共查询到20条相似文献,搜索用时 15 毫秒
1.
D. L. Anderson M. P. Failey W. H. Zoller W. B. Walters G. E. Gordon R. M. Lindstrom 《Journal of Radioanalytical and Nuclear Chemistry》1981,63(1):97-119
A facility for neutron-capture γ-ray spectroscopy for analytical purposes has been developed and tested at the National Bureau
of Standards reactor. The system consists of an internal beam tube with collimators, an external beam tube and irradiation
station, a Compton-suppressed Ge(Li) γ-ray detection system, and a minicomputer-based data-collection and-analysis system.
Detection limits have been established for many elements and errors arising from neutron self shielding, γ-ray peak overlap,
neutron beam variations, and sample matrix evaluated. 相似文献
2.
G. Küppers 《Journal of Radioanalytical and Nuclear Chemistry》1999,241(3):503-509
First results of γ-spectrometric measurements of radionuclides produced in a tantalum target irradiated for 500 days with
800 MeV protons are presented. The activities of the γ-ray-emitting nuclides measured after a cooling period of 2–4 years
differ by more than four orders of magnitude. Within this cooling period about 95% of the activity of the target is determined
by172Lu,173Lu,174Lu,172Hf (daughter nuclide of172Lu) and182Ta nuclides. These highly active nuclides, together with some other medium-active nuclides, were measured with good precision
by γ-ray spectrometry directly in the sample solution. Weakly active nuclides could not be measured in this way because of
the high Compton background in the γ-ray spectrum. For the sensitive measurement of many other nuclides present in weaker
activities a simple chemical separation procedure was developed to separate Lu, Hf and Ta. With the separation of these elements
and simultaneously of the high-active nuclides, the Compton background in the γ-ray spectra could be drastically reduced and
many weakly active nuclides additionally measured. 相似文献
3.
Yuichi Hatsukawa Takahito Osawa Masumi Oshima Yosuke Toh Atsushi Kimura Mitsuo Koizumi Kazuyoshi Furutaka 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):143-145
In this study, the Ir concentrations in some standard rock samples were determined by using the multiple γ-ray detection method.
The use of the multiple γ-ray detection method, which was developed for nuclide quantification, yielded better resolution
and sensitivity than the ordinary singles γ-ray detection method. Iridium is one of the least abundant elements in Earth’s
crust, with an average mass fraction of 0.001 ppm in a crust rock. However, iridium is relatively more abundant (concentration:
0.5 ppm or more) in undifferentiated meteorites. Therefore iridium abundance anomalies in geological samples provide important
information about meteorite impact. The standard rock samples used in this study were SARM-76, FC-1 and FC-2. The SARM-76
was prepared from a platinum ore, and issued by the south African bureau of standards. FC-1 and FC-2 were obtained from fish
clay sediment samples from Stevens Klint, Denmark. 相似文献
4.
T. Bennett D. Cavers J. M. D'Auria 《Journal of Radioanalytical and Nuclear Chemistry》1973,13(1):201-212
The purpose of this study was to demonstrate the versatility of combining the use of high resolution, Ge(Li) γ-detectors with
the techniques of fast neutron activation analysis. A compilation of γ-ray spectra are presented for irradiation of 30 elements
with 14.8 MeV neutrons under standard conditions and the origin of all major photopeaks is determined. 相似文献
5.
Pulsed neutron-based on-line coal analysis 总被引:2,自引:0,他引:2
L. Dep M. Belbot G. Vourvopoulos S. Sudar 《Journal of Radioanalytical and Nuclear Chemistry》1998,234(1-2):107-112
A neutron generator-based on-line coal analysis system is described, capable of measuring the content of the major and minor
elements in coal. The system utilizes reactions produced from fast and themal neutrons, as well as from neutron activation
with half lives of seconds or minutes. Characteristic γ-rays, detected with BGO detectors are used for the identification
of the various chemical elements. The method for the analysis of the γ-ray spectra is presented, and the measurements of coal
density, carbon and sulfur content are shown. 相似文献
6.
A comprehensive compilation of X- and γ-ray emitting isotopes produced by the (n, γ) reaction is reported in this paper for
application to instrumental neutron activation analysis (INAA). The X- and γ-ray sensitivities are computed theoretically
by a computer code. Interfering photons from isotopes of neighbouring elements are identified by the code and the percentage
interference is computed. Additionally an advantage factor (X-ray: γ-ray sensitivity) is computed, which is a figure of merit
for X-ray spectroscopy in INAA. Further, mathematical representation of background continua for typical matrices encountered
in INAA allow the calculation of elemental detection limits for the X-ray and γ-ray photons. 相似文献
7.
