Krauss, Mark Srednicki and Frank Wilczek. A major limitation of early detectors was the problem of surface events. Due to incomplete charge collection, a particle interaction near the surface of the crystal gave no ionization signal, so electron recoils near the surface could be mistaken for nuclear recoils. To avoid this, the collaboration developed new detectors with interdigitised electrodes. Different voltages are applied to a series of electrodes so the direction of electric field is different near the surface of the crystal, allowing over 99.5% of surface events to be rejected. Results The results from the first phase of the experiment (EDELWEISS I) were published in 2005, excluding WIMP dark matter with an interaction cross-section above (at ≈85 GeV). EDELWEISS-II ran 2009–10 with 10 detectors, that is, 4 kg of detector mass (for a total effective exposure of 384 kg·d) limiting high mass and low mass WIMPs, and axions. A cross-section of is excluded at 90% C.L. for WIMP mass of 85 GeV. (Just above projected CDMS results in Fig A.) EDELWEISS-III had 40 detectors. EDELWEISS-III conducted first science run 2014-2015 with results published in 2016. EURECA design work will continue for operation after the EDELWEISS-III run. It is planned that EURECA would start operating after 2017. Collaboration EDELWEISS is a collaboration of the following member institutions: CEA – Commissariat à l'Énergie Atomique IRFU - Institut de Recherche sur les Lois Fondamentales de l'Univers IRAMIS - Institut Rayonnement Matière de Saclay CNRS – Centre National de la Recherche Scientifique CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Orsay IPNL - Institut de Physique Nucléaire de Lyon Institut NÉEL, Grenoble IAS - Institut d'Astrophysique Spatiale, Paris Institutions outside France Universität Karlsruhe, Germany Forschungszentrum Karlsruhe, Germany JINR – Joint Institute for Nuclear Research, Dubna, Russia University of Oxford References External links EDELWEISS Collaboration home page EURECA Collaboration home page Experiments for dark matter search