ECFA Linear Collider Workshop 2013

ABSTRACTS

Number of abstracts: 18 (submitted) + 1 (via CALICE) + 1 Plenary Talk

Plenary Talk

CLIC detector status

• Speaker: Christian Grefe (CERN)

RD 1: Higgs Physics / Electroweak Symmetry Breaking

Measurement of the Higgs couplings to b- and c-quarks and to gluons at 350 GeV, 1.4 TeV and 3 TeV CLIC

• Author(s): Tomas Lastovicka (Czech Academy of Sciences)
• (Proposed) Speaker: Tomas Lastovicka (Czech Academy of Sciences)
• Status: submitted
• Abstract:
  The discovery of a Higgs boson-like particle at the LHC has triggered great interest in the determination of its couplings. A test of the predicted linear dependence of the branching ratios on the fermion mass of the final state, is currently one of the most compelling arguments for building a linear collider. We demonstrate that precision measurements of the Higgs decay branching ratios to bb, cc and gg pairs are feasible at a CLIC machine. Cross section times branching ratio results are summarized in this presentation for various energy stages and a Higgs boson mass of 126 GeV.

Measurement of the Higgs couplings to gauge bosons at CLIC

• Author(s): Eva Sicking (CERN)
• (Proposed) Speaker: Eva Sicking (CERN)
• Status: submitted 16 April 2013
• Abstract:
  The studies presented in this talk are part of an ongoing effort to investigate the complete physics potential of a CLIC collider operated at various energies for measurements of the SM Higgs boson properties. Various measurements of Higgs boson couplings to gauge bosons are discussed. The cross sections times branching ratios for the rare decays H -> Z gamma and H -> gamma gamma are measured at 1.4 TeV. The decay H -> WW* is being investigated at 350 and 1400 GeV. Finally, Higgs boson production in ZZ fusion is studied at 1.4 TeV. All analyses are based on full detector simulations using Geant4. Beam-induced backgrounds from gamma gamma -> hadrons interactions are overlaid to the physics events.

Measurement of the Higgs boson decay to tau leptons at a CLIC collider operating at 350 and 1400 GeV

• Author(s): Astrid Münnich (DESY)
• (Proposed) Speaker: Astrid Münnich (DESY)
• Status: submitted 16 April 2013
• Abstract:
  The study presented in this talk is part of an ongoing effort to investigate the complete physics potential of a CLIC collider operated at various energies for measurements of the SM Higgs boson properties. The production cross section times branching ratio for the decay H -> tau+tau- is measured using hadronic tau decays at centre-of-mass energies of 350 and 1400 GeV. The analysis is based on a full detector simulation using Geant4. Beam-induced backgrounds from gamma gamma -> hadrons interactions are overlaid to the physics events.

Measurement of the Higgs boson decay to muons at a CLIC collider operating at 1.4 and 3 TeV

• Author(s): Ivanka Bozovic-Jelisavcic (University of Belgrade)
• (Proposed) Speaker: Ivanka Bozovic-Jelisavcic (University of Belgrade)
• Status: submitted 16 April 2013
• Abstract:
  The study presented in this talk is part of an ongoing effort to investigate the complete physics potential of a CLIC collider operated at various energies for measurements of the SM Higgs boson properties. The production cross section times branching ratio for the decay H -> mu+mu- is measured at a centre-of-mass energy of 1.4 TeV. Additionally, results for the same decay mode obtained at 3 TeV for the CLIC CDR are reviewed. The analysis is based on a full detector simulation using Geant4. Beam-induced backgrounds from gamma gamma -> hadrons interactions are overlaid to the physics events.

