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Chamonix Workshop 2026
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Europe/Zurich
le Majestic (Chamonix)
le Majestic
Chamonix
Oliver Bruning
(CERN)
Description
The 2026 Chamonix Workshop will take place from 2 - 5 February 2026 at the "Majestic" conference centre in Chamonix.
This Workshop will bring together CERN’s accelerator and experimental communities to reflect on past performance, address current challenges, and anticipate future advancements. As a cornerstone event in CERN’s calendar, the workshop fosters collaborative discussions that help shape the laboratory’s strategic direction.
Starting with a look back at 2025 operation, the workshop will address progress in the injector complex and LHC in preparation for the final year of Run 3 operation and highlight what is still to be learnt to be ready for post-LS3 exploitation. With LS3 looming large on the horizon, the majority of the workshop will be devoted to this transformative phase that will see major upgrades and consolidation across all of CERN’s facilities. Whilst ensuring readiness for High-Luminosity LHC (HL-LHC) takes centre stage, progress with preparation for consolidation of the North Area and ISOLDE, and construction of the HiECN3 facility will also be addressed.
The workshop will close with a look at how the outcome of the European Strategy for Particle Physics (ESPP) will guide CERN’s future. This includes a review of progress on the Future Circular Collider (FCC), the technologies required for next generation accelerators and what we can learn from our non-collider physics programme.
Attendance is by invitation only and information regarding accommodation and practical details will be sent by the ATS Director office only.
Chair: Oliver Brüning
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Scientific Secretaries |
Giulia Papotti and Guido Sterbini (LMC) |
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Nikolaos Charitonidis and Sam Pitman (IEFC) Charlotte Duchemin (LS3C)
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Participants
209
View full list
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Session 1: Run 3 OperationConveners: Foteini Asvesta (CERN), Michi Hostettler (CERN)
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2
Injector performance 2025
The 2025 operation for the injector complex was remarkable in many regards. The delivery of the beam met expectations, with little to no exception, and records were broken in terms of total intensity delivery. The presentation highlights the achieved beam performance, with record operational intensity for the ISOLDE beams, record protons on target for the nTOF facility and the EAST area, as well as excellent delivery for the SPS North Area. High brightness beams were delivered to the LHC, making use of the experience gained to make HL-LHC beams operational in the injectors. These were demonstrated up to SPS extraction for the first time in 2025. Beyond records, beams still require significant attention to maintain their quality. The question is raised regarding the effective cost to keep this level of performance and how to sustain a culture of excellence more efficiently. It is first shown that the good performance can be attributed to the high availability of the hardware and that future performance is determined by consolidation of ageing equipment. Selected examples of improved monitoring and automation are highlighted to illustrate the work done to address the request for improved reliability of the injector complex and reduce the number of manual interventions. The presentation concludes on the point that no important change of operational configuration is expected in 2026, and that the focus is put on activities to prepare for operation in Run 4 with HL-LHC and high-performance fixed target beams.
Speaker: Alexandre Lasheen (CERN) -
3
LHC proton performance 2025
The 2025 LHC proton run marked the most productive year of Run 3, delivering record integrated luminosities while operating under increasingly tight hardware and radiation constraints.
The operational cycle was modified to mitigate radiation damage to the IP5 inner triplets by inverting magnet polarity and rotating the crossing angles at both IP1 and IP5, resulting in a flat, asymmetric β optics scheme.
Luminosity production was optimized thanks to combined separation, β, and crossing-angle levelling. A small but constant luminosity imbalance between ATLAS and CMS emerged after the crossing angle change, and studies were conducted to understand and mitigate the issue.
Automation significantly improved operational efficiency and reproducibility. Efforts to improve existing tools, as well as the creation of new ones, reduced human error and commissioning time, while maintaining operator oversight. Further automation during LS3 is identified as critical to reduce expert workload during commissioning in the HL-LHC era.
