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1.
Separation and purification of <Superscript>249</Superscript>Cf and <Superscript>245</Superscript>Cm
There is a need to provide radioactivity standards of the higher actinides in support of both decommissioning and remediation
activities as well as routine environmental analysis. In the case 249Cf, this will provide a useful calibration nuclide for both α-and γ-spectrometry as well as improving knowledge of the decay
scheme for this nuclide. There is anecdotal evidence to suggest that the chemical yield of americium and curium may differ
in radiochemical analysis. Thus, a chemical yield tracer of 245Cm may help to resolve this issue and will be suitable for both, suitable for use as a chemical yield tracer for both α-particle
spectrometry and mass spectrometry. An aged source of 249Cf was used as the source material for the separation of these two nuclides by cation-exchange, using 2-hydroxy-2-methyl-propanoic
acid at controlled pH as an eluant, 249Cf being eluted before the 245Cm daughter. The purity of both nuclides was measured by γ-ray spectrometry. 相似文献
2.
Summary The decay of 101Tc to 101Ru has been studied using high resulation HpGe detectors in single and coincidence mode. Technetium-101 was produced via the 98Mo(α,p)101Tc reaction. The results of the present experiment verified the previously reported levels of 101Ru, but in addition to the known transitions and levels, the 174.91, 226.02, 312.40, 408.77, and 417.91 keV gamma-rays were observed for the first time and they were placed in the decay scheme. At the same time, the transition position of 616.3 keV gamma-ray has been assigned. For most levels the intensities of β--decay and the values of log ft were calculated. 相似文献
3.
To reduce the influence of the between-spectra variability on the results of peptide quantification, one can consider the
18O-labeling approach. Ideally, with such labeling technique, a mass shift of 4 Da of the isotopic distributions of peptides
from the labeled sample is induced, which allows one to distinguish the two samples and to quantify the relative abundance
of the peptides. It is worth noting, however, that the presence of small quantities of 16O and 17O atoms during the labeling step can cause incomplete labeling. In practice, ignoring incomplete labeling may result in the
biased estimation of the relative abundance of the peptide in the compared samples. A Markov model was developed to address
this issue (Zhu, Valkenborg, Burzykowski. J. Proteome Res. 9, 2669–2677, 2010). The model assumed that the peak intensities were normally distributed with heteroscedasticity using a power-of-the-mean
variance funtion. Such a dependence has been observed in practice. Alternatively, we formulate the model within the Bayesian
framework. This opens the possibility to further extend the model by the inclusion of random effects that can be used to capture
the biological/technical variability of the peptide abundance. The operational characteristics of the model were investigated
by applications to real-life mass-spectrometry data sets and a simulation study. 相似文献
4.
Huang Donghui Wang Pingsheng Chen Xilin Tian Weizhi Ni Bangfa Zhang Lanzhi Zhang Guiying Liu Cunxiong Liu Likun 《Journal of Radioanalytical and Nuclear Chemistry》2005,265(3):499-503
Summary The half-life of 97Zr, used for the calculation of thermal/epithermal neutron flux ratio in k0-NAA, is re-determined using three measurement systems with different pulse processing principles. The result of 16.755±0.013 hours clarifies the discrepancy between two widely used literature values, 16.744±0.011 and 16.90±0.05 hours. Different dead-time correction methods used on various measurement systems are evaluated. Factors influencing precise measurement of relative peak counting rates are discussed in time-series measurements over a dynamic range of 1000-fold radioactive intensities (10 half-lives). 相似文献
5.
M. S. Abdelmonem A. A. Naqvi Hanan Al-Ghamdi Ghada Al-Misned 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(1):131-137
Performance of a 241Am-Be neutron source-based and 2.8 MeV neutrons-based moisture measurement setups have been compared using Monte Carlo simulation.
In the setup fast neutrons transmitted through the sample were detected by a fast neutron detector, which was placed behind
a massive long double truncated collimator. The setup geometry was optimized to detect maximum effect of 1–7 wt.% moisture
on the neutron intensity transmitted through the sample. The yield of neutrons transmitted through concrete, coal, wood and
soil samples containing 1–7 wt.% moisture was calculated for 2.8 MeV neutrons and neutrons from an 241Am-Be source. The slopes of the fast neutron intensities transmitted through the samples vs. their moisture contents are very
sensitive to the neutron energy and the sample composition. Higher slopes have been observed for the samples with larger bulk
density. The slopes of fast neutron yield show dependence on the incident neutron energy. Larger slopes have been observed
for neutrons with samller energy. Due to the overall large slopes of the transmitted intensity data of the samples for 2.8
MeV neutrons, it is expected to achieve better sensitivity in moisture measurements for a 2.8 MeV neutrons based moisture
setup. 相似文献
6.
