The Determination of Metals in Welding Fume by X-Ray-Spectrometry

Analysis of the current hygienic situation in the welding production showed that the intensification of welding processes involves the deterioration of air quality, which negatively affects the welders health. Respiratory effects seen in full-time welders have included bronchitis, airway irritation, lung function changes, and a possible increase in the incidence of lung cancer. The metal concentration in the air of the working area have been determined using the photometric method of analysis, which involves the stage of decomposition of the sample material before analysis. However, losses of the analyzed elements are possible when the sample is decomposed. The X-ray fluorescence method of analysis has the advantage of being nondestructive. The investigations shown the data of photometric determination of metals in welding aerosols is 1.5(-:)2 times lower than the results of X-ray fluorescence analysis

The Determination of Metals in Welding Fume by X-Ray-Spectrometry

Analysis of the current hygienic situation in the welding production showed that the intensification of welding processes involves the deterioration of air quality, which negatively affects the welders health. Respiratory effects seen in full-time welders have included bronchitis, airway irritation, lung function changes, and a possible increase in the incidence of lung cancer. The metal concentration in the air of the working area have been determined using the photometric method of analysis, which involves the stage of decomposition of the sample material before analysis. However, losses of the analyzed elements are possible when the sample is decomposed. The X-ray fluorescence method of analysis has the advantage of being nondestructive. The investigations shown the data of photometric determination of metals in welding aerosols is 1.5(-:)2 times lower than the results of X-ray fluorescence analysis

Search for the Supersymmetric Partner of the Top-Quark in ppˉp \bar{p} Collisions at s=1.8TeV\sqrt{s} = 1.8 {\rm TeV}

We report on a search for the supersymmetric partner of the top quark (stop) produced in $t \bar{t}$ events using $110 {\rm pb}^{-1}$ of $p \bar{p}$ collisions at $\sqrt{s} = 1.8 {\rm TeV}$ recorded with the Collider Detector at Fermilab. In the case of a light stop squark, the decay of the top quark into stop plus the lightest supersymmetric particle (LSP) could have a significant branching ratio. The observed events are consistent with Standard Model $t \bar{t}$ production and decay. Hence, we set limits on the branching ratio of the top quark decaying into stop plus LSP, excluding branching ratios above 45% for a LSP mass up to 40 {\rm GeV/c}$^{2}$.Comment: 11 pages, 4 figure

Measurement of the B0 anti-B0 oscillation frequency using l- D*+ pairs and lepton flavor tags

The oscillation frequency Delta-md of B0 anti-B0 mixing is measured using the partially reconstructed semileptonic decay anti-B0 -> l- nubar D*+ X. The data sample was collected with the CDF detector at the Fermilab Tevatron collider during 1992 - 1995 by triggering on the existence of two lepton candidates in an event, and corresponds to about 110 pb-1 of pbar p collisions at sqrt(s) = 1.8 TeV. We estimate the proper decay time of the anti-B0 meson from the measured decay length and reconstructed momentum of the l- D*+ system. The charge of the lepton in the final state identifies the flavor of the anti-B0 meson at its decay. The second lepton in the event is used to infer the flavor of the anti-B0 meson at production. We measure the oscillation frequency to be Delta-md = 0.516 +/- 0.099 +0.029 -0.035 ps-1, where the first uncertainty is statistical and the second is systematic.Comment: 30 pages, 7 figures. Submitted to Physical Review

Разработка конструкции исполнительного оборудования, реализующего процесс генерации капель микро- и нанодиапазона

