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Thin films of linear low-density polyethylene show a significant time-dependent behavior, strongly reliant on temperature and strain rate effects. A constitutive nonlinear thermo-viscoelastic relation is developed to characterize the response of thin membranes up to yielding, in a wide range of temperatures, strain rates, and mechanical loading conditions. The presented plane stress orthotropic formulation involves the free volume theory of viscoelasticity and the time-temperature superposition principle, necessary to describe non-linearities and non-isothermal conditions. Uniaxial tension tests at constant strain rate and long-duration biaxial inflation experiments have been employed in the calibration of the material parameters. The model has been implemented in the Abaqus finite element code by means of a user-defined subroutine based on a recursive integration algorithm. The accuracy of the constitutive relation has been validated against experimental data of full field diaphragm inflation tests and uniaxial tension, relaxation and cyclic experiments, covering sub-ambient temperatures and strain rate ranges observed during the operation of stratospheric balloons. [ABSTRACT FROM AUTHOR]

A molecular formulation of the onset of plasticity is proposed to assess temperature and strain rate effects in anisotropic semi-crystalline rubbery films. The presented plane stress criterion is based on the strain rate-temperature superposition principle and the cooperative theory of yielding, where some parameters are assumed to be material constants, while others are considered to depend on specific modes of deformation. An orthotropic yield function is developed for a linear low density polyethylene thin film. Uniaxial and biaxial inflation experiments were carried out to determine the yield stress of the membrane via a strain recovery method. It is shown that the 3 % offset method predicts the uniaxial elastoplastic transition with good accuracy. Both the tensile yield points along the two principal directions of the film and the biaxial yield stresses are found to obey the superposition principle. The proposed yield criterion is compared against experimental measurements, showing excellent agreement over a wide range of deformation rates and temperatures. [ABSTRACT FROM AUTHOR]

Pressurised pipes are ubiquitous in chemical, nuclear and power plants. A sudden failure and release of high-speed fluid cause large inelastic displacements characterised by a whipping-type motion, which can ultimately hinder the surrounding structural and functional systems. In this paper, a beam user element has been developed, implemented and applied to analyse the in-plane flexural dynamic response of pipe whip. The two-dimensional Euler–Bernoulli beam element is based on the corotational kinematic formulation and elastoplastic constitutive models that include metal plasticity and moment–curvature relationships obtained from numerical bending tests, which highlighted the existence of two new dimensionless groups that govern the flexural response of slender pipes and enable the creation of moment–curvature master curves for thick and thin pipes. The corotational beam element formulation is compared against an analytical rigid-perfectly plastic model, numerical simulations employing shell elements and available experimental results, showing very good accuracy in the prediction of the inelastic deformation response of pipe whip and its hazardous area of influence. Furthermore, parametric studies are performed to investigate the effect of load intensity, cross-sectional geometry and concentrated tip mass on the post-failure deformation modes, plastic hinge formation and extension of the hazard zone. The presented results represent valid tools to assess the safety of industrial piping systems undergoing failure, and to optimally design pipe whip restraints. [ABSTRACT FROM AUTHOR]

A rod covering a fixed span is loaded at the middle with a transverse force, such that with increasing load a progressive deflection occurs. After a certain initial deflection, a phenomenon is observed where two points of the rod come in contact with each other. This is defined as the 'dripping point' and is when 'self-encapsulation' of the elastic rod occurs. Dripping seems at a first glance to be impossible and definitely cannot occur in the presence of 'ordinary' constraints (such as simple supports or clamps) at the ends of the span. However, the elastica governs oscillating pendulums, buckling rods and pendant drops, so that a possibility for self-encapsulation might be imagined. This phenomenon is indeed demonstrated (both theoretically and experimentally) to occur when at least one of the constraints at the ends of the rod is a sliding sleeve. This mechanical device generates a configurational force, causing the dripping of the rod, in a fully elastic set-up. [ABSTRACT FROM AUTHOR]

Abstract: Mechanical experiments have been designed and performed to investigate the elasto-plastic behaviour of green bodies formed from an aluminum silicate spray dried powder used for tiles production. Experiments have been executed on samples obtained from cold compaction into a cylindrical mould and include: uniaxial strain, equi-biaxial flexure and high-pressure triaxial compression/extension tests. Two types of powders have been used to realize the green body samples, differing in the values of water content, which have been taken equal to those usually employed in the industrial forming of traditional ceramics. Yielding of the green body during compaction has been characterized in terms of yield surface shape, failure envelope, and evolution of cohesion and void ratio with the forming pressure, confirming the validity of previously proposed constitutive models for dense materials obtained through cold compaction of granulates. [Copyright &y& Elsevier]