T. Belgya 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(3):609-614
The 14N(n,γ)15N reaction is a primary γ-ray source for high energy calibration of detectors. The relative γ-ray-intensities of 15N and the relative γ-ray detection efficiency function have been simultaneously determined up to 10 MeV from γ-peak areas
alone. Absolute γ-ray-intensities were obtained with proper renormalization to known absolute intensity. The influence of
these new intensity values are assessed for use in PGAA. Any consistently used set of calibration intensities applied in the
creation of library values and for analysis do not influence the concentrations. Contrary to this, quantities based on sums
of γ-ray cross sections may provide different answers with the new 15N intensities and they give means to validate them. 相似文献
7.
T. Newton Nathaniel K. Sudarshan A. Goswami A. V. R. Reddy 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(2):481-485
A non-destructive assay technique based on prompt gamma-ray neutron activation analysis for the determination of 238U to 232Th ratio in the mixed oxide fuel materials has been established. The method uses closely spaced high energy gamma-rays in
the region of 4000 keV to 4150 keV enabling it to be applied for samples of any geometry and thickness without having any
correction for gamma-ray attenuations and detection efficiencies. 相似文献
8.
The changes of decay rates of radionuclide 111in (electron capture) and 32p (β decay) induced by external mechanic motion are studied. The results indicate that, in the external circular rotation in clockwise and anticlockwise centrifuge on Northern Hemisphere (radius 8 cm, 2000 r/min), the half life of 111in compared with the referred (2.83 d) is decreased at 2.83% and increased at 1.77%, respectively; the half life of 32P compared with the referred (14.29 d) is decreased at 3.78% and increased at 1.75%, respectively. When the clockwise and anticlockwise rotations increase to 4000 r/min, the half life of 111in is decreased at 11.31% and increased at 6.36%, respectively; the half life of 32P is decreased at 10.08% and increased at 4.34%, respectively. When the circular rotation is removed, the decay rates of 111in and 32P return back to the referred, respectively. It is found that the external circular rotations in clockwise and anticlockwise centrifuge selectively increased and decreased the decay rates of 111in and 32p, respectively, and the effects are strongly dependent on the strength of circular rotation. It is suggested that these effects may be caused by the chiral interaction. 相似文献
9.
N. M. Antovic V. Popovic I. Antovic N. Svrkota P. Vukotic 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):81-88
A coincidence method for measuring 137Cs, 40K, 226Ra and 232Th decay products activity in soil, vegetation and fish samples, was applied to the six-crystal gamma-coincidence spectrometer
PRIPYAT-2M. In this way, some problems appeared in simultaneous measurement of 137Cs, 226Ra and 232Th by NaI(Tl) detectors and the PRIPYAT-2M spectrometer were solved. The obtained results were agreeable with the HPGe spectrometer
ones. 相似文献
10.
B. S. Cao Z. Q. Feng Y. Y. He H. Li B. Dong 《Journal of Sol-Gel Science and Technology》2010,54(1):101-104
The Er3+-Li+ codoped TiO2 powders have been prepared by the non-aqueous sol–gel method. The green and red upconversion emissions centered at about
526, 550 and 663 nm were observed by the 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+, respectively. Li+ codoping has opposite effect on the upconversion emissions intensities for Er3+-doped TiO2 at sintering temperatures of 1,073 and 1,273 K. At 1,073 K, the Er3+-doped TiO2 phase transition from anatase to rutile was accelerated with increasing Li+ codoping concentration, leading to the increase of crystal field symmetry of Er3+, thus the upconversion emissions intensities decreased. At 1,273 K, Li+ codoping had no effect on the phase structure of Er3+-doped TiO2 and only increased the Er–O bond length, it indicated that the upconversion emissions intensities greatly enhanced because
of the decrease of crystal field symmetry of Er3+. 相似文献
11.
Baki B. Sadi Christopher Rinaldo Norman Spencer Chunsheng Li 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(1):179-189
A radiobioassay method has been developed for the sequential determination of 90Sr, 241Am and Pu isotopes in a urine sample. Unlike the existing methods using multiple extraction chromatographic cartridges, this work demonstrates an application of an automated ion chromatographic (IC) system for the separation of these radionuclides on a single IC column. The method meets the bioassay performance criteria for relative bias and relative precision as recommended by ANSI/HPS N13.30-2011. The detection limits for the radionuclides are found to be satisfactory for medical intervention in case of an accidental exposure scenario. Sample preparation time is less than 11 h. 相似文献
12.