An empirical study has been made of the potential of high energy γ photon activation and high resolution γ-ray spectrometry
for the survey analysis of trace elements in a variety of materials. Human blood, urine, bone ash, standard glass (NBS, SRM
612) and air particulates, along with synthetic multi-element standards, have been studied following irradiation with γ photons
of maximum energy 17–45 MeV. Elements found to be suited to determination by γ activation include Sb, As, Bi, Cd, Cs, Ca,
Ce, Cr, Fe, Au, Pb, Mg, Mo, Ni, Nb, Rb, Sr, Tl, Ti, Tm, Zn and Zr. γ spectra, elemental concentrations measured, and/or limits
of detection observed, for the matrices studied are given. 相似文献
8.
Monte Carlo calculations were carried out to study the dependence of γ-ray yield on the bulk density and moisture content
of a sample in a thermal-neutron capture-based prompt gamma neutron activation analysis (PGNAA) setup. The results of the
study showed a strong dependence of the γ-ray yield upon the sample bulk density. An order of magnitude increase in yield
of 1.94 and 6.42 MeV prompt γ-rays from calcium in a Portland cement sample was observed for a corresponding order of magnitude
increase in the sample bulk density. On the contrary the γ-ray yield has a weak dependence on sample moisture content and
an increase of only 20% in yield of 1.94 and 6.42 MeV prompt γ-rays from calcium in the Portland cement sample was observed
for an order of magnitude increase in the moisture content of the Portland cement sample. A similar effect of moisture content
has been observed on the yield of 1.167 MeV prompt γ-rays from chlorine contaminants in Portland cement samples. For an order
of magnitude increase in the moisture content of the sample, a 7 to 12% increase in the yield of the 1.167 MeV chlorine γ-ray
was observed for the Portland cement samples containing 1 to 5 wt.% chlorine contaminants. This study has shown that effects
of sample moisture content on prompt γ-ray yield from constituents of a Portland cement sample are insignificant in a thermal-neutrons
capture-based PGNAA setup. 相似文献
9.
H. Matsumura K. Masumoto A. Toyoda N. Kinoshita 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(3):733-738
Highly selective and sensitive γ-ray detection was performed by coincidence and anticoincidence event analysis after list-mode
data acquisition using an HPGe spectrometer equipped with NaI(Tl) and plastic scintillation detectors. In order to obtain
the most suitable detection of specific nuclides, coincidence or anticoincidence spectra could be freely constructed by extracting
events with particular time and energy correlations. Although the detector arrangement of this system was the same as that
of a typical Compton suppression spectrometer, background counts were drastically reduced and γ-rays of particular nuclides
could be selectively detected by using γ-γ, γ-X, γ-X-X, and γ-β+ coincidences. 相似文献
10.
J. Kuncíř J. Benada Z. Řanda M. Vobecký 《Journal of Radioanalytical and Nuclear Chemistry》1970,5(2):369-378
The use of high-resolution Ge(Li) detectors in non-destructive instrumental neutron activation analysis (INAA) of mineral
materials makes possible the simultaneous determination of a number of trace elements. In routine applications of INAA the
use of a multi-element standard (MES) has proved to have advantages over a set of standards for each determined element. An
MES has been prepared containing 8 trace elements mixed in a suitable proportion and giving, after neutron activation, long-lived
γ-emitters, the γ-ray lines of which regularly occur in the γ-ray spectra of silicate mineral materials. This method has been
used in the determination of Sc, Cr, Co, Rb. Cs, Eu, Hf and Th in samples of standard rocks and moldavites. 相似文献
11.
Measured values of the intensities of characteristic γ-rays emitted under the bombardment of protons on a thick target of
phosphorus are tabulated. The intensity of each characteristic γ-ray is measured and used for quantitative analysis of phosphorus
in any sample with a sensitivity of 50 to 1000 ppm. 相似文献
12.
Y. Shiokowa T. Mitsugashira S. Suzuki 《Journal of Radioanalytical and Nuclear Chemistry》1979,54(1-2):267-279
A method is proposed for the resolution enhancement transformation (RET) of the γ-ray spectrum, which is not only a simple
convolution operation but also have a definite analytical significance because of the introduction of the parameter ω representing
the degree of the resolution enhancement. We apply the RET to the peak detection method for complex overlapping peaks. The
validity of this method is ascertained by the analysis of X-ray overlapping peaks. 相似文献
13.
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
14.
The procedure in use at our institute for the extraction of the desired element concentrations in a sample from the peak data
obtained by a spectrum analysis program, is described in detail. The method is based on the use of zinc as a single comparator
and takes into consideration primary activation products as well as their daughter isotopes. After assigning isotopes to spectrum
peaks on the basis of γ-ray energies, the list of possible isotopes is reduced to a list of present isotopes with their concentrations
using criteria based on half life, specificity and intensity of γ-rays. For elements not observed, detection limits are estimated.
The procedure has been used extensively during the last two years and has shown to produce reliable results. 相似文献
15.