The concept of a 'deformable arm scale' (completely different from a traditional rigid arm balance) is theoretically introduced and experimentally validated. The idea is not intuitive, but is the result of nonlinear equilibrium kinematics of rods inducing configurational forces, so that deflection of the arms becomes necessary for equilibrium, which would be impossible for a rigid system. In particular, the rigid arms of usual scales are replaced by a flexible elastic lamina, free to slide in a frictionless and inclined sliding sleeve, which can reach a unique equilibrium configuration when two vertical dead loads are applied. Prototypes designed to demonstrate the feasibility of the system show a high accuracy in the measurement of load within a certain range of use. Finally, we show that the presented results are strongly related to snaking of confined beams, with implications for locomotion of serpents, plumbing and smart oil drilling. [ABSTRACT FROM AUTHOR]

Oxyplumboroméite, Pb2Sb2O7, is a new mineral of the roméite group of the pyrochlore supergroup (IMA 2013-042). It is found together with calcite and leucophoenicite in fissure fillings in tephroite skarn at the Harstigen mine, Värmland, Sweden. The mineral occurs as yellow to brownish yellow rounded grains or imperfect octahedra. Oxyplumboroméite has a Mohs hardness of ∼5, a calculated density of 6.732 g/cm3 and is isotropic with a calculated refractive index of 2.061. Oxyplumboroméite is cubic, space group Fd3m, with the unit-cell parameters a = 10.3783(6) Å, V = 1117.84(11) Å3 and Z = 8. The strongest five X-ray powder-diffraction lines [d in Å (I)(hkl)] are: 2.9915(100)(222), 2.5928(32)(400), 1.8332(48)(440), 1.5638(38)(622) and 1.1900(12)(662). The crystal structure of oxyplumboroméite was refined to an R1 index of 3.02% using 160 unique reflections collected with MoKα radiation. Electron microprobe analyses in combination with crystal-structure refinement, infrared, Mössbauer and electronic absorption spectroscopy resulted in the empirical formula A(Pb0.92Ca0.87Mn0.09Sr0.01Na0.05)Σ1.93 B(Sb1.73Fe3+ 0.27)Σ2.00X+Y[O6.64(OH)0.03]Σ6.67. Oxyplumboroméite is the Pb analogue of oxycalcioroméite, ideally Ca2Sb2O7. [ABSTRACT FROM AUTHOR]

The stabilities of possible Y(R3+ + R2+ + Li+) clusters around the W anion (O1 site) of the tourmaline structure were checked using the bond-valence approach. Arrangements involving R3+ = Al3+ or Fe3+ and R2+ = (Fe, Mn, Mg)2+ were all found to be stable. Structural data show a strong linear correlation between the mean formal valence (MFV) of the Y cations and the long-range average bond valence sum (BVS) at the O1 site, as estimated from bond-valence parameters. This correlation is observed for all chemical compositions of tourmaline, except for fluor-buergerite where the O3 site is dominated by oxygen anions. Results show that the long-range site populations of the Y and O1 sites are related to each other by valence constraints described by the empirical and theoretical equations: BVS(O1) = [0.99 MFV(Y) − 1.20] and MFV(O1) = [1.00 MFV(Y) − 1.00], respectively. The systematic deviation of the empirical equation from the ideal one is ascribed to the occurrence of bond strain involving the O1 site. An important implication of the correlation between MFV(Y) and BVS(O1) is that the (OH) content at the O1 site may be estimated by the equation W (OH) = 2 − [1.01 BVS(O1)] − 0.21 − F. [ABSTRACT FROM AUTHOR]

Abstract: The development of micro-scale mechanical systems has been moving rapidly, allowing an opportunity to the semiconductor detectors to have ever more power located on the active region. Miniaturization associated with micro-channel technologies allows the design of micro-system structures that are able to cool silicon pixel detectors with power of the order of some W/cm2 with thickness less than 0.3% of radiation length. We present the design and thermo-hydraulic test results for low material budget support and cooling obtained through forced liquid convection in micro-channels, developed for the innermost layer (Layer 0) of SuperB silicon vertex tracker. [Copyright &y& Elsevier]

Abstract: Pixel detectors at future colliders will need to match very stringent requirement on position resolution. To ensure the needed mechanical stability and the removal of the power dissipated by the read-out electronic, the support structure and cooling add an important contribution to the total material in the active area, in terms of radiation length. We present the development, the construction and the mechanical–thermal characterization of prototypes of light material support for pixel detectors with microchannel for heat evacuation through forced convection of liquid coolant. The solution we choose shows several advantages: heat exchange is taking place efficiently due to the high ratio surface/volume and so high thermal conductivities can be obtained, minimally affecting the stiffness of the structure; the thermal resistances are reduced because of the contiguity between the fluid and the circuit dissipating power; the uniformity of temperature on the surface covered by of the sensors is also kept under control. Several prototypes implementing different geometries of micro-machined channels have been realized in composites materials (CFRP). FEA studies have been performed to validated the experimental test conducted in the thermo-fluid dynamic test bench we recently assembled in the INFN Pisa laboratory. [Copyright &y& Elsevier]

