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1.
A systematic non-destructive determination of eighteen trace elements (F, Na, Cl, Sc, Mn, Zn, Br, Sr, I, Ba, La, Ce, Sm, Eu,
Tb, Yb, Th and U) in carbonate samples by thermal neutron activation analysis was developed. Three 0.2–0.5g samples were irradiated
for 15 sec (in the case of determination of F), for 3 min (in the case of Na, Cl, Mn, Sr and I) and for 60 hrs (in the case
of Sc, Zn, Br, Ba, La, Ce, Sm, Eu, Tb, Yb, Th and U) in the TRIGA MARK II Reactor at a thermal neutron flux of 5·1011 n·cm−2·sec−1 (15 sec and 3 min irradiation) and 1.5·1012n·cm−2·sec−1 (60 hrs irradiation), respectively. According to the half life of the nuclides formed, the activities were measured with
a Ge(Li) spectrometer as follows,20F∶15 sec counting after 20–25 sec cooling,24Na,38Cl,56Mn,87mSr and128I∶600 sec couting after 30–120 min cooling,82Br,140La,153Sm,175Yb and239Np (daughter of239U)∶3000 sec counting after 1 week cooling,46Sc,65Zn,131Ba,141Ce,152Eu,160Tb and233Pa (daughter of233Th)∶5000 sec counting after 1 month cooling. The errors due to the fluctuation of the neutron flux and the counting geometry
were minimized by the use of calcium determined previously with EDTA-titration as an internal standard. The interferences
from24Mg(n, p)24Na and235U(n, fission) reactions were corrected by the activities produced by the reactions in unit weight of magnesium and uranium,
and their concentrations in samples measured experimentally. The data of Na, Mn, Zn and Sr were compared with the results
obtained by atomic absorption analysis. 相似文献
2.
H. Rausch 《Journal of Radioanalytical and Nuclear Chemistry》1976,33(2):201-207
Activation analysis and autoradiography were used to investigate the concentration distribution of contaminants in poly-Si−Si3N4−SiO2−Si substrate multilayer structures (SNOS) on sampling each technological product. Samples were irradiated for 36 hrs at a
thermal neutron flux of 4·1013n·cm−2·sec−1. The thin films of the analysed sample were removed stepwise by selective chemical etching using appropriate masking techniques.
Simultaneously autoradiographs were made of the surface of parallel samples activated under the same conditions. The concentration
of the technological contaminants (e.g. Na, Cu, Au) increases in the junction interface of the layers as unambiguously shown
by the results obtained.
Presented at the “4th Symposium on the Recent Developments in Neutron Activation Analysis” Churchill College, Cambridge, 4–7
August, 1975. 相似文献
3.
Jye-Bin Lin Jui-Ping Lee Ding-Bang Lin Wen-Kang Chen Wen-Shan Liu Chien-Yi Chen 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(3):481-487
Stray neutron distribution in a medical cyclotron vault room was evaluated by neutron activation analysis (NAA). Neutrons
were generated in the production of radioactive nuclides, such as 18F, 11C, 13N and 15O, for diagnostic usage. Indium foil was adopted to evaluate the stray fast and thermal neutron intensity based on 115In(nf, n′)115mIn and 115In(nth, γ)116m1In reactions, respectively. The indium foils were weighed, sealed and placed at 62 points around the 6.7×8.2 m2 cyclotron room. Additionally, each indium foil was exposed for over 80 minutes during cyclotron operation and γ-peaks were
analyzed using an HPGe detector to evaluate the number of stray fast (Φ
f) or thermal (Φ
th) neutrons. The minimum to maximum numbers of fast and thermal neutrons were (3.47±0.11)×103 to (1.06±0.21)×104 n·cm−2·s−1 and 9 to 965 n·cm−2·s−1, respectively. The minimum detectable limit for stray neutrons was included herein to demonstrate the reliability. Accordingly,
60 and two points, respectively, the confidence level associated with the reported intensities of fast and thermal neutrons
reached 95%. The low qualified ratio in the evaluation of stray thermal neutrons might have been caused by either the high
Compton scattering plateau or the low intensity of the gamma-ray peak in the relevant spectrum. 相似文献
4.
M. Kubota 《Journal of Radioanalytical and Nuclear Chemistry》1977,36(2):565-576
In determining the trace impurities existing in high-purity rare earth samples by the neutron activation analysis, there are
much interference due to nuclides induced from neutron induced second order nuclear reaction. This paper presents the degree
of interference calculated over the ranges of irradiation time from 105 to 107 sec and of thermal-neutron flux from 1·1012 to 1·1015 n·cm−2·sec−1. According to the results of these calculations, degree of interference under the neutron irradiation condition for 288 hrs
in the thermal-neutron flux of 3·1013n·cm−2·sec−1 is concluded to be 6.4·106 ppm Gd in Eu, 2.2·104 ppm Sm in Eu, 1.9·104 ppm Ho in Dy, 1.1·103 ppm Eu in Sm, 1.1·102 ppm Ce in La and 1.1·10 ppm Tb in Gd, respectively. Especially, the Gd determination in the Eu target is extremely affected
by153Gd formed from the151Eu (n, γ)
reaction. On the contrary, this reaction is effective in producing153Gd activity. 相似文献
5.
