The performance of the jet trigger for the ATLAS detector during 2011 data taking

The performance of the jet trigger for the ATLAS detector at the LHC during the 2011 data taking period is described. During 2011 the LHC provided proton–proton collisions with a centre-of-mass energy of 7 TeV and heavy ion collisions with a 2.76 TeV per nucleon–nucleon collision energy. The ATLAS trigger is a three level system designed to reduce the rate of events from the 40 MHz nominal maximum bunch crossing rate to the approximate 400 Hz which can be written to offline storage. The ATLAS jet trigger is the primary means for the online selection of events containing jets. Events are accepted by the trigger if they contain one or more jets above some transverse energy threshold. During 2011 data taking the jet trigger was fully efficient for jets with transverse energy above 25 GeV for triggers seeded randomly at Level 1. For triggers which require a jet to be identified at each of the three trigger levels, full efficiency is reached for offline jets with transverse energy above 60 GeV. Jets reconstructed in the final trigger level and corresponding to offline jets with transverse energy greater than 60 GeV, are reconstructed with a resolution in transverse energy with respect to offline jets, of better than 4 % in the central region and better than 2.5 % in the forward direction

The effect of afforestation on water recharge and nitrogen leaching in the Netherlands

Water balances and nitrogen budgets were studied in two chronosequences of oak and spruce on former arable land. Quantity and quality of rainfall and throughfall, soil water contents and concentrations in the soil solution were measured during a period of 1¿2 years. Hydrological fluxes were calculated using the soil hydrological model SWAP. Nitrogen leaching fluxes were based on monthly measured concentrations and simulated hydrological fluxes. Results showed that water recharge declined from approximately 485 mm/yr in arable land to 172 mm in the 18-year old oak stand and approximately 100 mm in the 13 and 14-year old spruce stands. For both chronosequences the decline in water recharge upon afforestation can be described by a power function; the exponent being ¿0.22 for oak and somewhat higher, ¿0.31, for spruce. Nitrogen leaching fluxes were negligible in the spruce stands and declined with age in the oak stands, from 16 kg/ha/yr at the youngest stand to 8 kg/ha/yr at the 18-year old stand. The nitrogen budget for the four oak stands increased with age. An explanation for this unexpected result may be the declining release of nitrogen by mineralization of organic matter present in the (former) agricultural soil. The data provide valuable information for the validation of simulation models and decision support systems used for policy decisions

Impact of atmospheric nitrogen deposition on the exchange of carbon dioxide, nitrous oxide and methane from European forests.

This paper discusses the interactions between anthropogenic nitrogen deposition and exchanges of CO2, N2O and CH4 between forest ecosystems and the atmosphere in Europe. Topics covered include the processes and factors controlling exchanges of CO2, N2O and CH4 between forests and the atmosphere; estimates of the net greenhouse gas exchange by European forests and forest soils; the methods and data that were used to quantify the effects of nitrogen deposition on the net greenhouse gas exchange; and the net CO2, N2O and CH4 emissions and the nitrogen deposition impacts on those emissions in terms of CO2 equivalents

Abatement strategies to reduce air pollution from transport in Germany

Large scale exceedances of PM10 and N02 ambient air limit values will continue in Germany despite the implementation of national and international policies. An integrated approach has therefore been developed to assess different cost-effective mitigation strategies for all source groups on a national level. On-road and ofT-road transport emission abatement strategies such as more stringent emission limit values, cost internalisation, speed limits and levelling of fuel taxes can contribute to the overarching goal of an improved air quality