ATLAS is a general purpose experiment approved for the LHC collider at CERN. An important component of the detector is the central hadronic calorimeter; for its construction more than 600,000 Wave Length Shifting fibres (corresponding to a total length of 1120 km) have been used. We have built and put into operation a dedicated instrument for the measurement of light yield and attenuation length over groups of 20 fibres at a time. The overall accuracy achieved in the measurement of light yield (attenuation length) is 1.5% (3%). We also report the results obtained using this method in the quality control of a large sample of fibres. [Copyright &y& Elsevier]

The dynamic behavior of the class of periodic waveguides whose unit cells are generated through a quasicrystalline sequence can be interpreted geometrically in terms of a trace map that embodies the recursive rule obeyed by traces of the transmission matrices. We introduce the concept of canonical quasicrystalline waveguides, for which the orbits predicted by the trace map at specific frequencies, called canonical frequencies, are periodic. In particular, there exist three families of canonical waveguides. The theory reveals that for those (i) the frequency spectra are periodic and the periodicity depends on the canonical frequencies, (ii) a set of multiple periodic orbits exists at frequencies that differ from the canonical ones, and (iii) perturbation of the periodic orbit and linearization of the trace map define a scaling parameter, linked to the golden ratio, which governs the self-similar structure of the spectra. The periodicity of the waveguide responses is experimentally verified on finite specimens composed of selected canonical unit cells. [ABSTRACT FROM AUTHOR]

A challenge in soft robotics and soft actuation is the determination of an elastic system that spontaneously recovers its trivial path during postcritical deformation after a bifurcation. The interest in this behavior is that a displacement component spontaneously cycles around a null value, thus producing a cyclic soft mechanism. An example of such a system is theoretically proven through the solution of the elastica and a stability analysis based on dynamic perturbations. It is shown that the asymptotic self-restabilization is driven by the development of a configurational force, of similar nature to the Peach-Koehler interaction between dislocations in crystals, which is derived from the principle of least action. A proof-of-concept prototype of the discovered elastic system is designed, realized, and tested, showing that this innovative behavior can be obtained in a real mechanical apparatus. [ABSTRACT FROM AUTHOR]

We study the effects of cation inversion x (Mg ↔ Al, with x representing the fraction of Mg and Al exchanged) and magnetic substitution (Mn → Mg) on the elastic properties of the MgAl 2 O 4 spinel system using density functional theory and Brillouin scattering techniques. Our computations show that cation inversion decreases the molar volume of spinel and produces a stiffening of C 11 and a softening of C 12. Simulations and experiments agree within 2 %. Density functional theory also captures the qualitative effect of Mg ↔ Al on C 44 , that is, an initial softening for inversion degree at x < 0.125 and stiffening at x = 1 , with a disagreement of < 4%. The Zener anisotropy factor A decreases with increasing degree of inversion. All these trends are preserved at high pressures. The substitution of Mn for Mg produces and increases the molar volume of spinel, and it is accompanied by the softening of both C 11 and C 44 , and the stiffening of C 12 in good agreement with experimental results at ambient conditions. All these effects, which are qualitatively opposite to those of cation inversion, are enhanced at high pressures. The effect of Mn → Mg on the elastic anisotropy of spinel is, however, qualitatively similar to that of cation inversion, i.e., it causes a decrease in the Zener factor A. [ABSTRACT FROM AUTHOR]

The Belle II experiment at KEK in Japan considers an upgrade for the vertex detector system in line with the accelerator upgrade for higher luminosity at long shutdown 2 planned for 2028. One proposal for the upgrade of the vertex detector called VTX aims to improve background robustness and reduce occupancy using small and fast pixels. VTX accommodates the OBELIX depleted monolithic active CMOS pixel sensor (DMAPS) on all five proposed layers. OBELIX is specifically developed for the VTX application and based on the TJ-Monopix2 chip initially developed to meet the requirements of the outer layers of the ATLAS inner tracker (ITk). This paper will review recent tests of the TJ-Monopix2 chip as well as various design aspects of the OBELIX-1 chip currently under development. [ABSTRACT FROM AUTHOR]

The Eshelbian (or configurational) force is the main concept of a celebrated theoretical framework associated with the motion of dislocations and, more in general, defects in solids. In a similar vein, in an elastic structure where a (smooth and bilateral) constraint can move and release energy, a force driving the configuration is generated, which therefore is called by analogy ‘Eshelby-like’ or ‘configurational’. This force (generated by a specific movable constraint) is derived both via variational calculus and, independently, through an asymptotic approach. Its action on the elastic structure is counterintuitive, but is fully substantiated and experimentally measured on a model structure that has been designed, realized and tested. These findings open a totally new perspective in the mechanics of deformable mechanisms, with possible broad applications, even at the nanoscale. [ABSTRACT FROM AUTHOR]

