The COMPASS RICH-1 detector has undergone a major upgrade in 2016 with the installation of four novel MPGD-based photon detectors. They consist of large-size hybrid MPGDs with multi-layer ...architecture composed of two layers of Thick-GEMs and bulk resistive MicroMegas. A dedicated high voltage power supply system, based on CAEN HV modules, has been built and put in operation: it controls more than 100 HV channels. The system is required to protect the detectors against errors by the operator, monitor voltages and currents at a 1 Hz rate and automatically react to detector misbehavior. It includes also a HV compensation system against environmental pressure and temperature variation to grant the detector stability. The operation of a MPGD based single photon detector poses challenging requirements to the high voltage power supply systems employed in terms of high-resolution diagnostic features and dynamic voltage control. Systems satisfying all the needed features are not commercially available; for this reason a novel single channel high voltage system matching the MPGD needs has been designed and realized. In this article the COMPASS RICH-1 MPGD HV system implementation is described as well as its performance in terms of stability of the novel MPGD-based photon detectors during the physics data taking at COMPASS. The design, implementation and performance of a novel HV power supply system based on DC to DC converters and controlled by a FPGA device is presented. The capabilities of the first prototype of the new single HV channel power supply are illustrated when operated with a MPGD based single photon detector during a test beam exercise. The preliminary result of the multi channel system are briefly discussed.
It has become increasingly apparent that studying how dark matter haloes are populated by galaxies can provide new insights into galaxy formation and evolution. In this paper, we present a detailed ...investigation of the changing relationship between galaxies and the dark matter haloes they inhabit from z ~ 1.2 to the present day. We do this by comparing precise galaxy clustering measurements over 133 deg2 of the “Wide” component of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) with predictions of an analytic halo occupation distribution (HOD) model where the number of galaxies in each halo depends only on the halo mass. Starting from a parent catalogue of ~3 × 106 galaxies at i′AB<22.5 we use accurate photometric redshifts calibrated using ~104 spectroscopic redshifts to create a series of type-selected volume-limited samples covering 0.2 < z < 1.2. Our principal result, based on clustering measurements in these samples, is a robust determination of the luminosity-to-halo mass ratio and its dependence on redshift and galaxy type. For the full sample, this reaches a peak at low redshifts of Mhpeak = 4.5×1011 h-1 M⊙ and moves towards higher halo masses at higher redshifts. For redder galaxies the peak is at higher halo masses and does not evolve significantly over the entire redshift range of our survey. We also consider the evolution of bias, average halo mass and the fraction of satellites as a function of redshift and luminosity. Our observed growth of a factor of ~2 in satellite fraction between z ~ 1 and z ~ 0 is testament to the limited role that galaxy merging plays in galaxy evolution for ~1012 h-1 M⊙ mass haloes at z < 1. Qualitatively, our observations are consistent with a picture in which red galaxies in massive haloes have already accumulated most of their stellar mass by z ~ 1 and subsequently undergo little evolution until the present day. The observed movement of the peak location for the full galaxy population is consistent with the bulk of star-formation activity migrating from higher mass haloes at high redshifts to lower mass haloes at lower redshifts.
The proposed new Electron–Ion Collider poses a technical and intellectual challenge for the detector design to accommodate the long-term diverse physics goals envisaged by the program. This requires ...a 4π detector system capable of reconstructing the energy and momentum of final state particles with high precision. The Electron-Ion Collider also requires identification of particles of different masses over a wide momentum range.
A diverse spectrum of Particle IDentification detectors has been proposed. Of the four types of detectors for hadron identification, three are based on Ring Imaging Cherenkov Counter technologies, and one is realized by the Time of Flight method. The quest for a novel photocathode, sensitive in the far vacuum ultraviolet wavelength range and more robust than cesium iodide, motivated an R&D programme to explore nano-diamond (ND) based photocathodes, started by a collaboration between INFN and CNR Bari and INFN Trieste. Systematic measurements of the photoemission in different Ar:CH4 and Ar:CO2 gas mixtures with various types of ND powders and Hydrogenated ND (H-ND) powders are reported. A first study of the response of THGEMs coated with different photocathode materials is presented.
The progress of this R&D programme and the results obtained so far by these exploratory studies are described.
