Finite element simulation of a gradient elastic half-space subjected to thermal shock on the boundary

The influence of the microstructure on the macroscopical behavior of complex materials is disclosed under thermal shock conditions. The thermal shock response of an elastic half-space subjected to convective heat transfer at its free surface from a fluid undergoing a sudden change of its temperature is investigated within the context of the generalized continuum theory of gradient thermoelasticity. This theory is employed to model effectively the material microstructure. This is a demanding initial boundary value problem which is solved numerically using a higher-order finite element procedure. Simulations have been performed for different values of the microstructural parameters showing that within the gradient material the thermoelastic pulses are found to be dispersive and smoother than those within a classical elastic solid, for which the solution is retrieved as a special case. Energy type stability estimates for the weak solution have been obtained for both the fully and weakly coupled thermoelastic systems. The convergence characteristics of the proposed finite element schemes have been verified by several numerical experiments. In addition to the direct applicative significance of the obtained results, our solution serves as a useful benchmark for modeling more complicated problems within the framework of gradient thermoelasticity

E. Borsato

The principle of operation of a newly developed proximity focused Hybrid Photon Detector is described. The HPD characteristics, performance and calibration are reported. Results from beam tests of aerogel threshold counters read-out by HPD and the particle identification performance are presented. 1 The Hybrid Photon Detector The operating principle of the proximity focused Hybrid Photon Detector (HPD) is shown in figure 1. Light striking on a 2 mm thick quartz window hits an S20 UV photocathode that features a high quantum efficiency response peaked in the UV region (figure 2). Photoelectrons are accelerated by a uniform electric field and penetrate in the depleted region of a 300 ¯m thick 1 inch diameter silicon diode operated in reverse-bias mode. The kinetic energy is converted into a charge pulse picked up at the diode contacts. The gain is about 3300 at the operating high voltage of 15 kV . The electric output signal is subsequently amplified and conveniently shaped to be measur..

The SuperB muon detector, status and perspectives2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

The superB project foresees the construction of a high intensity super-flavor factory at the Cabibbo Lab, in Tor Vergata (near Rome). The experiment, based on a high intensity asymmetric electron-positron collider, and on the related detector, is expected to reach a very high luminosity: 2 7 10^36cm-2s-1, that will allow the high statistic study of rare decays and, possibly, will show evidences of new physics

The SuperB muon detector, status and perspectives

The superB project foresees the construction of a high intensity super-flavor factory at the Cabibbo Lab, in Tor Vergata (near Rome). The experiment, based on a high intensity asymmetric electron-positron collider, and on the related detector, is expected to reach a very high luminosity: 2 × 1036cm-2s-1, that will allow the high statistic study of rare decays and, possibly, will show evidences of new physics. © 2012 IEEE

Performance of a Prototype Aerogel Counter Readout by

The BABAR experiment, in order to achieve its physics program, requires pion/kaon identification capability up to 4.3 GeV/c. The recent development of new processes has lead to the fabrication of low density silica aerogel with high optical quality. An aerogel threshold counter using the combination of 2 refractive indices (1.055 and 1.007) can be used to complete the angular coverage of the particle identification system in the forward region of the BABAR experiment. We present final test-beam results on a 2 layer aerogel prototype, readout by Hamamatsu fine mesh photo-tubes, as required by the high magnetic field environment of the BaBar experiment. Several configurations have been tested, with different aerogels, photo-tubes and reflective materials. We have performed a Monte-Carlo simulation, in order to understand the sensitivity of light collection to the optical parameters. The result of the test shows that such a detector can achieve the desired performances

The ZEUS barrel and rear muon detector

Design, construction and performance characteristics of the ZEUS barrel and rear muon detector are presented

Measurement of the diffractive cross-section in deep inelastic scattering

Diffractive scattering of $\gamma^* p \to X + N$, where $N$ is either a proton or a nucleonic system with $M_N~<~4$~GeV has been measured in deep inelastic scattering (DIS) at HERA. The cross section was determined by a novel method as a function of the $\gamma^* p$ c.m. energy $W$ between 60 and 245~GeV and of the mass $M_X$ of the system $X$ up to 15~GeV at average $Q^2$ values of 14 and 31~GeV$^2$. The diffractive cross section $d\sigma^{diff} /dM_X$ is, within errors, found to rise linearly with $W$. Parameterizing the $W$ dependence by the form d\sigma^{diff}/dM_X \propto (W^2)^{(2\overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} -2)} the DIS data yield for the pomeron trajectory \overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} = 1.23 \pm 0.02(stat) \pm 0.04 (syst) averaged over $t$ in the measured kinematic range assuming the longitudinal photon contribution to be zero. This value for the pomeron trajectory is substantially larger than \overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} extracted from soft interactions. The value of \overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} measured in this analysis suggests that a substantial part of the diffractive DIS cross section originates from processes which can be described by perturbative QCD. From the measured diffractive cross sections the diffractive structure function of the proton F^{D(3)}_2(\beta,Q^2, \mbox{x_{_{I\hspace{-0.2em}P}}}) has been determined, where $\beta$ is the momentum fraction of the struck quark in the pomeron. The form F^{D(3)}_2 = constant \cdot (1/ \mbox{x_{_{I\hspace{-0.2em}P}}})^a gives a good fit to the data in all $\beta$ and $Q^2$ intervals with $a = 1.46 \pm 0.04 (stat) \pmComment: 45 pages, including 16 figure