LCWS15 - International Workshop on Future Linear Colliders

Abstracts

Session: Plenary talks

CLIC detector and physics

• Speaker: Aidan Robson (Glasgow University)
• Status: invited
• Time: ~25min
• Abstract: not needed
• Slides

CLICdp detector model

• Speaker: Nikiforos Nikiforou (CERN)
• Status: invited
• Time: ~20min
• Abstract: not needed
• Slides

Session: Vertex/Tracking

Thin-sensor studies for the CLIC vertex detector

• Speaker: Sophie Redford (CERN)
• Time: 25 + 5 min.
• Abstract: A vertex-detector concept based on hybrid pixel-detector technology is currently under development for CLIC. To reach the low material budget of only 0.2% X0 per layer, sensors and readout ASICs will each have to be thinned down to approximately 50 um. Pulse-height information of the individual pixel hits will be used to improve the position resolution through charge interpolation within clusters. Prototype assemblies have been produced using planar slim-edge and active-edge sensors of varying thickness (50-500 um) hybridised to Timepix and Timepix3 readout ASICs. We present new results from a response-calibration campaign with photons of known energy, as well as new test-beam data analysis results for a variety of sensor designs. Measurements are compared to simulations based on the ALLPix/GEANT4 framework.
• Slides

CLICpix planar-sensor assemblies

• Speaker: Dominik Dannheim (CERN)
• Time: 20 + 5 min.
• Abstract: Prototypes of 25 um pitch CLICpix readout ASICs with a 64x64 pixel matrix and matching planar sensors of 50 to 280 um thickness have been produced within Multi-Project Wafer Runs. An indium bump-bonding process is under development for interconnecting the individual dies of readout chips and sensors. In a first phase of the project, several prototype assemblies of 200 um thick sensors hybridised to CLICpix readout chips have been produced and characterised with test pulses, radioactive sources and in beam tests. We present results of these measurements and draw preliminary conclusions on the achieved interconnect yield and tracking performance. An outlook is given on the design of the next version of the readout ASIC (CLICpix2), which features an enlarged pixel matrix (128x128) and an improved pulse-height and timing measurement range.
• Slides

Capacitively coupled pixel detectors for the CLIC vertex detector

• Speaker: Steven Green (Cambridge U)
• Time: 25 + 5 min.
• Abstract: Prototypes of a novel hybridisation concept based on capacitive coupling between active CCPDv3 HV-CMOS sensors and 25-um-pitch CLICpix readout ASICs have been produced and characterised with test pulses, radioactive sources and in beam tests. We present results of the characterisation measurements, as well as TCAD based simulations of the HV-CMOS sensor response. The performance of the assemblies is related to parameters of the capacitive interconnect, such as glue-layer uniformity and alignment precision.
• Slides

Tracker-technology R&D for CLIC

• Speaker: Andreas Nurnberg (CERN)
• Time: 20 + 5 min.
• Abstract: The physics aims at the future CLIC high-energy linear e+e- collider set very high precision requirements on the performance of the tracking detectors. Moreover, these detectors have to be well adapted to the experimental conditions, such as the time structure of the collisions and the presence of beam-induced backgrounds. A single-point resolution of 7 um and time slicing at the level of approximately 10 ns have to be achieved with a material budget of only 1% X0 per layer. An all-silicon tracking system meeting these requirements is currently under development. Both hybrid concepts and fully integrated sensors are under consideration. Systematic studies of various tracker readout architectures have been performed, combining Geant4 and TCAD device simulations with parametric simulations of the readout ASICs. The simulations are validated with test-beam data from existing pixel-detector prototypes.
• Slides

Session: Calorimetry/Muon Systems (submitted via CALICE and FCAL)

Shower characteristics of particles with momenta up to 150 GeV in the CALICE W-AHCAL

• Speaker: Felix Sefkow (DESY)
• Authors: Eva Sicking (CERN), Felix Sefkow (DESY)
• Time: 20 + 5 min.
• Abstract: We present a study of showers initiated by electrons, pions, kaons, and protons with beam momenta from 15 GeV to 150 GeV in the CALICE W-AHCAL for data recorded at CERN SPS in 2011. The first part of the presentation will focus on optimisations of the data reconstruction and simulation as well as on studies of systematic uncertainties of the measurement. In the second part, we will show the W-AHCAL analysis results including measurements of the calorimeter response to each particle type as well as the energy resolution and studies of the longitudinal and radial shower development for selected particles. The results are compared to simulations of Geant4 version 9.6.p02.
• Slides

Session: Simulation/Detector Performance/Reconstruction

All Silicon Tracking + Conf. Mapping PatRec

• Speaker: Rosa Simoniello (CERN)
• Authors: F. Gaede, D. Hynds, R. Simoniello, Y. Voutsinas
• Time: 20 + 5 min.
• Abstract: The development of a new software chain used for the updated CLIC detector model is well under way. The reconstruction software has been interfaced with the DD4hep geometry description. In this talk an overview of the track reconstruction procedure is given. Currently, two pattern recognition strategies are under development for the CLIC full silicon tracker and included in ILCSOFT. The first approach exploits the double layer structure of the CLIC vertex detector, while the second approach is based on conformal mapping. The performances are investigated for single muons as well as for ttbar and di-jet events at different energies.
• Slides

Developments in ILC Dirac and grid tools

• Speaker: Marko Petric (CERN)
• Time: 20 + 5 min.
• Abstract: We present recent development and features of the grid interware ILCDirac. The presentation includes a review of performance, challenges and the future roadmap of the project.
• Slides

CLIC Similation Model

• Speaker: Marko Petric (CERN)
• Time: 15 + 5 min.
• Abstract: We present the implementation of the new CLICdp detector model in DD4hep.
• Slides

DD4hep – based reconstruction

• Speaker: Nikiforos Nikiforou (CERN)
• Time: 20 + 5 min.
• Abstract: DD4hep is a toolkit that aims to be an easy to use single source of a consistent detector description for simulation, visualization, alignment and calibration as well as physics data reconstruction. The ILD detector model has already been ported to DD4hep, while the CLIC new detector model is being implemented and refined in parallel to the optimization efforts. With the simulation and visualization goals already achieved, this talk will present the efforts to interface DD4hep with already established iLCSOft reconstruction software and techniques. The talk will focus on the DDRec reconstruction data interfaces and the developing paradigms to connect the information provided by DD4hep to the PandoraPFA particle flow reconstruction software within the Marlin framework.
• Slides

Other general CLICdp related talks in the scope of the Simulation/Detector Performance/Reconstruction session:

Pandora PFA developments

• Speaker: John Marshall (Cambridge)
• Time: 25 + 5 min.
• Abstract: This talk will give an overview of the Pandora Particle Flow Algorithm, with an emphasis on the most recent algorithm developments. Information will also be provided to help users of Pandora PFA harness the full potential of this powerful and flexible software package. The underlying software framework, the Pandora Software Development Kit (SDK), is the subject of a publication recently accepted by EPJ C (see arXiv:1506.05348) and key features of the SDK will be discussed.
• Slides

Updates to the Pandora photon reconstruction

• Speaker: Boruo Xu (Cambridge)
• Time: 25 + 5 min.
• Abstract: This talk will describe recent improvements to the photon reconstruction performed by the Pandora Particle Flow Algorithm. The emphasis will be on improvements to the completeness of reconstructed photons, reducing the number of times that individual photons are fragmented into multiple reconstructed particles. Recent attempts to recover photons that deposit energy in close proximity to charged hadrons will also be discussed.
• Slides

HCal Optimisation Studies for the ILD

• Speaker: Steven Green (Cambridge)
• Time: 30 + 5 min.
• Abstract: This talk will aim to provide a full set of optimisation studies for the HCal for the ILD detector model. A number of parameters will be varied including cell sizes, total depth, number of layers and absorber material. The detector performance will be determined using primarily the jet energy resolution figure of merit, but will also examine a number of other metrics including single particle resolution and raw jet energies.
• Slides

Session: Higgs/EW

Measurement of the Higgs to EW bosons decays at low and intermediate CLIC energies

• Speaker: Ivanka Bozovic Jelisavcic (Vinca Institute of Nuclear Sciences, Univ. of Belgrade, Serbia)
• Authors: I. Bozovic Jelisavcic, S. Lukic, G. Milutinovic Dumbelovic, P. Roloff, M. Pandurovic
• Time: 15 + 5 min.
• Abstract: The studies presented in this talk are part of the effort to investigate a complete physics potential of the future Compact Linear Collider (CLIC) in the Higgs sector. Foreseen as an energy staged machine with a high-energy reach, CLIC offers a possibility for precision measurements of the Higgs boson couplings. Of particular importance are couplings to EW bosons that can probe the structure of the Higgs sector. Higgs couplings are determined from the cross section times branching ratio measurements of the corresponding decays. Physics analyses of the H->WW* decay at 350 GeV and H->ZZ* decay at 1.4 TeV CLIC will be presented in this talk. The analyses are based on the full simulation of the CLIC_ILD detector, including realistic luminosity spectrum and physics and machine-induced backgrounds.
• Slides

Measurement of double Higgs production at CLIC

• Speaker: Rosa Simoniello (CERN)
• Authors: Rosa Simoniello (CERN), Philipp Roloff (CERN)
• Time: 15 + 5 min.
• Abstract: The possibility for a precision measurement of gHHH via the double-Higgs production process is investigated for the case of a CLIC collider operating at multi-TeV energies. Since the double-Higgs production also gives processes sensitive to the quartic coupling (gHHWW), a simultaneous extraction of gHHH and gHHWW is attempted in this analysis. For the time being, only the channel in which both Higgs decay into bb pairs is considered. The analysis is performed in full simulation including pile-up from gamma gamma -> hadrons and all relevant physics background channels. The entire analysis chain from physics object optimisation to selection and preliminary results is presented. A comparison of different jet finding algorithms is included.
• Slides

Physics potential for the measurement of hadronic Higgs decays and the Higgs mass at high-energy CLIC operation

• Speaker: Philipp Roloff (CERN)
• Time: 15 + 5 min.
• Abstract: The study presented in this talk is part of an 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 sections times branching ratios for the decays H->bb, H->cc and H->gg are measured at the centre-of-mass energies of 1.4 TeV and 3 TeV. Compared to earlier studies, backgrounds from electron-photon and photon-photon collisions are included. The Higgs mass is extracted from the reconstructed invariant mass distribution. The analysis is based on a full detector simulation using Geant4. Pileup from gamma gamma -> hadrons interactions is overlaid to the physics events.
• Slides

H->bb/cc/gg at 350 GeV at CLIC

• Speaker: Marco Szalay (MPP Munich)
• Time: 15 + 5 min.
• Abstract:The Higgs production cross-section at the lowest energy stage of CLIC allows to investigate at the same time Higgsstrahlung and vector boson fusion production modes. The combination of efficient flavor tagging capabilities and high resolution in multi-jets events allow to disentangle bb, cc and gg final states. Providing a measurement of transverse momentum allows to separate the different Higgs production modes and analyze them simultaneously. In this study we present the achievable precision in determining the branching fraction of the Higgs boson in hadronic decays for an integrated luminosity of 500 fb-1, using a full detector simulation with realistic background estimation.
• Slides

Session: Joint ILD/SiD/CLICdp software session

Grid Production Tools

• Speaker: Marko Petric (CERN)
• Time: 10 min.
• Abstract: We present the ILCDirac grid production tool. A common solution to run centralised production and user jobs using linear collider software on the grid. We will show the available resources, give examples, and discuss problems commonly encountered by users.
• Slides

Simulation Tools

• Speaker: Nikiforos Nikiforou (CERN)
• Time: 20 min.
• Abstract: Not needed
• Slides