Measurement of nuclide cross-sections of spallation residues in 1 A GeV 238U + proton collisions

The production of heavy nuclides from the spallation-evaporation reaction of 238U induced by 1 GeV protons was studied in inverse kinematics. The evaporation residues from tungsten to uranium were identified in-flight in mass and atomic number. Their production cross-sections and their momentum distributions were determined. The data are compared with empirical systematics. A comparison with previous results from the spallation of 208Pb and 197Au reveals the strong influence of fission in the spallation of 238U.Comment: 20 pages, 10 figures, background information at http://www-wnt.gsi.de/kschmidt

Cross-sections of spallation residues produced in 1.A GeV 208Pb on proton reactions

Spallation residues produced in 1 GeV per nucleon $^{208}$Pb on proton reactions have been studied using the FRagment Separator facility at GSI. Isotopic produc- tion cross-sections of elements from $_{61}$Pm to $_{82}$Pb have been measured down to 0.1 mb with a high accuracy. The recoil kinetic energies of the produced fragments were also determined. The obtained cross-sections agree with most of the few existing gamma-spectroscopy data. Data are compared with different intra nuclear-cascade and evaporation-fission models. Drastic deviations were found for a standard code used in technical applications.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. Lett. Revised version May 12, 200

Evaporation residues produced in spallation of 208Pb by protons at 500A MeV

The production cross sections of fragmentation-evaporation residues in the reaction Pb+p at 500A MeV have been measured using the inverse-kinematics method and the FRS spectrometer (GSI). Fragments were identified in nuclear charge using ionisation chambers. The mass identification was performed event-by-event using the B-rho - TOF - Delta-E technique. Although partially-unresolved ionic charge states induced an ambiguity on the mass of some heavy fragments, production rates could be obtained with a high accuracy by systematically accounting for the polluting ionic charge states. The contribution of multiple reactions in the target was subtracted using a new, partly self-consistent code. The isobaric distributions are found to have a shape very close to the one observed in experiments at higher energy. Kinematic properties of the fragments were also measured. The total and the isotopic cross sections, including charge-pickup cross sections, are in good agreement with previous measurements. The data are discussed in the light of previous spallation measurements, especially on lead at 1 GeV

Optical model of laser scatterometry for surface flaws of railway rails

W artykule przedstawiono opis zjawisk fizycznych towarzyszących rozpraszaniu się światła lasera (skaterometrii laserowej), na wadach zlokalizowanych na powierzchni tocznej szyn kolejowych. Przeanalizowano wzorce powierzchni imitujące typowe kształty wad kontaktowo-naprężeniowych. W oparciu o prawa Kirchhoffa, wyznaczono modele optyczne dla tych wzorców uszkodzeń, ze szczególnym uwzględnieniem wad head checking - HC.The paper presents phenomena occurring during scattering the laser beam in surface flaws of the head of rail. During the analysis process, the patterns corresponding to typical shape of stress-contact flaws were taken into account. Based on Kirchhoff law, optical model of these flaws were determined with particular emphasis on head-checking flaws

First Principles Study of Gas Adsorption Dynamics on Pristine and Defected Graphene

We present the results of ab initio calculations of gas adsorption processes on graphene. Static density functional theory framework is used to obtain adsorption energies of several species on a Stone-Wales defected graphene monolayer. The Van der Waals interaction is taken into account by a semi-empirical correction. Sites closer to the defect are found to induce stronger adsorption compared to sites further away, where the graphene crystal structure is intact. The Car-Parrinello ab initio molecular dynamics simulations are performed at high temperatures. CH₃ is found to be stably physisorbed or chemisorbed at 300 K

The influence of water on the tribological properties of sole regenerative coverings

W pracy przedstawiono metodykę oraz wyniki badań tarciowych kompozytów przeznaczonych do regeneracji spodów obuwia, wykonanych z żywicy poliuretanowej napełnianej i sadzą, granulatem szklanym, miałem węglowym, garnetem oraz elektrokorundem. Kompozyty podczas testów współpracowały z próbką wykonaną z Al2O3, która zastępowała materiał posadzkowy. Badania przeprowadzono w warunkach tarcia technicznie suchego oraz w obecności wody. Analiza wyników badań pozwoliła na stwierdzenie, że najodpowiedniejszym kompozytem do regeneracji warstw podeszew obuwia jest kompozyt z dodatkiem sadzy, który posiada najwyższy współczynnik tarcia zarówno w warunkach tarcia technicznie suchego, jak i obecności wody.The methodology and the results of frictional composites destined for the regeneration of bottom of the shoes made of filled polyurethane resins and soot, glass granulate, culm, garnet, and aloxite were presented. During the test, composites worked with a sample made of Al2O3, which replaced flooring. The tests were performed in the conditions of technically dry friction and with the presence of water. The analysis of the test results led to a conclusion that the most appropriate composite to regenerate the layers of the bottom of a shoe is a composite with a soot, which has the highest coefficient of friction in the conditions of technically dry friction and in the presence of water