Acoustic sensor to measure snowdrift and wind velocity for avalanche forecasting

A new mathematical model of slushflow dynamics is developed. A slushflow is treated as a two-layer flow. The lower layer consists of pure liquid phase (water) and the upper layer is a floating water saturated snow (slush). The equations of mass and impulse conservation for each layer are written. These equations include an interaction and mass exchange between the layers and between the water or slush layer and snow cover. The model equations were integrated numerically according to a developed for PC program. Series of numerical experiments for uniform slope were carried out. The structure and dynamics of slushflow were investigated. The dependencies of depths, velocities of flow and front coordinates of the upper and the lower layers on the parameters of the model are established. These parameters are the coefficient of snow entrainment, the coefficient of dry friction, the coefficients of turbulent friction, the discharge of water feeding at the rear end of flow, the snow cover thickness and the slope angle. An effect of exhaustion of the water layer is revealed. This effect is due to fast water absorption by entrained masses of snow

A high resolution cavity BPM for the CLIC Test Facility

In frame of the development of a high resolution BPM system for the CLIC Main Linac we present the design of a cavity BPM prototype. It consists of a waveguide loaded dipole mode resonator and a monopole mode reference cavity, both operating at 15 GHz, to be compatible with the bunch frequencies at the CLIC Test Facility. Requirements, design concept, numerical analysis, and practical considerations are discussed.Comment: 5 pp. 14th Beam Instrumentation Workshop (BIW10) 2-6 May 2010. Santa Fe, New Mexic

The electron accelerator for the AWAKE experiment at CERN

The AWAKE collaboration prepares a proton driven plasma wakefield acceleration experiment using the SPS beam at CERN. A long proton bunch extracted from the SPS interacts with a high power laser and a 10 m long rubidium vapour plasma cell to create strong wakefields allowing sustained electron acceleration. The electron bunch to probe these wakefields is supplied by a 20 MeV electron accelerator. The electron accelerator consists of an RF-gun and a short booster structure. This electron source should provide beams with intensities between 0.1 and 1 nC, bunch lengths between 0.3 and 3 ps and an emittance of the order of 2 mm mrad. The wide range of parameters should cope with the uncertainties and future prospects of the planned experiments. The layout of the electron accelerator, its instrumentation and beam dynamics simulations are presented

The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance

A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability

The ATLAS TRT electronics

The ATLAS inner detector consists of three sub-systems: the pixel detector spanning the radius range 4cm-20cm, the semiconductor tracker at radii from 30 to 52 cm, and the transition radiation tracker (TRT), tracking from 56 to 107 cm. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift tubes (or straws) and of electron identification based on transition radiation from fibres or foils interleaved between the straws themselves. This paper describes the on and off detector electronics for the TRT as well as the TRT portion of the data acquisition (DAQ) system

Détection acoustiques des avalanches. Site La Sionne-Anzère, Valais, Suisse

Automatic detection methods are necessary to overcome difficulties inherent to the practical state of the art human obersation, which is conditioned by the presence of observers and has severe limitations due to weather, lack of visibility at night, masking reliefs's, avalanche types, etc. Seismic and acoustic techniques are considered. To test the acoustic detection method, an experimental system was installed in-situ during 94-95 winter in order to record acoustic events during periods of artificial release of avalanches. The experimentation has shown that the movement of avalanches produces acoustic signals suitable for automatic detection and localisation over extended areas. The present experimental system consists of four outside weatherproofed microphones combined in such a way as to constitue an acoustic goniometer. An additional very low noise microphone - dedicated to the record of the acoustic signatures of avalanches - completes the instrumentation. The article describes the results of the first experimental campaign, the intrinsic limits of the method - range, wind effects - and the potential of the system ARFANG to evolve in an operational way-optimisation of sound detection, automatic identification of events. / Actuellement, la seule méthode pratiquée est l'observation visuelle - impossible de nuit ou par mauvais temps. En vue de disposer dans le futur de systèmes opérationnels de mesure automatique de l'activité avalancheuse, les techniques de détection sismique et/ou acoustique sont envisagées. Pour évaluer la détection acoustique, un système expérimental a été installé sur le site de La Sionne afin d'enregistrer, durant tout l'hiver 94-95, les sons lors de déclenchements artificiels d'avalanches. L'expérience a permis de constater l'émission d'infrasons par les avalanches et a démontré la possibilité d'utiliser ces signaux pour détecter et localiser automatiquement les avalanches se produisant dans un rayon de plusieurs kilomètres. Le sytème comportait quatre microphones identiques installés de manière permanente en extérieur et reliés à une instrumentation de sorte à former un goniomètre acoustique. Un microphone extérieur supplémentaire - à très faible bruit - était utilisé exclusivement pour l'enregistrement des signatures acoustiques. L'article décrit les résultats de la 1ère campagne de mesures, les possibilités et limites de la méthode, et les perspectives d'évolution du système expérimental en un système opérationnel