The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). The initial configuration and expected performance of the detector and associated systems, as established by test beam measurements and simulation studies, is described.

region at a hadron collider. This document discusses the implications of these first measurements on classes of extensions to the Standard Model, bearing in mind the interplay with the results of searches for on-shell production of new particles at ATLAS and CMS. The physics potential of an upgrade to the LHCb detector, which would allow an order of magnitude more data to be collected, is emphasised.

The LHCb Outer Tracker is a gaseous detector covering an area of 5 × 6 m 2 with 12 double layers of straw tubes. The detector with its services are described together with the commissioning and calibration procedures. Based on data of the first LHC running period from 2010 to 2012, the performance of the readout electronics and the single hit resolution and efficiency are presented.The efficiency to detect a hit in the central half of the straw is estimated to be 99.2%, and the position resolution is determined to be approximately 200 µm. The Outer Tracker received a dose in the hottest region corresponding to 0.12 C/cm, and no signs of gain deterioration or other ageing effects are observed.

No abstract

This study aims to determine the rate of chemical denudation and the relationships between dominant geochemical reactions operating in the proglacial and subglacial environments of the polythermal glacier Werenskioldbreen (SW Svalbard) during an entire ablation season. Water sampling for major ion chemistry was performed at a proglacial hydrometric station and from subglacial outflows from May to September 2011. These data were combined with measurements of discharge and supraglacial ablation rates. The slopes and intercepts in bestfit regressions of [*Ca 2+ +*Mg 2+ vs. *SO 4 2-] and [HCO 3 vs. *SO 4 2-] in meltwater from icemarginal subglacial channels were close to the stoichiometric parameters of sulfide oxidation and simple hydrolysis coupled to carbonate dissolution (*concentrations corrected for input of sea-salt). This shows that these relationships predominates the meltwater chemistry. Our findings also show that sulfide oxidation is a better indicator of the configuration of subglacial drainage systems than, for instance, Na + and K +. In the proglacial area and in sub-artesian outflows, the ion associations represent sulfide oxidation but other processes such as ion exchange and dissolution of Ca and Mg efflorescent salts may also contribute to the solute variations. These processes may cause enhanced fluxes of Ca 2+ and HCO 3 from glacierised basins during the early ablation and peak flow seasons as the proglacial salts re-dissolve. The overall chemical denudation rate in the basin for 2011 (ranging from 1601 and 1762 meq m-2 yr-1 (121.9 and 132.2 t km-2 yr-1)) was very high when compared to other Svalbard valley glaciers suggesting that the high rate of chemical denudation was mostly caused by the high rates of discharge and ablation. Chemical weathering intensities (876 and 964 meq m-3 yr-1) exceeded previously reported intensities in Svalbard.

The WASA 4π multidetector system, aimed at investigating light meson production in light ion collisions and η meson rare decays at the CELSIUS storage ring in Uppsala is presented. A detailed description of the design, together with the anticipated and achieved performance parameters are given.

The question why aquatic communities are often absent in suitable pools still remains a topic of debate and is often explained by dispersal limitation or biological barriers. Cryoconite holes (water‐filled depressions on glaciers) as natural, simple and dynamic habitats in a glacial biome seem to be a good model for addressing this question. The main aim of our research was to investigate links between changes in weather conditions and short temporal changes in invertebrate densities on glaciers. For this study, we selected cryoconite holes on the valley Longyear Glacier and collected samples at two‐day intervals from the same holes in August 2016. During the sampling campaigns, we detected freezing, shrinking and ablation of cryoconite holes. In the samples, we found only two groups of invertebrates, Tardigrada and Rotifera. We observed invertebrates in cryoconite holes until calm weather patterns were interrupted by wind and rainstorm, after which no individuals were detected. Before the storm event, densities in the samples reached up to 149 tardigrades/cm3 and 119 rotifers/cm3 of cryoconite. In addition, we found a strong erosion of cryoconite granules, redistribution into sediments (mud‐like forms), and the migration of granules after rain, which confirmed the mechanical removal of invertebrates by streaming water. Water depth, pH or electrical conductivity did not seem to shape invertebrates communities. Their frequency and densities on valley glaciers depend on stochastic events, for example, weather breakdown (rainstorms). Furthermore, such events may form new niches for tardigrades and rotifers on polar glaciers and influence their coexistence within cryoconite holes.

No abstract