The crystal chemistry of a natural, gem-quality, blue-grey Zn-rich spinel crystal from Jemaa, Kaduna State, Nigeria, was studied using electron microprobe, single-crystal X-ray diffraction, optical absorption and Raman spectroscopies. The composition of the crystal approaches the gahnite endmember (ZnAl2O4), ∼94 mol.%, with the remainder being dominated by a hercynite component (FeAl2O4). The unit-cell dimension is 8.0850(3) Å and the tetrahedral and octahedral bond distances are determined as T-O 1.9485(6) Å and M-O 1.9137(3) Å . Crystal chemical analysis resulted in the empirical structural formula T(Zn0.94Fe2+0.03Al0.03)M(Al1.96Fe2+0.03Fe3+0.0.1)O4, which shows Zn and Al almost fully ordered in the tetrahedrally and octahedrally coordinated T and M sites, respectively. Raman spectra obtained using the excitation of the blue 473.1 nm line of a Nd:YAG laser display three of the five Raman-active modes predicted for the general oxide spinel group of minerals. These are the Eg mode at 420.6 cm-1 and the T2g modes at 510 cm-1 and 661 cm-1, due to vibrations in the AlO6 octahedra. Optical absorption spectra recorded in the UV/VIS-NIR-MIR range 2000-29000 cm-1 show a dominant absorption band at ∼5000 cm-1 which is caused by spin-allowed electronic d-d transitions in Fe2+ located at the T sites. The blue-grey hue exhibited by the sample is mainly due to spin-forbidden electronic transitions in TFe2+ and to MFe2+ → MFe3+ intervalence charge transfer, and the poor saturation of the colour is due to the small concentration of Fe2+ and Fe3+. [ABSTRACT FROM AUTHOR]

We present a fully active-controlled He-Ne ring laser gyroscope operating in square cavity having a side length of 1.35 m. The apparatus is designed to provide a very low mechanical and thermal drift of the ring cavity geometry and is conceived to be operative in two different orientations of the laser plane, in order to detect rotations around the vertical or the horizontal direction. Since June 2010, the system is active inside the Virgo interferometer central area with the aim of performing high-sensitivity measurements of environmental rotational noise. So far, continuous unattended operation of the gyroscope has been longer than 30 days. The main characteristics of the laser, the active remote-controlled stabilization systems and the data acquisition techniques are presented. An offline data processing, supported by a simple model of the sensor, is shown to improve the effective long-term stability. A rotational sensitivity at the level of $10^{-8}~\mathrm{rad}/\sqrt{\mathrm{Hz}}$ below 1 Hz, very close to the required specification for the improvement of the Virgo suspension control system, is demonstrated for the configuration where the laser plane is horizontal. [ABSTRACT FROM AUTHOR]

A hot-press molding technique is developed to design and manufacture carbon fiber reinforced polymer (CFRP) X-core sandwich panels that allowed both the composite face sheets and its X-core to be simultaneously molded together. Compression tests were performed on the sandwich panels to assess the effects of relative density on its compressive properties and the failure mode that it develops. Analytical models were developed to predict the panel stiffness and strength; and a failure map of its deformation mode is generated based on the geometric parameters of the unit cell. Linear and nonlinear finite element analyses were performed to further investigate the effects of initial geometric imperfection and progressive damage on the response of the sandwich panels with different cell wall slenderness. Predictions from analytical and numerical models will be shown to be in good agreement with the experiments. The CFRP X-core sandwich panels will be shown to attain good compressive properties that are comparable to typical high strength cellular materials, which will be potentially useful for lightweighting applications. • The compressive properties of CFRP X-core sandwich panels are investigated experimentally, analytically and numerically. • A failure mechanism map is generated based on the geometric parameters of the unit cell. • Nonlinear finite element analyses are performed to investigate the effects of initial geometric imperfection and progressive damage on the response of the sandwich panels with different cell wall slenderness. • The CFRP X-core sandwich panels attain compressive properties higher or comparable to other cellular materials, with potential applications in lightweight structures. [ABSTRACT FROM AUTHOR]

The "chip-on-sensor" concept of this detector minimizes the distance of the signal propagation from the double-sided silicon detector strips to the readout chips and thus reduces noise from strip capacitance. One half of the detector is built, the second half is being assembled at the time of writing. Prototypes have been tested in several test beams as well as in the so-called Phase 2 setup inside the detector structure. First results from a commissioning run of the Belle-II prototype SVD detector are presented. The measured signal-to-noise and timing performance are found to be according to design specifications. • The Belle-II Silicon Vertex Detector is based on a "chip-on-sensor" concept. • One half of the detector is built, the second half is being assembled. • Prototypes have been tested in a commissioning run inside the detector structure. • The measured SNR and hit time are found to be according to design specifications. [ABSTRACT FROM AUTHOR]

