The G-1 intercomparison is one of the first undertakings of the International Atomic Energy Agency for the investigation of the performance of the routinely used evaluating programs for gamma ray spectra of semiconductor detectors. The details and the conclusions of this procedure are presented.
A quantitative method for the analysis of -emitters in infinitely thin and thick samples was described in Part I. The calculation of errors in intensity, intensity ratio and activity concentration is discussed here in detail. Different definitions of detection sensitivity are compared and evaluated on the basis of the relative statistical error associated therewith. Dependence between the relative error of the net signal and the required measurement time is deduced and illustrated.
A method for determining bulk or surface activity concentration of -emitters in infinitely thick or thin samples using energy selective detectors without any prior chemical separation or qualitative analysis was introduced in Part I. In addition to that method, a correction procedure is often required in order to compensate for the -sensitivity of the -detector. A system or two — preferably identical —detectors positioned to the front and rear side of a sample has been established. The rear side detector is shielded against -radiation. The -response of both detectors is determined as a function of -energy using monoenergetic calibration standards. Response pulses are selected to form 8 or 16 energy intervals, and separate series of correction coefficients are then computed for each interval and standard energy using the ratio of the respective counts. When a sample having mixed - and -radiation is evaluated, an effective
-energy is first calculated from the pulse height distribution of the rear side detector, the appropriate series of correction coefficients is selected and finally net -counts are generated from the counts of the front side detector. Sensitivities in natural and elevated -background are presented.
The activity concentration of bulk and surface samples contaminated with -emitting radioisotopes is difficult to measure without the a priori knowledge of the nature of the non-gamma emitting components. Beta-emitters cannot be identified from any measured spectral distribution. The counting efficiency of the measuring system changes significantly with -energy so it cannot be assumed to have a single value obtained with a standard source with known energy. Application of an energy selective -detector is introduced for determining bulk and surface activity concentration. Samples of infinitely thick or infinitelythin nature are to be prepared. The distribution of -energy deposited in the detector is registered as counts in 8 or 16 energy intervals. No information is needed on the qualitative composition of the sample. Normalised integral distributions (intensity ratios) are derived from the count rates of the intervals. These distributions are then compared to calibrated intensity ratios obtained with suitable standard sources. An average (effective) counting efficiency is generated from this comparison by a special algorithm. Activity concentration of an unknown sample is then obtained using this average efficiency. Calibration and sensitivity data are presented for different types of bulk and surface samples.
Investigations on the disintegration rate of fission products of238U and239Pu are presented. The intensity of the - and -radiation of fission products were measured continuously in an interval of 1–1300 hours following the fission, offering the possibility for determining the general and specific characteristics of the individual fission products. A universal measuring procedure was elaborated for the rapid in situ determination of the dosimetric features of fission products, which is suitable for the accurate evaluation and prediction of external absorbed dose even in case of fission products of various origin and unknown composition.
Authors:M. Földvári, P. Kovács-Pálffy, N. Nagy and J. Kónya
Various cation-exchanged montmorillonites (Li+, Na+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Cu2+, Ag+, Cd2+, Hg2+, Al3+, Pb2+ and NH4+)
were prepared from calcium montmorillonite and their properties were studied by means of X-ray diffraction and thermal analysis.
The two methods give information on the cation exchange in the interlayer space only. X-ray diffraction studies at room temperature
are mainly suitable for estimation of the exchange of cations of different valencies. At 500C, when the structure is completely
collapsed, the d value of montmorillonite depends on the non-hydrated ionic radius of the interlayer cation, but the measurement
interval is limited for fine interpretation. The thermoanalytical method is suitable for a better distinction of different
exchangeable cations of higher hydration energy on the basis of the DTG or DDTG curve.
Authors:D. Vuono, C. C. Pavel, P. De Luca, J. B. Nagy and A. Nastro
Summary The ETS-10 is a newly formed titano-silicate the structure of which was resolved thanks to the XRD, EDS, HREM and mass NMR. The ETS-10 is a potentially good catalyst. The aim of this research is to study the physicochemical properties of ET(Zr)S-10 obtained from a gel containing different amounts of Zr. The analyses used are XRD, thermal analysis (TG-DSC), SEM, and 29Si NMR.
Authors:M. Veltri, D. Vuono, P. De Luca, J. Nagy and A. Nastro
aim of this work is the synthesis and the characterization of a microporous
material obtained from gels with titanium and silicon: NTS (titanosilicate).
The structure of NTS zeotype is similar to that of AM-1 and JDF-L1 (titanosilicates).
The synthesis were carried out with gels
of composition: 3.5Na2O–yTiO2–4.48HCl–xSiO2–110H2O
with 1.0≤x≤12.0 and 0.2≤y≤0.7. The temperature of reaction was 1902C.
In most of the cases NTS was prepared in a pelletted form. NTS pellets
are produced at TiO2 content higher than 0.3 moles
and SiO2 comprised between 3 and 7. NTS in a powder
form is produced for TiO2<0.3 and SiO2 between 3
and 5 moles. It describes crystallization field and the kinetic curves of
The samples are characterized by X-ray diffraction
(XRD), thermogravimetry (TG), derivative thermogravimetry (DTG), differential
scanning calorimetry (DSC), nuclear magnetic resonance spectroscopy-high resolution
solid state MAS 29Si-NMR, scanning electron microscope
(SEM), energy dispersive spectroscopy (EDS) X-ray microanalysis.
Authors:J. Somlai, Á. Torma, P. Dombovári, N. Kávási, K. Nagy and T. Kovács
The radiation dose of workers and patients resulting from inhaling radon and through the consumption of spring waters was
examined in the hospital near the Héviz lake in Hungary. The radiation dose originating from radon was 2.15–3.95 mSv·y−1 concerning workers at the spa. The radiation dose originating from radon in the case of those regularly taking a bath was
an average of 0.75 mSv·y−1. Due to the limited duration of treatments a bound effective dose of maximum 100 µSv·y−1 may originate from radon and inhaling radon, while a maximum of 1.4 µSv·y−1 may originate from ingestion of 222Rn, 226Ra, 234U and 238U radionuclides.