P. Bussiere A. Laurent E. Junod 《Journal of Radioanalytical and Nuclear Chemistry》1969,2(3-4):211-217
A method applicable for serial determination of traces of chlorine in SiO2−Al2O3 catalysts by neutron activation is described. The results are evaluated by means of a computer. The38Cl activity is subtracted from the activity of the interfering components (56Mn,24Na) and this enables a direct γ-spectrometric determination. In praxis ten samples should be irradiated simultaneously and
for this reason 3 standards are irradiated together with the samples to correct for the fluxus gradient. The reproducibility
of the method is better than 2 per cent for 10–300 mg samples with a Cl content of 10 ppm.
相似文献
6.
Determination of isotopic composition of lithium by neutron activation analysis; comparison with mass spectrometry 总被引:1,自引:0,他引:1
An activation analysis method is described for routine determination of6Li-abundances in various lithium compounds on the basis of the reaction sequence6Li(n,α)T and16O(t, n)18F and the measurement of18F. Irradiations of diluted equeous solutions of samples containing CrO3 as internal flux monitor were carried out at a thermal neutron flux density of ϕ≤1011 n·cm−2·sec−1. Interferences from variations in neutron self-shielding oxygen concentration and triton range do not exceed 0.5% when using
the dilution technique. The results for6Li abundances from 3.52 to 7.60% with standard deviations of 1 to 2.5% were confirmed by mass spectrometric measurements. 相似文献
7.
A sensitive, simple and time-saving method has been developed for the neutron activation analysis of gallium at concentrations
around 10−4 ppm in biological tissues. After a 24-hour irradiation in a thermal neutron flux of 2.8·1013 n·cm−2·s−1 and a purification by ion-exchange chromatography to eliminate troublesome elements such as sodium, iron and copper, the72Ga activity is measured with enough accuracy for the method to be applicable in animal physiology and clinical toxicology. 相似文献
8.
A collimated neutron beam capable of providing a thermal neutron flux of 4.75·107 n·cm−2·sec−1 has been used to analyze alloy samples of 1–5 g during relatively short irradiation times of 30 min by the use of neutron
capture gamma-ray spectrometry. The analyses were performed by using a mathematical treatment that relates the count ratio
of every constituent present in the matrix with the concentration and thus it requires no standards. The technique was applied
to the analysis of steel and gold alloy samples. Errors ranged from 0.8%–10%. 相似文献
9.
A rapid method has been developed for the determination of tungsten, especially in rocks. The reaction182W(n, γ)183mW (T=5.3 sec), with a thermal neutron capture cross-section of 0.5 b was used. The samples were irradiated in the fast pneumatic
system of the FRM, which is described briefly. The low-energy γ-rays of the isomer183mW were measured by a high-resolving Ge(Li) detector. The sensitivity of the method is 0.1 mg tungsten with an accuracy of
about 5%; the minimum concentration is 0.1–0.2% W in geological samples. The analysis time is 2 min per sample. 相似文献
10.
A. Godelitsas M. Kokkoris P. Misaelides 《Journal of Radioanalytical and Nuclear Chemistry》2007,271(2):339-344
To enhance the applicability of the nuclear analytical technique in the field of industry and the environment, the inorganic
elemental content of the bottom ash from a municipal solid waste incinerator was determined by instrumental neutron activation
analysis. Bottom ash samples were monthly collected from an incinerator located at a metropolitan city in Korea, strained
through a 5 mm sieve, dried by an oven and pulverized by an agate mortar. The samples were irradiated at the NAA #1 irradiation
hole (thermal neutron flux: 2.92·1013 n·cm−2·s−1) in the HANARO research reactor of the Korea Atomic Energy Research Institute and the irradiated samples were measured by
a HP Ge gamma-ray spectrometer. Thirty-three elements including As, Cr, Cu, Fe, Mn, Sb and Zn were analyzed by an absolute
method. The quality control was conducted by a simultaneous analysis with NIST standard reference materials. The average concentrations
of the major elements such as Ca, Fe, Al, Na, Mg, K and Ti measured in the sample were 19.9%, 4.85%, 3.79%, 2.11%, 1.84%,
1.22% and 1.02%, respectively. In addition, the concentrations of the hazardous metals like Zn, Cu, Cr, Sb and As were 0.77%,
0.31%, 729 mg·kg−1, 116 mg·kg−1 and 22.2 mg·kg−1, respectively. 相似文献
11.