Modeling of velocities and temperatures processes distribution in the plasma-forming channel determining the design features and optimal parameters of the plasma torch nozzle is one of promising directions in development of plasma technologies. The aim of this work was to simulate the processes of velocities and temperature distribution in the plasma-forming channel and to determine the design features and optimal geometric parameters of the plasmatron nozzle  which  ensures  the  formation  of  necessary  direction  of  plasma  flows for generation of surface waves on the surface of a liquid metal droplet under the influence of the investigated instabilities.One of the main tasks is to consider the process of plasma jet formation and the flow of electric arc plasma. For obtaining small-sized particles one of the main parameters is the plasma flow  velocity.  It  is necessary that the plasma outflow velocity be close to supersonic. An increase of  the  supersonic  speed  is possible due to design of the plasmatron nozzle especially the design feature and dimensions of the gas channel in which the plasma is formed. Also the modeling took into account dimensions of the plasma torch nozzle, i. e. the device should provide a supersonic plasma flow with the smallest possible geometric dimensions.As a result models of velocities and temperatures distribution in the plasma-forming channel at the minimum and maximum diameters of the channel were obtained. The design features and optimal geometric parameters of the plasmatron have been determined: the inlet diameter is 3 mm, the outlet diameter is 2 mm.The design of the executive equipment has been developed and designed which implements the investigated process of generating droplets of the micro- and nanoscale range. A plasmatron nozzle was manufactured which forms the necessary directions of plasma flows for the formation of surface waves on the metal droplet surface under the influence of instabilities. An algorithm has been developed for controlling of executive equipment that implements the process of generating drops of micro- and nanoscale range.Моделирование процессов распределения скоростей и температур в плазмообразующем канале, определение конструктивных особенностей и оптимальных параметров сопла плазмотрона является одним из перспективных направлений в развитии плазменных технологий. Целью данной работы являлось моделирование процессов распределения скоростей и температур в плазмообразующем канале и определение конструктивных особенностей и оптимальных геометрических параметров сопла плазмотрона, которое должно обеспечивать формирование необходимых направлений плазменных потоков для образования на поверхности капли жидкого металла поверхностных волн под действием исследуемых неустойчивостей.Одной из главных задач является рассмотрение процесса формирования плазменной струи и течения электродуговой плазмы. Для получения мелкоразмерных частиц одним из главных параметров является скорость течения плазмы. Необходимо, чтобы скорость истечения плазмы была близка к сверхзвуковой. Увеличение скорости до сверхзвуковой возможно добиться за счёт конструкции сопла плазмотрона, а именно конструктивной особенностью и размерами газового канала, в котором образуется плазма. Также при моделировании учитывались размеры сопла плазмотрона, т. е. устройство должно обеспечивать сверхзвуковое течение плазмы при возможно меньших геометрических размерах.В результате исследований получены модели процессов распределения скоростей и температур в плазмообразующем канале при минимальных и максимальных диаметрах канала. Определены конструктивные особенности и оптимальные геометрические параметры сопла плазмотрона: диаметр на входе 3 мм, диаметр выходной 2 мм.Разработана и спроектирована конструкция исполнительного оборудования, реализующая исследуемый процесс генерации капель микро- и наноразмерного диапазона. Изготовлено сопло плазмотрона, формирующее необходимые направления плазменных потоков для образования на поверхности капли жидкого металла поверхностных волн под действием исследуемых неустойчивостей. Разработан алгоритм управления исполнительным оборудованием, реализующем процесс генерации капель микро- и наноразмерного диапазона

Measurement of the Inclusive Jet Cross Section in pˉp{\bar p p} collisions at s=1.8\sqrt{s}=1.8 TeV

We present results from the measurement of the inclusive jet cross section for jet transverse energies from 40 to 465 GeV in the pseudo-rapidity range $0.1<|\eta|<0.7$. The results are based on 87 $pb^{-1}$ of data collected by the CDF collaboration at the Fermilab Tevatron Collider. The data are consistent with previously published results. The data are also consistent with QCD predictions given the flexibility allowed from current knowledge of the proton parton distributions. We develop a new procedure for ranking the agreement of the parton distributions with data and find that the data are best described by QCD predictions using the parton distribution functions which have a large gluon contribution at high $E_T$ (CTEQ4HJ).Comment: 123 pages, 46 figure

Measurement of dsigma/DM Forward-Backward Charge Asymmetry for High Mass Drell-Yan e+e- Pairs from p-pbar Collisions at sqrt(s)=1.8 TeV

We report on a measurement of the mass dependence of the forward-backward charge asymmetry, A_FB, and production cross section dsigma/dM for e+e- pairs with mass M_ee>40 GeV/c2. The data sample consists of 108 pb-1 of p-pbar collisions at sqrt(s)=1.8 TeV taken by the Collider Detector at Fermilab during 1992-1995. The measured asymmetry and dsigma/dM are compared with the predictions of the Standard Model and a model with an extra Z' gauge boson.Comment: 7 pages submitted to Phys. Rev. Lett. 1 figure, 2 Table

Measurement of the average time-integrated mixing probability of b-flavored hadrons produced at the Fermilab Tevatron

We have measured the number of like-sign (LS) and opposite-sign (OS) lepton pairs arising from double semileptonic decays of b and (b) over bar hadrons, pair produced at the Fermilab Tevatron collider. The data samples were collected with the Collider Detector at Fermilab during the 1992-1995 collider run by triggering on the existence of mumu or emu candidates in an event. The observed ratio of LS to OS dileptons leads to a measurement of the average time-integrated mixing probability of all produced b-flavored hadrons which decay weakly, (χ) over bar =0.152+/-0.007 (stat)+/-0.011 (syst), that is significantly larger than the world average (χ) over bar =0.118+/-0.005

Cross Section and Heavy Quark Composition of Photon+Muon Events Produced in ppbar Collisions

We present a measurement of the cross section and the first measurement of the heavy flavor content of associated direct photon + muon events produced in hadronic collisions. These measurements come from a sample of 1.8 TeV ppbar collisions recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily due to Compton scattering process charm+gluon -> charm+photon, with the final state charm quark producing a muon. The cross section for events with a photon transverse momentum between 12 and 40 GeV/c is measured to be 46.8+-6.3+-7.5 pb, which is two standard deviations below the most recent theoretical prediction. A significant fraction of the events in the sample contain a final-state bottom quark. The ratio of charm to bottom production is measured to be 2.4+-1.2, in good agreement with QCD models.Comment: 15 pages, 5 figure