LeptonPhoton2021

Abstracts

Prospects for observing the charged IDM scalars at high energy CLIC

• Speaker: Jan Franciszek Klamka
• Status: accepted for an oral presentation (15+5)
• Abstract: The Compact Linear Collider (CLIC) was proposed as the next energy-frontier infrastructure at CERN, to study e+e− collisions at three centre-of-mass energy stages: 380 GeV, 1.5 TeV and 3 TeV. The main goal of its high-energy stages is to search for the new physics beyond the Standard Model (SM). The Inert Doublet Model (IDM) is one of the simplest SM extensions and introduces four new scalar particles: H±, A and H; the lightest, H, is stable and hence a natural dark matter (DM) candidate. A set of benchmark points is considered, which are consistent with current theoretical and experimental constraints and promise detectable signals at future colliders. Prospects for observing pair-production of the IDM scalars at CLIC were previously studied using signatures with two leptons in the final state. In the current study, discovery reach for the IDM charged scalar pair-production is considered for the semi-leptonic final state at the two high-energy CLIC stages. Full simulation analysis, based on the current CLIC detector model, is presented for five selected IDM scenarios. Results are then extended to the larger set of benchmarks using the Delphes fast simulation framework. The CLIC detector model for Delphes has been modified to take pile-up contribution from the beam-induced 𝛾𝛾 interactions into account, which is crucial for the presented analysis. Results of the study indicate that heavy, charged IDM scalars can be discovered at CLIC for most of the proposed benchmark scenarios, with very high statistical significance.

• Slides

Silicon pixel-detector R&D for future lepton colliders

• Speaker: Katharina Dort
• Status: accepted for an oral presentation (15+5)
• Abstract: The physics aims at future lepton colliders such as CLIC or FCC-ee pose challenging demands on the performance of the proposed all-silicon vertex and tracking-detector systems. A single-plane spatial resolution of a few micrometers is needed, combined with a low mass of ~0.2% X0 per layer for the vertex detectors and ~1% X0 per layer for the main trackers. Moreover, hit-time tagging with a few nanosecond resolution is required for CLIC, to reduce the impact of beam-induced background on the measurement accuracy to an acceptable level. An even better timing precision below 100 ps on pixel level would improve the background rejection further, and opens up the possibility of particle-identification by time of flight measurements within the tracking layers. To address these detector requirements, a broad R&D program on new silicon detector technologies is being pursued within various collaborative frameworks, such as the CERN EP R&D programme, AIDAinnova and the CLICdp collaboration. Different small pitch (25 micron) hybrid technologies with innovative sensor concepts are explored as candidates for the inner vertex-detector layers. A dedicated 65 nm readout chip (CLICpix2) has been developed and interconnected via fine pitch bump-bonding to 50-150 micron thin planar active-edge sensors. Furthermore, alternative interconnects such as bonding using anisotropic conductive films (ACF) are explored. Fully monolithic CMOS technologies are considered both for the vertex and the tracking detectors. Based on 3D TCAD simulations and previous test results, innovative concepts for CMOS sensors with a small collection electrode have been developed, targeting various future projects. Several prototype chips have been produced using variants of a modified 180 nm CMOS process with different substrate materials. The CLICTD tracker demonstrator design includes an innovative sub-pixel segmentation scheme for a readout pitch of 300 micron x 30 micron. An extensive test-beam measurement campaign has been performed to compare the various CLICTD design and processing variants. Recent measurements with the ATTRACT FASTPIX timing demonstrator produced in the same 180 nm CMOS process have demonstrated the feasibility of performing time tagging on single-hit level with a precision of approximately 100 ps for a pixel pitch of 20 micron and below. Similar concepts are currently being explored in a 65 nm CMOS process offering further performance improvements. To predict and optimise the performance of the various prototype technologies, a fast and versatile Monte Carlo Simulation Tool (Allpix-Squared) has been developed. This contribution introduces the requirements and gives an overview of the R&D program for silicon-based vertex and tracking detectors at future lepton colliders, highlighting new results from measurements and simulations of recent prototypes.

• Slides