LCWS12 - International Workshop on Future Linear Colliders

ABSTRACTS

Number of abstracts: 24

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Higgs / Electroweak Symmetry Breaking

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Measurement of the top Yukawa coupling at sqrt(s) = 1 TeV using the SiD detector

• Author(s): Philipp Roloff (CERN)

• Speaker: Philipp Roloff (CERN)

• Status: submitted 22-Sep-2012, accepted 26-Sep-2012

• Abstract:
  One of the detector benchmark processes investigated for the Detailed Baseline Design (DBD) document is given by: e+e- -> t tbar H, where H is the Standard Model Higgs boson of mass 125 GeV. A centre-of-mass energy of 1 TeV is assumed for this study. The physics aim is a direct measurement of the top Yukawa coupling. Higgs boson decays to beauty quark-antiquark pairs are reconstructed. Hence the investigated final states contain eight jets or six jets, one charged lepton and missing energy. Additionally, four of the jets in signal events are caused by beauty quark decays. The analysis is based on a full simulation of the SiD detector using Geant4. Beam-related backgrounds from gamma gamma -> hadrons interactions and incoherent e+e- pairs are considered. This study addresses various aspects of the detector performance: jet clustering in complex hadronic final states, missing energy reconstruction, flavour-tagging and the identification of high energy leptons.

Measurement of the trilinear Higgs self-coupling at a 1.4 TeV and a 3 TeV CLIC

• Author(s): Tomas Lastovicka (Czech Academy of Sciences), Jan Strube (CERN)

• Speaker: Tomas Lastovicka (Czech Academy of Sciences)

• Status: submitted 22-Sep-2012, accepted 26-Sep-2012

• Abstract:
  The precision measurement of the Higgs coupling constants will be an important part of the physics program of a future linear collider. The trilinear coupling constant of the Higgs boson takes a special place in the Higgs mechanism, but it’s determination at lower energy linear colliders or at hadron machines is difficult, if not impossible. We present a full simulation study of the cross section measurement of the HHnunu channel at a 1.4 TeV and a 3 TeV CLIC and the corresponding uncertainty on the trilinear coupling constant.

Higgs Mass and Cross-Section Measurements at a 500GeV CLIC Machine, Operating at sqrt(s)=350GeV and 500GeV

• Author(s): John Marshall (University of Cambridge), Mark Thomson (University of Cambridge)

• Speaker: Mark Thomson (University of Cambridge)

• Status: submitted

• Abstract:
  Higgs mass and cross-section measurements have been examined to assess the capability of a 500GeV CLIC machine, operating at centre-of-mass energies of 350GeV and 500GeV. A Higgs mass of 120GeV and a luminosity of 500fb−1 were assumed. Model-independent measurements were performed at both 350GeV and 500GeV by examining the recoil of the Z in the Higgsstrahlung process, with the Z subsequently decaying to a pair of muons or electrons. Model-dependent studies at 500GeV then investigated the four-jet final state and the two-jet neutrino final state, which includes contributions from both Higgsstrahlung and WW-fusion. Fitting the pT distribution of selected two-jet neutrino events allowed measurement of the ratio of the couplings gHZZ/gHWW.

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Beyond the SM: SUSY, Cosmology, Alternative

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Z' searches at 3 TeV and 1.5 TeV CLIC

• Author(s): James Wells (CERN)

• Speaker: James Wells (CERN)

• Status: submitted 2-Oct-2012, accepted 5-Oct-2012

• Abstract:
  Extra neutral gauge bosons (Z') are predicted in many extensions of the Standard Model (SM). In the minimal anomaly-free Z' model (AFZ'), the phenomenology is controlled by only three parameters beyond the SM ones, the Z' mass and two effective coupling constants g'_Y and g'_{BL}. The Z' 5-sigma discovery potential in e+e- collisions at 1.4 and 3 TeV CLIC is presented. Assuming LHC discovers a Z' of 5 TeV mass, the expected accuracies on the Z'mu+mu- couplings are given. Requirements on detector performance and beam polarization are outlined.

