Multianode Photo Multiplier Tubes as Photo Detectors for Ring Imaging Cherenkov Detectors

The 64-channel Multianode Photo Multiplier (MaPMT) has been evaluated as a candidate for the LHCb Ring Imaging Cherenkov (RICH) photo detectors. We present result from data taken with a 3x3 array of closely packed MaPMTs mounted onto the RICH 1 prototype vessel, exposed to charged particle beams at CERN, and read out at LHC speed. Using a LED light source, we have performed spatial light scans to study the light collection efficiency of the MaPMTs We have also measured the performance of the MaPMTs as a function of the applied high voltage. Different dynode resistor chains have been used to study the tubes at low gains. In addition, we have studied the behaviour of the MaPMT in magnetic fields.Comment: 5 pages, 6 figures, 8 .eps files, RICH2002 conference, Pylo

On the structure of thin4He films on solid hydrogen

We have investigated the adsorption of4He onto a quench-condensed H2 film by means of surface state electrons. Oscillations in the surface state electron conductivity clearly reveal the layerwise character of the adsorption. At temperatures below 2K we have observed an anomaly in the conductivity around the completion of the first monolayer. This new feature is interpreted as an indication of a liquid-to-solid phase transition in the first layer

Triadic resonances in non-linear simulations of a fluid flow in a precessing cylinder

We present results from three-dimensional non-linear hydrodynamic simulations of a precession driven flow in cylindrical geometry. The simulations are motivated by a dynamo experiment currently under development at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in which the possibility of generating a magnetohydrodynamic dynamo will be investigated in a cylinder filled with liquid sodium and simultaneously rotating around two axes. In this study, we focus on the emergence of non-axisymmetric time-dependent flow structures in terms of inertial waves which - in cylindrical geometry - form so-called Kelvin modes. For a precession ratio ${\rm{Po}}=\Omega_p/\Omega_c=0.014$ the amplitude of the forced Kelvin mode reaches up to one fourth of the rotation velocity of the cylindrical container confirming that precession provides a rather efficient flow driving mechanism even at moderate values of ${\rm{Po}}$. More relevant for dynamo action might be free Kelvin modes with higher azimuthal wave number. These free Kelvin modes are triggered by non-linear interactions and may constitute a triadic resonance with the fundamental forced mode when the height of the container matches their axial wave lengths. Our simulations reveal triadic resonances at aspect ratios close to those predicted by the linear theory except around the primary resonance of the forced mode. In that regime we still identify various free Kelvin modes, however, all of them exhibit a retrograde drift around the symmetry axis of the cylinder and none of them can be assigned to a triadic resonance. The amplitudes of the free Kelvin modes always remain below the forced mode but may reach up to 6% of the of the container's angular velocity. The properties of the free Kelvin modes will be used in future simulations of the magnetic induction equation to investigate their ability to provide for dynamo action.Comment: 26 pages, 14 figures, submitted to New J. Phy

Letter from F. M. Albrecht to Representative Burdick Regarding Sanish and Van Hook Garrison Dam Relocations, July 18, 1950

This letter, dated July 18, 1950, from Colonel F. M. Albrecht of the United States (US) Army Corps of Engineers to US Representative Usher Burdick concerns the relocation of the towns of Sanish and Van Hook to make way for Garrison Dam. Albrecht refers to Burdick\u27s July 10 inquiry regarding the status of the Sanish and Van Hook acquisition program. Albrecht explains that there is a question of legal authority regarding permission for the US government to pay for improvements of tenants located on railroad property. Albrecht writes that he is forwarding Burdick\u27s letter to the Chief of Engineers, as he does not have enough of the facts to answer fully. As for the rest of the program, he writes that appraisals are underway and that funds should be appropriated by 1951; he then details the sequence in which these appraisals will occur. He explains that the two towns are planning on combining at the southwest site, and concludes by noting that there have been some issues with a minority of Sanish residents who prefer to remain a separate town.https://commons.und.edu/burdick-papers/1447/thumbnail.jp

Winners and Losers in Reforestation Efforts in the Lower Rio Grande Valley of Texas, and the Predictive Power of Xylem Anatomy on Long-Term Growth and Survival

Reforestation has been ongoing in the Lower Rio Grande Valley annually since the 1980s, and to date over 6400 ha of land has been reforested in this area. However, there has been little subsequent study of the change and development of those forests as they mature. This thesis consists of two, interrelated, studies: (1) surveys of a five-site chronosequence of restored forests and (2) quantification of xylem anatomical traits of a subset of species present at the reforestation sites. Surveys showed a consistent reduction in species diversity and stem number density on the landscape, and identified a suite of species which predictably persist or increase on the landscape. Analysis of xylem anatomical results are ongoing

Planet at Risk from Grazing Animals?

The famous FAO report “Livestock’s Long Shadow” (Steinfeld et. al. 2006) and hundreds of subsequent publications blamed domestic livestock, in general, and grassland-based production systems in the (sub) tropics, in particular, of causing serious environmental hazards such as climate change, claiming that 18% of anthropogenic greenhouse gas (GHG) emissions are from livestock, more than from the transport sector. Few reviews challenged this claim, and those that did received little attention from the media. Pitseky et al. (2009) revealed the double standard applied by the FAO in this matter. Whereas for livestock products a full life cycle assessment for GHG emissions was applied, for the transport sector only fuel consumption was taken into account. This striking weakness of the FAO report alone considerably disburdens livestock husbandry

Gyrokinetic Large Eddy Simulations

The Large Eddy Simulation (LES) approach is adapted to the study of plasma microturbulence in a fully three-dimensional gyrokinetic system. Ion temperature gradient driven turbulence is studied with the {\sc GENE} code for both a standard resolution and a reduced resolution with a model for the sub-grid scale turbulence. A simple dissipative model for representing the effect of the sub-grid scales on the resolved scales is proposed and tested. Once calibrated, the model appears to be able to reproduce most of the features of the free energy spectra for various values of the ion temperature gradient