[en] We present a pulse counting multichannel data acquisition system, characterized by the high number of high speed acquisition channels, and by the modular, embedded system architecture. The former leads to very fast acquisitions and allows to obtain sequences of snapshots, for the study of time dependent phenomena. The latter, thanks to the integration of a CPU into the system, provides high computational capabilities, so that the interfacing with the user computer is very simple and user friendly. Moreover, the user computer is free from control and acquisition tasks. The system has been developed for one of the beamlines of the third generation synchrotron radiation sources ELETTRA, and because of the modular architecture can be useful in various other kinds of experiments, where parallel acquisition, high data rates, and user friendliness are required. First experimental results on a double pass hemispherical electron analyser provided with a 96 channel detector confirm the validity of the approach. (author)

[en] Photoelectron spectra from sublimed layers of chromatographically separated La at sign C₈₂ are presented. Using photon energies corresponding to the La 3d to 4f transition, a resonant enhancement of the La-derived valence states is observed. From the calculated resonant intensities of La 5d and 5p states in a La atom we estimate that about (1)/(3) of an electron charge is left in the La-valence orbitals for La at sign C₈₂ . In contrast to previous interpretations of La core-level photoemission studies our results demonstrate that the La valence electrons are not completely delocalized on the fullerene cage. copyright 1997 The American Physical Society

[en] We present a targeted search for blazar flux-correlated high-energy (${\mathrm{\epsilon <!--\; ??\; -->}}_{\mathrm{\nu <!--\; ??\; -->}}$ ≳ 1 TeV) neutrinos from six bright northern blazars, using the public database of northern hemisphere neutrinos detected during “IC40” 40-string operations of the IceCube neutrino observatory (2008 April to 2009 May). Our six targeted blazars are subjects of long-term monitoring campaigns by the VERITAS TeV γ-ray observatory. We use the publicly available VERITAS light curves to identify periods of excess and flaring emission. These predefined intervals serve as our “active temporal windows” in a search for an excess of neutrinos, relative to Poisson fluctuations of the near-isotropic atmospheric neutrino background, which dominates at these energies. After defining the parameters of an optimized search, we confirm the expected Poisson behavior with Monte Carlo simulations prior to testing for excess neutrinos in the actual data. We make two searches: one for excess neutrinos associated with the bright flares of Mrk 421 that occurred during the IC40 run, and one for excess neutrinos associated with the brightest emission periods of five other blazars (Mrk 501, 1ES 0806+524, 1ES 1218+304, 3C 66A, and W Comae), all significantly fainter than the Mrk 421 flares. We find no significant excess of neutrinos from the preselected blazar directions during the selected temporal windows. We derive 90% confidence upper limits on the number of expected flux-associated neutrinos from each search. These limits are consistent with previous point-source searches and Fermi GeV flux-correlated searches. Our upper limits are sufficiently close to the physically interesting regime that we anticipate that future analyses using already-collected data will either constrain models or yield discovery of the first blazar-associated high-energy neutrinos.

[en] The design and first tests of a new supersonic molecular beam are presented. The instrument is dedicated to study in a controlled way the interaction of atoms and molecules with solid surfaces in combination with high-resolution core level photoemission at the SuperESCA beamline of ELETTRA, the third-generation synchrotron radiation source in Trieste, Italy. The design of the instrument together with the characterization and optimization of the molecular flux and energy resolution are discussed. As a first example of application, we present the results of a time-resolved photoemission study (O₂+H₂→H₂O reaction) on a PtRh single-crystal alloy. Time resolution of 100 ms/spectrum has been achieved by using a double-pass electron energy analyzer equipped with a novel 96 channel detector

[en] At the Elettra synchrotron light laboratory, a new undulator-based beamline with photon energy ranging from about 4.6 to 40 eV has been installed and opened to users. The beamline, based on a 4 m normal-incidence monochromator (NIM) with spherical gratings and movable exit slit, serves an end station to perform primarily high-resolution angle-resolved photoemission spectroscopy experiments in the low photon energy regime. The salient features of the instrument and some of the commission data are reported in this paper.