Effective Rheology of Bubbles Moving in a Capillary Tube

We calculate the average volumetric flux versus pressure drop of bubbles moving in a single capillary tube with varying diameter, finding a square-root relation from mapping the flow equations onto that of a driven overdamped pendulum. The calculation is based on a derivation of the equation of motion of a bubble train from considering the capillary forces and the entropy production associated with the viscous flow. We also calculate the configurational probability of the positions of the bubbles.Comment: 4 pages, 1 figur

Alignment of the ALICE Inner Tracking System with cosmic-ray tracks

37 pages, 15 figures, revised version, accepted by JINSTALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 micron in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10^5 charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.Peer reviewe

Centrality Dependence Of The Pseudorapidity Density Distribution For Charged Particles In Pb-pb Collisions At √snn=2.76tev

7264/Mai61062

Neutron emission from electromagnetic dissociation of Pb nuclei at √ s NN = 2.76 TeV measured with the ALICE ZDC

The ALICE Zero Degree Calorimeter system (ZDC) is composed of two identical sets of calorimeters, placed at opposite sides with respect to the interaction point, 114 meters away from it, complemented by two small forward electromagnetic calorimeters (ZEM). Each set of detectors consists of a neutron (ZN) and a proton (ZP) ZDC. They are placed at zero degrees with respect to the LHC axis and allow to detect particles emitted close to beam direction, in particular neutrons and protons emerging from hadronic heavy-ion collisions (spectator nucleons) and those emitted from electromagnetic processes. For neutrons emitted by these two processes, the ZN calorimeters have nearly 100% acceptance. During the √ sNN = 2.76 TeV Pb-Pb data-taking, the ALICE Collaboration studied forward neutron emission with a dedicated trigger, requiring a minimum energy deposition in at least one of the two ZN. By exploiting also the information of the two ZEM calorimeters it has been possible to separate the contributions of electromagnetic and hadronic processes and to study single neutron vs. multiple neutron emission. The measured cross sections of single and mutual electromagnetic dissociation of Pb nuclei at √ s NN = 2.76 TeV, with neutron emission, are σ single EMD = 187:4 ± 0.2 (stat.)-11.2 +13.2 (syst.) b and σmutual EMD = 5.7 ± 0.1 (stat.) ±0.4 (syst.) b, respectively [1]. This is the first measurement of electromagnetic dissociation of 208Pb nuclei at the LHC energies, allowing a test of electromagnetic dissociation theory in a new energy regime. The experimental results are compared to the predictions from a relativistic electromagnetic dissociation model'701st International Conference on New Frontiers in Physics, ICFP 20122012-06-10Kolymbari, Crete; Greecesem informaçã

The effect of nitrogen ion implantation on nano-scale hardness and elastic modulus of WC-Co indexable knives for wood materials machining

The effect of nitrogen ion implantation on nano-scale hardness and elastic modulus of WC-Co indexable knives for wood materials machining. The paper presents the results of a study investigating the effects of nitrogen ion implantation into the surface layer of WC-Co blades, used for machining wood materials, on their hardness and modulus of elasticity at the nano-scale. The modified blades were analyzed in six variants of implantation process parameters, and compared with control blades (virgin, unmodified). Three energies of accelerating nitrogen ions were used in the implantation process (5, 50 and 500 keV) and two doses of implanted ions (1e17 and 5e17 cm-2). The nano-hardness and elastic modulus of all blades were measured using an Anton Paar TriTec (UNHT) hardness tester.Wpływ implantacji jonów azotu na twardość i moduł sprężystości w nano-skali noży wymiennych WC-Co do obróbki materiałów drzewnych. W artykule przedstawiono wyniki wpływu procesu implantacji jonów azotu do warstwy wierzchniej ostrzy WC-Co do obróbki materiałów drzewnych na ich twardość i moduł sprężystości w nano-skali. Analizowano ostrza modyfikowane w sześciu wariantach parametrów procesu implantacji, oraz w celach porównawczych, ostrza kontrolne (niemodyfikowane). Zastosowano trzy energie przyspieszenia jonów azotu w procesie implantacji (5, 50 i 500 keV) oraz dwie dawki implantowanych jonów (1e17 oraz 5e17 cm-2). Pomiaru twardości i modułu sprężystości w nano-skali wszystkich ostrzy dokonano przy użyciu twardościomierza Anton Paar TriTec (UNHT)

