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Abstract  

Measurements of 222Rn (“radon”) in the environment are important in the geosciences and radiation-protection fields. We demonstrate here a simple laboratory-based calibration system to evaluate the efficiency of radon detectors with a reproducibility of about ±2%. The system uses a closed-loop air circulation design with 226Ra adsorbed onto MnO2-impregnated fiber as a radon source. Two RAD7 radon detectors (Durridge Co., Inc.) that were precisely calibrated at Durridge’s in-house calibration facility are used as secondary standards. By parallel analysis of the radon-enriched air within the closed loop, the test RAD7s are assigned a calibration coefficient to be applied to future measurements. We also performed a side-by-side intercomparison with two RAD7s in a high-radon natural environmental setting (limestone cave in Florida) that produced comparable results.

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Abstract  

A useful method for crystal detector calibration by using point sources is presented. The method is applied to determine the total efficiency of a 80×80 mm NaI/Tl/ crystal in an energy window suitable for134Cs+137Cs activity evaluation in a sample of 750 cm3.

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The Unified Grain Moisture Algorithm is capable of improved accuracy and allows the combination of many grain types into a single “unified calibration”. The purposes of this research were to establish processes for determining unifying parameters from the chemical and physical properties of grains. The data used in this research were obtained as part of the United States Department of Agriculture-Grain Inspection, Packers and Stockyards Administration's Annual Moisture Calibration Study. More than 5,000 grain samples were tested with a Hewlett-Packard 4291A Material/Impedance Analyzer. Temperature tests were done with a Very High Frequency prototype system at Corvinus University of Budapest. Typical chemical and physical parameters for each of the major grain types were obtained from the literature. Data were analyzed by multivariate chemometric methods. One of the most important unifying parameters (Slope) and the temperature correction coefficient were successfully modeled. The Offset and Translation unifying parameters were not modeled successfully, but these parameters can be estimated relatively easily through limited grain tests.

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Abstract  

A procedure for calibrating the temperature scale of a DSC is described. A different calibration trend was obtained using the transition points of organic compounds compared to that found using the melting points of highly pure metals. The crystal-crystal transitions of three ammonium salts were studied by this method; ammonium dihydrogen phosphate and ammonium sulphate were found to be suitable reference materials in the region −150 to 0°C, but ammonium nitrate was found to be unsuitable due to poorly defined transition points and inconsistent thermal behaviour.

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Abstract  

This paper first explains the need to define subfields of science by means of “filters” that selectively retrieve papers from a database, and then describes how such filters are constructed and calibrated. Good filters should have precision and recall of the order of 90% so as to be representative of a subfield; they are created by an interactive partnership between an expert in the subject and a bibliometrician. They are based primarily on the use of title keywords, often in combination rather than singly, and specialist journals. Their calibration depends on experts marking lists of papers extracted by the filter as relevant, don't know or not relevant. This allows the actual size of a subfield to be estimated and hence the relative importance accorded to it within a major field of science. It permits organisations and countries to see their contributions to individual scientific subfields in detail.

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Journal of Thermal Analysis and Calorimetry
Authors: E. Charsley, J. Davies, E. Glöggler, N. Hawkins, G. Höhne, T. Lever, K. Peters, M. Richardson, I. Rothemund, and A. Stegmayer

Abstract  

With some attention to temperature calibration but no other special precautions the temperatures of both solid-solid and melting transitions can be determined to within a few tenths of a Kelvin of absolute values in a range of heat-flux and power-compensation DSC instruments. Materials showing several solid-solid transitions are potentially useful multiple calibrants but require some work to define appropriate thermal treatments that lead to reproducible behaviour.

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Abstract  

The evaluation of the accuracy of thin elemental standards produced by Micromatter Co., which are widely used for the calibration of the detection sensitivity of PIXE analysis systems, is presented in terms of Rutherford scattering measurements of the thickness of 68 standards covering a range of 59 different elements.

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Abstract  

In this paper, it is made a study of the accuracy of an isothermal titration calorimeter in the operating mode of ‘continuous injection’. The experimental equipment has been a TAM2277-201/2250 by Thermometric AB and the liquid mixtures used in the calibration have been the mixture cyclohexane+benzene and the mixture water+ethanol. The calibration contemplates different effects that affect the uncertainty in the determination of the sensitivity, the effect of the liquid injection, the treatment of the calorimetric signal, the variation of the experimental baseline and the different noises included in the calorimetric signal.

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Abstract  

A number of compounds is investigated for DSC calibration during cooling. Adamantane and Zn show fast reversible transitions and can be applied both for temperature and for heat calibrations. A third compound, namely 4,4’-azoxyanisole, has a liquid crystal to isotropic liquid transition at 409K. This compound can be used for temperature calibration. Heat calibration with this compound is more problematic because of the small heat effect and the construction of the baseline. Other compounds like NaNO3, In, Hg and Pb, show a slight supercooling. Nevertheless they can be used for heat calibration. The use of large samples of NaNO3 and In gives the possibility to construct the equilibrium onset temperatures of the cooling peaks, so these two compounds are also appropriate for temperature calibration on cooling.

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Abstract  

Particle track techniques, which enable estimation of the uranium and thorium contents in films where energy self-absorption is negligible, are presented. These techniques allow calibration of uranium and thorium thin films with adequate precision to be used in neutron fluence determinations for fission-track dating. Calibration via a particles is relatively simple for the case of uranium films, whereas for thorium films it is necessary to use the spectrometric characteristics of the employed track detector. Besides those based on a particles, calibration procedures via fission fragments are presented both for uranium as well as for thorium films.

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