Structure and Stability of an Amorphous Metal

Using molecular dynamics simulations, with a realistic many-body embedded-atom potential, and a novel method to characterize local order, we study the structure of pure nickel during the rapid quench of the liquid and in the resulting glass. In contrast with previous simulations with pair potentials, we find more crystalline order and fewer icosahedra for slower quenching rates, resulting in a glass less stable against crystallization. It is shown that there is not a specific amorphous structure, only the arrest of the transition from liquid to crystal, resulting in small crystalline clusters immersed in an amorphous matrix with the same structure of the liquid.Comment: 4 pages, 4 ps figs., to appear in Phys. Rev. Let

Radiation Monitoring System for the LHCb Inner Tracker

The performance requirements and the design of the Radiation Monitoring System (RMS) for the LHCb Inner Tracker are presented. Details of the Metal Foil Detector technology employed for the RMS are described, along with results from tests of RMS prototypes

Performance of Long Ladders for the LHCb Silicon Tracker

The LHCb Silicon Tracker uses detector ladders with readout strips with an effective length of up to 36,cm. Kapton interconnect cables of up to 54,cm in length are employed in between silicon sensors and front-end readout hybrids. Fast front-end readout electronics with a shaping time of around 25,ns are employed to avoid pile-up of events from consecutive LHC bunch crossings. An extensive measurement program as well as simulations have been carried out to study the expected noise performance of these detectors. Presented at the 14th International Workshop on Vertex Detectors, Chuzenji Lake, Nikko, Japan, November 7-11, 2005 Proceedings submitted for publication in Nucl. Instr. and Meth.

Subcellular compartmentation of glutathione in dicotyledonous plants

This study describes the subcellular distribution of glutathione in roots and leaves of different plant species (Arabidopsis, Cucurbita, and Nicotiana). Glutathione is an important antioxidant and redox buffer which is involved in many metabolic processes including plant defense. Thus information on the subcellular distribution in these model plants especially during stress situations provides a deeper insight into compartment specific defense reactions and reflects the occurrence of compartment specific oxidative stress. With immunogold cytochemistry and computer-supported transmission electron microscopy glutathione could be localized in highest contents in mitochondria, followed by nuclei, peroxisomes, the cytosol, and plastids. Within chloroplasts and mitochondria, glutathione was restricted to the stroma and matrix, respectively, and did not occur in the lumen of cristae and thylakoids. Glutathione was also found at the membrane and in the lumen of the endoplasmic reticulum. It was also associated with the trans and cis side of dictyosomes. None or only very little glutathione was detected in vacuoles and the apoplast of mesophyll and root cells. Additionally, glutathione was found in all cell compartments of phloem vessels, vascular parenchyma cells (including vacuoles) but was absent in xylem vessels. The specificity of this method was supported by the reduction of glutathione labeling in all cell compartments (up to 98%) of the glutathione-deficient Arabidopsis thaliana rml1 mutant. Additionally, we found a similar distribution of glutathione in samples after conventional fixation and rapid microwave-supported fixation. Thus, indicating that a redistribution of glutathione does not occur during sample preparation. Summing up, this study gives a detailed insight into the subcellular distribution of glutathione in plants and presents solid evidence for the accuracy and specificity of the applied method

Printing Dynamics : Nip Pressure and Its Relationship with Materials’ Viscoelasticity

A theoretical framework of nip dynamics of conventional printing, including dynamic models deducted from nip geometry,printing speed, and physics laws, is proposed. Different from previous works, the present work focuses at obtaining the nippressure from a given nip geometric setting, the common way in full-scale printing. The effects of viscoelastic characteristicsof paper substrate and print form (rubber and/or polymer) on the nip pressure, which become pronounced in a full-scale printingprocess due to high speed, are accounted and illustrated by three physical models, e.g., Maxwell model, Kelvin–Voigtmodel, and Burgers model. Details of the nip dynamic features, shape, amplitude, duration, and effective nip width, etc.,have been worked out. The viscoelastic nature of the materials was found to be responsible for the so-called speed-hardening,asymmetric nip profile, variations in the nip amplitude and effective nip width, etc. It was also found that how the viscoelasticproperties of the materials affect the nip dynamics depend on the how the elastic components and the viscos count parts areconnected with each other. The framework is applicable to calendaring, gravure, offset, and flexography

Measurements of a prototype ladder for the TT station in a 120~GeV/c pi−pi^- beam

The results of a comprehensive measurement program carried out at the CERN X7 test facility in June 2004 on a prototype ladder readout via a long Kapton interconnect are described. For a shaping time consistent with LHCb operational requirements the most probable value of the S/N ratio is found to be 16 for particles that cross the detector close to the centre of a readout strip and 13 for particles that cross midway between two readout strips. These values are in excellent agreement with expectations

Test-beam measurements on prototype ladders for the LHCb TT station and Inner Tracker

The results of a comprehensive measurement program carried out at the CERN X7 test facility in May 2003 on prototype ladders for the LHCb Silicon Tracker are described

Production and Quality Assurance of Detector Modules for the LCHb Silicon Tracker

The LHCb experiment, which is currently under construction at the Large Hadron Collider~(CERN, Geneva), is designed to study CP violation and find rare decays in the B meson system. To achieve the physics goals the LHCb detector must have excellent tracking performance. An important element of the LHCb tracking system is the Silicon Tracker, which covers a sensitive surface of about 12~m2 with silicon microstrip detectors and includes about 272k readout channels. It uses up to 132~cm long detector modules with readout strips of up to 38~cm in length and up to 57~cm long Kapton interconnects in between sensors and readout hybrids. The production of detector modules has been completed recently and the detector is currently under installation. A rigorous quality assurance programme has been performed to ensure that the detector modules meet the mechanical and electrical requirements and study their various characteristics. In this paper, the detector design, the module production steps, and the module quality assurance programme are briefly described

Studies of the Beetle 1.2 Pipeline Homogeneity

The pipeline homogeneity in general and the behaviour of the edge channels of the Beetle 1.2 readout chip [1] were studied with data taken during the Silicon Tracker test beam period in May 2003. A contribution of roughly 10\% from pipeline inhomogeneities to the strip noise was observed. All channels including the first and the last one were found to be fully functional