The success of the Belle II experiment in Japan relies on the very high instantaneous luminosity, close to 6 × 1 0 35 cm − 2 s − 1 , expected from the SuperKEKB collider. The corresponding beam conditions at such luminosity levels generate large rates of background particles and creates stringent constraints on the vertex detector, adding to the physics requirements. Current prospects for the occupancy rates in the present vertex detector (VXD) at full luminosity fall close to the acceptable limits and bear large uncertainties. In this context, the Belle II collaboration is considering the possibility to install an upgraded VXD system around 2027 to provide a sufficient safety margin with respect to the expected background rate and possibly enhance tracking and vertexing performance. The VTX collaboration has started the design of a fully pixelated VXD, called VTX, based on fast and highly granular Depleted Monolithic Active Pixel Sensors (DMAPS) integrated on light support structures. The two main technical features of the VTX proposal are the usage of a single sensor type over all the layers of the system and the overall material budget below 2% of radiation length, compared to the current VXD which has two different sensor technologies and about 3% of radiation length. A dedicated sensor (OBELIX), taylored to the specific needs of Belle II, is under development, evolving from the existing TJ-Monopix2 sensor. The time-stamping precision below 100 ns will allow all VTX layers to take part in the track finding strategy contrary to the current situation. The first two detection layers are designed according to a self-supported all-silicon ladder concept, where 4 contiguous sensors are diced out of a wafer, thinned and interconnected with post-processed redistribution layers. The outermost detection layers follow a more conventional approach with a cold plate and carbon fibre support structure, and light flex cables interconnecting the sensors. This document will review the context, technical details and development status of the proposed Belle II VTX. [ABSTRACT FROM AUTHOR]

The Belle II experiment at the asymmetric SuperKEKB collider in Japan will operate at an instantaneous luminosity approximately 50 times greater than its predecessor (Belle). The central feature of the experiment is a vertex detector comprising two layers of pixelated silicon detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). One of the key measurements for Belle II is CP violation asymmetry in the decays of beauty and charm hadrons, which hinges on a precise charged-track vertex determination and low-momentum track measurement. Towards this goal, a proper assembly of the SVD components with precise alignment ought to be performed and the geometrical tolerances should be checked to fall within the design limits. We present an overview of the assembly procedure that is being followed, which includes the precision gluing of the SVD module components, wire-bonding of the various electrical components, and precision 3D coordinate measurements of the final SVD modules. Finally, some results from the latest test-beam are reported. [ABSTRACT FROM AUTHOR]

The Belle II Experiment at the High Energy Accelerator Research Organization (KEK) in Tsukuba, Japan, will explore the asymmetry between matter and antimatter and search for new physics beyond the standard model. 172 double-sided silicon strip detectors are arranged cylindrically in four layers around the collision point to be part of a system which measures the tracks of the collision products of electrons and positrons. A total of 1748 radiation-hard APV25 chips read out 128 silicon strips each and send the analog signals by time-division multiplexing out of the radiation zone to 48 Flash Analog Digital Converter Modules (FADC). Each of them applies processing to the data; for example, it uses a digital finite impulse response filter to compensate line signal distortions, and it extracts the peak timing and amplitude from a set of several data points for each hit, using a neural network. We present an overview of the SVD data readout system, along with front-end electronics, cabling, power supplies and data processing. [ABSTRACT FROM AUTHOR]

The Belle II experiment is evaluating an upgrade program aiming at the time frame 2026–2027 for the installation of the upgraded detectors, to improve the detector performance and robustness against beam-induced backgrounds. The VTX concept, a fully-pixelated system based on depleted monolithic active pixel sensors, has been developed as a replacement of the current pixel-and-strip vertex detector. A simulation framework for the VTX has been developed and integrated with the standard Belle II simulation, facilitating the comparison among different layouts. Simulation results (such as tracking efficiency and vertex resolution) on benchmark physics channels are presented, showing a significant improvement with respect to the current detector. [ABSTRACT FROM AUTHOR]

The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector. [ABSTRACT FROM AUTHOR]

The silicon vertex detector of the Belle II experiment, structured in a lantern shape, consists of four layers of ladders, fabricated from two to five silicon sensors. The APV25 readout ASIC chips are mounted on one side of the ladder to minimize the signal path for reducing the capacitive noise; signals from the sensor backside are transmitted to the chip by bent flexible fan-out circuits. The ladder is assembled using several dedicated jigs. Sensor motion on the jig is minimized by vacuum chucking. The gluing procedure provides such a rigid foundation that later leads to the desired wire bonding performance. The full ladder with electrically functional sensors is consistently completed with a fully developed assembly procedure, and its sensor offsets from the design values are found to be less than 200 μm. The potential functionality of the ladder is also demonstrated by the radioactive source test. [ABSTRACT FROM AUTHOR]

High-energy physics experiments at the high-intensity frontier place ever-greater demands on detectors, and in particular on tracking devices. In order to compare the performance of many possible small-size tracking prototypes, a high-resolution cosmic ray tracker may be used as an external track reference. We have constructed a telescope by assembling four spare ladders of the external layers of the Silicon Vertex Tracker of the BaBar experiment. This test facility, operating at INFN Sezione di Pisa, provides the detector under test with an external track with an intrinsic resolution of 15–30 ~\mu\m. The DAQ originally used in the BaBar experiment was replaced by custom-designed boards coupled with an acquisition front-end personal computer through commercial field-programmable gate array evaluation boards. We show that the facility is operative, and we present the performance in terms of tracking resolution and efficiency. A first device has been characterized, and some plots from the analysis demonstrating the telescope performance are shown. [ABSTRACT FROM PUBLISHER]

