共查询到20条相似文献,搜索用时 0 毫秒
1.
Wuon-Shik Kim Hyon-Soo Kim Jong-Youl Kim Ki-Hwan Kim Yong-Uhn Kim Kwang-Pill Lee 《Journal of Radioanalytical and Nuclear Chemistry》1997,216(1):75-79
The 1.369 MeV -rays emitted from24Na24Mg+–+ after23Na(n,)24Na reaction were counted by high purity germanium (HPGe) detector and the half-life of24Na was derived. This process was simulated by Monte Carlo Neutron and Photon Transport Code (MCNP-4A).252Cf neutron source was moderated by a polyethylene (PE) cylinder to increase the cross section of neutron absorption reaction and to decrease the biological hazard. NaCl powder of 20 cm3 and 40 cm3 volume in cylindrical polypropylene capsules were irradiated by the neutrons passed through the moderator. MCNP-4A was used to determine the optimum size of PE moderator, to assume the realistic geometry of the HPGe detector, and to assume the absolute efficiencies of the detector. The count rates for 1.369 MeV -rays in the HPGe detector were calculated by MCNP-4A for 20 cm3 and 40 cm3 NaCl. The accumulated counts calculated tumed out to be higher than those actually measured by 31% with a relative error of 3%. The half-life of24Na measured within 4% and 1% for 20 cm3 and 40cm3 NaCl agrees with that of the reference. So, we can say that the result of MCNP-4A has about 30% of accuracy and 3% of precision in simulating the neutron activation analysis. 相似文献
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L. Larsson M. Alpsten S. Mattsson 《Journal of Radioanalytical and Nuclear Chemistry》1987,114(1):181-185
A set up forin vivo determination of nitrogen has been built. Phantoms containing different amounts of nitrogen have been measured as well as a volunteer in a pilot study. A total body protein content of 18.8 kg was calculated, to be compared with 17.0 kg estimated from potassium measurements. 相似文献
4.
Sang-Tae Park 《Journal of Radioanalytical and Nuclear Chemistry》2003,256(1):163-166
The neutron energy spectrum of the following sources were measured using a fast neutron spectrometer with the NE-213 liquid scintillator: 252Cf, Am-Be and D(d,n)3He reaction from a 3 MeV Pelletron accelerator in Tokyo Institute of Technology. The measured proton recoil pulse height data of 252Cf, Am-Be and D(d,n)3He were unfolded using the mathematical program to obtain the neutron energy spectrum. The 252Cf and Am-Be neutron energy spectra were measured and the results obtained showed a good agreement with the spectra usually published in the literature. The neutron energy spectrum from D(d,n)3He was measured and the results obtained also showed a good agreement with the calculation by time of flight (TOF) methods. 相似文献
5.
An evaluation of the sensitivity of mercury and cadmium determinations in large volumes of water is presented. A 10-μg252Cf source immersed in the water sample served as a neutron source. The (n, γ) reaction on hydrogen and the inelastic scattering
from oxygen produced a background count rate that limited sensitivity. A lower limit of 20 ppm for both mercury and cadmium
was found. The procedures described here can be applied to most of the other heavy metals.
Research sponsored by the U.S. Atomic Energy Commission under contract with the Union Carbide Corporation. 相似文献
6.
A rapid method for the determination of Al, V and Ti has been developed and is used for the analysis of these elements in different ores and alloys. An isotopic neutron source252Cf having a thermal neutron flux of the order of 8.5×107 n·cm–2 sec–1 has been used for thermal neutron bombardment. Activity measurements were performed on a HPGe detector coupled to a PC based MCA unit. Depending on the half-life of the (n, ) product, different irradiation and cooling times were employed and thus the elements of interest were analyzed sequentially. 相似文献
7.
Y. J. Park B. C. Song M. I. Chowdhury K. Y. Jee 《Journal of Radioanalytical and Nuclear Chemistry》2004,260(3):585-594
A neutron induced prompt γ -ray spectrometry (NIPS) facility has been developed at the Nuclear Chemistry Research Division,
of the Korea Atomic Energy Research Institute (KAERI) with the aim of analyzing the major components of various elements in
aqueous samples. The facility is equipped with a 252Cf neutron source and a γ-γ coincidence setup with two n-type coaxial HPGe detectors based on NIM spectrometric modules in
association with data acquisition and spectral analysis systems. The development of the system, its set-up and the calibration
of detection efficiency up to 8 MeV using a set of radionuclides and the (n,γ) reactions of chlorine are described in the
paper.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
J. T. Gerard C. C. Swanson L. J. Ver Weire J. L. Pietruszewski 《Journal of Radioanalytical and Nuclear Chemistry》1979,54(1-2):59-68
A nondestructive neutron activation technique for the simultaneous direct determination of chlorine, bromine, and iodine in
silver halide mixtures is described using a252Cf neutron multiplier (CFX). About 5–50 mg of sample are used. The analysis is semiroutine, without the need for a monitor
included with each sample since the flux stability and reproducibility are within ±1%, decaying only with the 2.65 year half-life
of252Cf. The precision and accuracy are counting-statistics controlled and are generally ±1% RSD or better. The method offers an
attractive alternative to existing chemical and instrumental methods for these determinations in silver halide mixtures because
it has the potential for providing reasonably rapid analyses with good precision and accuracy. 相似文献
9.
