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  • Author or Editor: H. Choi x
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Abstract  

The design features are described of a prompt gamma neutron activation analysis system at HANARO, a 30 MW research reactor in the Korea Atomic Energy Research Institute. The beam consists of polychromatic thermal neutrons diffracted by a set of pyrolytic graphite crystals at orders n in the range 1 n 6 at a Bragg angle of 45° on a horizontal beam line. A neutron flux of 1.0·108 n·cm–2·s–1 is calculated at the sample position from the reflectivity of the crystal which has been confirmed in a measurement of a diffracted neutron spectrum using a time-of-flight spectrometer and gold-wire activation. The fast neutron and gamma backgrounds will be low due to the use of a diffracted beam and a tapered collimator. The detection system comprises a 30% n-type HPGe detector, signal electronics and a fast ADC. The first application of this system will be the analysis of boron concentration in biological samples for neutron capture therapy. Construction of the beam line and the arrangement of the detection system is proceeding.

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Abstract  

Doppler broadening of a 477.6 keV line combined with a recoil of an excited Li nucleus is the characteristic of PGAA, which leads to complicated gamma-ray spectrum which is difficult to analyze. For this solution, a modified algorithm for an automated analysis of the Doppler-broadened peak spectrum is presented. The modified algorithm maintained the consistency of a Doppler-broadened peak with the finest analysis algorithm used for a Gaussian gamma-ray peak analysis in the HYPERMET code.

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Abstract  

Prompt k 0-factors relative to chlorine and relative g-emission intensities were determined for the strong non-1/v absorbers 113Cd, 149Sm, 151Eu,155Gd and 157Gd. Measurements were performed using the SNU-KAERI prompt gamma activation analysis (PGAA) facility at the Korea Atomic Energy Research Institute (KAERI). For proper experimental determination of the prompt k 0-factors, the effective g-factor and cadmium ratio were taken into account, in consideration of the effects from the non-1/v capture cross section and neutron spectrum in the thermal and epithermal energy region. By using the actual spectrum of the neutron beam in this study, the effective g-factor was obtained by calculation, and the influence of epithermal neutrons on the capture rate was corrected by measuring the cadmium ratio for each non-1/v target isotope. The measured prompt k 0-factors were used to check the consistency between the existing dataset of the absolute g-emission intensity and the 2200 m/s capture cross section for these isotopes.

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This study aimed to develop a chromatographic method to quantitatively determine phenol in fish tissues. This method involves solvent extraction of acidified samples, followed by derivatization to phenyl acetate and analysis with gas chromatography coupled with mass spectrometry (GC–MS). Phenol in a representative tissue sample (belly, gill, or renal tubules), which was homogenized with 2 N sulfuric acid, was extracted with ethyl acetate and derivatized to phenyl acetate using acetic anhydride and K2CO3 in water. An n-butyl acetate extract was injected into the GC–MS. The linearity (r 2) of the calibration curve was greater than 0.996. The analytical repeatability, which is expressed as the relative standard deviation, was less than 6.14%, and the recovery was greater than 96.3%. The method detection limit and the limit of quantitation were 8.0 μg/kg and 26 μg/kg, respectively. The proposed method is also applicable to the analysis of other biological tissues for phenol and its analogs, such as pentachlorophenol.

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Abstract  

Elution chromatographic separation of lithium isotopes was carried out with aminobenzo-15-crown-5 bonded merrifield resin. This resin have a capacity of 0.24 meq/g dry resin. By column chromatography using 1.0M NH4Cl solution as an eluent, a single separation factor 1.026 was obtained from the elution curve and isotope ratios according to the Glucckauf theory. The heavier isotope, 7Li was concentrated in the resin phase, while the lighter isotope, 6Li enriched in the solution phase.

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Abstract  

Correction equations of the coincidence-summing effect for efficiencies of HpGe detector based on the decay scheme were developed by considering the summing up to triple coincidence. The correction equations which do not dependent on the kind of the Ge detector are very useful for efficiency calibrations of a Ge detector in the energy region from 60 to 400 keV by using75Se radionuclide even with very short source-to-detector distances.

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Preparation of samples for the α—Spectrometry of transplutonium elements

Electrolytic deposition of rare earth and transplutonium elements from α—Hydroxyisobutyrate solutions

Journal of Radioanalytical and Nuclear Chemistry
Authors: H. Bruchertseifer, Choi Valsek, K. Gavrilov, and M. Schwarzenberg

Abstract  

The electrolytic deposition of the hydroxides of rare earth and transplutonium elements on nickel holders from α-hydroxyisobutyrate solutions of 10−5 M to 5·10−1 M concentrations has been investigated in the presence of ammonium chloride. It is shown that at total concentrations of ≥10−12 M of rare earth and transplutonium elements, their electrodeposition proceeds with a 90% yield.

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Summary  

The prompt k 0,H factors for B, N, Si, P, S and Cl were determined relative to the 2223.25 keV gamma-line from the 1H(n,γ) reaction. The measurements were performed at the SNU-KAERI Prompt Gamma Activation Analysis facility, of which the background was greatly reduced recently by upgrading the detection system to a Compton suppressed g-ray spectrometer with a BGO/NaI(Tl) guard detector and by improving the shield geometry. From the measured prompt k 0,H factors, the partial γ-ray production cross sections were determined using the latest cross section for H. The measured prompt k 0,H factors were tabulated and compared with the other reported data.

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Abstract  

ThO2(cr) was dissolved in the solutions containing various carbonate ion concentrations, and the results were compared with thorium solubility in a domestic granitic groundwater having very low ionic strength. The soluble thorium concentration excluding colloids after phase separation increased with increasing carbonate concentration. However, the thorium concentration in the real groundwater was remarkably greater than that in the carbonate-containing solutions with a similar concentration of carbonate and pH condition. This might be attributable to other species as well as Th(OH)4(aq) and Th(OH)3(CO3). These species form colloids or precipitates, and their concentration can be reduced in the ultra-filtered solution by an aging effect.

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