One edge of an elastic rod is inserted into a frictionless and fitting socket head, whereas the other edge is subjected to a torque, generating a uniform twisting moment. It is theoretically shown and experimentally proved that, although perfectly smooth, the constraint realizes an expulsive axial force on the elastic rod, which amount is independent of the shape of the socket head. The axial force explains why screwdrivers at high torque have the tendency to disengage from screw heads and demonstrates torsional locomotion along a perfectly smooth channel. This new type of locomotion finds direct evidence in the realization of a 'torsional gun', capable of transforming torque into propulsive force. [ABSTRACT FROM AUTHOR]

Abstract: Physics and high background conditions set very challenging requirements on readout speed, material budget and resolution for the innermost layer of the SuperB Silicon Vertex Tracker operated at the full luminosity. Monolithic Active Pixel Sensors (MAPS) are very appealing in this application since the thin sensitive region allows grinding the substrate to tens of microns. Deep N-Well MAPS, developed in the ST 130nm CMOS technology, achieved in-pixel sparsification and fast time stamping. Further improvements are being explored with an intense R&D program, including both vertical integration and 2D MAPS with the INMAPS quadruple well. We present the results of the characterization with IR laser, radioactive sources and beam of several chips produced with the 3D (Chartered/Tezzaron) process. We have also studied prototypes exploiting the features of the quadruple well and the high resistivity epitaxial layer of the INMAPS 180nm process. Promising results from an irradiation campaign with neutrons on small matrices and other test-structures, as well as the response of the sensors to high energy charged tracks are presented. [Copyright &y& Elsevier]

Abstract: The Electromagnetic Calorimeter (ECAL) of the AMS-02 experiment is a fine grained lead-scintillating fibres sampling calorimeter that allows for a precise three-dimensional imaging of the longitudinal and lateral shower development. It provides a high ( ) electron/hadron discrimination with the other AMS-02 detectors [1] and good energy resolution. The calorimeter also provides a standalone photon trigger capability to AMS-02. The mechanical assembly was realized to ensure minimum weight, still supporting the intrinsically heavy calorimeter during launch. ECAL light collection system and electronics are designed to measure electromagnetic particles over a wide energy range, from GeV up to TeV. A full-scale flight-like model was tested using electrons and proton beams with energies ranging from 6 to 250GeV. [Copyright &y& Elsevier]

We present an analysis of the structure of the monomethylammonium nitrate (MMAN) compound. Vibrational Raman spectroscopy and X-ray powder diffraction have been used to characterize the bulk phases of MMAN, and assignment of the resonant frequencies has been performed by ab initio (DFT) computations on small clusters of the compound. The theoretical spectra are in excellent agreement with the experimental ones and provide a means by which an interpretation of the hydrogen-bonding network that exists in such compound can be analyzed. In particular, we found that the spectrum of one of the solid phases is structurally very similar to that of the liquid. We present experimental evidence for the existence of such phase both from X-ray data and Raman spectra which, in turn, is easily interpreted with a one-to-one correspondence with the ab initio simulation of the small clusters. A geometric structure of the short-range local arrangement in these two bulk phases is therefore proposed. [ABSTRACT FROM AUTHOR]

Abstract: The high luminosity SuperB asymmetric collider, to be built near the INFN National Frascati Laboratory in Italy, has been designed to deliver a luminosity greater than 1036 cm−2 s−1 with moderate beam currents and a reduced center of mass boost with respect to earlier B-Factories. An improved vertex resolution is required for precise time-dependent measurements and the SuperB Silicon Vertex Tracker will be equipped with an innermost layer of small radius (about 1.5cm), resolution of in both coordinates, low material budget ( X0), and able to withstand a background rate of several tens of MHz/cm2. The ambitious goal of designing a thin pixel device with these stringent requirements is being pursued with specific R&D programs on different technologies: hybrid pixels, CMOS MAPS and pixel sensors developed with vertical integration technology. The latest results on the various pixel options for the SuperB SVT will be presented. [Copyright &y& Elsevier]

Abstract: We report on further developments of our proposed design approach for a full in-pixel signal processing chain of deep N-well monolithic active pixel sensor, by exploiting the triple well option of a CMOS 130nm process. Two different geometries of the collecting electrode (namely “Apsel 3T 1 M 1” and “Apsel 3T 1 M 2”) was implemented to compare their charge collection efficiency. The results of the characterization of the various versions of pixel matrices with a pion beam of 120GeV/c at the SPS H6 CERN facility will be presented. The performances of an “Apsel 3T 1” chip irradiated with a dose up to 10Mrad (Co60) was also measured. Comparison will be presented among the irradiated and the new chip showing the impact of radiation damages on tracking efficiencies. [ABSTRACT FROM AUTHOR]

