Paul Scherrer Institute

About: Paul Scherrer Institute is a facility organization based out in Villigen, Switzerland. It is known for research contribution in the topics: Neutron & Large Hadron Collider. The organization has 9248 authors who have published 23984 publications receiving 890129 citations. The organization is also known as: PSI.

Gasoline emissions dominate over diesel in formation of secondary organic aerosol mass

Abstract: Although laboratory experiments have shown that organic compounds in both gasoline fuel and diesel engine exhaust can form secondary organic aerosol (SOA), the fractional contribution from gasoline and diesel exhaust emissions to ambient SOA in urban environments is poorly known. Here we use airborne and ground-based measurements of organic aerosol (OA) in the Los Angeles (LA) Basin, California made during May and June 2010 to assess the amount of SOA formed from diesel emissions. Diesel emissions in the LA Basin vary between weekdays and weekends, with 54% lower diesel emissions on weekends. Despite this difference in source contributions, in air masses with similar degrees of photochemical processing, formation of OA is the same on weekends and weekdays, within the measurement uncertainties. This result indicates that the contribution from diesel emissions to SOA formation is zero within our uncertainties. Therefore, substantial reductions of SOA mass on local to global scales will be achieved by reducing gasoline vehicle emissions.

Multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4.

Abstract: The origin of two large peaks in the atmospheric radiocarbon ((14)C) concentration at AD 774/5 and 993/4 is still debated. There is consensus, however, that these features can only be explained by an increase in the atmospheric (14)C production rate due to an extraterrestrial event. Here we provide evidence that these peaks were most likely produced by extreme solar events, based on several new annually resolved (10)Be measurements from both Arctic and Antarctic ice cores. Using ice core (36)Cl data in pair with (10)Be, we further show that these solar events were characterized by a very hard energy spectrum with high fluxes of solar protons with energy above 100 MeV. These results imply that the larger of the two events (AD 774/5) was at least five times stronger than any instrumentally recorded solar event. Our findings highlight the importance of studying the possibility of severe solar energetic particle events.

The complex-mass scheme for perturbative calculations with unstable particles

Abstract: Perturbative calculations with unstable particles require the inclusion of their finite decay widths. A convenient, universal scheme for this purpose is the complex-mass scheme. It fully respects gauge-invariance, is straight-forward to apply, and has been successfully used for the calculation of various tree-level processes and of the electroweak radiative corrections to e + e − → 4 f and H → 4 f .

Timing of deglaciation on the northern Alpine foreland (Switzerland)

Abstract: In order to understand the forcing and the feedback mechanisms working within the climate system knowledge of the timing of cold events across the globe is necessary. This information is especially crucial for the last glacial maximum (LGM) and the subsequent deglaciation. Our approach is to directly date the classical terminal moraines of the Rhone Glacier on the northern Alpine foreland. The Rhone Glacier was the dominant piedmont glacier of the Swiss Alps during the LGM. We have analyzed four erratic blocks from the Wangen a.d. Aare region (near Solothurn) for in-situ cosmogenic 10Be, 26Al, 36Cl and 21Ne. Weighted mean ages based on all radionuclide measurements for each boulder indicate that break down of the Rhone piedmont glacier system occurred between 21.1 and 19.1 ka. The oldest age obtained, 21.1 ka from block ER 1, pinpoints the onset of deglaciation. Pull-back from the Wangen maximum position was complete by no later than 19.1 ka. Reaching of the maximum extent of the Rhone Glacier, during the last glaciation, was contemporaneous with the worldwide ice maximum between 24 and 19 ka.