New mechanism of pulsar radio emission

It is shown that pulsar radio emission can be generated effectively through a streaming motion in the polar-cap regions of a pulsar magnetosphere causing nonresonant growth of waves that can escape directly. As in other beam models, a relatively low-energy high-density beam is required. The instability generates quasi-transverse waves in a beam mode at frequencies that can be well below the resonant frequency. As the waves propagate outward growth continues until the height at which the wave frequency is equal to the resonant frequency. Beyond this point the waves escape in a natural plasma mode (L-O mode). This one-step mechanism is much more efficient than previously widely considered multi-step mechanisms.Comment: 4 pages, PRL 2002 (in press

Canal lock variable speed hydropower turbine design and control

The design of a novel submerged hydraulic turbine for producing electricity by converting the available hydropower on canal locks during raising and lowering ships, but with the minimum overall impact on the facility, is being considered. The hydraulic head in such applications is low (few meters) and varies over time (from its maximum value down to zero) resulting in a low potential conversion of hydraulic head in electrical energy. The study involves the modification of the hydraulic transient system, the design and performance estimation of a hydraulic turbine. Based on the performance curves, a permanent magnet Vernier generator is designed. The models of hydraulic turbine and generator are added to the system model and simulations results of the whole system are presented.Region Hauts de Franc

MuPix and ATLASPix -- Architectures and Results

High Voltage Monolithic Active Pixel Sensors (HV-MAPS) are based on a commercial High Voltage CMOS process and collect charge by drift inside a reversely biased diode. HV-MAPS represent a promising technology for future pixel tracking detectors. Two recent developments are presented. The MuPix has a continuous readout and is being developed for the Mu3e experiment whereas the ATLASPix is being developed for LHC applications with a triggered readout. Both variants have a fully monolithic design including state machines, clock circuitries and serial drivers. Several prototypes and design variants were characterised in the lab and in testbeam campaigns to measure efficiencies, noise, time resolution and radiation tolerance. Results from recent MuPix and ATLASPix prototypes are presented and prospects for future improvements are discussed.Comment: 10 pages, proceedings, The 28th International Workshop on Vertex Detectors (VERTEX 2019), 13 - 18 Oct 2019, Lopud Island, Croati

First radiation hardness results of the TeraPixel Active Calorimeter (TPAC) sensor

The TeraPixel Active Calorimeter (TPAC) sensor is a novel Monolithic Active Pixel Sensors (MAPS) device developed for use as the active layers of a large area, digital electromagnetic calorimeter (DECAL) at a future e +e- collider. Further applications, which include the tracking and vertex systems for future lepton colliders and LHC upgrades have been proposed and it is therefore essential to characterise the behaviour of the sensor for these applications. We present the first studies of radiation hardness testing of the TPAC sensor. The performance of the sensor has been evaluated after exposures up to 5 Mrad of 50 keV x-rays. Under realistic ILC operating conditions a maximum decrease in the signal to noise ratio of 8% (15%) was observed after 200 krad (5 Mrad) which is already sufficient for proposed applications in future e+e- colliders. © 2013 IOP Publishing Ltd