A computer program is described to perform the identification of isotopes in neutron activated samples. The γ-ray energies
as obtained from a Ge(Li) γ-ray spectrum are compared with those of a library, containing data for about 250 isotopes. Isotopes
whose γ-ray energies match closely with the unknowns are selected as possible constituents. Unlikely attributions are then
eliminated by a careful inspection of the γ-rays found. Further exploitation of half-life, the way of production and the sensitivity
for the given irradiation and measurement conditions, allow the selection of the most likely constituents in the source. The
results of the automated identification agree closely to those obtained by an experienced investigator. The program is written
in FORTRAN IV for a PDP-9 computer with a 16 K word memory. 相似文献
16.
T. Sano T. Fukuoka T. Hasenaka C. Yonezawa H. Matsue H. Sawahata 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(3):613-617
An accurate and efficient analytical method using neutron-induced prompt γ-ray was developed for the determination of boron
contents in volcanic rocks. We corrected the effect of sample geometry and flux fluctuation by using silicon as an internal
standard. However, we found that the slopes of the calibration line vary among volcanic samples with different matrix. Because
the increase of boron activity correlates positively with γ-ray count rate of hydrogen (water), we call this as the hydrogen
effect. The hydrogen effect was confirmed by our experiment in which the boron activities showed systematic increase with
the amount of added hydrogen (water). Most volcanic rocks, however, contain little water (<2 wt.%) to show this effect. We
determined boron contents in various volcanic rocks in order to confirm the validity of the procedure that we established.
The analyzed boron contents agreed well with the previous reported values. For efficient PGA of boron in volcanic rocks, we
recommend JB-2 (GSJ standard rock) as a single geochemical standard, because of its high boron content (31.2 ppm). 相似文献
17.
T. Ishikawa M. Hosoda A. Sorimachi S. Tokonami S. Katoh S. Ogashiwa 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(3):709-713
Nowadays, artificial “radon spa sources” for home baths are commercially available. Although these sources could give a potential
radiation exposure to the users, few studies have been reported on their radiological measurements. In the present study,
five types of radon spa sources were collected and their radiological characterization was investigated. The followings were
estimated for these samples: (1) radon emanation coefficients (dry and water-saturated conditions), (2) surface γ-ray dose
rate, (3) surface count rates for α- and β-rays, (4) activity concentrations of 226Ra, 232Th and 40K, and (5) concentrations of radon and thoron generated from the sources located in an air flow system. The activity concentrations
were very high (except for one sample (named “sample B”), although radon emanation coefficient was low compared with soil.
This leads to high concentrations of radon/thoron generated from the sample. The maximum surface γ-ray dose rate was observed
for sample A (2.7 μGy h−1). If people stay very close to the sample for a long time, the exposure might be significant. 相似文献
18.
I. Valente M. J. Minski H. J. M. Bowen 《Journal of Radioanalytical and Nuclear Chemistry》1978,45(2):417-421
A rapid non-destructive activation analysis method has been developed for the determination of antimony. A high resolution
low energy Ge detector is used to measure the 61.6 keV γ-ray from122mSb (T=4.2 min). Sensitivities and detection limits for biological and environmental samples activated with thermal and epithermal
neutrons are listed. The time required for the anlaysis is about 12 min per sample using thermal activation and 22 minutes
using epithermal activation analysis. 相似文献
19.
G. Demortier 《Journal of Radioanalytical and Nuclear Chemistry》1978,45(2):459-496
Gamma-ray yields from bombardment with protons of thick targets of Ti, V, Mn, Cr, Fe, Co, Ni, Cu and Zn are tabulated for
proton energies ranging between 0.6 and 3.2 MeV. The applications of these reactions for quantitative analysis of these chemical
elements are discussed. The sensitivity of this technique of analysis is poorer than the PIXE method for these transition
elements, but is sufficient for rapid and accurate quantitative analysis of alloys when elements are present in concentrations
down to 1%. The knowledge of the γ-ray energies and intensities produced by the bombardment of these elements with protons
is also necessary for solving interferences with several γ-rays induced in light elements, for which the proton induced γ-ray
technique is sensitive, without any correction for photon attenuation. 相似文献
20.
C. Yonezawa P. P. Ruska H. Matsue M. Magara T. Adachi 《Journal of Radioanalytical and Nuclear Chemistry》1999,239(3):571-575
Determination of ppm levels of B in 21 igneous and sedimentary rocks of the Japanese geochemical reference samples prepared
by the Geological Survey of Japan (GSJ) has been performed by neutron-induced prompt γ-ray analysis (PGA) using cold and thermal
guided neutron beams of the JRR-3M. Owing to the Doppler broadened γ-ray line of B 478 keV, many elements such as Na, Ni,
Cl and so on showed spectral interference in the determination of B. The interference was corrected by computer fitting and
a reference peak method. The analytical results obtained by the present method almost agreed with the GSJ values recommended
in 1994 within the standard deviation of the recommended values. Sodium contents determined by the PGA in the reference rock
samples are also reported. 相似文献