Performance targets were exceeded: ATLAS and CMS achieved 125 fb⁻¹ (vs. a 120 fb⁻¹ target), and LHCb delivered 12.5 fb⁻¹, surpassing its full Run 1+2 statistics. Availability and turnaround matched the best Run 3 year (2024).
Among the main issues in 2025, many were due to radiation-induced effects (R2E), particularly affecting the cryo system at Point 8 due to increased LHCb luminosity.
The issue with RF module M1B2 degradation, ongoing since 2023, also impacted availability.
Vacuum issues in the interconnect module VMSIO 6L2 imposed bunch intensity limits and required asymmetric beam operation. Problems with vacuum leaks at collimator bellows highlighted the proximity to hardware end-of-life. Hierarchy breakage at high intensity underscores the need for enhanced validation strategies ahead of HL-LHC.Speaker: Delphine Jacquet (CERN) -
4
Ions through the complex - injectors to LHC - 2025 and outlook to 2026
The 2025 ion programme at CERN was exceptionally challenging, delivering oxygen, neon and lead beams to fixed-target experiments and the Large Hadron Collider within a very tight schedule. It combined a short and complex light-ion run in summer, requiring rapid commissioning of the full injector chain for new species and several non-standard LHC configurations, with a high-performance Pb–Pb run at the end of the year.
Injector performance was overall excellent, delivering stable intensities well above LIU targets for most of the year, thanks to improvements implemented and operational experience accumulated in previous years. The 2025 Pb run achieved high intensities and very good transmission along the accelerator chain to the LHC. However, a major power cut significantly degraded LEIR performance, with difficult recovery and reduced intensity for a fraction of the run, highlighting the need for improved monitoring and diagnostics.
LHC Pb–Pb operation closely followed the very successful 2024 configuration. Beam transmission and bunch intensities exceeded HL-LHC targets, and luminosity production surpassed goals for all experiments, supported by mitigation of previously encountered LHC issues. Constraints of the ALICE detector nevertheless imposed a lower luminosity-leveling target, and some experimental background issues remain to be addressed in 2026. In parallel, new Pb beam schemes aimed at further increasing LHC luminosity were successfully tested during MDs, achieving record bunch intensities and the first Pb collisions with 25 ns bunch spacing.
The light-ion run was operationally demanding but highly successful. Oxygen and neon beams were commissioned rapidly, with a fast and transparent switch between species, and luminosity targets were exceeded by large factors. Overall good availability, resulted in excellent physics output and confirming that ion operation is already in the HL-LHC era. In 2026, the focus will be on the Pb run to reach the overall Run 3 luminosity targets, together with a proposed short O⁸⁺ beam test up to the PS to prepare for future ion operation.Speaker: Theodoros Argyropoulos (CERN) -
10:15
Coffee break
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5
Injector / fixed target experiment feedback and priorities 2026
Last year, 2025, was, once more, a very successful year, during which all LHCC and SPSC related beam requests could be fulfilled.
Most other user requests for the Proton Run could also be covered, while for the Pb Run, shortened to only 10 days, several requests for test beam had to be refused/postponed to 2026.
All experiment requests were fulfilled, both for the proton and Pb runs.
The feedback from experiments/test beam users is, overwhelming positive.
They could all, with a single exception, achieve their scientific goals.
The exception was NA61/SHINE which could not collect the needed statistics and had to be rescheduled this year for two weeks of additional data taking.
The dedication and commitment of all people involved in the running of the FT facilities, from machine operators to beam physicists, support services and experimental area managers is highly praised by all groups, without exceptions.
The impact of the LHC filling on the NA was not negligible, especially during the Pb run.
This year, 2026, will be an interesting year, with less than 70% of the beam time available, compared to 2025, but with an increasing/stable number of requests and equally demanding requirements in term, for instance, intensity and total PoT.
ISOLDE and AWAKE being already in LS3 will hopefully help to mitigate.
The impact of the several MD’s and tests foreseen in preparation of HL-LHC on the availability of the beam, especially in the NA, is difficult to foretell and the LHC Pb Run will fully overlap with the proton run in the East and North Areas.
