• Energy Research

AbstractWe present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the spectrum is observed, confirming the presence of the so-called second-knee feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays.

This paper summarizes some highlights from the Pierre Auger Observatory that were presented at the ICRC 2011 in Beijing. The cumulative exposure has grown by more than 60% since the previous ICRC to above 21000 km^2 sr yr. Besides giving important updates on the energy spectrum, mass composition, arrival directions, and photon- and neutrino upper limits, we present first measurements of the energy spectrum down to 3 x 10^{17} eV, first distributions of the shower maximum, X_max, together with new surface detector related observables sensitive to X_max, and we present first measurements of the p-air cross section at ~ 10^{18} eV. Serendipity observations such as of atmospheric phenomena showing time evolutions of elves extend the breadth of the astrophysics research program. Proceedings of Highlight talk presented at ICRC 2011, Beijing. 10 pages, 13 figures

An update of the search for sleptons, neutralinos and charginos in the context of scenarios where the lightest supersymmetric particle is the gravitino and the next-to-lightest supersymmetric particle is a slepton, is presented, together with the update of the search for heavy stable charged particles in light gravitino scenarios and Minimal Supersymmetric Standard Models. Data collected in 1999 with the DELPHI detector at centre-of-mass energies around 192, 196, 200 and 202 GeV were analysed. No evidence for the production of these supersymmetric particles was found. Hence, new mass limits were derived at 95% confidence level. 21 pages, 6 figures, Accepted by Phys. Lett. B