Measurement of the top Yukawa coupling at a 1.4 TeV CLIC collider

• Author(s): Sophie Redford (CERN)
• (Proposed) Speaker: Sophie Redford (CERN)
• Status: submitted 16 April 2013
• Abstract:
  The study presented in this talk is part of an ongoing effort to investigate the complete physics potential of a CLIC collider operated at various energies for measurements of the SM Higgs boson properties. The cross section for the process the e+e- -> ttH is measured using final states with six and eight jets at a centre-of-mass energy of 1.4 TeV. This cross sections is directly sensitive to the top Yukawa coupling. The analysis is based on a full detector simulation using Geant4. Beam-induced backgrounds from gamma gamma -> hadrons interactions are overlaid to the physics events.

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

• Author(s): Jan Strube (CERN)
• (Proposed) Speaker: Jan Strube (CERN)
• Status: submitted 16 April 2013
• Abstract:
  The study presented in this talk is part of an ongoing effort to investigate the complete physics potential of a CLIC collider operated at various energies for measurements of the SM Higgs boson properties. The cross section for pair production of the Higgs boson is measured using hadronic decays at centre-of-mass energies of 1.4 and 3 TeV. These cross sections are sensitive to the trilinear Higgs self-coupling. The analysis is based on a full detector simulation using Geant4. Beam-induced backgrounds from gamma gamma -> hadrons interactions are overlaid to the physics events.

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

• Author(s): Philipp Roloff (CERN), Jan Strube (CERN)
• (Proposed) Speaker: Philipp Roloff (CERN)
• Status: submitted 4 April 2013
• Abstract:
  One of the detector benchmark processes that was investigated for the Detailed Baseline Design (DBD) document is given by: e+e- -> tth, where h is the Standard Model Higgs boson of mass 125 GeV. A centre-of-mass energy of 1 TeV was assumed for this study. The physics aim is a direct measurement of the top Yukawa coupling. Higgs boson decays to beauty quark-antiquark pairs were 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-induced backgrounds from gamma gamma -> hadrons interactions and incoherent e+e- pairs were 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.

RD 2: Beyond Standard Model: SUSY, Cosmology, Alternatives

Overview of SUSY studies for CLIC

• Author(s): Frank Simon (MPI Munich)
• (Proposed) Speaker: Frank Simon (MPI Munich)
• Status: submitted 11 April 2013
• Abstract:
  With collision energies up to 3 TeV, CLIC provides an excellent basis for direct and indirect searches for New Physics with a high degree of complementarity to the LHC, extending beyond the LHC reach in particular in the weak sector. We will give an overview over recent studies of the CLIC performance for selected BSM models in a staged construction scenario, considering the two highest-energy stages at 1.4 TeV and at 3 TeV. This includes full simulation studies of supersymmetric squarks, sleptons, gauginos and heavy Higgs particles as well as well as parametric studies of the discovery reach for new heavy gauge bosons, illustrating the role of CLIC as a discovery tool for BSM physics at the energy frontier.

Slepton Mass Measurements and the Luminosity Spectrum at CLIC

• Author(s): Stephane Poss (CERN), Andre Sailer (CERN)
• (Proposed) Speaker: Andre Sailer (CERN)
• Status: submitted 12 April 2013
• Abstract:
  A precise knowledge of the luminosity spectrum at future e+e- colliders is mandatory for many precision measurements, e.g., slepton and neutralino mass measurements. The shape of the lepton energy distribution used to extract the mass of the slepton and neutralino is affected by the luminosity spectrum. A general reconstruction method for the luminosity spectrum -- using a phenomenological model and a reweighting fit to large angle Bhabha events -- is described and applied to the 3 TeV CLIC. The reconstructed luminosity spectrum is used to estimate the systematic error of the smuon and neutralino mass in the study of the smuon pair production process of the 3~TeV CLIC physics benchmarks.

