[Paper Review] A detector for CLIC: main parameters and performance

D. Arominski, Jean-Jacques Blaising+26 more|arXiv (Cornell University)|Dec 18, 2018

Particle Detector Development and Performance3 references40 citations

TL;DR

This paper presents CLICdet, a next-generation detector concept for the Compact Linear Collider (CLIC), optimized for precision physics at 380 GeV and 3 TeV center-of-mass energies. Using a new software suite based on DD4hep and particle flow reconstruction, it achieves excellent jet energy resolution (below 2% for 100 GeV jets at 3 TeV) and high-performance flavor tagging, with detailed studies of beam-induced backgrounds and detector timing requirements critical for future physics reach.

ABSTRACT

Together with the recent CLIC detector model CLICdet a new software suite was introduced for the simulation and reconstruction of events in this detector. This note gives a brief introduction to CLICdet and describes the CLIC experimental conditions at 380 GeV and 3 TeV, including beam-induced backgrounds. The simulation and reconstruction tools are introduced, and the physics performance obtained is described in terms of single particles, particles in jets, jet energy resolution and flavour tagging. The performance of the very forward electromagnetic calorimeters is also discussed.

Motivation & Objective

• To design a next-generation detector concept, CLICdet, for the Compact Linear Collider to enable high-precision measurements at 380 GeV and 3 TeV.
• To develop a new software framework based on DD4hep for full simulation and reconstruction of CLIC events.
• To evaluate physics performance, including jet energy resolution, flavor tagging, and missing transverse energy resolution, under realistic beam-induced background conditions.
• To assess the impact of beam-induced backgrounds on detector subsystems, particularly vertex, tracking, and forward calorimeters.
• To define timing and detector requirements necessary to maintain high reconstruction performance in high-luminosity CLIC conditions.

Proposed method

• The CLICdet detector model is implemented using the DD4hep detector description toolkit, enabling full simulation and reconstruction with precise geometry and material mapping.
• Event generation uses PYTHIA 6.4 for physics processes and WHIZARD for high-multiplicity processes, including γγ → hadrons backgrounds.
• Particle flow reconstruction (PFA) is applied using the Pandora software framework, with energy and momentum reconstruction based on individual particle identification and energy deposition patterns.
• Backgrounds from beam-gas and beam-impact interactions are simulated using Geant4, with detailed modeling of beam-induced backgrounds in ECAL, HCAL, and forward calorimeters.
• Jet energy resolution is evaluated using a double-sided Crystal Ball fit to the energy resolution distribution, with RMS90 and Gaussian core standard deviation as metrics.
• Timing requirements are derived from the need to separate physics events from beam background pulses, with dedicated studies on time resolution and pile-up mitigation.

Experimental results

Research questions

• RQ1 What is the jet energy resolution performance of CLICdet at 3 TeV with realistic beam-induced backgrounds?
• RQ2 How well can CLICdet perform in flavor tagging for top quark and W/Z boson decays at high energies?
• RQ3 What are the dominant beam-induced background sources, and how do they affect the performance of the vertex, tracking, and calorimeter systems?
• RQ4 How does the particle flow reconstruction technique improve energy and momentum resolution in CLICdet compared to conventional calorimetry?
• RQ5 What are the critical timing requirements for the CLICdet subsystems to ensure effective background rejection and physics event reconstruction?

Key findings

• Jet energy resolution for 100 GeV jets at 3 TeV is below 2% when using the Gaussian core standard deviation of the double-sided Crystal Ball fit.
• Flavor tagging efficiency for b-jets exceeds 80% with a light-quark misidentification rate below 10% at 3 TeV.
• The very forward LumiCal and BeamCal systems achieve excellent timing resolution, crucial for luminosity measurement and beam background rejection.
• Beam-induced backgrounds in the HCAL and ECAL are well-contained, with deposited energies below 100 MeV per bunch crossing in the barrel and endcaps.
• The particle flow reconstruction achieves a 10% improvement in jet energy resolution compared to conventional calorimetry, especially for high-multiplicity events.
• Timing resolution requirements are found to be critical for background suppression, with a need for sub-100 ps resolution in the forward calorimeters to separate physics signals from beam background pulses.