Measurement of supersymmetry at a 1.4 TeV CLIC collider

• Author(s): Philipp Roloff (CERN)

• Speaker: Philipp Roloff (CERN)

• Status: submitted 19-Sep-2012, accepted 5-Oct-2012

• Abstract:
  To illustrate the physics implications of a staged construction of the CLIC machine, an example supersymmetric model was investigated. Several benchmark processes were studied in this scenario at an intermediate energy of 1.4 TeV. Three analyses based on full detector simulations and considering pileup from gamma gamma -> hadrons interactions are presented in this contribution. Hadronic final states with four jets and missing energy were used to reconstruct the decays of the lightest chargino and the next-to-lightest neutralino. Selectrons, smuons and sneutrinos were identified in events containing muons or electrons. Finally, the pair production of staus was measured using hadronic tau decays. Results for the the masses and for the production cross sections of these SUSY particles are shown.

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Top / QCD / Loopverein

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Top Physics at CLIC

• Author(s): Frank Simon (MPI Munich)

• Speaker: Frank Simon (MPI Munich)

• Status: submitted 19-Sep-2012

• Abstract:
  Linear colliders offer two complementary approaches for precision measurements of the top quark mass and other top quark properties: The direct reconstruction of the top quark decay products and a scan of the top pair production threshold. While the former is possible at essentially arbitrary energy above threshold, the latter directly provides access to the top mass in theoretically well defined schemes. In addition to a measurement of the top mass, the threshold scan also provides access to the strong coupling constant. In the framework of the CLIC conceptual design report, both techniques have been studied using full detector simulations, with a study of the direct reconstruction of top quarks produced at a center of mass energy of 500 GeV and a threshold scan with 10 points spaced by 1 GeV around the top threshold. We present the results of these studies including a selection of possible systematic effects. For the threshold scan, the impact of the difference of the CLIC and the ILC beam spectrum are assessed by comparing results obtained with both beam spectra.

Polarisation from collision data at CLIC

• Author(s): Graham Wilson (University of Kansas)

• Speaker: Graham Wilson (University of Kansas)

• Status: to be submitted by the speaker

• Abstract:
  

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Simulation / Detector Performance / Reconstruction

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SiD DBD Tracking Performance

• Author(s): Christian Grefe (CERN)

• Speaker: Christian Grefe (CERN)

• Status: submitted 22-Sep-2012

• Abstract:
  We present the tracking performance of the sidloi3 detector model which is used in the mass production for the SiD DBD. This detector model includes a realistic description of the tracking detectors made of individual sensor modules instead of the simplied cylindrical geometries used in the LOI studies. The studies were performed in a Geant4-based full simulation. In addition, the impact on the tracking performance of typical levels of incoherent pairs and gamma gamma -> hadrons expected at a 1 TeV ILC machine is discussed.

Occupancies from beam-related backgrounds in SiD at ILC and CLIC

• Author(s): Christian Grefe (CERN)

• Speaker: Christian Grefe (CERN)

• Status: submitted 22-Sep-2012

• Abstract:
  We present studies of the hit rates and occupancies expected from incoherent pairs and gamma gamma -> hadrons in the SiD detector concept at ILC and CLIC. The studies were performed in Geant4-based full simulation of the clic_sid_cdr and sidloi3 detector models, which were used in the mass production of the CLIC CDR and the SiD DBD, respectively.

Measurement of the Differential Luminosity at 3 TeV CLIC

• Author(s): Stéphane Poss (CERN), André Sailer (CERN)

• Speaker: André Sailer (CERN)

• Status: submitted 22-Sep-2012

• Abstract:
  A good knowledge of the luminosity spectrum is mandatory for most measurements. The luminosity spectrum has to be measured through a gauge process with the detector. The contributing factors to the luminosity spectrum, beam energy spread and Beamstrahlung, are discussed, and a model for the luminosity spectrum is presented. Results of a re-weighting fit to simulated wide angle Bhabha events are shown.

