dust sampler's microcyclone. Such solution enables simultaneous measurements of PAEC and dust content. Moreover, the information which is stored in TLD chips is the energy of alpha particles, not the number of counted particles. Therefore, the readout of TL detector shows directly potential alpha energy, with no dependence on equilibrium factor, etc. This technique, which had been used only for radon decay products measurements, was modified by author to allow simultaneous measurements of radon and thoron PAEC. The LSC method can be used for calibration of portable radon decay products monitors. The LSC method has the advantage to be an absolute one, the TLD method to measure directly the (dose relevant) deposited energy.

Background characterization of an ultra-low background liquid scintillation counter

The Ultra-Low Background Liquid Scintillation Counter developed by Pacific Northwest National Laboratory will expand the application of liquid scintillation counting by enabling lower detection limits and smaller sample volumes. By reducing the overall count rate of the background environment approximately 2 orders of magnitude below that of commercially available systems, backgrounds on the order of tens of counts per day over an energy range of ~3–3600keV can be realized. Initial test results of the ULB LSC show promising results for ultra-low background detection with liquid scintillation counting.

Liquid scintillation counting of environmental radionuclides: a review of the impact of background reduction

Liquid scintillation counting (LSC) supports a range of environmental science measurements. At Pacific Northwest National Laboratory, we are constructing an LSC system with an expected background reduction of 10–100 relative to values reported in the literature. In this paper, a number of current measurement applications of LSC have been considered with an emphasis on determining which aspects of such measurements would gain the greatest benefit: improved minimum detectable activity (MDA), reduction in sample size, and reduction in total analysis time.

A method for optimum PSA setting in the absence of a pure α or β emitter and its application in the determination of 237Np/233Pa

In the application of liquid scintillation counting (LSC), the α/β discrimination is carried out with the function of pulse shape analysis (PSA), which requires the setting of the optimum PSA level. The optimum PSA are usually determined by the generation of cross-over plots, whereby a pair of vials, one containing a pure α emitter and the other a pure β emitter, is counted. However, in some cases such as the determination of 237Np/233Pa, a pure α emitter or a pure β emitter is not available. Therefore, we have developed a new approach to set the optimum PSA by measuring the sample itself of mixed α/β emitters. The count rate of the sample in the α-multi-channel analyzer changes monotonically with the increase of the PSA, and there is always an inflection point which is related to the optimum PSA. By fitting the data near the inflection point with the function y=ax3+bx2+cx+d, we can obtain the optimum PSA as −b/(3a), which can be used to determine the radioactivity of 237Np/233Pa. The results obtained with this new approach were in good agreement with those obtained by HPGe γ spectrometry that was calibrated with an LSC sample of 237Np/233Pa under a radioactive secular equilibrium. The new approach is promising to be used in simultaneous determination of gross α and β emitters, especially in the absence of a pure α or β emitter.

A general method for optimizing the parameter of α/β discrimination in liquid scintillation counting

In the application of liquid scintillation counting (LSC), the α/β discrimination is carried out with the function of pulse shape analysis (PSA), which requires the setting of the optimum PSA level. The optimum PSA is usually determined by the generation of cross-over plots (referred as Conventional Method), whereby a pair of pure α and β emitters is essential. However, in some cases, a pure α or β emitter is not available. In order to deal with this problem, we have developed a new approach (referred as Present Method) to set the optimum PSA by measuring the sample itself of mixed α/β emitters. The results from Present Method are in good agreement with those from Conventional Method when a pair of pure α and β emitters is available. Besides the obvious advantage that Present Method can be applied no matter whether a pure α emitter or a pure β emitter is available or not, Present Method has another important advantage that it is not necessary to prepare the quench curves for the measurement of samples with different quench levels. Therefore, Present Method is a general method for optimizing the parameter of α/β discrimination in LSC. In addition, the application of Present Method can be broadened by combining the method with α spectrometry.

Expanded Applications of Liquid Scintillation Counting and Several Related Issues

Liquid scintillation counting (LSC) is widely used in the field of radiation measurements. Some main developments in the application of LSC in our laboratory have been introduced briefly in this paper. These developments include: the use of LSC alone to determine 152Eu and 241Am simultaneously instead of using the common γ spectrometry, and the use of LSC in combination with α or γ spectrometry in various cases. All these developments expand the applications of LSC, which can lead to significant increase in production of radioactive measurement work. In addition, we have discussions about several issues which are very important to LSC application, i.e. the quenching effect on α/β discrimination, the influences of anticoincidence shield on count rates for various kinds of radionuclides, the effect of statistical fluctuations in external standard spectrum on quench index parameter, and the long-term stability on basic performances of LSC cocktails.

Application of LSC and TLD methods for the measurement of radon and thoron decay products in air

Liquid scintillation counting (LSC) is a measuring technique, broadly applied in environmental monitoring. One of the possible applications of LSC is the measurement of radon and thoron progeny. Such a method can be stated as an absolute one. For long-term measurements, a different technique can be applied-monitors of potential alpha energy concentration (PAEC) with thermoluminescent detectors (TLDs). Such solution enables simultaneous measurements of PAEC and dust content. Moreover, the information which is stored in TLD chips is the energy of alpha particles and not the number of counted particles. Therefore, the readout of TL detector directly shows the potential alpha energy, with no dependence on equilibrium factor, etc. This technique, which had been used only for radon progeny measurements, was modified to allow simultaneous measurements of radon and thoron PAEC.

