4,522 research outputs found
Study of the readout chip and silicon sensor degradation for the CMS pixel upgrade
Hybrid silicon pixel detectors are currently used in the innermost tracking
system of the Compact Muon Solenoid (CMS) experiment. Radiation tolerance up to
fluences expected for a few years of running of the Large Hadron Collider (LHC)
has already been proved, although some degradation of the part of the silicon
detector closer to the interaction point is expected. During the LHC upgrade
phases, the level of dose foreseen for the silicon pixel detector will be much
higher. To face this aspect, dedicated irradiation tests with fluences above
n/cm have been performed on the
silicon sensor and readout chip. Changes in the operation of the sensor and
readout chip as a function of the fluence are presented. The charge collection
efficiency has been studied: partial recovery of the detector efficiency can be
achieved by operating the detectors in a controlled environment and at higher
bias voltage.Comment: conference; 6 pages; 5 figure
High Frequency Peakers: The Faint Sample
We present a sample of sources with convex radio spectra peaking at
frequencies above a few GHz, known as "High Frequency Peakers" (HFPs). A
"bright" sample with a flux density limit of 300 mJy at 5 GHz has been
presented by Dallacasa et al. (2000). Here we present the "faint" sample with
flux density between 50 and 300 mJy at 5GHz, restricted to the area around the
North Galactic Cap, where the FIRST catalogue is available. The candidates have
been observed with the VLA at several frequencies ranging from 1.4 to 22 GHz,
in order to derive a simultaneous radio spectrum. The final list of confirmed
HFP sources consists of 61 objects.Comment: 3 pages. Accepted for publication in Astronomische Nachrichte
Dimissioni e risoluzioni consensuali di lavoratori e lavoratrici: uno studio sulle tecniche di controllo = Resignation and consensual termination of male and female workers: a study on control techniques. WP C.S.D.L.E. “Massimo D’Antona”.IT – 340/2017
The essay reconstructs the legal rules about resignation and consensual resolution of women and men employees. Particular reference is made to the evolution of controls against possible abuses by the employer. An empirical research about the functioning of the most important of these control techniques – the mandatory validation of resignation by the employment inspectorate, foreseen for working parents – shows its multi-purpose nature. A guarantee against abuses and discriminations but a support to work-life balance rights too. The research takes into consideration recent years statistical data (up to 2016 ones published in summer 2017), as regards resignations and consensual resolution of mother and father employees
Vapor nucleation paths in lyophobic nanopores
Abstract.: In recent years, technologies revolving around the use of lyophobic nanopores gained considerable attention in both fundamental and applied research. Owing to the enormous internal surface area, heterogeneous lyophobic systems (HLS), constituted by a nanoporous lyophobic material and a non-wetting liquid, are promising candidates for the efficient storage or dissipation of mechanical energy. These diverse applications both rely on the forced intrusion and extrusion of the non-wetting liquid inside the pores; the behavior of HLS for storage or dissipation depends on the hysteresis between these two processes, which, in turn, are determined by the microscopic details of the system. It is easy to understand that molecular simulations provide an unmatched tool for understanding phenomena at these scales. In this contribution we use advanced atomistic simulation techniques in order to study the nucleation of vapor bubbles inside lyophobic mesopores. The use of the string method in collective variables allows us to overcome the computational challenges associated with the activated nature of the phenomenon, rendering a detailed picture of nucleation in confinement. In particular, this rare event method efficiently searches for the most probable nucleation path(s) in otherwise intractable, high-dimensional free-energy landscapes. Results reveal the existence of several independent nucleation paths associated with different free-energy barriers. In particular, there is a family of asymmetric transition paths, in which a bubble forms at one of the walls; the other family involves the formation of axisymmetric bubbles with an annulus shape. The computed free-energy profiles reveal that the asymmetric path is significantly more probable than the symmetric one, while the exact position where the asymmetric bubble forms is less relevant for the free energetics of the process. A comparison of the atomistic results with continuum models is also presented, showing how, for simple liquids in mesoporous materials of characteristic size of ca. 4nm, the nanoscale effects reported for smaller pores have a minor role. The atomistic estimates for the nucleation free-energy barrier are in qualitative accord with those that can be obtained using a macroscopic, capillary-based nucleation theory. Graphical abstract: [Figure not available: see fulltext.]
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