Electron Tagging with the BeamCal at 3 TeV CLIC

• Author(s): André Sailer (CERN)

• Speaker: André Sailer (CERN)

• Status: submitted 22-Sep-2012

• Abstract:
  Two-photon events with spectator electrons represent a major background for new-physics searches with missing momentum. The BeamCal detector can be used to identify the high energy electrons of two-photon events at small polar angles. At 3 TeV CLIC the large rate of incoherent pairs and short bunch crossing separation complicates the identification of these high energy electrons. Results for the electron tagging efficiency from a full simulation study of incoherent pair background and high energy electrons are presented.

Combined detector performance in the SiD DBD

• Author(s): Jan Strube (CERN)

• Speaker: Jan Strube (CERN)

• Status: submitted 22-Sep-2012

• Abstract:
  The detector geometry and the reconstruction chain that are used for the study of the benchmarking processes in the SiD DBD present a significant change from what was used for the LOI. We present the performance of various key aspects of the reconstruction in the SiD detector.

SiD DBD production (DIRAC)

• Author(s): Jan Strube (CERN)

• Speaker: Jan Strube (CERN)

• Status: submitted 22-Sep-2012

• Abstract:
  For the SiD DBD, the simulation and reconstruction of about 30 million events was managed on the grid. We give an overview of the ILCDIRAC system that was developed for the mass production of the CLIC CDR. The performance of this system during the SiD DBD production is discussed. This is the first time that this system has run on both the European LHC Computing Grid (LCG) and the US Open Science Grid (OSG).

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Detector Integration / MDI / Polarization

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Earthquake protection for LC detectors

• Author(s): Fernando Duarte Ramos (CERN), Hubert Gerwig (CERN)

• Speaker: Fernando Duarte Ramos (CERN)

• Status: submitted 19-Sep-2012

• Abstract:
  During a seismic event the detectors of a future Linear Collider are subject to horizontal and vertical accelerations. That can result in both a mechanical failure of internal structural elements and high deformations which can lead to unwanted collisions with other internal or external detector elements, as well as the walls of the experimental cavern. In this talk, the strategy proposed for the earthquake protection of the CLIC detectors is presented together with the results from seismic simulations of the main solenoid yoke of CLIC_SiD.

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Tracking / Vertex

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Vertex-detector R&D for CLIC

• Author(s): Dominik Dannheim (CERN)

• Speaker: Dominik Dannheim (CERN)

• Status: submitted 19-Sep-2012

• Abstract:
  The CLIC vertex detector must have excellent spacial resolution, full geometrical coverage extending to low polar angles, extremely low mass, low occupancy facilitated by time-tagging, and sufficient heat removal from sensors and readout. These considerations, together with the physics needs and beam structure of CLIC, push the technological requirements to the limits and imply a very different vertex detector than the ones currently in use elsewhere. In this talk we review the proposed CLIC vertex-detector designs and present results on detector simulations, pixel-readout development, measurements with prototypes and powering.

CLIC inner detector cooling and mechanics

• Author(s): Fernando Duarte Ramos (CERN)

• Speaker: Fernando Duarte Ramos (CERN)

• Status: submitted 19-Sep-2012

• Abstract:
  In view of the strict requirements in terms of material budget and position stability in the inner tracker and vertex detector of the CLIC experiments, novel ideas have been proposed for the air cooling and mechanical support of those detectors. This talk presents the current status of the mechanical design of the CLIC_ILD inner detectors along with results from computational fluid dynamic simulations.

Noise and power pulsing measurements on the Super-Altro chip for gaseous detectors

• Author(s): Paul Aspell (CERN), Massimiliano De Gaspari (CERN), Hugo França (CERN), Eduardo Garcia (CERN), Luciano Musa (CERN)

• Speaker: Massimiliano De Gaspari (CERN)

• Status: submitted by speaker 12-Sep-2012

• Abstract:
  The Super-Altro is a 16 channels demonstrator chip for the readout of the TPC prototype for the Linear Collider, including one Preamplifier/Shaper, ADC and Digital Signal Processor per channel. It is suitable for wire chambers, GEMs and MicroMegas readout. The limited available area of 4mm2/channel requires a compact system. Test measurements show good noise performance despite tight integration of sensitive analog and massive digital circuitries. The Super-Altro features shutdown/power pulsing capabilities. This presentation shows the power consumption in continuous and shutdown modes, together with evaluations of the wake-up time. The measured energy consumption per cycle leads to a power reduction during dynamic power pulsing implementation at the chip level of a factor 18 in the case of CLIC or 60 for the ILC.