C. Vandecasteele R. Kieffer J. Hoste 《Journal of Radioanalytical and Nuclear Chemistry》1977,37(1):255-265
Fast neutrons produced by irradiation of a thick beryllium target with 20–50 MeV deuterons are used for activation analysis.
The spatial neutron flux distribution around the target is measured. A rotating sample holder is used for the simultaneous
irradiation of samples and standards. Instrumental analysis can be applied for a number of elements. As an example, results
for calcium and strontium in some reference materials are given. The19F(n, 2n)18F reaction is used for the radiochemical determination of fluorine in rocks with a fluorine concentration ranging from 9 to
5400 μg·g−1
Aspirant of the N.F.W.O. 相似文献
12.
P. K. Nayak B. Wierczinski S. Lahiri 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(1):179-184
Representative banded iron-formations (BIFs) from various locations of the eastern Indian geological belt were investigated
by instrumental neutron activation analysis (INAA). After pre-concentration, irradiation was carried out using a neutron flux
of 5.1·1016 m−2·s−1, 1.0·1015 m−2·s−1 and 3.7·1015 m−2s−1, with thermal, epi-thermal and fast neutrons, respectively. The activities in these samples were measured by a HPGe detector.
Ten rare-earth elements, such as La, Ce, Nd, Sm, Eu, Tb, Ho, Tm, Yb and Lu, have been qualitatively identified and quantitatively
estimated in these samples. The present investigation is an example of employing a pre-concentration method for high iron-containing
ores prior to neutron activation analysis. 相似文献
13.
R. K. Singhal J. Preetha Rupali Karpe P. Hema Ajay Kumar V. M. Joshi A. K. Ranade A. G. Hegde 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(1):301-306
During this work the determination of uranium in the range of μg·L−1 to tens of μg·L−1 was done by alpha-spectrometry after electroplating the aliquots of water sample using (NH4)2SO4 as an electrolyte. In general, the determination of uranium by alpha-spectrometry needs its separation from other transuranics
specially thorium. The process described here does not involve any sample digestion and radiochemical separation of uranium
from other transuranics. In this method an aliquot (1 to 3 mL) of the sample was dried and dissolve in (NH4)2SO4 and thereafter the sample was electroplated on a stainless steel (SS) planchet by using an electrochemical cell of special
design. The proposed techniques have a distinct advantage over the determination of uranium by adsorptive stripping voltammetry
(AdSV) in which uranium-chloranilic (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) acid complex was used for concentrating
the uranium from the solution. Since in the case of AdSv, the determination of uranium was not possible for samples having
dissolved organic carbon (DOC) more than 15 mg·L−1 and Cl− concentration is in the range of 40,000 μ·g−1. In the case of spike experiments with 232U the recovery was observed in the range of 90–95% in aqueous medium having higher concentration of Cl− and DOC as indicated above. 相似文献
14.
Bangfa Ni Caijing Xiao Donghui Huang Hongchao Sun Guiying Zhang Cunxiong Liu Pingsheng Wang Haiqing Zhang Weizhi Tian 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):313-319
China Advance Research Reactor (CARR) at China Institute of Atomic Energy (CIAE), with a non-perturbed maximum thermal neutron
flux of 1 × 1015 cm−2 s−1 at the center of active area, is one of the most powerful research reactors in the world. Three neutron channels have been
allocated for conventional neutron activation analysis (NAA), thermal neutron prompt gamma activation analysis (PGAA) and
cold neutron PGAA, respectively. Two irradiation tube systems are installed in the conventional NAA channel. One of them is
for short irradiation with the rabbit size of diameter (Φ)19 × 40 mm, the other one is for long irradiation with the rabbit
size of Φ39 × 70 mm. The medium temperature is about 45 °C and the thermal neutron flux is about 3 × 1014 cm−2 s−1 at sample positions. The flux gradient is expected to be very small according to the designed neutron flux distribution.
Pneumatic systems are used for samples transfer. The speed of rabbits is designed to be about 20 m/s, and it takes 3 s to
travel from irradiation position to detector. Three sets of gamma counting systems and one delayed neutron counting system
are being equipped for routine analysis. They are designed for running continuously and automatically. And all the functions
can be operated at laboratory or office through remote controlled computer. Software has been made domestically for spectrum
peak search, concentration calculation with relative method and k0 method with interference corrections and some other functions for the convenience of users. 相似文献
15.