Abstract: A low material budget silicon demonstrator has been tested by the SLIM5 collaboration with 12GeV/c protons at the PS-T9 beam line at CERN. Two devices were placed inside a reference telescope and their characteristics were measured. The first was a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130nm CMOS technology, providing digital sparsified readout. The other one was a high resistivity double-sided silicon detector, with short strips at a angle to the detector''s edge, read out by the FSSR2 chip. In this paper we describe the main features of both sensors. The primary goal of the test was to measure the efficiency and the resolution of the DUTs under different conditions of threshold setting and incident angle of the impinging particles. The data-driven approach of the readout chips has been fully exploited by the DAQ system to take data with a track-based level-1 trigger provided by a pattern matching algorithm with very low latency. [Copyright &y& Elsevier]

Abstract: In September 2008 the SLIM5 collaboration submitted a low material budget silicon demonstrator to test with 12GeV/c protons, at the PS-T9 test-beam at CERN. Two different detectors were placed as DUTs inside a high-resolution and fast-readout beam telescope. The first DUT was a high resistivity double sided silicon detector, with short strips (“striplets”) and with reduced thickness, at angle to the detector''s edge, readout by the data-driven FSSR2 chip. The other one was a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130nm CMOS Technology, providing digital sparsified readout. In the following, I present the striplets and also the beam telescope characteristics, with some details about the frontend readout (based on the FSSR2 chip) and some preliminary results of the data-analysis. [Copyright &y& Elsevier]

Abstract: The results obtained by the Slim5 collaboration on a low material budget tracking silicon demonstrator put on a 12GeV/ proton test beam at CERN are reported. Inside a reference telescope, two different and innovative detectors were placed for careful tests. The first was a 4k-Pixel Matrix of Deep N Well MAPS, developed in a 130nm CMOS Technology, square pixels wide, thinned down to and equipped with a digital sparsified readout running up to 50MHz. The other was a high resistivity double sided silicon detector, thick, with short strips with pitch at angle to the detector''s edge. The detectors were equipped with dedicated fast readout architectures performing on-chip data sparsification and providing the timing information for the hits. The criteria followed in the design of the pixel sensor and of the pixel readout architecture will be reviewed. Preliminary measurements of the pixel charge collection, track detection efficiencies and resolutions of pixel and strip sensors are discussed. The data driven architecture of the readout chips has been fully exploited in the test beam by a data acquisition system able to collect on electronic board up to 2.5 Million events per second before triggering. By using a dedicated Associative Memory board, we were able to perform a level 1 trigger system, with minimal latency, identifying cleanly tracks traversing the detectors. System architecture and main performances are shown. [Copyright &y& Elsevier]

The Belle II experiment at the SuperKEKB asymmetric e + e − collider in Japan will operate at a luminosity approximately 50 times larger than its predecessor (Belle). At its heart lies a six-layer vertex detector comprising two layers of pixelated silicon detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). One of the key measurements for Belle II is time-dependent CP violation asymmetry, which hinges on a precise charged-track vertex determination. Towards this goal, a proper assembly of the SVD components with precise alignment ought to be performed and the geometrical tolerances should be checked to fall within the design limits. We present an overview of the assembly procedure that is being followed, which includes the precision gluing of the SVD module components, wire-bonding of the various electrical components, and precision three dimensional coordinate measurements of the jigs used in assembly as well as of the final SVD modules. [ABSTRACT FROM AUTHOR]

The Belle-II VerteX Detector (VXD) has been designed to improve the performances with respect to Belle and to cope with an unprecedented luminosity of 8 × 10 35 cm − 2 s − 1 achievable by the SuperKEKB. Special care is needed to monitor both the radiation dose accumulated throughout the life of the experiment and the instantaneous radiation rate, in order to be able to promptly react to sudden spikes for the purpose of protecting the detectors. A radiation monitoring and beam abort system based on single-crystal diamond sensors is now under an active development for the VXD. The sensors will be placed in several key positions in the vicinity of the interaction region. The severe space limitations require a challenging remote readout of the sensors. [ABSTRACT FROM AUTHOR]

The paper describes a mixed-mode ASIC composed of a fast readout architecture that interfaces with a matrix of 4096 Monolithic Active Pixel Sensors (MAPS). The matrix has 128 columns and 32 rows of pixels and is divided into 256 regions of 4 x 4 pixels, named macro-pixels (MPs). The chip is an upgrade of a smaller version having 256 pixels that was designed and tested. The two chips were designed via STM 130 nm CMOS technology. The pixel dimension is 50 by 50 μm². The work is aimed at improving the design of MAPS detectors with an on-chip fast sparsification system, for particle tracking, to match the requirements of future high-energy physics experiments. The readout architecture implemented is data driven to extend the flexibility of the system, to be also used in first level triggers on tracks in vertex detectors. Simulations indicate that the readout system can cope with an average hit rate up to 100 MHz/cm² if a master clock of 80 MHz is used, while maintaining an overall efficiency over 99%. [ABSTRACT FROM AUTHOR]

