Search Results
You are looking at 1 - 10 of 25 items for
- Author or Editor: R. Jačimović x
- Refine by Access: All Content x
Abstract
The k
0-standardization method of neutron activation analysis (NAA) is very sensitive to the irradiation and counting time during measurement of the induced radionuclide by 
-spectrometry on the HP Ge detector. If the irradiation and counting time of the sample and co-irradiated standard is relatively short or the decay constant small, the application of the standard equation in the software for the specific count rate may become numerically unstable and the program aborts. In this work, attention is focused on the direct influence of saturation and "measurement" factors on the specific count rate for simple decay and for more complex types calculated directly by exponential functions, and by an alternative form using a truncated Taylor's series expression.
Abstract
The accuracy and precision of the results obtained for total mercury in various environmental and biological samples and certified reference materials (CRMs) by various analytical methods, including k 0-instrumental neutron activation analysis (k 0-INAA), radiochemical neutron activation analysis (RNAA) and cold vapour atomic absorption (and atomic fluorescence) spectrometry (CVAAS/AFS) used in routine analysis in our laboratory, were investigated. Three natural matrix reference materials (RMs) from the International Atomic Energy Agency (IAEA), five CRMs from the Institute for Reference Materials and Measurements (IRMM), six CRMs from the National Institute of Standards and Technology (NIST) and one from the Jožef Stefan Institute (IJS) were analyzed. The results obtained show good agreement between certified or assigned values, and between the methods used, except for some data obtained by k 0-INAA in biological samples. This can be explained by losses during irradiation in semi-open systems (irradiation in plastic ampoules) and/or spectral interferences.
Abstract
The Laboratory for Neutron Activation Analysis at CDTN/CNEN, Brazil, acquired the k0_IAEA software package during the Workshop on Nuclear Data for Activation Analysis, 2005, held at the Abdus Salam International Centre for Theoretical Physics, Italy. The IAEA distributed the software to several laboratories and has accepted suggestions from the users about the performance of the program. This paper describes the validation procedure carried out aiming at the validation of the software package. The procedure was to analyze the SMELS samples and to compare the results obtained by this software to the commercial KayWin software package, already established at CDTN/CNEN. The results were compared to the values obtained by the Jožef Stefan Institute, Slovenia. The laboratories applied the same software: k0_IAEA and KayWin. The overall results pointed out that the k0_IAEA software set up at CDTN/CNEN, Brazil, is working properly. The u-score test showed that all results, except data in SMELS Type III for Se obtained at the JSI, are within 95% confidence interval once setting up u-score as 1.96 (P = 95% or ±2σ).
Abstract
The contents of Hg, Cr, La, Sc, Co, Fe and Sb in some human concretions have been determined by instrumental radioactivation analysis. Urinary bladder and kidney concretions surgical removed from the patient have also been analyzed.
Abstract
Department of Environmental Sciences, Jo
ef Stefan Institute
Abstract
An experimental verification of Monte Carlo neutron flux calculations in typical irradiation channels in the TRIGA Mark II reactor at the Joef Stefan Institute is presented. It was found that the flux, as well as its spectral characteristics, depends rather strongly on the position of the irradiation channel. Comparison of the results for parameter f (thermal-to-epithermal flux ratio), experimentally obtained by the 
Cd ratio multi-monitor
method and Monte Carlo simulations shows relatively good agreement for most studied configurations except for the channel IC40 in the carousel facility, where differences are relatively large and not understood.
Abstract
Quantitative data on trace elements in two tobacco leaf (candidate) reference materials OTL-1 and VTL-2 prepared by the Polish Academy of Sciences and the Institute of Nuclear Chemistry and Technology, Warsaw, Poland, are presented and compard to recommended values, where available. By instrumental neutron activation analysis (INAA), as well as by radiochemical technique (RNAA) 30 elements were quantitatively determined and fair agreement was found between the results and recommended values for the first material.
Abstract
Intézet neve
Abstract
The k0-standardization method of neutron activation analysis was applied for the multielement analysis of the NIST (National Institute of Standards and Technology) proposed Standard Reference Material (SRM) No. 1547 Peach Leaves. At the moment, 50 elements can be determined from a one day irradiation, using the TRIGA Mark II reactor of the 
Jo
ef Stefan
Institute, Ljubljana. Among them, 28 elements were determined quantitatively, and for the remaining 22 elements, less than values were obtained.
Abstract
The neutron distribution in a defined volume (gradient) for different matrices (air, water, cellulose, biological material and silicon dioxide) in two typical irradiation channels (pneumatic tube (PT) and IC40-channel in the carousel facility) in the TRIGA Mark II reactor at the Joef Stefan Institute (IJS) was studied. Our experiment was based on inserting Fe wires (flux monitors) into the chosen matrices. The wires were cut into small pieces after irradiation and the induced activities of 59Fe measured. The results showed that for the studied geometry the average spatial thermal neutron flux inhomogeneities (for five studied matrices) are about 2.3% in the PT-channel and about 2.9% in the IC40-channel.