Ishwar Prasad Sahu D. P. Bisen Raunak Kumar Tamrakar Ravi Shrivastava 《Research on Chemical Intermediates》2016,42(3):1823-1843
The Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+, Dy3+ long afterglow phosphors were synthesized under a weak reducing atmosphere by the traditional high temperature solid state reaction method. The synthesized phosphors were characterized by powder X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) techniques. The luminescence properties were investigated using thermoluminescence (TL), photoluminescence (PL), long afterglow, mechanoluminescence (ML), and ML spectra techniques. The crystal structure of sintered phosphors was an akermanite type structure, which belongs to the tetragonal crystallography. TL properties of these phosphors were investigated, and the results were also compared. Under the ultraviolet excitation, the emission spectra of both prepared phosphors were composed of a broad band peaking at 535 nm, belonging to the broad emission band. When the Ca2MgSi2O7:Eu2+ phosphor is co-doped with Dy3+, the PL, afterglow and ML intensity is strongly enhanced. The decay graph indicates that both the sintered phosphors contain fast decay and slow decay process. The ML intensities of Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors were proportionally increased with the increase of impact velocity, which suggests that this phosphor can be used as sensors to detect the stress of an object. 相似文献
13.
S. Salminen J. Paatero P. Roos K. Helariutta 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):405-413
Activity concentrations of 237Np in peat and lichen samples in Finland were determined and contributions from nuclear weapons testing in 1950–1960s and
the Chernobyl accident were estimated. 237Np was determined with ICP-MS using 235Np as a tracer. Activity concentrations of 237Np in peat samples varied between 1.98 ± 0.05 and 14.1 ± 0.3 mBq/m2. The contribution from the Chernobyl accident to the total 237Np deposition in peat was 0.1–13%, the Chernobyl-derived fraction of total 237Np in peat being much lower than the previously determined corresponding Chernobyl-derived fractions of 239+240Pu, 241Pu, 241Am and 244Cm. 相似文献
14.
Methodologies for the quantification of measurement uncertainties associated with the determination of 210Pb- and 210Po-specific activities by liquid scintillation counting (LSC) and alpha-particle spectrometry are presented, and are demonstrated
using the soil reference material IAEA-326. Major contributors to the combined uncertainty associated with the measurement
result of 210Pb were the uncertainties of net count rates in the 210Pb energy region of the sample spectrum and in the 210Bi energy region of the blank spectrum. The predominant sources of uncertainty in the measurement of 210Po were the uncertainties of net count rates in the regions of interest of 209Po and 210Po. The relative standard uncertainty of 210Po exponentially increases with the time interval between the sampling date and the separation date of Po, and this effect
is strongly dependent on the 210Po/210Pb activity ratio. When the specific activity of 210Pb is much higher than that of 210Po in the sample, the relative standard uncertainty of the 210Po determination increases significantly within a short time interval between the sampling date (or reference date) and the
separation date of Po in samples. 相似文献
15.
Chang Heon Lee Moo Yul Suh Kwang Yong Jee Won Ho Kim 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(1):187-194
A sequential separation procedure has been developed for the determination of 99Tc, 94Nb, 55Fe, 90Sr and 59/63Ni in various radioactive wastes generated from nuclear power plants. Ion exchange and extraction chromatography were adopted
for individual separation of the radionuclides. Precipitation was supplementarily utilized for both purification of the individual
radionuclides and preparation of the radionuclide sources for use in a radioactivity measurement. The chromatographic separation
behavior of the radionuclides both from the sample matrix metals and from one another was investigated using stable metals,
Re (as a surrogate of 99Tc), Nb, Fe, Sr and Ni. The validity of the procedure for reliability and applicability was evaluated by measuring the recovery
of the metal carriers added to synthetic radioactive waste solutions. The recoveries by the chromatographic separation were
in the range of 84.8 to 102.2% with 2s of less than 8.6%, the recoveries by the precipitation being in the range of 84.3 to 97.3% with 2s of less than 10.9%. 相似文献
16.
P. Vesterbacka S. Klemola K. Salahel-Din M. Saman 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):441-448
An intercomparison of the methodology (alpha, beta and gamma spectrometry) used for 238U, 235U and 210Pb determination was carried out based on 38 sediment samples. The activity range of the samples varied from 10–700 Bq/kg
for 210Pb, 1–35 Bq/kg for 235U and 10–800 Bq/kg for 238U. Results obtained using the three methods were not statistically different at high activity levels, but agreement between
the results decreased at lower sample activity levels. For 210Pb, the smallest difference was found between alpha and gamma spectrometry. A good correlation between results from alpha
and gamma spectrometry was observed over the whole activity range. In beta spectrometry, the results were slightly higher
than those obtained by alpha or gamma spectrometry due to the impurity of 228Ra. In 238U analysis, good correspondence was observed between 238U determined by gamma and alpha spectrometry, particularly at higher 238U activity concentrations over 100 Bq/kg. In 235U analysis, attention needs to be paid to interference from 226Ra and its reduction. 相似文献
17.
