Prospects for Higgs boson & top quark measurements and applications of digital calorimetry at future linear colliders

Within the next few years a decision must be made by the global community on what type of high energy colliders should be built in the post LHC era. Here we present studies showing what might be achieved if a linear lepton collider such as Compact Linear Collider ( CLIC ) is chosen. Two physics studies are presented showing the precision achievable in the electroweak sector when operating at 1.4 TeV. Firstly the measurement of σ Hν ν̄ × BR(H → W W ∗ ), an integral component for model independent Higgs measurements, is described using the semileptonic decay channel and is shown to yield a statistical precision of 1.3% for 1.5 ab −1 of data. A differential measurement of the top quark forward backward asymmetry is also performed as a probe of the electroweak form factors of the ttX vertex yielding a statistical precision of O(1%) for 1.5 ab −1 of data. Lastly, the potential for using a novel design of a Digital Electromagnetic Calorimeter ( DECAL ) at the International Linear Collider ( ILC ) is studied showing that an energy resolution ofσ E⁄E=16.1 "\%"⁄E⊕0.5 "\%"⁄E⊕0.4"\%" be achieved, similar to what is seen for the standard design choice, when using 30 μm pitch pixels with a 12 μm epitaxial thickness

Optimal Configuration of Proton-Therapy Accelerators for Relative-Stopping-Power Resolution in Proton Computed Tomography

The determination of relative stopping power (RSP) via proton computed tomography (pCT) of a patient is dependent in part on the knowledge of the incoming proton kinetic energies; the uncertainty in these energies is in turn determined by the proton source—typically a cyclotron. Here, we show that reducing the incident proton beam energy spread may significantly improve RSP determination in pCT. We demonstrate that the reduction of beam energy spread from the typical 1.0% (at 70 MeV) down to 0.2% can be achieved at the proton currents needed for imaging at the Paul Scherrer Institut 250-MeV cyclotron. Through a simulated pCT imaging system, we find that this effect results in RSP resolutions as low as 0.2% for materials such as cortical bone, up to 1% for lung tissue. Several materials offer further improvement when the beam (residual) energy is also chosen such that the detection mechanisms used provide the optimal RSP resolution

Calorimeters for the FCC-hh

The future proton-proton collider (FCC-hh) will deliver collisions at a center of mass energy up to $\sqrt{s}=100$ TeV at an unprecedented instantaneous luminosity of $L=3~10^{35}$ cm$^{-2}$s$^{-1}$, resulting in extremely challenging radiation and luminosity conditions. By delivering an integrated luminosity of few tens of ab$^{-1}$, the FCC-hh will provide an unrivalled discovery potential for new physics. Requiring high sensitivity for resonant searches at masses up to tens of TeV imposes strong constraints on the design of the calorimeters. Resonant searches in final states containing jets, taus and electrons require both excellent energy resolution at multi-TeV energies as well as outstanding ability to resolve highly collimated decay products resulting from extreme boosts. In addition, the FCC-hh provides the unique opportunity to precisely measure the Higgs self-coupling in the di-photon and b-jets channel. Excellent photon and jet energy resolution at low energies as well as excellent angular resolution for pion background rejection are required in this challenging environment. This report describes the calorimeter studies for a multi-purpose detector at the FCC-hh. The calorimeter active components consist of Liquid Argon, scintillating plastic tiles and Monolithic Active Pixel Sensors technologies. The technological choices, design considerations and achieved performances in full Geant4 simulations are discussed and presented. The simulation studies are focused on the evaluation of the concepts. Standalone studies under laboratory conditions as well as first tests in realistic FCC-hh environment, including pileup rejection capabilities by making use of fast signals and high granularity, have been performed. These studies have been performed within the context of the preparation of the FCC conceptual design reports (CDRs)

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Physics Potential of CLIC Operation at 380 GeV

The Compact Linear Collider (CLIC) is a multi-TeV linear electron positron collider proposed as a future project for CERN aiming to provide high precision measurements of the standard model and discovery potential for new physics at the TeV scale. We present the physics potential of the CLIC experiment in its 380 GeV stage, which focuses on measurement of the Higgs boson and the top quark. In particular, the precision with which the mass, width and couplings of each particle can be measured will be examined

Measurement of the H→\rightarrowWW∗^* Branching Ratio at 1.4TeV using the semileptonic final state at CLIC

This note summarises a study to evaluate the potential to measure the H$\rightarrow$WW$^*$ branching fraction at CLIC, 1.4TeV centre-of-mass energy, with the CLIC_ILD detector, using the WW$\rightarrow$qql$\nu$ channel. We discuss the approach to reconstructing the final state and the methods used to separate signal events from backgrounds. The expected statistical precision on the production cross section times branching fraction, $\delta(\sigma_{H\nu\nu}\;\times\;$BR(H$\rightarrow$WW$^*$)), is found to be 1.3% for an integrated luminosity of 1.5ab$^{-1}$