An Enhanced Fractional Order Model of Ionic Polymer-Metal Composites Actuator

Ionic polymer-metal composites (IPMCs) are electroactive polymers which transform the mechanical forces into electric signals and vice versa. The paper proposes an enhanced fractional order transfer function (FOTF) model for IPMC membrane working as actuator. In particular the IPMC model has been characterized through experimentation, and a more detailed structure of its FOTF has been determined via optimization routines. The minimization error was attained comparing the simple genetic algorithms with the simplex method and considering the error between the experimental and model derived frequency responses as cost functions

Mathematical modelling with experimental validation of viscoelastic properties in non-Newtonian fluids

The paper proposes a mathematical framework for the use of fractional-order impedance models to capture fluid mechanics properties in frequency-domain experimental datasets. An overview of non-Newtonian (NN) fluid classification is given as to motivate the use of fractional-order models as natural solutions to capture fluid dynamics. Four classes of fluids are tested: oil, sugar, detergent and liquid soap. Three nonlinear identification methods are used to fit the model: nonlinear least squares, genetic algorithms and particle swarm optimization. The model identification results obtained from experimental datasets suggest the proposed model is useful to characterize various degree of viscoelasticity in NN fluids. The advantage of the proposed model is that it is compact, while capturing the fluid properties and can be identified in real-time for further use in prediction or control applications. This article is part of the theme issue 'Advanced materials modelling via fractional calculus: challenges and perspectives'

Construction and commissioning of a technological prototype of a high-granularity semi-digital hadronic calorimeter

A large prototype of 1.3m3 was designed and built as a demonstrator of the semi-digital hadronic calorimeter (SDHCAL) concept proposed for the future ILC experiments. The prototype is a sampling hadronic calorimeter of 48 units. Each unit is built of an active layer made of 1m2 Glass Resistive Plate Chamber(GRPC) detector placed inside a cassette whose walls are made of stainless steel. The cassette contains also the electronics used to read out the GRPC detector. The lateral granularity of the active layer is provided by the electronics pick-up pads of 1cm2 each. The cassettes are inserted into a self-supporting mechanical structure built also of stainless steel plates which, with the cassettes walls, play the role of the absorber. The prototype was designed to be very compact and important efforts were made to minimize the number of services cables to optimize the efficiency of the Particle Flow Algorithm techniques to be used in the future ILC experiments. The different components of the SDHCAL prototype were studied individually and strict criteria were applied for the final selection of these components. Basic calibration procedures were performed after the prototype assembling. The prototype is the first of a series of new-generation detectors equipped with a power-pulsing mode intended to reduce the power consumption of this highly granular detector. A dedicated acquisition system was developed to deal with the output of more than 440000 electronics channels in both trigger and triggerless modes. After its completion in 2011, the prototype was commissioned using cosmic rays and particles beams at CERN.Comment: 49 pages, 41 figure

NEMO: A Project for a km3^3 Underwater Detector for Astrophysical Neutrinos in the Mediterranean Sea

The status of the project is described: the activity on long term characterization of water optical and oceanographic parameters at the Capo Passero site candidate for the Mediterranean km$^3$ neutrino telescope; the feasibility study; the physics performances and underwater technology for the km$^3$; the activity on NEMO Phase 1, a technological demonstrator that has been deployed at 2000 m depth 25 km offshore Catania; the realization of an underwater infrastructure at 3500 m depth at the candidate site (NEMO Phase 2).Comment: Proceeding of ISCRA 2006, Erice 20-27 June 200

First test of a power-pulsed electronics system on a GRPC detector in a 3-Tesla magnetic field

An important technological step towards the realization of an ultra-granular hadronic calorimeter to be used in the future International Linear Collider (ILC) experiments has been made. A 33X50 cm2 GRPC detector equipped with a power-pulsed electronics board offering a 1cm2 lateral segmentation was successfully tested in a 3-Tesla magnet operating at the H2 beam line of the CERN SPS. An important reduction of power consumption with no deterioration of the detector performance is obtained when the power-pulsing mode is applied. This important result shows that ultra-granular calorimeters for ILC experiments are not only an attractive but also a realistic option.Comment: 10 pages, 9 figure

Measurement of the atmospheric muon flux with the NEMO Phase-1 detector

The NEMO Collaboration installed and operated an underwater detector including prototypes of the critical elements of a possible underwater km3 neutrino telescope: a four-floor tower (called Mini-Tower) and a Junction Box. The detector was developed to test some of the main systems of the km3 detector, including the data transmission, the power distribution, the timing calibration and the acoustic positioning systems as well as to verify the capabilities of a single tridimensional detection structure to reconstruct muon tracks. We present results of the analysis of the data collected with the NEMO Mini-Tower. The position of photomultiplier tubes (PMTs) is determined through the acoustic position system. Signals detected with PMTs are used to reconstruct the tracks of atmospheric muons. The angular distribution of atmospheric muons was measured and results compared with Monte Carlo simulations.Comment: Astrop. Phys., accepte

Pion and proton showers in the CALICE scintillator-steel analogue hadron calorimeter

Showers produced by positive hadrons in the highly granular CALICE scintillator-steel analogue hadron calorimeter were studied. The experimental data were collected at CERN and FNAL for single particles with initial momenta from 10 to 80 GeV/c. The calorimeter response and resolution and spatial characteristics of shower development for proton- and pion-induced showers for test beam data and simulations using Geant4 version 9.6 are compared.Comment: 26 pages, 16 figures, JINST style, changes in the author list, typos corrected, new section added, figures regrouped. Accepted for publication in JINS

The ANTARES Optical Beacon System

ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented.Comment: 21 pages, 18 figures, submitted to Nucl. Instr. and Meth. Phys. Res.

Performance of the first prototype of the CALICE scintillator strip electromagnetic calorimeter

A first prototype of a scintillator strip-based electromagnetic calorimeter was built, consisting of 26 layers of tungsten absorber plates interleaved with planes of 45x10x3 mm3 plastic scintillator strips. Data were collected using a positron test beam at DESY with momenta between 1 and 6 GeV/c. The prototype's performance is presented in terms of the linearity and resolution of the energy measurement. These results represent an important milestone in the development of highly granular calorimeters using scintillator strip technology. This technology is being developed for a future linear collider experiment, aiming at the precise measurement of jet energies using particle flow techniques

Hadron shower decomposition in the highly granular CALICE analogue hadron calorimeter

The spatial development of hadronic showers in the CALICE scintillator-steel analogue hadron calorimeter is studied using test beam data collected at CERN and FNAL for single positive pions and protons with initial momenta in the range from 10 to 80 GeV/c. Both longitudinal and radial development of hadron showers are parametrised with two-component functions. The parametrisation is fit to test beam data and simulations using the QGSP_BERT and FTFP_BERT physics lists from Geant4 version 9.6. The parameters extracted from data and simulated samples are compared for the two types of hadrons. The response to pions and the ratio of the non-electromagnetic to the electromagnetic calorimeter response, h/e, are estimated using the extrapolation and decomposition of the longitudinal profiles.Comment: 38 pages, 19 figures, 5 tables; author list changed; submitted to JINS