RD 3: Top Physics, QCD, Loopverein

Top quark mass measurements at and above threshold in e+e- collisions at Linear Colliders

• Author(s): Frank Simon (MPI Munich)
• (Proposed) Speaker: Frank Simon (MPI Munich)
• Status: submitted 10 April 2013
• Abstract:
  Linear electron-positron colliders provide possibilities for top quark mass measurements with unprecedented precision, which are of high relevance to explore the stability of the Standard Model. Two complementary techniques for the measurement of the top mass in e+e- annihilation exist: The direct reconstruction of the invariant mass of the top quark decay products at energies above the top pair production threshold and the measurement of the mass in a threshold scan. Both of these approaches have recently been studied for CLIC using GEANT4-based detector simulations and full event reconstruction including realistic physics and beam-induced background levels. For both techniques, total errors of around 100 MeV or better are achieved, including a first study of expected systematic uncertainties. For the threshold scan, the precision at ILC is also studied to provide a comparison of the two linear collider technologies.

RD 5: Simulation, Detector Performance, Reconstruction

Precise luminosity measurement in the forward region at CLIC

• Author(s): Strahinja Lukic (University of Belgrade)
• (Proposed) Speaker: Strahinja Lukic (University of Belgrade)
• Status: submitted
• Abstract:
  Method of precise measurement of luminosity spectrum in the upper 25% of energy using Bhabha counting in the LumiCal at the 3 TeV CLIC is described. The method involves correction of the angular counting loss due to the beam-beam effects, as well as deconvolution of the luminosity spectrum distortion due to ISR. The method is based on experimental observables, relativistic kinematics, and theoretical dependence of the Bhabha cross section on the scattering angle. The method is tested by Monte-Carlo method, using the BHLUMI Bhabha-events generator, and the Guinea-PIG beam-beam simulation. Luminosity spectrum is reconstructed in the upper 25% of CM energy with systematic uncertainty in the order of permille. The precision of the measurement is essentially independent of the precision of the knowledge of beam parameters.
  
  This work has been released as CERN-LCD note LCD-Note-2012-008, and submitted to Journal of Instrumentation for review

RD 6: Detector Integration and Engineering, Machine-Detector Interface

Development and characterization of a large size Al-Ni stabilized Nb-Ti/Cu superconducting cable for the Linear Collider detector solenoid

• Author(s): Stefanie Langeslag (CERN and University of Twente), Benoit Curé (CERN), Stefano Sgobba (CERN), Alexey Dudarev (CERN), and Herman ten Kate (CERN)
• (Proposed) Speaker: Stefanie Langeslag (CERN and University of Twente)
• Status: submitted 23 April 2013
• Abstract:
  For future high-resolution particle physics experiments like ILC and CLIC, wide bore, high-field magnets are being developed. The self-supporting magnet structure needs to sustain the large electromagnetic force as a result of the high peak magnetic field, requiring for the conductor to exhibit challenging mechanical properties. A prototype for a 60 kA at 5 T, 4.2 K class conductor is produced by co-extrusion of a large, 40-strand Nb-Ti/Cu superconducting cable with a precipitation type Al-0.1wt%Ni stabilizer. Microalloying with nickel contributes to the strength of the stabilizer, and avoids significant degradation in residual resistivity ratio, owing to its low solid solubility in aluminum. Sections of the conductor are work hardened to increase the mechanical properties of the as-extruded temper. Mechanical and resistivity characteristics are assessed as function of the amount of work hardening, at room temperature as well as at 4.2 K.

RD 7: Tracking, Vertexing

Engineering studies for the inner region of the CLIC_ILD detector concept

• Author(s): Fernando Duarte Ramos (CERN)
• (Proposed) Speaker: Fernando Duarte Ramos (CERN)
• Status: submitted 5 April 2013
• 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 engineering studies for the CLIC_ILD inner detectors with focus on cooling, support and integration solutions.

