Resonant graphene dopants, such as hydrogen adatoms, experience long-range effective interaction mediated by conduction electrons. As a result of this interaction, when several adatoms are present in the sample, hopping of adatoms between sites belon
ging to different sublattices involves significant energy changes. Different inelastic mechanisms facilitating such hopping -- coupling to phonons and conduction electrons -- are considered. It is estimated that the diffusion of hydrogen adatoms is rather slow, amounting to roughly one hop to a nearest neighbor per millisecond.
In the field of gamma-ray astronomy, irregular and noisy datasets make difficult the characterization of light-curve features in terms of statistical significance while properly accounting for trial factors associated with the search for variability
at different times and over different timescales. In order to address these difficulties, we propose a method based on the Haar wavelet decomposition of the data. It allows statistical characterization of possible variability, embedded in a white noise background, in terms of a confidence level. The method is applied to artificially generated data for characterization as well as to the the very high energy M87 light curve recorded with VERITAS in 2008 which serves here as a realistic application example.
Experiments are in progress to prepare for intensity interferometry with arrays of air Cherenkov telescopes. At the Bonneville Seabase site, near Salt Lake City, a testbed observatory has been set up with two 3-m air Cherenkov telescopes on a 23-m ba
seline. Cameras are being constructed, with control electronics for either off- or online analysis of the data. At the Lund Observatory (Sweden), in Technion (Israel) and at the University of Utah (USA), laboratory intensity interferometers simulating stellar observations have been set up and experiments are in progress, using various analog and digital correlators, reaching 1.4 ns time resolution, to analyze signals from pairs of laboratory telescopes.
