[en] One of the objectives of the vast physics programme of the recently commissioned WASA-at-COSY facility is the study of fundamental symmetries via the measurements of the η and η' mesons decays. Especially interesting are isospin violating hadronic precesses of these mesons into 3π systems driven by the term of QCD Lagrangian which depends on the mass difference of the u and d quarks. When an η or an η' meson is created in the hadronic reaction signals from such decays may be significantly obscured by the prompt production of π mesons. In this thesis we present the estimation of the upper limit of the background due to prompt pion production for the η'→3π⁰ and η'→π⁺π^-π⁰ decays. Using the data from proton-proton collisions measured by the COSY-11 group we have extracted differential cross sections for the multimeson production with the invariant mass corresponding to the mass of the η' meson. Based on these results and on parametrizations of the total cross sections for the η' meson as well as parametrization of the upper limit for the prompt pi⁺pi^-pi⁰ production in the collisions of protons we discuss in details the feasibility of a measurement of the η' meson decay into 3π channels with the WASA-at-COSY facility. Based on the chiral unitary approach the value of the branching ratio BR(η'→π⁺π^-π⁰) was recently predicted to be about 1%. We show that the WASA-at-COSY has a potential to verify this result empirically. (orig.)

[en] With ³He particles of an energy of 6.23 MeV via the reaction ¹²C(³He,p)¹⁴N* fast nitrogen nuclei in the first two excited states at 2.3 MeV and 3.9 MeV were produced. The nuclei were stopped in nickel, copper, and silver targets. From the Doppler-broadened spectra of the (2.3 → 0) MeV transition measured in coincidence with the protons first for the three materials each the product of the lifetime τ₁ and the differential energy loss as well as the ratio τ₂/τ₁ could be determined. The comparison with existing energy-loss data for nickel and silver then yielded the values τ₁ = (97.7 ± 5.5) fs and τ₂ = (5.6 ± 1.1) fs as well as the differential energy loss of ¹⁴N projectiles in nickel, copper, and silver in the velocity range from 0.004 c to 0.022 c. As the systematic errors in Doppler shift experiments are generally relatively high in the analysis of the spectra it was precisely studied which secondary effects influence the shape of the spectra. The effects were quantitatively recorded, and it is shown how strongly they each alter the measurement results. The results for τ₁ and τ₂ are compared with those of other authors, and possible causes for the strong dispersion of the other measuring values are shown. The energy loss curves are discussed in connection with the Z₂ oscillations. (orig.)

[en] Previous methods of reduction of water vapors with zinc powder have been reviewed, the reduction of tritiated water with sublimated under vacuum zinc, used in tritium exchange and isotope effect studies, has been described and the value of tritium fractionation factor has been estimated. 10 refs. (author)

[en] I review present experimental and theoretical status of electromagnetic decays of light mesons. Special attention is paid to single-photon decays of charged resonances and to recent applications of the Primakoff technique to measure such processes. New data on radiative decays of pseudoscalar, vector, axial and tensor mesons are compared with several theoretical calculations involving quark models, unitary symmetry relations and the effective Lagrangian approach. Vector Meson Dominance ideas, as applied to meson spectroscopy, are discussed in detail. Also, the electromagnetic properties of the A₁ meson are examined in the context of resonance parameters observed in diffractive production and τ-lepton decays. Finally, I emphasize the importance of radiative processes in searching for glueball and hybrid states of matter. 187 refs., 18 figs., 6 tabs. (author)

[en] It has been shown that the radioactivity of hydrogen cyanide can be determined quantitatively without further chemical transformations by introducing into the effective space of a G.M. counter a known amount of gaseous HCN mixed with quenching gases such as hexane or ethyl formate vapours. (author)

[en] Hydrogen isotope exchange between pyridinium chloride and gaseous hydrogen chloride has been studied both experimentally and theoretically over the temperature range of 273 to 353 K. The experimental fractionation factor obtained shows some dependence on the composition of the substrates. This phenomenon can be accounted for by specific interactions in pyridinium chloride + hydrogen chloride system. The calculated fractionation factor in harmonic approximation and within the framework of quantum statistical theory of isotope effects agrees satisfactorily with the experimental results in these cases when well-defined species of Py(HCl)₂ were formed and the nature of the interactions were well enough known. In other cases some interaction models have been proposed and briefly discussed

[en] Predictions of perturbative QCD (pQCD) for the inclusive production of direct photons and mesons at high p_T have been tested using new high-statistics measurements from Fermilab experiment E706. Inclusive π⁰ and direct-γ cross sections in the kinematic range 3.5< p_T<12 GeV/c with central rapidities have been measured for 530 and 800 GeV/c proton beams and a 515 GeV/c π^- beam incident on a Be target. Current next-to-leading order (NLO) pQCD calculations fail to describe the data for usual choices of scales. Other aspects of the data indicate the presence of a substantial initial state parton transverse momentum (k_T) in the hard scattering. Incorporating a kinematic model of k_T effects improves the agreement between the calculations and the observed cross sections. Gluon distributions are extracted from deep inelastic scattering (DIS), Drell-Yan (DY), and our direct photon data using fitting procedures similar to those used by the CTEQ collaboration; calculations using these new parton distribution fits yield jet cross sections consistent with CDF and DOe measurements. (orig.)

[en] The viability of Primakoff technique in searching for hybrid states, and exotic J^PC = 1^-+ isovector meson bar ρ in particular, is discussed. Results of searches for Primakoff production of an bar ρ in ρπ and ηπ final states produced in high energy interactions of pions with large-Z nuclei are reviewed, and the limits for the radiative coupling Γ( bar ρ⁺ → π⁺γ) are presented. Based on available experimental information, electromagnetic production rate estimates are given for the favored bar ρ → πf₁(1285) channel. It is argued that a dedicated Primakoff production experiment can be sensitive to values of Γ( bar ρ⁺ → π⁺γ) ∼ keV, which makes such measurement a very interesting option for doing spectroscopy of gluonic (and conventional) meson states in the 1.5 ∼ 3 GeV mass range. 18 references, 2 figures

No abstract available

[en] The oxidative method for decomposition of lactic acid labelled with carbon and hydrogen isotopes has been worked out. The method consists in mixing the salt of lactic acid with manganese dioxide. Then the vacuum has been made in reaction vessel and sulphuric acid is being added to the reaction mixture. The stoichiometry of the redox reaction has been checked by using the lactic acid labelled with ¹⁴C in carboxyl group and ³H in unlabelled position