摘要:

On the basis of papers presented at the 7th International Conference on Modern Trends in Activation Analysis held in Copenhagen, Denmark, 23–27 June 1986 an attempt is made to evaluate future trends in the field of nuclear activation analysis. The diversity of applications and the significant improvements in methodology are highlighted in this review.

ISSN:0021-1915    

DOI:10.1080/10256018808623895

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Activation analysis is an important method for elemental analysis, mainly because of its sensitivity. The accuracy and precision obtainable with charged particle activation analysis (CPAA) have been significantly improved. Standardization problems were studied thoroughly and the accuracy was demonstrated during various inter-laboratory and intermethod comparisons. Most of the applications of CPAA deal with the determination of light elements, such as hydrogen, carbon, nitrogen and oxygen, in metals and semi-conductors. Because a surface layer containing the activity formed at the surface can be removed by chemical etching after irradiation, CPAA has shown that for some metals the concentrations are orders of magnitude lower than expected on the basis of chemical analytical methods. CPAA was very often applied as a reference method for certification analyses.

ISSN:0021-1915    

DOI:10.1080/10256018808623896

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Diffusion of phosphorous in oligo-crystalline silicon occurs along the grain boundaries and through the bulk of the crystals. High precision is required to separate these two phenomena. This can be achieved by using32P (T1/2= 14.3 d) as a radiotracer. The procedures for counting by a solid scintillator detector and by liquid scintillation are compared. In the first approach the remaining sample is counted after successive polishings. The second technique is based on dissolution and measurement of the polished off material. It appears that the attainable precision is a function of the concentration profile.

ISSN:0021-1915    

DOI:10.1080/10256018808623897

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A procedure for the preparation of soil samples for32Si measurements is described. Two different soil profiles have been studied. The obtained32Si concentrations in these profiles indicate a sorption of32Si on clay, ferric-manganese hydroxides as well as humic matter. On the base of a box model migration velocities of32Si in the soil have been estimated to be about 0.1 to 10 cm · α−1.

ISSN:0021-1915    

DOI:10.1080/10256018808623898

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Some series of granitic rock samples have been investigated by the aid of minicomputer spectral analysis after neutron activation. Maintaining an optimal relation between measurement time, precision of analysis, and a high sample through-put as well as a great number of elements, the concentrations of some elements have been determined. The total set of elements should than be reduced by statistical feature extraction in order to obtain an optimal set of elements with the same discrimination power. The presented paper especially concerns with the relation of tin-tungsten ore deposits near the areas of high differentiated granitic rocks (Variscian age).

ISSN:0021-1915    

DOI:10.1080/10256018808623899

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

An automatic sample changer equipment suitable to supply up to 50 samples has been developed. It can be applied to vertical dipstick Si(Li) X-ray spectrometers using ring shaped radioisotope sources for the excitation of elements. Controllable both automatically by a multichannel pulse-height analyser and manually.

ISSN:0021-1915    

DOI:10.1080/10256018808623900

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The method of the 14 MeV neutron flux monitoring based on reactions28Si(n, α)25Mg,28Si(n, p)28Al, occurring in lithium drifted silicon detectors Si(Li) is described. Monitoring of this type has not been applied before. The further advantage exhibited by the Si(Li) detectors is possibility of easy measurements of the integrated neutron flux and the total neutron yield. Some questions of radiation damage of the Si(Li) detectors are being also discussed. Three detectors were used for measurements: two Si(Li) detectors and the Bonner type detector with 8″ polyethylene sphere.

ISSN:0021-1915    

DOI:10.1080/10256018808623901

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

In reactor water from primary coolant239Np,238U,238Pu and239,240Pu was determined using isotope dilution and isotope dilution activation analysis. An example of crud and reactor water from a power station was also investigated by gamma spectroscopy and activation analysis. For localization and characterization methods of cladding failure the usefulness of analytićal determination of actinides in reactor water is emphasized.

ISSN:0021-1915    

DOI:10.1080/10256018808623902

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

An X-ray fluorescence method for the analysis of biological samples of any thickness has been developed. Concentration values are calculated from the characteristic X-ray line intensities of Z ≧ 15 atomic number elements using only one reference standard for calibration. For the excitation of elements55Fe and125I annular radioisotope sources are used. Measurements have been carried out with a conventional X-ray spectrometer on various types of IAEA, NBS and NIES standard biological samples. Good agreement has been obtained between certified and measured concentration values.

ISSN:0021-1915    

DOI:10.1080/10256018808623903

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Measurements of excited and backscattered fluorescence radiation intensity were applied for ash content determination in coal samples. Si(Li) detector and low energy X- and gamma ray sources Fe-55, Cd-109, Pu-238, Am-241 were used. The measurement facility consisting of argon filled proportional counter and a Pu-238 radiation source was tested and compared, as generally used radioanalytical method, for ash content determination. The evaluation of results was based on the Snedecor F test and the analysis of the root mean square of estimate. The best results were obtained when Fe-55 source was used. In the multivariate linear regression independent variables SiKα, CaKαand backscattered radiation intensities have been selected as variables that are best related with ash content in coal.

ISSN:0021-1915    

DOI:10.1080/10256018808623904

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor