12,419 research outputs found

    Computing the phase diagram of binary mixtures: a patchy particle case study

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    We investigate the phase behaviour of 2D mixtures of bi-functional and three-functional patchy particles and 3D mixtures of bi-functional and tetra-functional patchy particles by means of Monte Carlo simulations and Wertheim theory. We start by computing the critical points of the pure systems and then we investigate how the critical parameters change upon lowering the temperature. We extend the Successive Umbrella Sampling method to mixtures to make it possible to extract information about the phase behaviour of the system at a fixed temperature for the whole range of densities and compositions of interest.Comment: 13 pages, 13 figure

    PARISROC, a Photomultiplier Array Integrated Read Out Chip

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    PARISROC is a complete read out chip, in AMS SiGe 0.35 !m technology, for photomultipliers array. It allows triggerless acquisition for next generation neutrino experiments and it belongs to an R&D program funded by the French national agency for research (ANR) called PMm2: ?Innovative electronics for photodetectors array used in High Energy Physics and Astroparticles? (ref.ANR-06-BLAN-0186). The ASIC (Application Specific Integrated Circuit) integrates 16 independent and auto triggered channels with variable gain and provides charge and time measurement by a Wilkinson ADC (Analog to Digital Converter) and a 24-bit Counter. The charge measurement should be performed from 1 up to 300 photo- electrons (p.e.) with a good linearity. The time measurement allowed to a coarse time with a 24-bit counter at 10 MHz and a fine time on a 100ns ramp to achieve a resolution of 1 ns. The ASIC sends out only the relevant data through network cables to the central data storage. This paper describes the front-end electronics ASIC called PARISROC.Comment: IEEE Nuclear Science Symposium an Medical Imaging Conference (2009 NSS/MIC

    QP and QS of Campi Flegrei from the inversion of rayleigh waves recorded during the SERAPIS project

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    Seismic shots recorded during the SERAPIS experiment were used to search a 1D elastic and inelastic model of the Gulf of Pozzuoli, south of the CampiFlegrei caldera. Waveforms were gaussian filtered in the range 5-8 Hz with afrequency step of 0.5 Hz and a half-width of the filter equal to 0.5 Hz. A cleardispersion of the most energetic propagation mode was revealed. This pro-perty of the surface wave in the gulf of Pozzuoli was theoretically reprodu-ced using the classical wave-number technique. To infer the best fit propaga-tion model, we developed a semi-automated procedure of fitting of filteredtraces with progressive adjustment of the model. The quality of the fitting wasestimated using the semblance among each couple of waveform (syntheticand observed). Our formulation allowed us also to estimate the error onmodel parameter by mapping the noise on seismograms on the semblance. The obtained 1D model confirms that in average intrinsic Qp at the CampiFlegrei caldera is of the order of 300-500 which is a background value higherthan that of other volcanic areas. This report is a summary of a part of the phd thesis in Earth Sciences atUniversity of Bari of Maria Trabace
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