Hector Rene Vega-Carrillo Berenice Hernández-Almaraz Victor Martin Hernández-Dávila Arturo Ortíz-Hernández 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(1):261-265
Bonner sphere spectrometer with TLDs pairs has been utilized to measure the neutron spectrum 100 cm from isocenter of a 18
MV LINAC, simultaneously the ambient dose equivalent due to neutrons and photons was measured in the control room area with
neutron and gamma-ray area monitors. Measurements were carried out when the LINAC was delivering a dose of 600 MU at the isocentre
that was located at 5 cm depth of a head phantom. Undesired neutron field in the treatment room produce activation reactions
with nuclei in different materials of LINAC, couch, air, and phantom. To determine the dose due to decay of activation nuclei
the ambient dose due to gamma-rays was measured inside the treatment room immediately after dose was delivered. Measured spectrum
has two peaks, one between 0.1–1 MeV and other in the thermal region, the ambient dose equivalent in the control room are
3.1 and 0.93 μSv h−1 for photons and neutrons, respectively. In the treatment room the ambient dose equivalent due to photons produced during
decay of activation nuclei varies from 6 to 26.1 μSv h−1. 相似文献
10.
Compton profiles of water, methanol, ethanol and mixtures of methanol—water and ethanol—water have been measured using 60 keV gamma rays from a 5 Ci annular241 Am source. The profile of each mixture has been compared with the profile of the sum of the components and at all concentrations a linear behaviour has been found. 相似文献
11.
A comparative study of radioactive X-ray fluorescence and neutron activation analysis using a low-intensity252Cf source has been carried out. X-ray fluorescence proved to be superior to NAA if ion-exchange preconcentration preceds the
instrumental method, while less difference in the minimum detectable limit was found in direct analysis of aqueous solutions. 相似文献
12.
Some macro and micronutrients in soils from some districts of Maharashtra State have been determined by instrumental neutron
activation analysis. Neutrons from 252Cf have been used for irradiation. The activity induced was measured by a HPGe detector coupled to a MCA unit. The statistical
evaluation of the method has been explained.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
13.
John S. Showell Henry M. Fales Edward A. Sokoloski 《Journal of mass spectrometry : JMS》1989,24(8):632-636
A series of mixtures of solid triglycerides and waxes are examined using 252Cf plasma desorption mass spectrometry. The relative abundances of diagnostic ions are found to vary with sample preparation, handling, and composition. It is proposed that the less efficiently packing, shorter chain, compounds are forced to the analysis site, i.e. the surface. This takes place at varying rates that reflect the bulk properties of the mixture as revealed by its phase diagram and thermal history. Mixtures that remain liquids during analysis show ion abundances correctly reflecting their composition. Mixtures of isotopomeric glycerides also show normal ion abundances. 相似文献
14.
Zhao Xin Li Xueliang Guo Jingru Wang Fangding Tang Peijia Liu Daming Cui Anzhi Su Shuxin 《Journal of Radioanalytical and Nuclear Chemistry》1993,170(1):99-106
The potteries found on the Tremiti Isles (Italy, Adriatic Sea) have been characterized through their trace elements content. The goal of the work was to find out the number of ore deposits that supplied the clay used to manufacture the pottery. Neutron activation analysis has been employed for trace elements content determinations; the results have been statistically evaluated, clusterized and discussed. 相似文献
15.
