Breakdown of the Born-Oppenheimer approximation in solid hydrogen and hydrogen-rich solids

Hydrogen has been the subject of intense research following the discovery of high-temperature superconductivity in hydrides, and as a result of continuous efforts to produce solid hydrogen. The Born-Oppenheimer approximation is the central piece of the quantum mechanical description of molecules and solids and it is expected to have its weakest validity in hydrogen containing matter as it is the lightest element of all. The Born-Oppenheimer approximation is almost always assumed in the description of solids. Some beyond Born-Oppenheimer effects are likely included in the state-of-art method used to describe hydrogen-rich materials, but the effects on the electronic structure in solids have not been considered before. Here we compute the beyond Born-Oppenheimer corrections to electron density and report a breakdown of the Born-Oppenheimer approximation in experimentally known hydride superconductor YH6 and in Cs-IV structure of solid hydrogen. In both of these materials, we find a significant transfer of electron density from the volumes surrounding the expected positions of the hydrogen nuclei to volumes in between the nuclei. We expect these results to be the starting point of the beyond Born-Oppenheimer studies of electronic structure in solids, which is likely necessary to understand these forms of hydrogen-containing materials, also having significant technological importance.Comment: 11 pages, 4 figure

Coopetitive networks of microenterprises in the craft beer industry

Abstract. The objective of this thesis was to explain the optimal cooperative patterns of microenterprises in the same industry. Main research teams of the study where business networks and interconnectedness of the firms joined together with the coopetition approach which means simultaneous cooperation and competition of the companies. The research approach is taken to the Craft beer industry to find empirical data to verify theoretical concepts. Therefore the main research question is stated as How microenterprises utilize strategic partnerships with the competitors in the craft beer industry? The craft industry and microbreweries have shown a unique level of cooperation throughout the years, but they have not been connected to the academic field. Microenterprises have been also left to the minor role in the coopetitive literature. The network approach and strategic nets provide justified motives for the coopetitive ties. The study was conducted by gathering experiences and qualitative data from the 19 Finnish microbreweries. 17 of them were contacted through an open-end online survey and 2 were interviewed to find deeper insights of themes. It was evident that microbreweries in Finland have a large network horizon or strategic net to their size which is utilized more occasionally. Some breweries find cooperation with other breweries very essential and utilize it in their marketing and product development and some simply use it as support net. Microbreweries do not see themselves as the top competitors in the industry but as competitors to large industrial breweries. The low competitive pressure enables microbreweries to benefit greatly for their cooperation with other breweries. The results indicate that microenterprises would benefit from coopetitive ties if they manage to focus their competitive efforts to other channels than to themselves. Open information exchange not only benefit the companies, but the customers are also receiving better quality products. It is arguable how well the methods of the craft beer industry could be taken to the high technology field. However, it would be very intriguing to find out

Characterization of Thin p-on-p Radiation Detectors with Active Edges

Active edge p-on-p silicon pixel detectors with thickness of 100 $\mu$m were fabricated on 150 mm Float zone silicon wafers at VTT. By combining measured results and TCAD simulations, a detailed study of electric field distributions and charge collection performances as a function of applied voltage in a p-on-p detector was carried out. A comparison with the results of a more conventional active edge p-on-n pixel sensor is presented. The results from 3D spatial mapping show that at pixel-to-edge distances less than 100 $\mu$m the sensitive volume is extended to the physical edge of the detector when the applied voltage is above full depletion. The results from a spectroscopic measurement demonstrate a good functionality of the edge pixels. The interpixel isolation above full depletion and the breakdown voltage were found to be equal to the p-on-n sensor while lower charge collection was observed in the p-on-p pixel sensor below 80 V. Simulations indicated this to be partly a result of a more favourable weighting field in the p-on-n sensor and partly of lower hole lifetimes in the p-bulk.Comment: 23 pages, 16 figures, 1 tabl

First record of an indoor pest sawtoothed grain beetle Oryzaephilus surinamensis (Coleoptera: Silvanidae) from wild outdoor wood ant nest

