Uniformity of the 2000 test beam module with the new optimal filtering coefficients

An original method to reconstruct electron and pion signals in the Liquid ARGon barrel calorimeter (LARG) is applied to test beam data collected at the H8 line of the CERN North Area in July and August 2000. The method is based on the use of optimal filtering coefficients and takes into account the electrical description of the read-out electronics in the reconstruction of the physics pulses. Results on improvements in the LARG response and in particular on the energy uniformity of the calorimeter are shown

Halo and Tail Generation Studies for Linear Colliders

Halo particles in linear colliders can result in significant losses and serious background which may reduce the overall performances. We present a study of various halo generation processes with numerical estimates. The aim is to allow to predict and minimize the halo throughout the accelerator chain including the final focus up to the experimental detectors. We include estimates for the planned CLIC beam line

Uniformity Of The 2000 Test Beam Module With The New Optimal Filtering Coefficients

An original method to reconstruct electron and pion signals in the Liquid ARGon barrel calorimeter (LARG) is applied to test beam data collected at the H8 line of the CERN North Area in July and August 2000. The method is based on the use of optimal filtering coefficients and takes into account the electrical description of the read-out electronics in the reconstruction of the physics pulses. Results on improvements in the LARG response and in particular on the energy uniformity of the calorimeter are shown

Detection of coccolithophore blooms with biogeochemical‐argo floats

Coccolithophores (calcifying phytoplankton) form extensive blooms in temperate and subpolar oceans as evidenced from ocean-color satellites. This study examines the potential to detect coccolithophore blooms with BioGeoChemical-Argo (BGC-Argo) floats, autonomous ocean profilers equipped with bio-optical and physicochemical sensors. We first matched float data to ocean-color satellite data of calcite concentration to select floats that sampled coccolithophore blooms. We identified two floats in the Southern Ocean, which measured the particulate beam attenuation coefficient (c(p)) in addition to two core BGC-Argo variables, Chlorophyll-a concentration ([Chl-a]) and the particle backscattering coefficient (b(bp)). We show that coccolithophore blooms can be identified from floats by distinctively high values of (1) the b(bp)/c(p) ratio, a proxy for the refractive index of suspended particles, and (2) the b(bp)/[Chl-a] ratio, measurable by any BGC-Argo float. The latter thus paves the way to global investigations of environmental control of coccolithophore blooms and their role in carbon export. Plain Language Summary Coccolithophores are a group of phytoplankton that form an armor of calcite plates. Coccolithophores may form intense blooms which can be identified from space by so-called ocean-color satellites, providing global images of the color of the surface ocean. BioGeoChemical-Argo (BGC-Argo) floats, robots profiling down to 2,000 m with a variety of physicochemical and bio-optical sensors, present an increasingly attractive and cost-effective platform to study phytoplankton blooms and their impact on oceanic biogeochemical cycles. We show that coccolithophore blooms can be detected by BGC-Argo floats with high confidence, hence providing a new way to study them at the global scale as well as their role in sinking carbon. Key Points We matched profiling float trajectories with ocean-color satellite observations of coccolithophore blooms Two simple bio-optical indices permitted successful identification of coccolithophore blooms from floats in the Southern Ocean A method for identifying coccolithophore blooms at the global scale is proposed using regional thresholds of bio-optical float measurement

Halo Estimates and Simulations for Linear Colliders

Halo simulations and estimates are important for the design of future linear accelerators. We describe the main processes with analytic estimates and present our generic simulations in application to the ILC

Natural Dark Matter from an Unnatural Higgs Boson and New Colored Particles at the TeV Scale

The thermal relic abundance of Dark Matter motivates the existence of new electroweak scale particles, independent of naturalness considerations. However, most unnatural Dark Matter models do not ensure the presence of new particles charged under SU(3)_C, resulting in challenging LHC phenomenology. Here, we present a class of models with scalar electroweak doublet Dark Matter that require a host of colored particles at the TeV scale. In these models, the Higgs boson is apparently fine-tuned, but the Dark Matter doublet is kept light without any additional fine-tuning.Comment: 1+22 pages, 5 figures. Added references. Minor clarification

Energy Linearity and Resolution of the ATLAS Electromagnetic Barrel Calorimeter in an Electron Test-Beam

A module of the ATLAS electromagnetic barrel liquid argon calorimeter was exposed to the CERN electron test-beam at the H8 beam line upgraded for precision momentum measurement. The available energies of the electron beam ranged from 10 to 245 GeV. The electron beam impinged at one point corresponding to a pseudo-rapidity of eta=0.687 and an azimuthal angle of phi=0.28 in the ATLAS coordinate system. A detailed study of several effects biasing the electron energy measurement allowed an energy reconstruction procedure to be developed that ensures a good linearity and a good resolution. Use is made of detailed Monte Carlo simulations based on Geant which describe the longitudinal and transverse shower profiles as well as the energy distributions. For electron energies between 15 GeV and 180 GeV the deviation of the measured incident electron energy over the beam energy is within 0.1%. The systematic uncertainty of the measurement is about 0.1% at low energies and negligible at high energies. The energy resolution is found to be about 10% sqrt(E) for the sampling term and about 0.2% for the local constant term

Position resolution and particle identification with the ATLAS EM calorimeter

In the years between 2000 and 2002 several pre-series and series modules of the ATLAS EM barrel and end-cap calorimeter were exposed to electron, photon and pion beams. The performance of the calorimeter with respect to its finely segmented first sampling has been studied. The polar angle resolution has been found to be in the range 50-60 mrad/sqrt(E (GeV)). The neutral pion rejection has been measured to be about 3.5 for 90% photon selection efficiency at pT=50 GeV/c. Electron-pion separation studies have indicated that a pion fake rate of (0.07-0.5)% can be achieved while maintaining 90% electron identification efficiency for energies up to 40 GeV.Comment: 32 pages, 22 figures, to be published in NIM

The Higgs Working Group: Summary Report (2001)

Report of the Higgs working group for the Workshop `Physics at TeV Colliders', Les Houches, France, 21 May - 1 June 2001. It contains 7 separate sections: A. Theoretical Developments B. Higgs Searches at the Tevatron C. Experimental Observation of an invisible Higgs Boson at LHC D. Search for the Standard Model Higgs Boson using Vector Boson Fusion at the LHC E. Study of the MSSM channel $A/H \to \tau \tau$ at the LHC F. Searching for Higgs Bosons in $t\bar t H$ Production G. Studies of Charged Higgs Boson Signals for the Tevatron and the LHCComment: 120 pages, latex, many figures, proceedings of the Workshop `Physics at TeV Colliders', Les Houches, France, 21 May - 1 June 2001, full Author list included in paper. Typos corrected, author list and acknowledgements completed. Convernors: D. Cavalli, A. Djouadi, K. Jakobs, A. Nikitenko, M. Spira, C.E.M. Wagner, W.-M. Ya

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011