共查询到20条相似文献,搜索用时 15 毫秒
1.
D. Rodrigues P. Arenillas M.E. Capoulat C. Balpardo 《Applied radiation and isotopes》2008,66(6-7):1049-1054
A non-radionuclide-specific computer code to analyze data, calculate detection efficiency and activity in a TDCR system is presented. The program was developed prioritizing flexibility in measuring conditions, parameters and calculation models. It is also intended to be well structured in order to easily replace subroutines which could eventually be improved by the user. It is written in standard FORTRAN language but a graphical interface is also available. Several tests were performed to check the ability of the code to deal with different decay schemes such as H-3, C-14, Fe-55, Mn-54 and Co-60. 相似文献
2.
We describe a new standardization method in liquid scintillation counting based on the use of a temporary virtual tracer source created inside the scintillator by Compton interaction. The Compton tracer source is measured by the triple coincidence liquid scintillation counter after selection of the Compton events by a gamma-ray detector. The paper describes the principle of the method, the experimental setup and presents the results obtained by this method for the standardization of a 3H solution. These results are compared with those obtained using the classical triple to double coincidence ratio method. Possible application of this new method for international comparisons is addressed. 相似文献
3.
The NMISA participated in the international key comparison of the pure beta-emitter Technetium-99, CCRI(II)-K2.Tc-99. The comparison solution was standardized using three methods, namely the TDCR efficiency calculation method, the CIEMAT/NIST efficiency tracing method and the 4π(LS)β–γ coincidence tracing method with Co-60 as tracer. Excellent agreement between results obtained with the three methods confirmed the applicability of the beta spectral shape given by the latest (2011) DDEP evaluation of Tc-99 decay data, rather than the earlier (2004) evaluation. 相似文献
4.
Current state of the art solutions based on the Triple to Double Coincidence Ratio method are generally large size, heavy-weight and not transportable systems. This is due, on one side, to large detectors and scintillation chambers and, on the other, to bulky analog electronics for data acquisition. CAEN developed a new, full digital approach to TDCR technique based on a portable, stand-alone, high-speed multichannel digitizer, on-board Digital Pulse Processing and dedicated DAQ software that emulates the well-known MAC3 analog board. 相似文献
5.
The specific activity of natural 87Rb was measured by means of 4πβ liquid scintillation counting in a two-photomultiplier-tube spectrometer. 3H-efficiency tracing was used together with the CIEMAT/NIST method to obtain the detection efficiency. For this purpose a new parameterization of the shape factor for the third forbidden non-unique β-transition was performed. The hygroscopic behaviour of the salts used for sample preparation was studied. The half-life of 87Rb was found to be T1/2=4.967(32)×1010 y. 相似文献
6.
The liquid scintillation counting standardization of pure-beta solutions containing pure-beta emitter impurities is a difficult task because, unlike that which can be achieved by using gamma-ray spectrometry, the continuous characteristics of beta spectra and the poor intrinsic resolution of LSC spectrometers do not allow an easy identification and precise determination of the activity concentration of these impurities. This problem was recently encountered in the standardization of a 32P solution in the framework of an international comparison, where the activity contribution of the impurities was over 10% of the main nuclide activity at the reference date. This paper describes the method used to identify the impurities in this 32P solution and the calculation of the detection efficiencies using the triple to double coincidence ratio model. Details on the calculation of the uncertainties of each activity and the covariances between these activities are given. 相似文献
7.
The TDCR method (Triple to Double Coincidence Ratio) is widely implemented in National Metrology Institutes for activity primary measurements based on liquid scintillation counting. The detection efficiency and thereby the activity are determined using a statistical and physical model. In this article, we propose to revisit the application of the classical TDCR model and its validity by introducing a prerequisite of stochastic independence between photomultiplier counting. In order to support the need for this condition, the demonstration is carried out by considering the simple case of a monoenergetic deposition in the scintillation cocktail. Simulations of triple and double coincidence counting are presented in order to point out the existence of stochastic dependence between photomultipliers that can be significant in the case of low-energy deposition in the scintillator. It is demonstrated that a problem of time dependence arises when the coincidence resolving time is shorter than the time distribution of scintillation photons; in addition, it is shown that this effect is at the origin of a bias in the detection efficiency calculation encountered for the standardization of 3H. This investigation is extended to the study of geometric dependence between photomultipliers related to the position of light emission inside the scintillation vial (the volume of the vial is not considered in the classical TDCR model). In that case, triple and double coincidences are calculated using a stochastic TDCR model based on the Monte-Carlo simulation code Geant4. This stochastic approach is also applied to the standardization of 51Cr by liquid scintillation; the difference observed in detection efficiencies calculated using the standard and stochastic models can be explained by such an effect of geometric dependence between photomultiplier channels. 相似文献
8.
The available experimental data relating to processes in the liquid scintillation (LS) detector that lead to fluorescence have been analysed and the evaluated number of photons created are given. The evaluated global distribution of photons emitted from the LS-vial in the case of low-energy emitters is presented. The global distribution of photons is well fitted by the Polya distribution. 相似文献
9.
