We report recent results on the performance of FLASH (Free Electron Laser in Hamburg) operating at a wavelength of 13.7 nm where unprecedented peak and average powers for a coherent EUV radiation source have been measured. In the saturation regime the peak energy approached 170 µJ for individual pulses while the average energy per pulse reached 70 µJ. The pulse duration was in the region of 10 femtoseconds and peak

Previously published and as yet unpublished QCD results obtained with the ALEPH detector at LEP1 are presented. The unprecedented statistics allows detailed studies of both perturbative and non-perturbative aspects of strong interactions to be carried out using hadronic Z and tau decays. The studies presented include precise determinations of the strong coupling constant, tests of its avour independence, tests of the SU(3) gauge structure of QCD, study of coherence eects, and measurements of single-particle inclusive distributions and two-particle correlations for many identied baryons and mesons.

The Sloan Digital Sky Survey-II (SDSS-II) has embarked on a multi-year project to identify and measure light curves for intermediate-redshift (0.05 < z < 0.35) Type Ia supernovae (SNe Ia) using repeated five-band (ugriz) imaging over an area of 300 sq. deg. The survey region is a stripe 2.5• wide centered on the celestial equator in the Southern Galactic Cap that has been imaged numerous times in earlier years, enabling construction of a deep reference image for the discovery of new objects. Supernova imaging observations are being acquired between September 1 and November 30 of 2005-7. During the first two seasons, each region was imaged on average every five nights. Spectroscopic follow-up observations to determine supernova type and redshift are carried out on a large number of telescopes. In its first two three-month seasons, the survey has discovered and measured light curves for 327 spectroscopically confirmed SNe Ia, 30 probable SNe Ia, 14 confirmed SNe Ib/c, 32 confirmed SNe II, plus a large number of photometrically identified SNe Ia, 94 of which have host-galaxy spectra taken so far. This paper provides an overview of the project and briefly describes the observations completed during the first two seasons of operation.

Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the detection of a multiple-planet system with microlensing. We identify two planets with masses of approximately 0.71 and approximately 0.27 times the mass of Jupiter and orbital separations of approximately 2.3 and approximately 4.6 astronomical units orbiting a primary star of mass approximately 0.50 solar mass at a distance of approximately 1.5 kiloparsecs. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only six confirmed microlensing planet detections suggests that solar system analogs may be common.

Damped absorbers, seen in the spectra of background quasars, are unique probes to select H i-rich galaxies. These galaxies allow one to estimate the neutral gas mass over cosmological scales. The neutral gas mass is a possible indicator of gas consumption as star formation proceeds. The damped Lyα absorbers (DLAs; N H I ≥ 2 × 10 20 cm −2 ) and sub-DLAs (10 19 ≤ N H I ≤ 2 × 10 20 cm −2 ) are believed to contain a large fraction of neutral gas mass in the Universe. In Paper I of the series, we presented the results of a search for DLAs and sub-DLAs in the European Southern Observatory (ESO) Ultraviolet Visual Echelle Spectrograph (UVES) advanced data products dataset of 250 quasars. Here we use an unbiased subsample of sub-DLAs from this dataset to derive their statistical properties. We built a subset of 122 quasars ranging from 1.5 < z em < 5.0, suitable for statistical analysis. The statistical sample was analyzed in conjunction with other sub-DLA samples from the literature. This resulted in a combined sample of 89 sub-DLAs over a redshift path of Δz = 193. We derived the redshift evolution of the number density and the line density for sub-DLAs and compared them with the Lyman-limit systems (LLSs) and DLA measurements from the literature. The results indicate that these three classes of absorbers are evolving in the redshift interval 1.0 < z < 5.0. Thanks to the ESO UVES advanced data products data, we were able to determine the column density distribution, f H I (N, z), down to the sub-DLA limit. The flattening of f H I (N, z) in the sub-DLA regime is present in the observations. The redshift evolution of f H I (N, z) down to log N H I = 19.0 cm −2 is also presented, indicating that there are more sub-DLAs at high redshift than at low redshift. f H I (N, z) was also used to determine the neutral gas mass density, Ω g , at 1.5 < z < 5.0. The complete sample shows that sub-DLAs contribute 8-20% to the total Ω g from 1.5 < z < 5.0. In agreement with previous studies, no evolution of Ω g was observed from low to high redshift (i.e., 1.5 < z < 5.0), suggesting that star formation alone cannot explain this non-evolution and replenishment of gas and that recombination of ionized gas is needed.

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We present the analysis of optical and near-infrared spectra of the only four z > 6.5 quasars known to date, discovered in the UKIDSS-LAS and VISTA-VIKING surveys. Our data-set consists of new VLT/X-Shooter and Magellan/FIRE observations. These are the best optical/NIR spectroscopic data that are likely to be obtained for the z > 6.5 sample using current 6 -10 m facilities. We estimate the black hole mass, the Eddington ratio, and the Si iv/C iv, C iii]/C iv, and Fe ii/Mg ii emission-line flux ratios. We perform spectral modeling using a procedure that allows us to derive a probability distribution for the continuum components and to obtain the quasar properties weighted upon the underlying distribution of continuum models. The z > 6.5 quasars show the same emission properties as their counterparts at lower redshifts. The z > 6.5 quasars host black holes with masses of ∼ 10 9 M ⊙ that are accreting close to the Eddington luminosity ( log(L Bol /L Edd ) = −0.4 ± 0.2), in agreement with what has been observed for a sample of 4.0 < z < 6.5 quasars. By comparing the Si iv/C iv and C iii]/C iv flux ratios with the results obtained from luminosity-matched samples at z ∼ 6 and 2 ≤ z ≤ 4.5, we find no evidence of evolution of the line ratios with cosmic time. We compare the measured Fe ii/Mg ii flux ratios with those obtained for a sample of 4.0 < z < 6.4 sources. The two samples are analyzed using a consistent procedure. There is no evidence that the Fe ii/Mg ii flux ratio evolves between z = 7 and z = 4. Under the assumption that the Fe ii/Mg ii traces the Fe/Mg abundance ratio, this implies the presence of major episodes of chemical enrichment in the quasar hosts in the first ∼ 0.8 Gyr after the Big Bang.1 Based on observations collected at the European Southern Observatory, Chile, programs 286.A-5025, 087.A-0890 and 088.A-0897. This paper also includes data gathered with the 6.5 m Magellan Telescope located at Las Campanas Observatory, Chile.

Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse