Physics and Detectors at CLIC: CLIC Conceptual Design Report

Abstract: This report describes the physics potential and experiments at a future multi-TeV e+e- collider based on the Compact Linear Collider (CLIC) technology. The physics scenarios considered include precision measurements of known quantities as well as the discovery potential of physics beyond the Standard Model. The report describes the detector performance required at CLIC, taking into account the interaction point environment and especially beaminduced backgrounds. Two detector concepts, designed around highly granular calorimeters and based on concepts studied for the International Linear Collider (ILC), are described and used to study the physics reach and potential of such a collider. Detector subsystems and the principal engineering challenges are illustrated. The overall performance of these CLIC detector concepts is demonstrated by studies of the performance of individual subdetector systems as well as complete simulation studies of six benchmark physics processes. These full detector simulation and reconstruction studies include beaminduced backgrounds and physics background processes. After optimisation of the detector concepts and adopting the reconstruction algorithms the results show very efficient background rejection and clearly demonstrate the physics potential at CLIC in terms of precision mass and cross section measurements. Finally, an overview of future plans of the CLIC detector and physics study is given and a list of key detector R&D topics needed for detectors at CLIC is presented.

• The paper introduces innovative detector concepts and simulation techniques to enable precision measurements at multi-TeV energies.
• It demonstrates how enhanced timing and high-granularity calorimeters effectively mitigate severe beam-induced backgrounds.
• The report outlines a collaborative R&D roadmap addressing power, heat management, and integration challenges for next-generation experiments.

Summarizing the CLIC Conceptual Design Report

The Compact Linear Collider (CLIC) Conceptual Design Report (CDR) is a comprehensive document addressing the development of a future multi-TeV electron-positron collider based on CLIC technology. With a focus on advancing particle physics beyond the Standard Model (SM), CLIC is poised to facilitate precision measurements and explore novel phenomena, as outlined in this exhaustive study. This document exemplifies a meticulous synthesis of collaborative efforts encompassing contributions from diverse international research institutions.

Physics Potential and Experimental Environment

The report delineates the physics potential of CLIC, emphasizing its capability to complement the Large Hadron Collider (LHC) by providing additional insights into SM physics such as Higgs precision measurements. Furthermore, CLIC's prowess extends to discovering theories beyond the SM, including supersymmetry, extra dimensions, and strong electroweak symmetry breaking, effectively broadening its exploratory horizon. The challenges inherent to operating at multi-TeV energies are considerable, with significant beam-induced backgrounds such as e e pairs and gamma-gamma hadron events necessitating robust detector designs.

Detector Concepts and Design Considerations

Two primary detector concepts, CLIC_ILD and CLIC_SiD, draw upon mature designs from the International Linear Collider (ILC) but are significantly enhanced to address CLIC's challenging experimental conditions. Key features include tracking detectors with exceptional momentum resolution, vertex detectors with sophisticated pixel technology, and high-granularity calorimeters designed for particle flow analysis. These components are housed within a solenoidal assembly capable of mitigating substantial background suppression requirements due to closely spaced bunches and beamstrahlung effects.

Detector Performance and Background Mitigation

The document reports on extensive simulations to anticipate and mitigate the impact of CLIC's challenging machine environment, utilizing sophisticated software tools to evaluate interaction point detachment, coverage, and precision momentum measurements. The integration of high-energy backgrounds into simulations confirms the feasibility of achieving precision physics at CLIC through intricate detector timing capabilities, particulary with calorimeters designed to manage hadronic shower mitigation strategies across high-background scenarios. Strategies involve precise timing (ns scale) and spatial resolution to manage data over 156 ns bunch trains with 20 ms idle time for data pulsing.

Future Developments and Research Directions

Given the ambitious objectives of CLIC, the CDR delineates a roadmap for detector R&D, focusing on areas such as power delivery, heat management, high granularity semiconductor detectors, and novel materials. The seamless adaption of technologies like Silicon-On-Insulator (SOI) and 3D integrated detectors showcases means to transcend current technological impediments. The report explicitly advocates parallel, cross-institutional studies to identify synergies and research avenues, underscoring the imperative nature of innovation-driven physics instrumentation.

Conclusion

In intertwining chapters, this CDR lays out a blueprint for an experimental setup at CLIC, refining the paradigm of precision exploration in high energy physics. It proclaims CLIC as an essential tool aligned with ongoing LHC outputs, bolstering physics through broadened discovery reach and precision measurement capacity—a testament to human ingenuity in seeking to unravel the intricacies of the universe at unprecedented energy scales. The demonstrated approach reflects a consensus on the integration of advanced detector technology, capable of challenging the confines of current physics models with tangible potential for unveiling the substratum of dark matter, supersymmetry, and more.