We report the mechanical characterization by multiscale indentation of particle reinforced dense Ni/Al2O3 metal matrix nanocomposites (MMNC) obtained by high-kinetic processing (HKP) of ball milling ...of the powders with a systematic variation of alumina nanoparticles fractions (from 1 to 20 vol. %) and spark plasma sintering (SPS). The morphology and particle size distribution of powder were evaluated as a function of milling time up to 10 h. Samples from the 10 h milled powders were densified by SPS. The mechanical properties of the sintered samples were obtained by micro and nanoindentation using diamond tips of Vickers and Berkovich geometry, respectively. The combination of HKP and SPS allowed a homogeneous dispersion of Al2O3 nanoparticles in the nickel matrix and effective reinforcing effects, which is the case of Ni/10 vol. % Al2O3 and Ni/15 vol. % Al2O3 samples. The highest hardness (4.68 ± 0.37 GPa) was obtained for Ni/15 vol. % Al2O3 MMNC, which is almost twice that of pure nickel (2.45 ± 0.22 GPa) processed at the same conditions. The highest elastic modulus (346 ± 30 GPa) was obtained for the Ni/10 vol. % Al2O3 sample. The analysis of the load-depth curves confirmed the reinforcing of the MMNCs as a function of the alumina particle content. Discussion of the possible reinforcing mechanisms is also included. The Ni/Al2O3 MMNC sintered specimens exhibit outstanding mechanical property results, which make them candidates for various high-temperature applications.
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•Homogeneous dispersion of Al2O3 nanoparticles in dense Ni-matrix SPSed MMNCs.•HV Hardness increases with Al2O3-content (max. of 4.68 GPa at Ni/15 vol. % Al2O3).•Elastic modulus increases with Al2O3-content (max. of 346 GPa at Ni/10 vol. % Al2O3).•Nanoindentation results confirm reinforcing effects of Al2O3-nanoparticles in MMNCs.•A critical volume between 10 and 15 vol. % Al2O3 reinforcing particles was identified.
Power generation from renewable sources has greatly increased in the last decade. Accordingly, the planning of power system expansions must incorporate the special features of these types of energy ...sources. Long-term power transmission expansion planning usually does not take these differences among energy sources into account because of the long period considered. However, modelling the special features of renewable sources may influence the optimal transmission plan. In this study, the authors propose a methodology for long-term power transmission expansion planning that incorporates the costs associated with the operation of wind power plants. In particular, the authors model the transmission expansion planning problem as a mixed-integer linear program in which the variability of the wind resource, the impact of wind power operation in the system security and the impact of wind power operation in the reserve market are incorporated. The authors illustrate the methodology using a 34-node version of the main Chilean network. PUBLICATION ABSTRACT
We present the first quantitative detection of large-scale filamentary structure at z NOT approximately equal to 0.7 in the large cosmological volume probed by the VIMOS Public Extragalactic ...Redshift Survey (VIPERS). We use simulations to show the capability of VIPERS to recover robust topological features in the galaxy distribution, in particular the filamentary network. We then investigate how galaxies with different stellar masses and stellar activities are distributed around the filaments, and find a significant segregation, with the most massive or quiescent galaxies being closer to the filament axis than less massive or active galaxies. The signal persists even after downweighting the contribution of peak regions. Our results suggest that massive and quiescent galaxies assemble their stellar mass through successive mergers during their migration along filaments towards the nodes of the cosmic web. On the other hand, low-mass star-forming galaxies prefer the outer edge of filaments, a vorticity-rich region dominated by smooth accretion, as predicted by the recent spin alignment theory. This emphasizes the role of large-scale cosmic flows in shaping galaxy properties.
