Estimation of the energy deposited on the CNGS magnetic horn and reflector

In the CNGS (Cern Neutrino to Gran Sasso) installation two magnetic lenses, namely the horn and the reflector, focus the secondary beam generated in the target station. The gap between the horn and reflector is chosen to optimize a wide-band high-energy muon-neutrino beam. These two focusing elements are two coaxial lenses: the outer conductor has a cylindrical shape whereas the inner conductor consists of a sequence of conical shapes to optimize the focusing capacity. The evaluation of the heat load on the support structures is crucial since modifications in the elements around the horn and reflector are under way and the support structures can be adapted to the heat load found. Furthermore, the heat load in the whole horn area has been evaluated to optimize the cooling-ventilation system. The energy deposited on the horn and reflector as well as on their adjacent elements has been estimated using the FLUKA Monte Carlo package and results are presented in this paper. The FLUKA geometry input of the horn and reflector electrical connections has been notably improved in order to accommodate the detailed striplines design to the thermal expansion

Laser-fabricated porous alumina membranes (LF-PAM) for the preparation of metal nanodot arrays

We report on an efficient photonic-based method to prepare nanodot array of functional materials, independently of the nature of the substrate.Comment: Small (2008) Accepte

An updated Monte Carlo calculation of the CNGS neutrino beam

The new release of the CNGS neutrino beam simulation, which describes the beam-line features according to its final design, and its main results are presented and discussed. Storage of neutrino identity, energy and history in n-tuple format is also described, so that the experiments at the Gran Sasso can fully exploit all the informations from beam simulations

Possible surface plasmon polariton excitation under femtosecond laser irradiation of silicon

The mechanisms of ripple formation on silicon surface by femtosecond laser pulses are investigated. We demonstrate the transient evolution of the density of the excited free-carriers. As a result, the experimental conditions required for the excitation of surface plasmon polaritons are revealed. The periods of the resulting structures are then investigated as a function of laser parameters, such as the angle of incidence, laser fluence, and polarization. The obtained dependencies provide a way of better control over the properties of the periodic structures induced by femtosecond laser on the surface of a semiconductor material.Comment: 11 pages, 8 figures, accepted for publication in Journal of Applied Physic

The so-called dry laser cleaning governed by humidity at the nanometer scale

Illumination with single nanosecond pulses leads to the detachment of silica particles with 250nm radii from siliconsurfaces. We identify two laser-energy dependent cleaning regimes by time-of-flight particle-scattering diagnostics. For the higher energies, the ejection of particles is produced by nanoscale ablation due to the laser field enhancement at the particle-surface interface. The damage-free regime at lower energy is shown to be governed by the residual water molecules, which are inevitably trapped on the materials. We discuss the great importance that the humidity plays on the cleaning force and on the adhesion in the experiments.Peer reviewe

Femtosecond laser ablation of cemented carbides: properties and tribological applications

Laser ablation with fs laser pulses was performed in air on cobalt cemented tungsten carbide by means of a Ti : sapphire laser (800nm, 100fs). Small and moderate fluences (2, 5, 10J/cm2) and up to 5×104 pulses per irradiated spot were used to drill holes with aspect ratios up to 10. Cross-section cuts from laser-irradiated samples were produced and they were analysed with optical microscopy and SEM. EDX analyses were carried out on selected zones. Quasi-cylindrical holes were found for 2J/cm2, whereas for 5 and 10J/cm2 irregular shapes (lobes, bottoms wider than hole entrances) were found to occur after a given number of incident pulses. Layers with modified structure were evidenced at pore walls. SEM revealed a denser structure, while EDX analyses showed uniform and almost similar contents of W, C, and Co in these layers. As a direct application, patterning of coated WC-Co was carried out with 2J/cm2 and 100 pulses per pore. The resulted surfaces were tribologically tested and these tests revealed an improved friction and wear behaviou

Nine years of experimental warming did not influence the thermal sensitivity of metabolic rate in the medaka fish Oryzias latipes

A pressing challenge is to determine whether and how global-change drivers influence species physiology and survival. Recently, researchers have proposed the metabolic theory of ecology, defending the hypothesis of a universal thermal dependence of metabolic rate or, alternatively, the metabolic cold adaptation theory, stating that local adaptation can influence the thermal sensitivity of metabolic rate. However, the long-term (i.e. multigenerational) consequences of warming for the thermal sensitivity of metabolic rate remain largely unexplored although it determines energy use and is crucial for species response to climate change. In this study, we used an evolutionary experiment with medaka fishes Oryzias latipes maintained for more than 12 generations at warm and cold temperatures (30 and 20°C, respectively) to address this issue. Our objective was to investigate whether thermal adaptation influences the relationship between temperature and mass-corrected metabolic rate and how this may occur. In agreement with the universal thermal dependence hypothesis, we found that warming did not significantly influence the thermal sensitivity of mass-corrected metabolic rate: neither the intercept nor the slope of the temperature–metabolic rate relationship differed among fish lineages. Our small-scale laboratory experiment thus indicated that there is limited potential for evolutionary change in medaka fish metabolic rate in response to warmer temperatures. Overall, we provide evidence that 9 years of experimental warming did not influence the thermal sensitivity of metabolic rate. Our results highlight the invariability of the thermal dependence of metabolic rate, which has important implications for adaptation to climate warming. This finding suggests a limited potential for metabolic adaptations in response to long-term temperature changes, which may have negative consequences for the persistence of fish populations under climate change

Update On the Status of the FLUKA Monte Carlo Transport Code*

The FLUKA Monte Carlo transport code is a well-known simulation tool in High Energy Physics. FLUKA is a dynamic tool in the sense that it is being continually updated and improved by the authors. We review the progress achieved since the last CHEP Conference on the physics models, some technical improvements to the code and some recent applications. From the point of view of the physics, improvements have been made with the extension of PEANUT to higher energies for p, n, pi, pbar/nbar and for nbars down to the lowest energies, the addition of the online capability to evolve radioactive products and get subsequent dose rates, upgrading of the treatment of EM interactions with the elimination of the need to separately prepare preprocessed files. A new coherent photon scattering model, an updated treatment of the photo-electric effect, an improved pair production model, new photon cross sections from the LLNL Cullen database have been implemented. In the field of nucleus-- nucleus interactions the electromagnetic dissociation of heavy ions has been added along with the extension of the interaction models for some nuclide pairs to energies below 100 MeV/A using the BME approach, as well as the development of an improved QMD model for intermediate energies. Both DPMJET 2.53 and 3 remain available along with rQMD 2.4 for heavy ion interactions above 100 MeV/A. Technical improvements include the ability to use parentheses in setting up the combinatorial geometry, the introduction of pre-processor directives in the input stream. a new random number generator with full 64 bit randomness, new routines for mathematical special functions (adapted from SLATEC). Finally, work is progressing on the deployment of a user-friendly GUI input interface as well as a CAD-like geometry creation and visualization tool. On the application front, FLUKA has been used to extensively evaluate the potential space radiation effects on astronauts for future deep space missions, the activation dose for beam target areas, dose calculations for radiation therapy as well as being adapted for use in the simulation of events in the ALICE detector at the LHC