Pixel detector R&D for the Compact Linear Collider

The physics aims at the proposed future CLIC high-energy linear $e^+ e^-$ collider pose challenging demands on the performance of the detector system. In particular the vertex and tracking detectors have to combine precision measurements with robustness against the expected high rates of beam-induced backgrounds. A spatial resolution of a few microns and a material budget down to 0.2\% of a radiation length per vertex-detector layer have to be achieved together with a few nanoseconds time stamping accuracy. These requirements are addressed with innovative technologies in an ambitious detector R\&D programme, comprising hardware developments as well as detailed device and Monte Carlo simulations based on TCAD, Geant4 and Allpix-Squared. Various fine pitch hybrid silicon pixel detector technologies are under investigation for the CLIC vertex detector. The CLICpix and CLICpix2 readout ASICs with \SI{25}{\micro\meter} pixel pitch have been produced in a \SI{65}{\nano\meter} commercial CMOS process and bump-bonded to planar active edge sensors as well as capacitively coupled to High-Voltage (HV) CMOS sensors. Monolithic silicon tracking detectors are foreseen for the large surface ($\approx$ \SI{140}{\meter\squared}) CLIC tracker. Fully monolithic prototypes are currently under development in High-Resistivity (HR) CMOS, HV-CMOS and Silicon on Insulator (SOI) technologies. The laboratory and beam tests of all recent prototypes profit from the development of the CaRIBou universal readout system. This talk presents an overview of the CLIC pixel-detector R\&D programme, focusing on recent test-beam and simulation results.Comment: On behalf of CLICdp collaboration, Conference proceedings for PIXEL201

Return to Computer Use and Organizational Practices of the firm

In this paper, we test the hypothesis that computer use will lead to productivity gains only if the firm uses an appropriate set of organizational practices. Detailed data on organizational practices and workers. compensation are obtained through a Canadian longitudinal linked employer-employee database called the Workplace and Employee Survey (WES). Linked data allow us to take into account both worker and firm unobserved heterogeneity through the estimation of a linear mixed model of wage determination. Our results suggest a small but positive computer-wage premium whose size is related to a set of organizational practices.Wage determination; Human capital; New technologies; Computers; Mixed models; Linked employer-employee data; Organizational Practices of the Firm.

Sounding stellar cores with mixed modes

The space-borne missions CoRoT and Kepler have opened a new era in stellar physics, especially for evolved stars, with precise asteroseismic measurements that help determine precise stellar parameters and perform ensemble astero seismology. This paper deals with the quality of the information that we can retrieve from the oscillations. It focusses on the conditions for obtaining the most accurate measurement of the radial and non-radial oscillation patterns. This accuracy is a prerequisite for making the best with asteroseismic data. From radial modes, we derive proxies of the stellar mass and radii with an unprecedented accuracy for field stars. For dozens of subgiants and thousands of red giants, the identification of mixed modes (corresponding to gravity waves propagating in the core coupled to pressure waves propagating in the envelope) indicates unambiguously their evolutionary status. As probes of the stellar core, these mixed modes also reveal the internal differential rotation and show the spinning down of the core rotation of stars ascending the red giant branch. A toy model of the coupling of waves constructing mixed modes is exposed, for illustrating many of their features.Comment: Meeting: New advances in stellar physics: from microscopic to macroscopic processes Roscoff, 27-31 May 201

The Returns to Computer Use Revisited, Again

Using North American data, we revisit the question first broached by Krueger (1993) and re-examined by DiNardo and Pischke (1997) of whether there exists a real wage differential associated with computer use. Employing a mixed effects model to correct for both worker and workplace unobserved heterogeneity using matched employer-employee panel data, we find that computer users enjoy an almost 4 per cent wage premium over non-users. Failure to correct for the worker selection effect leads to a more than twofold overestimate of this premium, as does failure to correct for workplace unobserved heterogeneity.Wage determination; computers; mixed models; linked employer-employee data

The Returns to Computer Use Revisited, Again

Using North American data, we revisit the question first broached by Krueger (1993) and re-examined by DiNardo and Pischke (1997) of whether there exists a real wage differential associated with computer use. Employing a mixed effects model to correct for both worker and workplace unobserved heterogeneity using matched employer-employee panel data, we find that computer users enjoy an almost 4 per cent wage premium over non-users. Failure to correct for the worker selection effect leads to a more than twofold overestimate of this premium, as does failure to correct for workplace unobserved heterogeneity.Wage determination, Computers, Mixed models, Linked employer-employee data

Dynamic Behaviour of a Flexible Yacht Sail Plan

• Dynamic fluid structure interaction of a sail plan is modeled in harmonic pitching • Aerodynamic forces oscillations show hysteresis phenomena • Neglecting the structural deformation underestimates the forces oscillations • Both aerodynamic and structure inertia affect loads in the rig.A numerical investigation of the dynamic Fluid Structure Interaction (FSI) of a yacht sail plan submitted to harmonic pitching is presented to address both issues of aerodynamic unsteadiness and structural deformation. The FSI model | Vortex Lattice Method uid model and Finite Element structure model | has been validated with full-scale measurements. It is shown that the dynamic behaviour of a sail plan subject to yacht motion clearly deviates from the quasi-steady theory. The aerodynamic forces presented as a function of the instantaneous apparent wind angle show hysteresis loops, suggesting that some energy is exchanged by the system. The area included in the hysteresis loop increases with the motion reduced frequency and amplitude. Comparison of rigid versus soft structures shows that FSI increases the energy exchanged by the system and that the oscillations of aerodynamic forces are underestimated when the structure deformation is not considered. Dynamic loads in the fore and aft rigging wires are dominated by structural and inertial effects. This FSI model and the obtained results may be useful firstly for yacht design, and also in the field of auxiliary wind assisted ship propulsion, or to investigate other marine soft structures.This work was supported by the French Naval Academy

Testing the cores of first ascent red-giant stars using the period spacing of g modes

In the context of the determination of stellar properties using asteroseismology, we study the influence of rotation and convective-core overshooting on the properties of red-giant stars. We used models in order to investigate the effects of these mechanisms on the asymptotic period spacing of gravity modes ($\Delta \Pi_1$) of red-giant stars that ignite He burning in degenerate conditions (M$\lesssim$2.0 M$_{\odot}$). We also compare the predictions of these models with Kepler observations. For a given $\Delta\nu$, $\Delta \Pi_1$ depends not only on the stellar mass, but also on mixing processes that can affect the structure of the core. We find that in the case of more evolved red-giant-branch (RGB) stars and regardless of the transport processes occurring in their interiors, the observed $\Delta \Pi_1$ can provide information as to their stellar luminosity, within ~10-20%. In general, the trends of $\Delta \Pi_1$ with respect to mass and metallicity that are observed in Kepler red-giant stars are well reproduced by the models.Comment: 5pages, 6 figure