Effective Determination of the Long-lived Nuclide 41Ca in Nuclear Reactor Bioshield Concretes: Comparison of Liquid Scintillation Counting and Accelerator Mass Spectrometry

The routine application of liquid scintillation counting to (41)Ca determination has been hindered by the absence of traceable calibration standards of known (41)Ca activity concentrations. The introduction of the new IRMM (41)Ca mass-spectrometric standards with sufficiently high (41)Ca activities for radiometric detection has partly overcome this although accurate measurement of stable Ca concentrations coupled with precise half-life data are still required to correct the certified (41)Ca:(40)Ca ratios to (41)Ca activity concentrations. In this study, (41)Ca efficiency versus quench curves have been produced using the IRMM standard, and their accuracy validated by comparison with theoretical calculations of (41)Ca efficiencies. Further verification of the technique was achieved through the analysis of (41)Ca in a reactor bioshield core that had been previously investigated for other radionuclide variations. Calcium-41 activity concentrations of up to 25 Bq/g were detected. Accelerator mass spectrometry (AMS) measurements of the same suite of samples showed a very good agreement, providing validation of the procedure. Calcium-41 activity concentrations declined exponentially with distance from the core of the nuclear reactor and correlated well with the predicted neutron flux.

Radioactivity standardization in South Africa

South Africa's national radioactivity measurement standard is maintained at a satellite laboratory in Cape Town by the National Metrology Laboratory (NML) of the Council for Scientific and Industrial Research. Standardizations are undertaken by a number of direct methods utilizing liquid scintillation counting (LSC). The successful application of LSC to the 4 πβ– γ coincidence method is reviewed. The activity unit is maintained through radionuclide specific calibration factors relating to a pressurized re-entrant well type ionization chamber. A comparison is made between normalized factors given by the manufacturer and deduced factors obtained by a method used to transfer calibration factors from the International Reference System of the International Bureau of Weights and Measures based on the NML's own absolute standardizations.

Luminescence measurements of X-ray absorption spectra: An application of liquid scintillation counting in synchrotron radiation spectroscopy

Simultaneous ??? X-ray absorption spectra of tetramethyltin in organic scintillator solutions using photoconductivity (current yield) and ??? (luminescence yield) techniques are reported. It is found that the luminescence spectra are very similar to those obtained with the photoconductivity technique. The feasibility of luminescence yield X-ray absorption measurements and its applications in the development of liquid scintillation counters are discussed.

Quench correction in liquid scintillation counting by a combined internal standard-samples channels ratio technique

A well-known problem in liquid scintillation counting (LSC) is that radioactivity cannot be measured with 100% efficiency, e.g., due to ''quenching'', which thus needs be corrected for. Three methods (viz., those of internal standard (IS), samples channels ratio (SCR), and external standard channels ratio (ESCR) are in common use to accomplish quench correction. None of these methods is ideal. This paper shows that a combination of the IS and SCR methods (IS-SCR) ameliorates the major disadvantages of both techniques and the disadvantage of the SCR technique at low count rates have been eliminated in the IS-SCR method, which also has a low volume dependence compared to the IS and ESCR methods. The IS-SCR method is not affected by time-dependent diffusion of solutes and solvents into the walls of plastic counting vials, which is a major drawback of the ESCR technique. Used with a simple linear regression technique, the IS-SCR quench curves may be linearized over wide ranges of efficiencies. In view of the wide-spread application of LSC, the IS-SCR technique is therefore likely to be useful to many investigators. 2 figures, 2 tables.

Applications of liquid scintillation counting for environmental monitoring

Applications of liquid scintillation counting for environmental monitoring

Applications of liquid scintillation counting to radioimmunoassays

Applications of liquid scintillation counting to radioimmunoassays

Technical considerations in the application of liquid scintillation counting for the quantitation of chemiluminesce ce produced by phagocytisinf human blood leukocytes: [formula omitted], Department of Medicine, Dr. W.W. Cross Cancer Institute and Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada

Technical considerations in the application of liquid scintillation counting for the quantitation of chemiluminesce ce produced by phagocytisinf human blood leukocytes: [formula omitted], Department of Medicine, Dr. W.W. Cross Cancer Institute and Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada

Application of liquid scintillation counting in red cell survival studies with [ 32P]DF

Application of liquid scintillation counting in red cell survival studies with [ 32P]DF

Solubility Studies on Certain Barbiturates

The solubilities in water at 25° of five barbiturates were determined by the application of liquid scintillation counting of C 14 -tagged compounds to the technique of phase solubility analysis. The effects of several added solutes on these solubilities were also determined, and over-all salting-out constants were obtained from graphs based on the empirical Setschenow equation.

Application of liquid scintillation counting to I 131 measurement

Standard liquid scintillation techniques are feasible for counting the beta emission of I 131 and are up to seven times more efficient than a standard gamma detection system. The increased efficiency obtained and high degree of automation available in liquid scintillation systems minimize the restrictions of the technique.

Applications of Liquid Scintillation Counters

The liquid scintillator, in just a few years of development, has shown itself to be an extremely versatile chemical system for radiation detection. Its evolution has been characterized by penetration into almost every phase of experimental science. A survey of the most notable applications of liquid scintillation counting is presented.