Abstract: A prototype of a mixed-mode ASIC composed of a fast readout architecture that interfaces with a matrix of 4096 Monolithic Active Pixel Sensor (MAPS) was fabricated via STM 130nm CMOS technology. Groups of 4×4 pixels form a macro-pixel (MP). The readout architecture is parallel and could overcome the readout speed limit of big matrices. As the output port can only accept one-hit information at a time, an internal queuing system has been provided to face high hit-rate conditions. The ASIC can work in two different manners as it can be connected to an actual full-custom matrix of MAPS or to a digital matrix emulator composed of standard cells, for testing facilities. For both operating modes a slow-control phase is required to load the chip configuration. Previous versions of similar ASICs were designed and tested. The work is aimed at improving the design of MAPS detectors with an on-chip fast sparsification system, for particle tracking, to match the requirements of future high-energy physics experiments. The readout architecture implemented is data driven extending the flexibility of the system to be also used in first level triggers on tracks in vertex detectors. Preliminary simulations and tests indicate that the readout system can cope with an average hit-rate up to 100MHz/cm2 if a master clock of 80MHz is used, while maintaining an overall efficiency over 99%. [Copyright &y& Elsevier]

Abstract: By exploiting the triple-well option available in a deep-submicron CMOS process, we developed monolithic active pixel sensors (MAPS) with the unique features of full analog signal processing and digital functionality implemented at the pixel level. After briefly reviewing the results achieved with the first prototype chip, we report on the extensive measurements on the second prototype, containing both single-channel sensors, with an improved noise figure, and an pixel array. For the pixel having a collecting electrode area of we measured an equivalent noise charge of about 40 electrons. Using the 5.9keV line, we obtained a Signal-to-noise (S/N) ratio of about 30. The pixel matrix has been successfully readout up to 30MHz. Through noise scans, an expected significant threshold dispersion has been measured. The measurements presented in this paper confirm the capability of our MAPS, based on the deep n-well concept, to be operated as ionizing radiation detectors and suggest a series of improvements we are already implementing in the design of the next prototype chip. [Copyright &y& Elsevier]

The CMS Silicon tracker consists of 70 m2 of microstrip sensors which design will be finalized at the end of 1999 on the basis of systematic studies of device characteristics as function of the most important parameters. A fundamental constraint comes from the fact that the detector has to be operated in a very hostile radiation environment with full efficiency. We present an overview of the current results and prospects for converging on a final set of parameters for the silicon tracker sensors. [Copyright &y& Elsevier]

We report selected results of laboratory measurements and beam tests of heavily irradiated microstrip silicon detectors. The detectors were single-sided devices, produced by different manufacturers and irradiated with different sources, for several total ionizing doses and fluences up to 4 ×1014 1-MeV-equivalent neutrons per cm 2. Strip resistance and capacitance, detector leakage currents and breakdown performance were measured before and after irradiations. Signal-to-noise ratio and detector efficiency were studied in beam tests, for different values of the detector temperature and of the read-out pitch, as a function of the detector bias voltage. The goal of these test is to optimise the design of the final prototypes for the Silicon Strip Tracker of the CMS experiment at the CERN LHC collider [ABSTRACT FROM PUBLISHER]

Abstract: A battery-powered, wireless Radon sensor has been designed and realized using a BJT, fabricated on a high-resistivity-silicon substrate, as a radiation detector. Radon daughters are electrostatically collected on the detector surface. Thanks to the BJT internal amplification, real-time α particle detection is possible using simple readout electronics, which records the particle arrival time and charge. Functional tests at known Radon concentrations, demonstrated a sensitivity up to 4.9cph/(100Bq/m3) and a count rate of 0.05cph at nominally-zero Radon concentration. [Copyright &y& Elsevier]

Abstract: We report on recent beam test results for the APSEL4D chip, a new deep n-well MAPS prototype with a full in-pixel signal processing chain obtained by exploiting the triple well option of the CMOS process. The APSEL4D chip consists of a 4096 pixel matrix (32 rows and 128 columns) with pixel cell area, with custom readout architecture capable of performing data sparsification at pixel level. APSEL4D has been characterized in terms of charge collection efficiency and intrinsic spatial resolution under different conditions of discriminator threshold settings using a 12GeV/c proton beam in the T9 area of the CERN PS. We observe a maximum hit efficiency of 92% and we estimate an intrinsic resolution of about . The data driven approach of the tracking detector readout chips has been successfully used to demonstrate the possibility to build a Level 1 trigger system based on associative memories. The analysis of the beam test data is critically reviewed along with the characterization of the device under test. [ABSTRACT FROM AUTHOR]

Abstract: The SuperB asymmetric collider has been designed to deliver a luminosity greater than with moderate beam currents. Comparing to current B-Factories, the reduced center of mass boost of the SuperB machine requires improved vertex resolution to allow precision measurements sensitive to New Physics. We present the conceptual design of the silicon vertex tracker (SVT) for the SuperB detector with the present status of the R&D on the different options under study for its innermost Layer0. [Copyright &y& Elsevier]