Nano-scale hardness and elastic modulus of WC-Co composites and their relationship to the tools life during particleboard milling

Nano-scale hardness and elastic modulus of WC-Co composites and their relationship to the tool life during particleboards milling. The paper summarizes the results of the technique of hardness and elastic modulus determination using a load and displacement sensing indentation experiments. During the tests these properties were measured in nano-scale for different types of WC-Co composites using the Anton Paar TriTec Ultra Nano Hardness Tester (UNHT). In addition, durability examination of WC-Co tools during milling of particleboard was carried out. In the final stage, the correlation of the studied properties with the lifetime of tools was analyzed. The studies have revealed a relationship between micro-hardness and the total cutting length of the WC-Co tools.Twardość i moduł sprężystość kompozytów WC-Co w nano-skali i ich związek z trwałością narzędzi podczas frezowania płyt wiórowych. W artykule przedstawiono zastosowanie metody określania twardości i modułu sprężystości za pomocą techniki wgłębnika z rejestracją obciążenia i przemieszczenia. Mierzono ww. właściwości w nanoskali dla różnych rodzajów kompozytów WC-Co przy użyciu twardościomierza Anton Paar TriTec (UNHT). Ponadto przeprowadzono badania trwałości narzędzi WC-Co podczas frezowania płyty wiórowej. W końcowym etapie przeanalizowano korelację badanych właściwości z okresem trwałości ostrzy. Badania wykazały korelacyjny związek między twardością w nano-skali a całkowitą drogą skrawania ostrzy WC-Co

THE EFFECT OF ZINC CONTENT ON THE ENHANCEMENT Er3+-Yb3+ LUMINESCENCE PROPERTIES IN THE SILICATE GLASS MATRIX

Glasses doped with Er and Yb show strong luminescence around 1530 nm, which makes them attractive luminophores for the preparation of multifunctional optical components. This article is focused on the influence of ZnO on the optical and luminescence properties of Er-Yb zinc-silicate glasses. The influence of silver doping on the resulting luminescence properties of the prepared glasses has also been investigated. Three types of silicate glasses containing different amounts of ZnO and RE ions (Er and Yb) were prepared. For all the glasses prepared, their density, glass-transformation temperature and refractive index were determined. Moreover, these glasses were doped with silver using two methods - ion implantation and ion exchange. The presence of silver metal nanoparticles was observed using optical absorption in the UV-VIS range. Photoluminescence spectroscopy was used to observe the effect of the presence silver or zinc oxide on the intensity of luminescence. The results have shown that the enhancement of ZnO content positively influenced erbium luminescence at 1530 nm without affecting the transparency or homogeneity of the glass matrix. Moreover, the presence Ag+ ions in this special type of glass matrix positively contributed to the enhancement of erbium photoluminescence

Formation and Characterization of Shallow Junctions in GaAs Made by Ion Implantation and ms-Range Flash Lamp Annealing

With the demand of aggressive scaling in nanoelectronics, further progress can be realized by integration of high mobility semiconductors, such as III–V compound semiconductors, with complementary metal‐oxide‐semiconductor (CMOS) technology. In this study, the formation of shallow n–p and p–n junctions in GaAs utilizing ion implantation of S and Zn, respectively, followed by millisecond‐range flash lamp annealing (FLA) is presented. The distribution of implanted elements obtained by secondary ion mass spectrometry (SIMS) shows that the FLA process can effectively suppress the diffusion of dopants. Simultaneously, the ms‐range annealing is sufficient to recrystallize the implanted layer and to activate the dopants. Formation of p–n and n–p junctions is confirmed by current–voltage characteristics. The ratio of reverse to forward current can reach up to 1.7 × 107 in the n‐GaAs:Zn case