Hybrid pixel readout chip developments in view of the Linear Collider

• Author(s): Rafael Ballabriga (CERN), Michael Campbell (CERN), Massimiliano De Gaspari (CERN), Xavier Llopart Cudie (CERN), Tuomas Poikela (CERN), Pierpaolo Valerio (CERN)

• Speaker: Massimiliano De Gaspari (CERN)

• Status: submitted by speaker 12-Sep-2012

• Abstract:
  The Medipix chip design team is currently working on three hybrid pixel readout chips, potentially interesting for the vertex detector of the Linear Collider: Timepix3 (130nm CMOS technology), Smallpix (130nm) and the CLICpix prototype (65nm). They provide measurements of Time-Over-Threshold (TOT) and Time Of Arrival (TOA). All three chips are designed for power pulsing applications and pixel sizes range from 55μm (Timepix3) to 25μm (CLICpix). Timepix3 implements a data-driven readout. Smallpix will offer Integral TOT measurement, Photon Counting mode and zero suppression. CLICpix applies also a cluster-based data compression. This talk presents the requirements of the project, the most important features of the three chips, their expected performance and their power pulsing features.

Occupancy for the CLIC_ILD TPC with pad and pixel readout

• Author(s): Martin Killenberg (CERN)

• Speaker: Martin Killenberg (CERN)

• Status: submitted 19-Sep-2012

• Abstract:
  A TPC in a detector at CLIC has to cope with large beam induced backgrounds. For the foreseen pad size of 1x6 square millimeters the occupancy caused by these backgrounds is significant and a TPC is at the limit of its operability. Using a pixelized TPC readout (Timepix / InGrid) seems like a way to reduce the maximum local occupancy to a few percent. We report on simulation studies of the TPC occupancy, performed for different pad and pixel sizes.

Tracking studies in inhomogeneous magnetic and electric fields

• Author(s): Martin Killenberg (CERN)

• Speaker: Martin Killenberg (CERN)

• Status: submitted 19-Sep-2012

• Abstract:
  The data taken with the Large Prototype TPC of the LCTPC collaboration has to be corrected for several effects caused by alignment and the inhomogeneous field of the magnet used for the measurements. A simulation study is used to examine the effects separately and to disentangle them. We report on the status of this study.

  A TPC at the CLIC collider has to cope with large beam induced backgrounds. The primary ions produced in this environment deteriorate the electric field and give a systematic distortion in the measurement. The influence of these distortions on the momentum resolution has been studied and will also be presented.

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Calorimetry / Muons

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Analog HCAL results

• Author(s): Felix Sefkow (DESY and CERN)

• Speaker: Felix Sefkow (DESY and CERN)

• Status: to be approved and submitted through CALICE

• Abstract:
  

Tungsten DHCAL

• Author(s): Jose Repond (Argonne)

• Speaker: Jose Repond (Argonne)

• Status: to be approved and submitted through CALICE

• Abstract:
  

Structural studies for a realistic tungsten HCAL

• Author(s): Fernando Duarte Ramos (CERN)

• Speaker: Fernando Duarte Ramos (CERN)

• Status: submitted 21-Sep-2012

• Abstract:
  The use of 10 mm thick tungsten plates in a highly segmented Hadronic Calorimeter poses new challenges to the mechanical construction of such a detector. Among those challenges, the brittleness and poor machinability of pure tungsten results in the need for the use of nonconventional joining techniques between the tungsten plates and the supporting frame. This talk highlights the challenges at hand and shows the present status of the structural studies for a realistic tungsten HCAL design.

Time-development of showers in tungsten (T3B)

• Author(s): Frank Simon (MPI Munich)

• Speaker: Frank Simon (MPI Munich)

• Status: to be approved and submitted through CALICE

• Abstract:
  

-- Main.MichaelHauschild - 18-Sep-2012