Alive individual adult sawtoothed grain beetle Oryzaephilus surinamensis (Linnaeus, 1758) was discovered inside a nest mound of the red wood ant Formica rufa Linnaeus, 1758 during a survey of myrmecophilous invertebrates. The sawtoothed grain beetle is a widespread indoor pest that has not previously been found in an ant nest. It is one of the most common pests in stored grain and cereal products, but the natural life-style of the species is not known. As the site of discovery was exceptional, we verified the species identification using the DNA barcode. If the sawtoothed grain beetle can live in mounds of red wood ants, the mounds may become widespread source habitats for the future infestations of this serious stored product pest

Simulation study of signal formation in position sensitive planar p-on-n silicon detectors after short range charge injection

Segmented silicon detectors (micropixel and microstrip) are the main type of detectors used in the inner trackers of Large Hadron Collider (LHC) experiments at CERN. Due to the high luminosity and eventual high fluence of energetic particles, detectors with fast response to fit the short shaping time of 20-25 ns and sufficient radiation hardness are required. Charge collection measurements carried out at the Ioffe Institute have shown a reversal of the pulse polarity in the detector response to short-range charge injection. Since the measured negative signal is about 30-60% of the peak positive signal, the effect strongly reduces the CCE even in non-irradiated detectors. For further investigation of the phenomenon the measurements have been reproduced by TCAD simulations. As for the measurements, the simulation study was applied for the p-on-n strip detectors similar in geometry to those developed for the ATLAS experiment and for the Ioffe Institute designed p-on-n strip detectors with each strip having a window in the metallization covering the p(+) implant, allowing the generation of electron-hole pairs under the strip implant. Red laser scans across the strips and the interstrip gap with varying laser diameters and Si-SiO2 interface charge densities (Q(f)) were carried out. The results verify the experimentally observed negative response along the scan in the interstrip gap. When the laser spot is positioned on the strip p(+) implant the negative response vanishes and the collected charge at the active strip increases respectively. The simulation results offer a further insight and understanding of the influence of the oxide charge density in the signal formation. The main result of the study is that a threshold value of Q(f), that enables negligible losses of collected charges, is defined. The observed effects and details of the detector response for different charge injection positions are discussed in the context of Ramo's theorem.Peer reviewe

Finnish CMS-TOB cosmic rack

Peer reviewe

Exact factorization of the many-body Green's function theory of electrons and nuclei

We combine the recently developed many-body Green's function theory for electrons and nuclei with the exact factorization of the wave function. The existing Born-Oppenheimer Green's functions are shown to be special cases of our exact approach. We consider the limitations of the laboratory frame formulation of the Green's function theory and discuss why the body-fixed frame formulation is needed in order to go beyond the Born-Oppenheimer theory. We give exact forms of the electronic and nuclear Green's functions written in terms of the exact factorized states, providing a systematic approach beyond the Born-Oppenheimer approximation. The lowest order approximation to the exact electronic Green's function is found to be an expected value of the Born-Oppenheimer electronic Green's function with respect to the nuclear density.publishedVersionPeer reviewe

Tailoring of motional states in double-well potentials by time-dependent processes

We show that the vibrational state tailoring method developed for molecular systems can be applied for cold atoms in optical lattices. The original method is based on a three-level model interacting with two strong laser pulses in a counterintuitive sequence [M. Rodriguez et al., Phys. Rev. A 62, 053413 (2000)]. Here we outline the conditions for achieving similar dynamics with single time-dependent potential surfaces. It is shown that guided switching between diabatic and adiabatic evolution has an essential role in this system. We also show that efficient and precise tailoring of motional states in optical lattices can be achieved, for instance, simply by superimposing two lattices and moving them with respect to each other.Comment: 9 pages, 11 figures, 25 references; accepted to PRA; v2: minor explanatory remarks added & typos correcte

Evaluation of a coupled dispersion and aerosol process model against measurements near a major road

International audienceA field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17?20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm?10 ?m (aerodynamic diameter) by the Electrical Low Pressure Impactor (ELPI) and in the size range of 3?50 nm (mobility diameter) by Scanning Mobility Particle Sizer (SMPS), total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC), temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes). We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible at this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of condensable organic vapour of 1012 molecules cm?3 was shown to be in a disagreement with the measured particle size evolution, while the modelling runs with the concentration of condensable organic vapour of 109?1010 molecules cm?3 resulted in particle sizes that were closest to the measured values