S. M. Sprague J. T. Carrick B. W. Wilkinson G. H. Mayor 《Journal of Radioanalytical and Nuclear Chemistry》1979,52(2):421-426
We describe a method for gold analysis in kidney and liver. The technique is simpler than other methods in that it does not
require ashing or acid digestion of the sample. The tissue is dried, placed into a polyethylene vial and diluted with a 2
ml sodium chloride solution. Gold concentration is determined by neutron activation analysis. Samples are irradiated for two
hours at a thermal neutron flux of 1012n·cm−2·s−1 and are then allowed to decay for 3–4 days before counting. The detection limit (20 ng Au/ml) and precision (±6.1%) permits
the accurate analysis of gold in these tissues. This technique could aid in a re-examination of gold metabolism. 相似文献
16.
A procedure for the determination of chromium in blood has been developed with a sensitivity of 5×10−3 μg Cr. Dried blood was irradiated with a neutron flux of 1012 n·cm−2·sec−1 in the VVRS reactor for 4 weeks, then the sample was mineralized and the chromium isolated by extraction as perchromic acid.
The determination of the chromium content was accomplished by measuring the 0.32 MeV gamma energy of51Cr. In order to make correction for the interfering reaction54Fe(n,α)51Cr, the formation of chromium from high-purity iron was investigated. The chromium content of the blood samples was between
1.03×10−2 and 5.2×10−2 ppm Cr. 相似文献
17.
A method was developed for the determination of 15 trace elements in tin. High-purity tin samples (99.9999% and 99.999%) as
well as tin of technical quality were analysed. Reactor neutron activation of the tin samples was followed by distillation
of the matrix activities from a HBr−H2SO4 medium and Ge(Li) gamma-ray spectrometry of the distillation residue. The sensitivity of the method is generally high. For
the high-purity samples the detection limits vary from 0.02 ppb (scandium) to 200 ppb (iron) for irradiation of 1 g of tin
for 1 week at a thermal flux of 5·1012n·cm−2. ·sec−1. To decontaminate the surface of the tin samples, pre- and post-irradiation etching procedures were applied. The efficiency
of these etching techniques was studied. 相似文献
18.
Marián Kucharík Michal Korenko Du?an Jani?kovi? Magdaléna Kadle?íková Miroslav Bo?a Jozef Vincenc Oboňa 《Monatshefte für Chemie / Chemical Monthly》2010,38(5):7-13
Abstract
Rapid solidification processing (with a cooling rate in the interval 105–106 K s−1) was used to prepare deeply undercooled cryolite–alumina melts. These samples were analyzed by XRD, infrared, and Raman spectroscopy. Besides cryolite, the amorphous phase and a low amount of ι-Al2O3 were detected. Annealing of the quenched sample revealed the transformation of metastable amorphous phases into different products depending on the annealing conditions. The results obtained showed that all of the elements (Na, Al, O, and F) are probably present in the amorphous parts of the quenched samples. 相似文献19.
S. Ohde K. Tanaka A. Snidvongs H. Matsue 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):401-406
A systematic and non-destructive technique is proposed for the determination of boron in coral samples by neutron-induced
prompt γ-ray analysis (PGA) using a thermal neutron guide beam of the JRR-3M reactor. About 50–150 mg samples in sealed FEP
film were irradiated and measured for 5000 s in the PGA system at a neutron flux of 2.4 × 107 n cm−2 s−1. In order to determine B content in coral skeletons, the Doppler-broadened γ-ray peak of 478 keV (10B) was used together with the correction of interference from the Na-peak of 472 keV. The analytical precision was ~3% for
the JCp-1 coral standard. The data (n = 56) obtained by the present method showed a range of B content from 40.7 to 76.9 ppm which is similar to reported values.
Boron in corals showed the highest levels in Rukan-sho (Okinawa) with an average B content of 62.5 ppm, whereas corals collected
from Mizugama (Okinawa), Cebu (the Philippines) and Khang Khao (Thailand) exhibited B contents of 56.5, 53.0 and 45.7 ppm,
respectively. The uptake of boron by living corals may be influenced by seawater pH related to higher seawater B(OH)4−. In this paper we discuss factors controlling the B levels in corals. 相似文献
20.
F. Z. Khiari A. Aksoy A. Sahin 《Journal of Radioanalytical and Nuclear Chemistry》2004,261(3):507-511
Extensive sedimentary phosphate deposits exist in the Sirhan-Turayf basin in northwestern Saudi Arabia containing significant
amounts of uranium, thorium, vanadium and rare earth elements. The determination of the concentration and pattern of distribution
of some of these elements is essential for economic aspects. This study reports the analysis of vanadium in selected phosphate
rock samples from the basin using accelerator-based thermal neutrons activation analysis (TNAA). Samples were irradiated in
a thermal neutron flux of 2.5·106 n·cm−2·s−1. The induced activity was measured with a HP-GMX detector coupled to a PC-based data acquisition and analysis system. The
facility was calibrated using certified standards of vanadium. The minimum detection limit of vanadium was about 1 mg. Three
independent measurements on each sample yielded comparable results indicating the reliability of the technique. The vanadium
concentrations in the samples vary from 23 to 457 ppm.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献