Characterization of a high resolution triple Gas Electron Multiplier (GEM) detector
The development of a Gas Electron Multiplier (GEM) readout as an option for the TPC of the near detector of the T2K neutrino experiment is presented. The low track density and the wide range in polar angle of particles produced by neutrino interactions drive the initial choice of relatively large squared pads (8 mm) for the performance study. The physics requirements [T2K ND280 Conceptual Design Report, http://dpnc.unige.ch:8080/nu/Members/nabgrall/t2kge/t2kge_doc/cdr.pdf ] are a momentum resolution better than 10 % at 1 GeV/c and a 3 σ dE/dx separation between muons and electrons. Micro-pattern Gas Detectors (MPGDs) such as GEMs or Micromegas show several beneficial features compared to the traditional Multi-Wire Proportional Chambers. They have been tested in the HARP TPC environment at CERN. Preliminary results form the GEM tests are reported here.

title: Architecture of the HERA-B data acquisition system
abstract: The HERA-B experiment was dedicated for the measurement of CP-violation in decays of neutral B-mesons and for investigating the physics of charmed particles. One of the experimental requirements is a highly selective on-line filtering of data due to high interaction rates and a low signal-to-background ratio. This demands a hierarchical trigger and a high bandwidth data acquisition system. The challenge for the DAQ system is a readout free of deadtime, which requires an unprecedent speed of storing and processing the data. In this paper we will outline the general architecture and hardware implementation of the HERA-B DAQ.

title: Mass limit for the lightest neutralino
abstract: AbstractIndirect limits on the mass of the lightest neutralino are derived from the results of searches for charginos, neutralinos, and sleptons performed with data taken by the ALEPH Collaboration at centre-of-mass energies near the Z peak and at 130 and 136 GeV. Within the context of the Minimal Supersymmetric Standard Model and when
$$M_{\tilde \nu } \geqslant 200 GeV/c^2 $$
, the boundMx> 12.8 GeV/c2 at the 95% confidence level applies for any tanβ. The impact of lighter sneutrinos is presented in the framework of SUSY grand unified theories; a massless neutralino is allowed only for a narrow range of tanβ,μ, and the scalar mass parameterm0. Finally, by including Higgs mass constraints and requiring that radiative electroweak symmetry breaking occur, more stringent bounds onMx as a function of tanβ are derived.

title: Measurement of triple gauge-boson couplings at 172 GeV
abstract: The triple gauge-boson couplings, αWΦ, αW and αBΦ, have been measured using 34 semileptonically and 54 hadronically decaying W+W− candidate events. The events were selected in the data recorded during 1996 with the ALEPH detector at 172 GeV, corresponding to an integrated luminosity of 10.65 pb−1. The triple gauge-boson couplings have been measured using optimal observables constructed from kinematic information of W+W− events. The results are in agreement with the Standard Model expectation.

title: Search for neutrino-induced charged current coherent pion production with carbon in a 1.3 GeV wide band muon neutrino beam
abstract: The search for charged-current coherent pion production induced by neutrinos with a mean energy of 1.3 GeV is discussed. The data are collected with a fully active scintillator detector in the K2K long-baseline neutrino oscillation experiment. No evidence for coherent pion production is observed and an upper limit of 0.60 × 10−2 is set on the cross section ratio of coherent pion production to the total charged current interaction at the 90% confidence level.

title: Improved measurement of the $\bar{B}^0$ and $B^{-}$ meson lifetimes

title: Ultrahigh Energy Neutrinos at the Pierre Auger Observatory
abstract: The observation of ultrahigh energy neutrinos (UHE nu s) has become a priority in experimental astroparticle physics. UHE nu s can be detected with a variety of techniques. In particular, neutrinos can interact in the atmosphere (downward-going nu) or in the Earth crust (Earth-skimming nu), producing air showers that can be observed with arrays of detectors at the ground. With the surface detector array of the Pierre Auger Observatory we can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e., after having traversed a large amount of atmosphere). In this work we review the procedure and criteria established to search for UHE nu s in the data collected with the ground array of the Pierre Auger Observatory. This includes Earth-skimming as well as downward-going neutrinos. No neutrino candidates have been found, which allows us to place competitive limits to the diffuse flux of UHE nu s in the EeV range and above.

