[en] The vapor pressures of the isotopic methyl fluorides ¹²CH₃F, ¹²CD₃F, and ¹³CH₃F have been measured at temperatures between 132.48 and 213.12 K by differential manometric techniques in a precision cryostat. Throughout the whole temperature range of the measurements, P(¹²CH₃F) > P(¹²CD₃F) and P(¹²CH₃F) < P(¹³CH₃F). The data are best represented by T ln (f/sub c//f/sub g/) = (2225.2 +- 7.4)/T - (4.444 +- 0.046) for the D/H effect and by T ln (f/sub c//f/sub g/) = (56.58 +- 2.09)/T - (0.6383 +- 0.0133) for the ¹³C/¹²C effect. A series of calculations using Wilson's GF matrix method and a modified Schachtschneider-Snyder program resulted in temperature-dependent internal-external interactions in the liquid phase: Presence of such interactions between the molecular translation in the direction of the molecular figure axis and the parallel normal modes nu₂ and nu₃ is a necessary requirement for satisfactory explanation of all isotopic vapor pressure and spectroscopic data of the liquid. The specific internal-external interactions found are consistent with the structure of CH₃F clusters obtained by ab initio molecular orbital calculations. 5 figures, 8 tables

[en] A 20 mmole quantity of methyl-¹³C fluoride at a ¹³C-enrichment level of 90% was prepared by a two-step synthesis starting with methanol-¹³C. The overall yield was 60% of methanol used. A series of gas-chromatographic treatments using Ascarite, silica gel, and Chromosorb-102 columns yielded a highly purified methyl fluoride in which the major impurities were less than 10 parts per million of carbon dioxide and 10 parts per million of methyl chloride. (author)

[en] The vapor pressures of isotopic fluoroforms ¹²CHF₃, ¹³CHF₃, and ¹²CDF₃ have been measured at temperatures between 125 and 212 K in a modified Bigeleisen--Brooks--Ishida--Ribnikar cryostat. At all temperatures of measurement P(¹²CHF₃)>(¹²CDF₃) and P(¹²CHF₃)< P(¹³CHF₃). The results support the blue-shift of the C--H stretching frequency on condensation of fluoroform molecules due to a kinetic energy coupling between the stretching motion and the molecular translation in the direction of the molecular figure axis, caused in large part by a weak but directional coulombic interaction between hydrogen and fluorine atoms of neighbor molecules

[en] The track finding and parameter estimation algorithm for the Zeus Central Tracking Detector (CTD) is presented. A flexible track finding strategy has been developed based on the extension towards the interaction point of seed tracks found in the outer layers of the CTD. Several seed finding techniques have been developed including a vector processor option. By using an appropriate combination of these techniques, a robust track finder is created which is suitable for the high intensity environment expected at the HERA collider. Kalman filtering is used in the track parameter estimation and track finding algorithms

[en] The design concept and development of the ZEUS central tracking detector is described. This is a cylindrical drift chamber designed for track reconstruction, electron identification and event triggering in a high-crossing-rate, high-magnetic-field environment. (orig.)

[en] We report on total cross section and forward backward charge asymmetry measurements of the reaction e⁺e^-→τ⁺τ^- at centre of mass energies of 35.0 GeV and 42.4 GeV using the TASSO detector. Including previous data an analysis in terms of electroweak parameters of the standard model is presented, and lower limits on mass scale parameters of residual contact interactions are given. A combined analysis of electroweak couplings using all our results on leptonic reactions e⁺e^-→l⁺l^- has been performed. (orig.)

[en] Production of charmed mesons in γγ-interactions at PETRA energies has been observed in the TASSO detector. Cross sections for inclusive D^*± and D⁰anti D⁰ production have been measured. Neutral and charged meson pairs are estimated to be produced with comparable cross sections, and their sum to account for a sizeable function of σ_tot(γγ→hadrons) near the canti c threshold. (orig.)

[en] Data on jet masses, resulting from the decomposition of e⁺e^- hadronic final states into two hemispheres, are presented at centre of mass energies between 12 and 43.5 GeV. Comparisons are made with bare O(α_s²) QCD predictions as well as with QCD based fragmentation models. Values for α_s and Λsub(anti Manti S) are determined, both with and without hadronization effects included. Upper and lower limits for Λsub(anti Manti S) independent of fragmentation models have been determined to be 0.480±0.025 GeV and 0.047±0.007 GeV respectively. (orig.)

[en] Jet properties in e⁺e^- annihilation at center of mass energies of 14, 22, 35 and 43.7 GeV were studied with the data collected in the TASSO detector at PETRA, using the same evaluation procedures for all the energies. The total hadronic cross section ratio for the center of mass energy interval 39-47 GeV was determined to be R=4.11±0.05(stat.)±0.18(syst.) at <√s>=43.7 GeV. Corrected distributions of global shape variables are presented as well as the inclusive charged particle distributions for scaled momentum and transverse momentum. The center of mass energy evolution of the average sphericity, thrust, aplanarity and particle momentum is shown. (orig.)

[en] Intermittency effects have been studied directly for the first time in e⁺e^- annihilation, using 37509 hadronic events at an average CM energy of <√s>=35 GeV. The factorial moments F₂, F₃ and F₄ are given for the rapidity distribution and for the two-dimensional distributions in rapidity and azimuthal angle. The effects of cuts in sphericity and particle momentum are large. Comparison with several fragmentation models are made; some models like the Lund model with O(α_s²) matrix element give a qualitative description of the phenomena. The importance of detector effects is demonstrated. The results are discussed in terms of various suggested interpretations of this effect. (orig.)