It has become increasingly apparent that studying how dark matter haloes are populated by galaxies can provide new insights into galaxy formation and evolution. In this paper, we present a detailed ...investigation of the changing relationship between galaxies and the dark matter haloes they inhabit from z similar to 1.2 to the present day. We do this by comparing precise galaxy clustering measurements over 133 deg(2) of the “Wide” component of the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) with predictions of an analytic halo occupation distribution (HOD) model where the number of galaxies in each halo depends only on the halo mass. Starting from a parent catalogue of similar to 3 x 10(6) galaxies at i(AB)' \textless 22.5 we use accurate photometric redshifts calibrated using similar to 10(4) spectroscopic redshifts to create a series of type-selected volume-limited samples covering 0.2 \textless z \textless 1.2. Our principal result, based on clustering measurements in these samples, is a robust determination of the luminosity-to-halo mass ratio and its dependence on redshift and galaxy type. For the full sample, this reaches a peak at low redshifts of M-h(peak) = 4.5 x 10(11) h(-1) M-circle dot and moves towards higher halo masses at higher redshifts. For redder galaxies the peak is at higher halo masses and does not evolve significantly over the entire redshift range of our survey. We also consider the evolution of bias, average halo mass and the fraction of satellites as a function of redshift and luminosity. Our observed growth of a factor of similar to 2 in satellite fraction between z similar to 1 and z similar to 0 is testament to the limited role that galaxy merging plays in galaxy evolution for similar to 10(12) h(-1) M-circle dot mass haloes at z \textless 1. Qualitatively, our observations are consistent with a picture in which red galaxies in massive haloes have already accumulated most of their stellar mass by z similar to 1 and subsequently undergo little evolution until the present day. The observed movement of the peak location for the full galaxy population is consistent with the bulk of star-formation activity migrating from higher mass haloes at high redshifts to lower mass haloes at lower redshifts.
Typically, the structure of old monumental buildings differs significantly from that of contemporary ones. The massive walls, large indoor air volume and the small windows, compared to the opaque ...portion, drastically affect the microclimates of such constructions.
In such buildings is often quite difficult to perform a detailed monitoring campaign of the main microclimatic parameters. In this regard, experimental methodologies and non-invasive equipment, able to minimize the impacts on the building and on its users, should be adopted.
This research describes the methodology applied to carry out the monitoring campaign on the Milan Duomo, one of the biggest Cathedrals in Italy. The campaign was carried out by means of non-invasive measuring instruments, in order to keep the building intact and ensure the smooth running of the activities. In a second stage, sensors for the long-term monitoring were installed according to the most significant and accessible points inside the Cathedral.
The data collected during one year of monitoring was used to characterize the hygrothermal behaviour of the Cathedral, in order to assess the risks for the main materials which sacred objects, artworks, organs, sculptures and furnishing are made of.
The future developments of this work are oriented towards the realization of a simulation model aimed at designing and planning proper active or passive solutions to improve the microclimatic conditions for both artwork conservation and the comfort of visitors.
•Microclimate's monitoring is essential for assess the building's conservation state.•Non-invasive, cheap, sufficiently accurate microclimate's characterization is allowed.•A risk analysis based on conservation limits according several sources is presented.•A large and representative historic church in Italy has been taken as case study.•Information and data collected support the realization of a building energy model.
We study the evolution of the star formation rate (SFR) - stellar mass (M-star) relation and specific star formation rate (sSFR) of star-forming galaxies (SFGs) since a redshift z similar or equal to ...5.5 using 2435 (4531) galaxies with highly reliable spectroscopic redshifts in the VIMOS Ultra-Deep Survey (VUDS). It is the first time that these relations can be followed over such a large redshift range from a single homogeneously selected sample of galaxies with spectroscopic redshifts. The log(SFR) - log(M-star) relation for SFGs remains roughly linear all the way up to z = 5, but the SFR steadily increases at fixed mass with increasing redshift. We find that for stellar masses M-star \textgreater= 3.2 x 10(9) M-circle dot the SFR increases by a factor of similar to 13 between z = 0.4 and z = 2.3. We extend this relation up to z = 5, finding an additional increase in SFR by a factor of 1.7 from z = 2.3 to z = 4.8 for masses M-star = 1010 M-circle dot. We observe a turn-off in the SFR-M-star relation at the highest mass end up to a redshift z similar to 3.5. We interpret this turn-off as the signature of a strong on-going quenching mechanism and rapid mass growth. The sSFR increases strongly up to z similar to 2, but it grows much less rapidly in 2 \textless z \textless 5. We find that the shape of the sSFR evolution is not well reproduced by cold gas accretion-driven models or the latest hydrodynamical models. Below z similar to 2 these models have a flatter evolution (1+z)(Phi) with Phi = 2-2.25 compared to the data which evolves more rapidly with Phi = 2.8 +/- 0.2. Above z similar to 2, the reverse is happening with the data evolving more slowly with Phi = 1.2 +/- 0.1. The observed sSFR evolution over a large redshift range 0 \textless z \textless 5 and our finding of a non-linear main sequence at high mass both indicate that the evolution of SFR and M-star is not solely driven by gas accretion. The results presented in this paper emphasize the need to invoke a more complex mix of physical processes including major and minor merging to further understand the co-evolution of the SFR and stellar mass growth.
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