title: The Role of Molecular Gas in Obscuring Seyfert AGN
abstract: In a sample of local active galactic nuclei studied at a spatial resolution on the order of ten parsecs we show that the interstellar medium traced by the molecular hydrogen ν=1-0 S(1) line at 2.1 μm forms a geometrically thick, clumpy disk. The kinematics of the molecular gas reveals general rotation, although an additional significant component of random bulk motion is required by the high local velocity dispersion. The size scale of the typical gas disk is found to have a radius of ∼30 pc with a comparable vertical height. Within this radius the average gas mass is estimated to be ∼10 M⊙ based on a typical gas mass fraction of 10%, which suggests column densities of NH ∼ 5 × 10 23 cm. Extinction of the stellar continuum within this same region suggest lower column densities of NH ∼ 2 × 10 cm, indicating that the gas distribution on these scales is dominated by dense clumps. In half of the observed Seyfert galaxies this lower column density is still great enough to obscure the AGN at optical/infrared wavelengths. We conclude, based on the spatial distribution, kinematics, and column densities that the molecular gas observed is spatially mixed with the nuclear stellar population and is likely to be associated with the outer extent of any smaller-scale nuclear obscuring structure. Furthermore, we find that the velocity dispersion of the molecular gas is correlated with the star formation rate per unit area, suggesting a link between the two phenomena, and that the gas surface density follows known “Schmidt-Kennicutt” relations. The molecular/dusty structure on these scales may be dynamic since it is possible that the velocity dispersion of the gas, and hence the vertical disk height, is maintained by a short, massive inflow of material into the nuclear region and/or by intense, short-lived nuclear star formation.

title: Star Formation and Molecular Gas in AGN
abstract: We present initial results from a survey of nearby AGN using the near infrared adaptive optics integral field spectrograph SINFONI. These data enable us to probe the distribution and kinematics of the gas and stars at spatial resolutions as small as 0.085arcsec, corresponding in some cases to less than 10pc. In this contribution we present results concerning (1) the molecular gas in the nucleus of NGC1068 and its relation to the obscuring torus; and (2) the stars which exist on spatial scales of a few tens of parsecs around the AGN, the evidence for their remarkably young age and extreme intensities, and their relation to the AGN.

title: Eddington-limited starbursts in the central 10 pc of AGN and the Torus in NGC1068
abstract: We present results from a survey of nearby AGN using the near infrared adaptive optics integral field spectrograph SINFONI. These data enable us to probe the distribution and kinematics of the gas and stars at spatial resolutions as small as 0.085arcsec. We find strong evidence for recent but short lived starbursts residing in very dense nuclear disks. On scales of less than 10pc these would have reached Eddington-limited luminosities when active, perhaps accounting for their short duration. In addition, for NGC1068 at a resolution of 6pc, we present direct observations of molecular gas close around the AGN which we identify with the obscuring torus.

title: Near IR diffraction-limited integral-field SINFONI spectroscopy of the Circinus galaxy
abstract: Using the adaptive optics assisted near infrared integral field spectrometer SINFONI on the VLT, we have obtained observations of the Circinus galaxy on parsec scales. The morphologies of the H2 (1-0)S(1) 2.12 μm and Brγ 2.17 μm emission lines are only slightly different, but their velocity maps are similar and show a gradient along the major axis of the galaxy, consistent with rotation. Since Vrot/σ ≈ 1 suggests that random motions are also important, it is likely that the lines arise in a rotating spheroid or thickened disk around the AGN. Comparing the Brγ flux to the stellar continuum indicates that the star formation in this region began ∼108 yr ago. We also detect the [Si vi ] 1.96 μm, [Al ix ] 2.04 μm and [Ca viii ] 2.32 μm coronal lines. In all cases we observe a broad blue wing, indicating the presence of two or more components in the coronal line region. A correlation between the ionisation potential and the asymmetry of the profiles was found for these high excitation species.