The workshop focused on the application of ANAs to particle physics keeping in mind the ultimate goal of a collider at the energy frontier (10 TeV, e^+/e^-, e^-/e^-, or γγ). The development of ANAs is conducted at universities and national laboratories worldwide. The community is thematically broad and diverse, in particular since lasers suitable for ANA research (multi-hundred-terawatt peak power, a few tens of femtosecond-long pulses) and acceleration of electrons to hundreds of mega electron volts to multi giga electron volts became commercially available. The community spans several continents (Europe, America, Asia), including more than 62 laboratories in more than 20 countries. It is among the missions of the ICFA-ANA panel to feature the amazing progress made with ANAs, to provide international coordination and to foster international collaborations towards a future HEP collider. The scope of this edition of the workshop was to discuss the recent progress and necessary steps towards realizing a linear collider for particle physics based on novel-accelerator technologies (laser or beam driven in plasma or structures). Updates on the relevant aspects of the European Strategy for Particle Physics (ESPP) Roadmap Process as well as of the P5 (in the US) were presented, and ample time was dedicated to discussions. The major outcome of the workshop is the decision for ALEGRO to coordinate efforts in Europe, in the US, and in Asia towards a pre-CDR for an ANA-based, 10 TeV CM collider. This goal of this coordination is to lead to a funding proposal to be submitted to both EU and EU/US funding agencies. This document presents a summary of the workshop, as seen by the co-chairs, as well as short 'one-pagers' written by the presenters at the workshop.

Momentum bandwidth is an important characteristic for final focus systems (FFS) of future high-energy colliders. A large momentum bandwidth is a notable feature of the novel local-chromaticity-correction FFS, being demonstrated at the KEK Accelerator Test Facility 2 (ATF2), owing to the locality of chromaticity correction. In this article, analytical estimations and simulations of momentum bandwidth for various optics of ATF2 are presented. Possible deviations of the momentum bandwidth due to realistic machine imperfections are studied. Experimental measurements at ATF2 following successful tuning of small vertical beam size at the interaction point (IP) are also described, which agree well with numerical predictions and further verify the robustness of the local chromaticity correction scheme.

The Compact Linear Collider (CLIC) could provide ${e}^{+}{e}^{\ensuremath{-}}$ collisions in two detectors simultaneously possibly at a bunch train frequency in the linac twice the baseline design value. In this paper, a novel dual beam delivery system (BDS) design is presented in order to serve two interaction regions (IR1 and IR2) including optics designs and the evaluation of luminosity performance with synchrotron radiation (SR) and solenoid effects for both energy stages of CLIC, 380 GeV and 3 TeV. IR2 features a larger crossing angle than the current baseline. The luminosity performance of the novel CLIC scheme was evaluated by comparing the different BDS designs with and without the detector solenoid field effects. It has to be highlighted that the impact of the detector solenoid on luminosity had not been evaluated for the current CLIC baseline, which amounts to a loss of about 4% that corresponds to the same value of the old baseline design. At 380 GeV the novel dual BDS design features same luminosities than the current baseline. However at 3 TeV the luminosity performance is reduced by 2% from the baseline design for the IR1 and by 33% for the IR2. The dual CLIC BDS design provides adequate luminosities to two detectors and proves to be a viable candidate for future linear collider projects.

The Compact Linear Collider (CLIC) could provide e⁺e⁻ collisions in two detectors simultaneously possibly at a repetition frequency twice the design value. In this paper, a novel dual Beam Delivery System (BDS) design is presented including optics designs and the evaluation of luminosity performance with synchrotron radiation (SR) and solenoid effects for both energy stages of CLIC, 380 GeV and 3 TeV. In order to develop the novel optics design, parameters such as the longitudinal and the transverse detector separations were optimized. The luminosity performance of the novel CLIC scheme was evaluated by comparing the different BDS designs for both energy stages of CLIC. The dual CLIC BDS design provides a good luminosity and proves to be a viable candidate for future linear collider projects.

For future linear colliders, a nanometer-scale beam size at the interaction point (IP) is one of the most challenging technical aspects. To explore the feasibility of a final focus system with a high chromaticity level, comparable to that of the Compact Linear Collider, the ultralow beta* optics has been proposed and tuned at the KEK Accelerator Test Facility 2. In this paper, the recent experimental results are presented, which demonstrate the capability of achieving and stabilizing a vertical average beam size of 60 nm and below at the virtual IP. The observed vertical beam size is about 20 nm above the numerical predictions in the presence of static and dynamic imperfections. We interpret this discrepancy as beam size growth due to multipole fields, beam jitters and wakefield effects, and diagnostic errors.

The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear $e^+e^-$ collider under development at CERN. Following the CLIC conceptual design published in 2012, this report provides an overview of the CLIC project, its current status, and future developments. It presents the CLIC physics potential and reports on design, technology, and implementation aspects of the accelerator and the detector. CLIC is foreseen to be built and operated in stages, at centre-of-mass energies of 380 GeV, 1.5 TeV and 3 TeV, respectively. CLIC uses a two-beam acceleration scheme, in which 12 GHz accelerating structures are powered via a high-current drive beam. For the first stage, an alternative with X-band klystron powering is also considered. CLIC accelerator optimisation, technical developments and system tests have resulted in an increased energy efficiency (power around 170 MW) for the 380 GeV stage, together with a reduced cost estimate at the level of 6 billion CHF. The detector concept has been refined using improved software tools. Significant progress has been made on detector technology developments for the tracking and calorimetry systems. A wide range of CLIC physics studies has been conducted, both through full detector simulations and parametric studies, together providing a broad overview of the CLIC physics potential. Each of the three energy stages adds cornerstones of the full CLIC physics programme, such as Higgs width and couplings, top-quark properties, Higgs self-coupling, direct searches, and many precision electroweak measurements. The interpretation of the combined results gives crucial and accurate insight into new physics, largely complementary to LHC and HL-LHC. The construction of the first CLIC energy stage could start by 2026. First beams would be available by 2035, marking the beginning of a broad CLIC physics programme spanning 25-30 years.