G. L. Troyer M. A. Purcell W. I. Winters 《Journal of Radioanalytical and Nuclear Chemistry》2005,263(3):587-592
An infrared furnace (ULVAC RHL-410P) was newly applied to the extraction of tritium from concrete samples. After studying the tritium recovery yield regarding temperature and time, the best extraction conditions were set to 800 °C (setting temperature) for 30 minutes under Ar-gas flow of 200 ml/min. Tritium was collected in two cold traps and transferred to a vial for liquid scintillation counting. It took about one hour for the extraction of tritium. Reproducibility and recovery yield of tritium were about 100% compared to the values obtained by the ordinary heating method using an electric furnace. Gamma-ray emitters and tritium of concrete samples collected from several accelerator facilities have been determined. The specific activity of tritium strongly correlated with that of 152Eu and 60Co, so it was found that tritium was produced by thermal neutron reaction by the 6Li(n,)3H reaction. The results indicate that the tritium specific activity in concrete can be estimated from the 60Co specific activity obtained easily by -ray measurement.On leave from IHEP, Beijing.This work was supported by Japan Society for the Promotion of Science. The authors also are grateful to Dr. S. Watanabe, Center for Nuclear Study, University of Tokyo, Dr. T. Ohtsuki, Laboratory of Nuclear Science, Tohoku University, and Dr. T. Saito, Research Center for Nuclear Physics, Osaka University, and their colleagues for concrete sampling. 相似文献
16.
H. Aldousari M. Alkhorayef D. J. Highgate A. Kacperek N. M. Spyrou 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):807-810
Hydrophilic materials which refer to a group of cross-linked polymers originally developed in the 60s to produce soft contact lenses are characterised by an equilibrium water uptake in the range 15–95 % by wet weight when hydrated in water or normal saline solution at 25 °C. This ability to absorb controlled amounts of water makes them suitable human tissue substitutes. Four types of hydrophilic materials of different composition and thickness were placed between a 22Na calibrated point source and a single LaBr3: Ce (5 %) detector (Saint-Gobain) at a fixed distance between source and detector. The scatter-to-peak ratio was determined by selecting five scatter angle windows between 25 and 50° (467–376 keV), at 5° intervals, to study how the ratio varied with attenuating material, thickness and composition. From photon spectra recorded a ‘best’ estimate of the depth of the source in the hydrophilic material was obtained by finding the most sensitive scattering window. Theoretical and practical models of the source-to-detector geometries are included and discussed. 相似文献
17.
M. C. da Rocha L. M. da Silva C. R. Appoloni O. Portezan Filho F. Lopes F. L. Melquíades E. A. dos Santos A. O. dos Santos A. C. Moreira W. E. Ptker E. de Almeida C. Q. Tannous R. Kuramoto F. H. de M. Cavalcante P. F. Barbieri A. F. Caleffi B. T. Carbonari G. Carbonari 《Radiation Physics and Chemistry》2001,61(3-6):567-569
Samples of concrete for popular habitation (0.1×0.03×0.1 m) and cellular concrete (0.1×0.05×0.1 m) were submitted to water vertical ascending infiltration. The moisture content spatial and temporal evolution of each sample it was monitored in three halfway positions in a same horizontal line, applying the gamma rays transmission method. The data were taken with a 137Cs (3.7×1010 Bq, 0662 MeV) source, Nal (Tl) of 2×2″ detector coupled to gamma ray spectrometry standard electronic with multichannel analyzer and a micrometric table. For the popular habitation concrete, there was a clear correlation between wetting profiles and concrete strength. The cellular concrete showed a wetting profile compatible to its greater porosity. 相似文献
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Yu E. Loginov A. I. Egorov G. I. Karazhanova G. N. Popova 《Journal of Radioanalytical and Nuclear Chemistry》1993,176(5):361-370
The in-beam neutron induced prompt -ray method of quantitative elemental analysis of materials and compounds used in Neutron Research Department (NRD) of PNPI and experimental arrangement installed on the horizontal channel of WWR-M reactor are described. The results of measurements of antimony concentration in the antimony doped sample of HTSC ceramics after two stages of annealing are reported. 相似文献
20.
P. Fodor-Csányi E. Keszei J. Kasza L. Fehér 《Journal of Radioanalytical and Nuclear Chemistry》1989,134(2):265-276
The migration of HTO from a point source was studied in the soil of the storage of radioactive waste at horizontal distances of 10 to 40 cm from the source between 2 and 4 m depths at 5 different rainfalls, up to 7641/m2. The water movement changed from 0.17 cm/l (at 10 cm) to 0.28 cm/l (at 40 cm distance) when 186 1 was irrigated, while at 764 1 rainfall it was found to be 0.11 cm/l at every distance. The estimated parameters of a three-dimensional migration model constructed to characterize HTO movement revealed that the HTO distribution migrates downwards in a small, about 1 m thick layer with an initial rate of 0.17 cm/l to slow down to about 0.05 cm/l after 50 years. The distribution is spreading horizontally with a constant rate of about 0.08 cm/l. 相似文献