The Technical Committee for Ionizing Radiation (TCRI) of the Asia Pacific Metrology Programme (APMP) recently organized a regional key comparison of activity measurements of the radionuclide 133Ba. This paper reports on absolute measurements made at the National Metrology Institute of South Africa (NMISA) by the coincidence extrapolation technique, with liquid scintillation counting (LSC) comprising the 4π channel. A detection efficiency analysis was undertaken to predict the maximum efficiency likely to be achieved and to confirm that the method does indeed provide the source disintegration rate for 133Ba. Various experimental and data analysis difficulties to be aware of are discussed in the paper. 相似文献
10.
This work explores the application of the liquid scintillation counting of polycarbonates for measurement of the activity concentration of radioactive noble gases. Results from experimental studies of the method are presented. Potential applications in the monitoring of radioactive noble gases are discussed. 相似文献
11.
12.
A new preparation method was developed for obtaining low carbon content water from urine samples for the measurement of tritium by a liquid scintillation counter. The method uses a simple and convenient subboiling distillation bottle. Many urine samples have been purified by this method and the change of tritium level in a tritium-handling radiation-worker was observed. 相似文献
13.
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 109Cd and 125I 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. 相似文献
14.
A spectrum deconvolution method has been applied to logarithmic liquid scintillation spectra containing more than one radionuclide, to determine the activity of the individual components. The shape of the sample spectrum has been used for resolving the various components in the sample by fitting the reference spectrum of each component to the measured composite spectrum. The procedure has been applied to environmental samples containing 90Sr, 90Y and 85Sr, added as a tracer for the chemical recovery determination. Comparisons are made with results obtained using a modified window-based method and results obtained by measuring the 85Sr activity by gamma-ray spectrometry and subtracting its contribution to the LS count rate. It is demonstrated that this treatment of the beta-particle spectra represents a rapid and reliable method of determining these radionuclides in a mixture, even at low activity levels. 相似文献
15.
The Technical Committee for Ionizing Radiation (TCRI) of the Asia Pacific Metrology Programme (APMP) recently organized a regional key comparison of activity measurements of the radionuclide 133Ba. This paper reports on absolute measurements made at the National Metrology Institute of South Africa (NMISA) by the coincidence extrapolation technique, with liquid scintillation counting (LSC) comprising the 4π channel. A detection efficiency analysis was undertaken to predict the maximum efficiency likely to be achieved and to confirm that the method does indeed provide the source disintegration rate for 133Ba. Various experimental and data analysis difficulties to be aware of are discussed in the paper. 相似文献
16.
《Applied radiation and isotopes》2000,52(3):643-648
Detection efficiency variation is often used in liquid scintillation counting in order to evaluate a parameter in the detection efficiency calculation model. The aim of this paper is to compare the effects of three different detection efficiency variation methods in the activity measurement of three pure-beta radionuclides: 3H, 63Ni and 14C. Some general conclusions concerning the TDCR method are drawn. 相似文献
17.
This paper presents α-particle spectrometry and liquid scintillation spectrometry methods to determine plutonium isotopes in bilberry. The analytical procedure involves sample preparation steps for ashing, digestion of bilberry samples, radiochemical separation of plutonium radioisotopes and their measurement. The validity of the method was checked for coherence using the ζ test, z-test, relative bias and relative uncertainty outlier tests. The results indicated that the recommended procedures for both measurement systems could be successfully applied for the accurate determination of plutonium activities in bilberry samples. 相似文献
18.
A procedure to standardize 89Sr (as strontium chloride) solutions, within the frame of a BIPM intercomparison, by the CIEMAT/NIST method was presented for Instagel Plus, HiSafe III and Ultima Gold liquid scintillation cocktails. The stability was studied for two types of samples: those obtained by direct addition of the 89Sr solution and those by the extra addition of 0.5 ml of HCl (0.1 mol l(-1)) to the cocktails. The results only showed good stability with the three scintillants used when additional HCl was added to the cocktails. The activities per unit mass determined for 89Sr were: 26.344 kBq g(-1) for Instagel Plus; 26.335 kBq g(-1) for HiSafe III; and 26.310 kBq g(-1) for Ultima Gold (at a reference time of 2000.10.01, 00 h UT) with a total uncertainty of 0.5% in each case (k = 1). 相似文献
19.
P.J. Reddy S.P.D. Bhade K.K. Narayan A. Narayanan D.A.R. Babu D.N. Sharma 《Applied radiation and isotopes》2009,67(10):1945-1951
Different methods such as full spectrum DPM (FSDPM), dual isotope estimation and inclusion methods were studied for the activity quantification of 3H and 14C in dual beta labeled samples using liquid scintillation analyzer. A standardized Packard tritiated water was used as tritium source and 14C activity was standardized by CIEMAT/NIST method and compared with the results obtained by the above three methods. Minimum detectable activity was 2100 dpm/l for 3H and 1200 dpm/l for 14C with a counting time of 300 min. The accuracy of the results obtained was found to be within ±10% for 3H: 14C activity ratios 1:1, 1:2, 2:1, 6:1, 9:1, 13:1 and 18:1. 相似文献
20.
In this study the age and sediment accumulation rates of the lake sediment were calculated by using the 210Pb concentrations through the sediment core. The specific activity of 210Pb for each sediment section was determined by LSC with double energetic window method which relies on the direct determination of 210Pb without waiting for the in growth of 210Po from 210Pb. For the successful determination of this radionuclide two counting windows were optimized to eliminate the overlapping of the beta spectra of 210Pb and 210Bi. 相似文献