Aims. Archival observations of infrared fine-structure lines of the young Galactic supernova remnant Cassiopeia A allow us to test existing models and determine the physical parameters of various regions of the fast-moving knots, which are metal-dominated clouds of material ejected by the supernova explosion. Spitzer data are used to determine the fluxes of the O, Ne, Si, S, Ar, and Fe ion fine-structure lines originating in the fast-moving knots. The ratios of these line fluxes are used as plasma diagnostics. We also determine the infrared line flux ratios with respect to the optical [O iii] 5007 Å line in the knots with previously measured reddening. Additionally, we analyze several optical and near-infrared observations of the fast-moving knots to obtain clearer insight into the post-shock photoionized region structure. Results. We show that the infrared oxygen line flux predictions of all existing theoretical models are correct only to within a factor of a several. Comparison of the model predictions shows that to reproduce the observations it is essential to include the effects of the electron conductivity and dust. Detailed analysis of the diagnostic line flux ratios of various ions allows us to qualitatively confirm the general model of fast-moving knot emission and determine observationally for the first time the physical conditions in the photoionized region after the shock. We infer from the [O iii] line flux ratios that the pre-shock cloud densities are higher than assumed in existing theoretical models and most probably correspond to several hundred particles per cm 3 . We also determine the Cas A luminosity in the infrared continuum and lines. We show that accounting for the charge exchange processes in the post-shock photoionized region allows us to reproduce most of the relevant spectral line ratios even in the frame of a single-temperature model of this region. We also estimate its plasma parameters, thickness, and carbon abundance.

Hyperfine structure lines of highly-charged ions may open a new window in observations of hot rarefied astrophysical plasmas. In this paper we discuss spectral lines of isotopes and ions abundant at temperatures 10 5 − 10 7 K, characteristic for warm-hot intergalactic medium, hot interstellar medium, starburst galaxies, their superwinds and young supernova remnants. Observations of these lines will allow to study bulk and turbulent motions of the observed target and will broaden the information about the gas ionization state, chemical and isotopic composition. The most prospective is the line of the major nitrogen isotope having wavelength λ = 5.65 mm (Sunyaev & Churazov 1984). Wavelength of this line is well-suited for observation of objects at z ≈ 0.15 − 0.6 when it is redshifted to 6.5 − 9 mm spectral band widely-used in ground-based radio observations, and, for example, for z 1.3, when the line can be observed in 1.3 cm band and at lower frequencies. Modern and future radio telescopes and interferometers are able to observe the absorption by 14 N VII in the warm-hot intergalactic medium at redshifts above z ≈ 0.15 in spectra of brightest mm-band sources. Sub-millimeter emission lines of several most abundant isotopes having hyperfine splitting might also be detected in spectra of young supernova remnants. PACS: 32.10.Fn, 98.62.Ra, 32.30.Bv

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We describe the method for and results of the application of an EDXRF on-line analyzer for the analysis and quality testing of chrome-iron ores. For this task we used a BSI-2000 analyzer for measurement of lumpy material being transported by a conveyor belt. The task of fully automated quantitative analysis of material on a conveyor belt is not very simple, as the results of measurements should not depend significantly on many factors, such as the distance to the measured material, the lump size, unknown and changing amounts of elements unseen by the analyzer; air and material humidity and ambient temperature. To solve most of these problems we used the program AssayKit for elemental and molecular composition calculation based on the fundamental parameters method. The chosen configuration of the x-ray tube illumination cone and the detector registration cone allows measurements to be made at a wide range of distances between the analyzer and material. The XRF analyzer with this program was successfully applied to chrome-iron ore analysis in Kemi mine, Finland, for quality control of outgoing production. The accuracy of analysis -standard deviation of 1.1% for chrome and 0.8% for iron in full operation -was verified by more than 300 comparisons with chemical analysis measurements.