Wave breaking and particle jets in intense inhomogeneous charged beams

This work analyzes the dynamics of inhomogeneous, magnetically focused high-intensity beams of charged particles. While for homogeneous beams the whole system oscillates with a single frequency, any inhomogeneity leads to propagating transverse density waves which eventually result in a singular density build up, causing wave breaking and jet formation. The theory presented in this paper allows to analytically calculate the time at which the wave breaking takes place. It also gives a good estimate of the time necessary for the beam to relax into the final stationary state consisting of a cold core surrounded by a halo of highly energetic particles.Comment: Accepted in Physics of Plasma Letter

Morphological Biosignatures from Subsurface Environments: Recognition on Planetary Missions

The Earth is inhabited by life not just at its surface, but down to a depth of kms. Like surface life, this deep subsurface life produces a fossil record, traces of which may be found in the pore space of practically all rock types. The (palaeo)subsurface of other planetary bodies is therefore a promising target in the search for another example of life. Subsurface filamentous fabrics (SFFs), i.e. mineral encrustations of a filament-based textural framework, occur in many terrestrial rocks representing present or ancient subsurface settings. SFF are interpreted as mineral encrustations on masses of filaments/pseudofilaments of microbial origin. SFF are a common example of the fossil record of subsurface life. Macroscopic (pseudostalactites, U-shapes) and microscopic (filaments) characteristics make SFF's a biosignature that can be identified with relative ease. SFF in the subsurface are probably about as common and easily recognizable as are stromatolites in surface environments. Close-up imagers (∼50 micron/pixel resolution) and microscopes (∼3 micron/pixel resolution) on upcoming Mars lander missions are crucial instruments that will allow the recognition of biofabrics of surface- and subsurface origin. The resolution available however will not allow the recognition of small (∼1 micron) individual mineralized microbial cells. The microscopy of unprepared rock surfaces would benefit from the use of polarizing filters to reduce surface reflectance and enhance internally reflected light. Tests demonstrate the potential to visualize mineralized filaments using this procedur

Optimisation of downy mildew (Plasmopara viticola) control in organic viticulture with low copper doses, new copper formulations and plant strengtheners, results of four years of on farm research

In three different wine growing regions in Germany, due to weather and infection conditions several fungicide (copper formulations) and plant strengtheners (Myco-Sin VIN®, Kendal®, Frutogard ®) applications against downy mildew are required in order to obtain satisfactory disease control. Results of the four years of on farm trials confirmed good efficacy of the copper based substances like copper hydroxide, partly in combination with two or three applications of potassium phosphonate, new copper-hydroxide formulation or copper oxychloride used in a low doses of copper and alternative products like Myco-Sin-VIN® (clay with high aluminium content) in combination with Kendal® ( plant extract)

Homogeneous versus Spiral Phases of Hole-doped Antiferromagnets: A Systematic Effective Field Theory Investigation

Using the low-energy effective field theory for magnons and holes -- the condensed matter analog of baryon chiral perturbation theory for pions and nucleons in QCD -- we study different phases of doped antiferromagnets. We systematically investigate configurations of the staggered magnetization that provide a constant background field for doped holes. The most general configuration of this type is either constant itself or it represents a spiral in the staggered magnetization. Depending on the values of the low-energy parameters, a homogeneous phase, a spiral phase, or an inhomogeneous phase is energetically favored. The reduction of the staggered magnetization upon doping is also investigated.Comment: 35 pages, 5 figure

GeMSE: A new Low-Background Facility for Meteorite and Material Screening

We are currently setting up a facility for low-background gamma-ray spectrometry based on a HPGe detector. It is dedicated to material screening for the XENON and DARWIN dark matter projects as well as to the characterization of meteorites. The detector will be installed in a medium depth ($\sim$620 m.w.e.) underground laboratory in Switzerland with several layers of shielding and an active muon-veto. The GeMSE facility will be operational by fall 2015 with an expected background rate of $\sim$250 counts/day (100-2700 keV).Comment: The following article appeared in AIP Conf. Proc. 1672, 120004 (2015) and may be found at http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4928010. The muon spectrum in Figure 4 (left) was corrected due to a bug in the code. After correction the muon flux is reduced by a factor of about

A powerful computational crystallography method to study ice polymorphism

Classical Molecular Dynamics (MD) simulations are employed as a tool to investigate structural properties of ice crystals under several temperature and pressure conditions. All ice crystal phases are analyzed by means of a computational protocol based on a clustering approach following standard MD simulations. The MD simulations are performed by using a recently published classical interaction potential for oxygen and hydrogen in bulk water, derived from neutron scattering data, able to successfully describe complex phenomena such as proton hopping and bond formation/breaking. The present study demonstrates the ability of the interaction potential model to well describe most ice structures found in the phase diagram of water and to estimate the relative stability of sixteen known phases through a cluster analysis of simulated powder diagrams of polymorphs obtained from MD simulations. The proposed computational protocol is suited for automated crystal structure identification.Comment: RevTex 4.1, 7 figures - to be published in the Journal of Chemical Physic