[en] The 'Acta Physica Universitatis Comenianae' provides an international forum for rapid publication of original research and review papers on any aspects of modern physics. The journal is published two times a year (Summer and Winter). This issue of 'Acta Physica Universitatis Comenianae' as the honour to Assoc. Prof. RNDr. Martin Chudy, CSc., on the occasion of his sixtieth birthday. He is one of the founders of the Nuclear Physics Department of Comenius University and the leading experimentalists in the field of low radioactivity measurements by gamma ray-spectrometry and one of the founders of the Bratislava school in this field. His work has largely formed some of our development of experimental apparatus and methods. This issue comprised theoretical problems of nuclear interactions at high energies; kaon electromagnetic form factor light nuclei-proton interactions;quantification of uncertainty in gamma-ray spectrometry;planetary gamma-ray spectrometry of the surface of comet; geometrical aspect of the nonlinear least squares method; numerical simulation of particle fluxes and cosmogenic nuclide production rates in earth atmosphere; results of long-term measurement of 2^22Rn volume activity in soil air; analysis of the metal dynode photomultiplier single photoelectron spectra; relation between emitted spectral line intensities by the afterglow plasma and the temperature of electrons heated by microwaves

[en] The 'Acta Physica Universitatis Comenianae' provides an international forum for rapid publication of original research and review papers on any aspects of modern physics. The journal is published two times a year (Summer and Winter). This issue of 'Acta Physica Universitatis Comenianae' as the honour to Assoc. Prof. RNDr. Martin Chudy, CSc., on the occasion of his sixtieth birthday. He is one of the founders of the Nuclear Physics Department of Comenius University and the leading experimentalists in the field of low radioactivity measurements by gamma ray-spectrometry and one of the founders of the Bratislava school in this field. His work has largely formed some of our development of experimental apparatus and methods. This issue comprised theoretical problems of nuclear interactions at high energies; kaon electromagnetic form factor light nuclei-proton interactions;quantification of uncertainty in gamma-ray spectrometry;planetary gamma-ray spectrometry of the surface of comet; geometrical aspect of the nonlinear least squares method; numerical simulation of particle fluxes and cosmogenic nuclide production rates in earth atmosphere; results of long-term measurement of 2^22Rn volume activity in soil air; analysis of the metal dynode photomultiplier single photoelectron spectra; relation between emitted spectral line intensities by the afterglow plasma and the temperature of electrons heated by microwaves

[en] On June 18, 1996 the Slovak Government by its resolution No. 434/96 approved the project of building the cyclotron and related technological equipment within the Slovak Institute of Metrology in Bratislava-Karlova Ves. The site was chosen due to the existing infrastructure, space and localization. In 1996-98 more than one hundred top experts from Slovakia and other countries participated in the project. The initial strategy outline was technically worked out and a detailed economical analysis of the facility's construction and operation was made including the estimation of the economical profit for the Slovak Republic. The construction of the cyclotron laboratory complex includes the importation of the accelerator and related technologies and building of the blocks where they are to be situated. At present the matter that the cyclotron building as well should be constructed from debt means of Russian federation concerning Slovak Republic is still under discussion with Russian partner

[en] Results on the geometry of a nonlinear regression model and their statistical consequences are presented in a condensed form. The least squares method is considered here as a projection onto the expectation surface, which allows to explain the problem of uniqueness of the parameter estimates, and overcomes the danger of a false interpretation of the least squares in case of very curved or statistically overlapping models. Measures of nonlinearity (curvatures), and the Riemannian curvature tensor are presented briefly, and statistical consequences of having zero curvatures are given. In particular, the earlier author's results on the probability density of the estimator are discussed briefly, in relation to curvatures (Author)

[en] The time evolution of a random surface z=h(r,t)(r=x,y) formed by a deposition process of the Edwards-Wilkinson type is studied. A general expression derived for the autocorrelation function A_h (r-r',t,t') < h(r,t)h(r',t')> of the height function h(r,t) under the assumption of a stochastic initial condition. (At the initial time t=0, the function h(r,0) is defined as a statistically uniform random function.) This paper was written as a companion paper to another one with the intent to focus attention on some detailed and extensive mathematical derivations. The other paper which is written in a less mathematical style then quotes results of the present paper (Authors)

[en] Steps towards improving the accuracy and precision of gamma- spectrometric measurements of environmental samples are discussed. It is shown that proper detector efficiency calculations and the application of correction factors (matrix corrections, coincidence correction, etc.) are important for high precision data generation and for the quantification of the uncertainty budget.The Monte Carlo method has been found to be a powerful tool for improving quality assurance in gamma-spectrometry. Using the described procedures, it is possible to reach relative standard uncertainty below 5% even for very low activity environmental samples (Authors)

[en] To investigate the basic questions of the origin and evolution of comets and also of solar system the data about the chemical composition of cometary nuclei are necessary. Gamma rays emitted from the cometary nucleus can be measured by a gamma-ray spectrometer on board of an orbiting spacecraft. Flux of gamma rays emitted from the comet due to the interactions of cosmic ray particles with its surface was simulated using the Monte Carlo codes describing involved nuclear reactions (Authors)

[en] Physical model for the simulation of cosmic-ray particle interactions with the Earth's atmosphere and subsequent production and transport of secondary particles is presented. Neutron, proton, and muon spectra as a function of the coordinate in the atmosphere were calculated using the model based on approximate solution of Boltzmann transport equation. Using calculated particle fluxes and experimental or evaluated cross sections for the reactions producing particular nuclides, the production rates for ³H, ⁷Be,¹0Be, and ³⁶Cl were determined. The dependence of production rates on solar activity was investigated in detail (Authors)

[en] The paper analyses simulated Brillouin scattering in liquids. Based on the measured value of the wave number of hypersonic waves the speed of their propagation, coefficient of absorption and coefficient of dynamic viscosity are identified. These values are compared with those known from publications to evaluate the correctness of measurements. In addition, the same parameters have been measured for mixed solutions of blood + physiological solution, and the solution of enzyme trypsin + water (Authors)

[en] Series of investigation of projectile fragmentation has been done in the beams of accelerated nuclei such as vector polarized and unpolarized deuterons, ³ He and ⁴ He at the synchrophasotron- nuclotron accelerating complex. The isobaric state excitation in the dp→ppn and ⁴Hep→pX reactions manifests as a strong enhancement in the high energy tail of the proton momentum spectrum. It is shown that the final state interactions gives remarkable contribution to the angular asymmetry in the dp→ppn,³Hep→dpp, ⁴Hep→ and ³Hepn and ⁴Hep→³Hpp reactions at the incoming energies 1-4 GeV per nucleon. A new way of representation of the nuclei fragmentation data is suggested.The self-similarity behaviour of these processes is demonstrated (Authors)