1,100 research outputs found
The calorimetry at the future e+ e- linear collider
The physics programme for a coming electron linear collider is dominated by
events with final states containing many jets. We develop in this paper the
opinion that the best approach is to optimise the independent measurement of
the tracks in the tracker, the photons in the electromagnetic calorimeter and
the neutral hadrons in the camorimetry, together with a good lepton
identification. This can be achieved with a high granularity calorimetry
providing particle separation, through an efficient energy flow algorithm.Comment: 7 pages, 6 Postscript figures, to appear in the Proceedings of the
APS / DPF / DPB Summer Study on the Future of Particle Physics (Snowmass
2001), Snowmass, Colorado, 30 Jun - 21 Jul 200
Energy flow or Particle flow - The technique of "energy flow" for pedestrians
In the prospect of elucidating the physics accessible to an electron-positron linear collider in the range 0.09 to 1. TeV it is of prime importance to be very efficient and not miss any signal. This leads to the question of collecting every interesting event and extracting as much information as possible from every collected event. To achieve that, and considering that most of the physics of interest implies bosons like W, Z or possibly Higgses, the identification of these bosons when they decay into hadron jets is essential. This is the motivation for developing a method which best reconstructs the direction, energy and mass of these di-jets. We believe to have such a method with the so-called "energy flow" or "particle flow" approaches
Concevoir un détecteur à grand angle solide pour la physique des particules
École thématiqu
Testing the Higgs Mechanism in the Lepton Sector with multi-TeV e+e- Collisions
Multi-TeV e+e- collisions provide with a large enough sample of Higgs bosons
to enable measurements of its suppressed decays. Results of a detailed study of
the determination of the muon Yukawa coupling at 3 TeV, based on full detector
simulation and event reconstruction, are presented. The muon Yukawa coupling
can be determined with a relative accuracy of 0.04 to 0.08 for Higgs bosons
masses from 120 GeV to 150 GeV, with an integrated luminosity of 5 inverse-ab.
The result is not affected by overlapping two-photon background.Comment: 6 pages, 2 figures, submitted to J Phys G.: Nucl. Phy
Vibrio coralliilyticus Strain OCN008 Is an Etiological Agent of Acute Montipora White Syndrome
Identification of a pathogen is a critical first step in the epidemiology and subsequent management of a disease. A limited number of pathogens have been identified for diseases contributing to the global decline of coral populations. Here we describe Vibrio coralliilyticus strain OCN008, which induces acute Montipora white syndrome (aMWS), a tissue loss disease responsible for substantial mortality of the coral Montipora capitata in Ka ne‘ohe Bay, Hawai‘i. OCN008 was grown in pure culture, recreated signs of disease in experimentally infected corals, and could be recovered after infection. In addition, strains similar to OCN008 were isolated from diseased coral from the field but not from healthy M. capitata. OCN008 repeatedly induced the loss of healthy M. capitata tissue from fragments under laboratory conditions with a minimum infectious dose of between 107 and 108 CFU/ml of water. In contrast, Porites compressa was not infected by OCN008, indicating the host specificity of the pathogen. A decrease in water temperature from 27 to 23°C affected the time to disease onset, but the risk of infection was not significantly reduced. Temperature-dependent bleaching, which has been observed with the V. coralliilyticus type strain BAA-450, was not observed during infection with OCN008. A comparison of the OCN008 genome to the genomes of pathogenic V. coralliilyticus strains BAA-450 and P1 revealed similar virulence-associated genes and quorum-sensing systems. Despite this genetic similarity, infections of M. capitata by OCN008 do not follow the paradigm for V. coralliilyticus infections established by the type strain
The trpE Gene Negatively Regulates Differentiation of Heterocysts at the Level of Induction in Anabaena sp. Strain PCC 7120
Levels of 2-oxoglutarate (2-OG) reflect nitrogen status in many bacteria. In heterocystous cyanobacteria, a spike in the 2-OG level occurs shortly after the removal of combined nitrogen from cultures and is an integral part of the induction of heterocyst differentiation. In this work, deletion of one of the two annotated trpE genes in Anabaena sp. strain PCC 7120 resulted in a spike in the 2-OG level and subsequent differentiation of a wild-type pattern of heterocysts when filaments of the mutant were transferred from growth on ammonia to growth on nitrate. In contrast, 2-OG levels were unaffected in the wild type, which did not differentiate under the same conditions. An inverted-repeat sequence located upstream of trpE bound a central regulator of differentiation, HetR, in vitro and was necessary for HetR-dependent transcription of a reporter fusion and complementation of the mutant phenotype in vivo. Functional complementation of the mutant phenotype with the addition of tryptophan suggested that levels of tryptophan, rather than the demonstrated anthranilate synthase activity of TrpE, mediated the developmental response of the wild type to nitrate. A model is presented for the observed increase in 2-OG in the trpE mutant
Hadron shower decomposition in the highly granular CALICE analogue hadron calorimeter
The spatial development of hadronic showers in the CALICE scintillator-steel
analogue hadron calorimeter is studied using test beam data collected at CERN
and FNAL for single positive pions and protons with initial momenta in the
range from 10 to 80 GeV/c. Both longitudinal and radial development of hadron
showers are parametrised with two-component functions. The parametrisation is
fit to test beam data and simulations using the QGSP_BERT and FTFP_BERT physics
lists from Geant4 version 9.6. The parameters extracted from data and simulated
samples are compared for the two types of hadrons. The response to pions and
the ratio of the non-electromagnetic to the electromagnetic calorimeter
response, h/e, are estimated using the extrapolation and decomposition of the
longitudinal profiles.Comment: 38 pages, 19 figures, 5 tables; author list changed; submitted to
JINS
Shower development of particles with momenta from 15 GeV to 150 GeV in the CALICE scintillator-tungsten hadronic calorimeter
We present a study of showers initiated by electrons, pions, kaons, and
protons with momenta from 15 GeV to 150 GeV in the highly granular CALICE
scintillator-tungsten analogue hadronic calorimeter. The data were recorded at
the CERN Super Proton Synchrotron in 2011. The analysis includes measurements
of the calorimeter response to each particle type as well as measurements of
the energy resolution and studies of the longitudinal and radial shower
development for selected particles. The results are compared to Geant4
simulations (version 9.6.p02). In the study of the energy resolution we include
previously published data with beam momenta from 1 GeV to 10 GeV recorded at
the CERN Proton Synchrotron in 2010.Comment: 35 pages, 21 figures, 8 table
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