Power pulsing scheme based on a back-end current source for the analog electronics of the vertex detectors at CLIC

• Author(s): Georges Blanchot (CERN), Cristian Fuentes (CERN)
• (Proposed) Speaker: Cristian Fuentes (CERN)
• Status: submitted 28 March 2013
• Abstract:
  The precision requirements of the vertex detector at CLIC impose strong limitations on the mass of such a detector (<0.2 X0 per layer). To achieve such a low mass, ultra-thin hybrid pixel detectors are foreseen, while the mass for cooling and services will be reduced by implementing a power-pulsing scheme that uses the low duty cycle of the accelerator. The principal aim is to achieve significant power reduction without compromising the power integrity supplied to the front-end electronics. Analog and digital electronics will be powered separately, having an overall peak power consumption of around 2 W/cm2 during the bunch crossing. This paper proposes a power-pulsing scheme for the analog electronics based on a back-end current source that charges the local storage capacitors placed in the ladder, which complements the study presented at TWEPP 2012 where a DC-DC Buck converter placed 30 cm away form the ladder was used instead. The use of a current source to charge the storage capacitors allows the reduction of the material of the cables, which in the previous study showed to have a strong contribution (close to 50%) to the total material in the ladder zone. The proposed scheme was implemented using a FPGA to control the current supplied by the back-end source, and the results in terms of regulation of the analog voltage, power dissipation and material contribution will be presented. Both proposals could be used, after some modifications, to power the digital part and will be part of a future study.

R&D on sensors and readout for the CLIC vertex detector

• Author(s): Samir Arfaoui (CERN)
• (Proposed) Speaker: Samir Arfaoui (CERN)
• Status: submitted 5 April 2013
• Abstract:
  The requirements for the vertex detectors at the proposed Compact Linear Collider (CLIC) present an unprecedented combination of challenges in terms of material budget (0.2% X0 per layer, corresponding to 200 um of Si), spatial resolution (~3 um), time-tagging capability (~10 ns) and power dissipation (<50 mW/cm^2). A detector concept based on the hybrid planar pixel-detector technology is currently under development. It comprises fast, low-power and small-pitch readout ASICs (CLICpix) coupled to ultra-thin sensors via low-mass interconnects. In this talk we present the current status of simulations, laboratory measurements and beam tests of sensor and readout-ASICs.

Physics-performance optimization of the CLIC vertex detector

• Author(s): Philipp Roloff (CERN)
• (Proposed) Speaker: Philipp Roloff (CERN)
• Status: submitted 5 April 2013
• Abstract:
  The impact of the detector geometry on the physics performance of the CLIC vertex detector is being investigated. Different options for the barrel detector and alternative layouts of the endcap regions are compared. This study is based on a full detector simulation using Geant4. The beauty and charm tagging performances are the key benchmarks used to compare the different detector configurations.

Occupancy studies for the CLIC_ILD TPC with pad and pixel readout

• Author(s): Martin Killenberg (CERN, now at DESY)
• (Proposed) Speaker: Martin Killenberg (CERN, now at DESY)
• Status: submitted 24 April 2013
• Abstract:
  A TPC in a detector at CLIC has to cope with large beam induced backgrounds. For the foreseen pad size of 1x6 square millimetres the occupancy caused by these backgrounds is significant and a TPC is at the limit of its operability. Using a pixelised 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.

RD 8: Calorimetry, Muon Systems

Shower development of particles with momenta from 10 to 100 GeV in the CALICE scintillator-tungsten HCAL

• Author(s): tbc
• (Proposed) Speaker: tbc
• Status: to be submitted and approved via CALICE
• Abstract:
  A study of showers initiated by pions, protons, kaons and electrons with momenta from 10 to 100 GeV in the highly granular CALICE analogue scintillator-tungsten calorimeter is presented. The data were taken at the CERN SPS in 2011. The analysis includes measurements of the calorimeter response to each particle type and studies of the longitudinal and radial shower development. The results are compared to several GEANT4 simulation models.

AC 5: Accelerator Design and Integration

LC Detector Power Consumption Estimate

• Author(s): Andrea Gaddi (CERN)
• (Proposed) Speaker: Andrea Gaddi (CERN)
• Status: submitted 3 April 2013
• Abstract:
  Starting from the data available from LHC detectors, a comparison with the expected values for LC Detectors is made, considering in particular the advantages of the power pulsing mode.

-- Main.MichaelHauschild - 08-Apr-2013