W. E. Kieser X. L. Zhao C. Y. Soto B. Tracy 《Journal of Radioanalytical and Nuclear Chemistry》2005,263(2):375-379
Summary The advantages that accelerator mass spectrometry (AMS) provide for radiocarbon analysis, notably smaller sample sizes and shorter measurement times, also apply to the analysis of 129I. In this paper, the requirements for a mass spectrometry system for measuring extremely low concentrations of rare atoms are discussed and these requirements are illustrated using the details of the AMS analysis of 129I. As an example of an application of this AMS technology, a series of 129I measurements, used to identify isolated events in which radioactivity has been atmospherically transported into the Arctic, is described. Such investigations could not be carried out without the small sample size capability of AMS analysis. 相似文献
18.
Vladimir S. Semenishchev Viktor P. Remez Anna V. Voronina 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(3):1311-1318
The Sorben-Tec system was tested for rapid dosimetric evaluation of 222Rn level in drinking water in domestic conditions using a dosimeter of beta radiometer as a measurement equipment. It was shown that the method is cheap, rapid and very simple, therefore it can be used by population for rapid radiation safety assessment of drinking water. The sorption-active Sorben-Tec system contains iron hexacyanoferrate allowing for separation of approximately 40% of both 214Pb and 214Bi, the short-lived decay products of 222Rn from 5 L water sample. It was assessed that the Sorben-Tec system provides detection limits of radon in 5 L water samples of 35–40 and 10 Bq L?1 for dosimetric and radiometric measurements respectively. The total time consumption of analysis does not exceed 1 h excluding the time for 214Pb and 214Bi ingrowth in the water sample (min. 3 h). Due to an insignificant sorption of radon, it is possible to reuse spent Sorben-Tec system again 3–4 h after previous analysis. 相似文献
19.
Xiaolin Hou 《Journal of Radioanalytical and Nuclear Chemistry》2017,314(2):659-668
Technetium-99m is the principal radioisotope used in medical diagnostics; radionuclidic impurity is the major concern of its quality. This work presents a analytical method for sequential determination of all radionuclidic impurities listed in pharmacopoeia including gamma emitters, alpha emitters, 89Sr and 90Sr. Radioactive decay for removal of 99mTc, ion exchange and extraction chromatography for removal of 99Mo and 99Tc are effective for separation of interferences. Gamma spectrometry, LSC with alpha/beta discrimination, and Cherenkov counting using LSC are sensitive methods for measurement of the impurity radionuclides. The detection limits of this method are well meet the requirement of the quality control according to the limitation of the pharmacopoeia. 相似文献
20.
Marin Ayranov Dorothea Schumann 《Journal of Radioanalytical and Nuclear Chemistry》2010,286(3):649-654
The station for pions cancer therapy was operated at PSI from 1980 to 1992. After a cooling time of 12 years it’s made of
copper beam dump was cut and samples were taken for analytical purposes. The sampling collected about 500 g of high active
copper chips that can be used for separation of exotic radionuclides. The analyses by gamma spectrometry, LSC and AMS showed
main nuclides present to be 60Co, 54Mn, 22Na, 65Zn, 26Al, 53Mn, 59Ni, 63Ni, 55Fe and 60Fe and 44Ti with a daughter nuclide 44Sc. In the frame of ERAWAST project a procedure combining selective precipitation and ion exchange for the separation of the
rare radionuclides from the copper beam dump was developed. The proposed separation procedure is easy for remote controlled
implementation in a hot cell. The ion exchange separation of Ni, Al, Mg, Ti and Fe was complete and high decontamination factors
for copper and cobalt were achieved. Based on the developed procedure a remotely controlled system for separation of exotic
radionuclides from the copper chips was set up. The full scale system was installed in a hot cell where high activity levels
can be handled. In order to evaluate the reliability and functionality of the system extensive tests have been done. During
the test period 13.86 g in total of the proton irradiated copper beam dump were processed for separation of 26Al, 59Ni, 53Mn, 44Ti and 60Fe. The results showed that the system was operational and the radionuclide separation was selective with high chemical yield.
The procedure manages as well the generated liquid wastes containing high level of 60Co activity. 相似文献