The very large number of requests community , often with conflicting requirements (most of them concern the second half of the proton run) and increasing year after year, makes scheduling very difficult. Experiments based not only at CERN but worldwide, rely on the CERN facilities to develop their detectors.Speaker: Paolo Martinengo (CERN) -
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LHC experiment feedback and priorities 2026
The year 2025 was marked by outstanding performance of the CERN accelerator complex and the experiments, leading to exceptional productivity. The physics program included proton–proton (pp) and lead–lead (PbPb) data taking with corresponding van der Meer scans for luminosity calibration, as well as a dedicated period of light-ion (pO, OO, NeNe) collisions. The luminosity targets defined by the four main experiments were surpassed for all collision systems. Despite a few operational challenges, all issues were promptly resolved, ensuring smooth operation. Particularly remarkable was the light-ion run, during which the delivered luminosity exceeded expectations by more than an order of magnitude.
Throughout 2025, the experiments operated with impressive efficiency, delivering high-quality physics results from Run 3 data. These analyses advanced precision tests of the Standard Model, searches for new physics, and studies of the quark–gluon plasma. The first measurements based on light-ion data were produced extremely rapidly.
The 2026 run will be comparatively short, with 53.5 days dedicated to pp physics and 18 days to PbPb collisions, and the corresponding van der Meer scans. Following these periods, two weeks will be allocated to high-intensity machine tests in preparation for the High-Luminosity LHC. These tests aim to identify potential hardware limitations of the LHC in view of Run 4 operations.
During the 2026 pp running period, ATLAS and CMS will perform low pile-up data taking over a three-week interval to enable precision measurements of the W boson mass. The schedule also includes a two-day dedicated run at √s = 2 TeV for LHCb, to study cosmic antiproton production.
To enhance the likelihood of success of the high-intensity tests at the end of the run, it is proposed to advance a two-day block of these tests to the first Machine Development (MD1) period. This advancement is supported by conditions that mitigate associated risks: operating with single beams and imposing constraints on beam-induced power increases. Any resulting downtime from this advancement shall be distributed equitably between physics data taking (pp and PbPb) and machine activities (MD and high-intensity tests).Speaker: Chiara Zampolli (CERN) -
7
LHC limitations, configuration & cycle 2026
Given the short length of the run, the re-commissioning and the risk of down time must be reduced to the minimum while meeting the requests for proton physics and special runs. For this reason, the LHC cycle proposed for 2026 is almost identical to the one of 2025, featuring only a well tested optimisation of the cycle length by combining multiple operations during the ramp and a possible extension of the beta* levelling. The low pile-up run for ATLAS and CMS can be performed without overhead using the same cycle. The details of the SMOG run are still under discussion. It is expected to reach the targetted bunch intensity for Run 3 of 1.8·1011 p/b for both beams thanks to a sensible scrubbing that occured during 2025 and the repair of the non-conforming vacuum module at 6L2. The secondary collimator featuring a vacuum leak at its bellow was exchanged thus restoring nominal performance for the collimation insersion. Some magnets in the high luminosity insertions have reached or will reach their damage limits. Procedures are ready in case of a failure, yet with an associated downtime.
Speaker: Xavier Buffat (CERN)
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2
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16:00
Coffee break
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Session 2: Preparing for Run 4Conveners: Alexander Huschauer (CERN), Helga Timko (CERN)
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8
Beam performance and preparation in the injectors
2025 marked a key step in demonstrating HL-LHC beam performance in the injectors and in establishing the first reference points for fixed-target high-intensity beams. The outlook for 2026 is more demanding, with the SPS reliability run emerging as a critical milestone in preparing for HL-LHC operation. A key pre-LS3 milestone for demonstrating injector readiness is the LHC high-intensity run. Continued improvements in injector performance remain essential to sustain fixed-target operation in the SHiP era and beyond. 2026 therefore represents a unique opportunity to explore operational limits, consolidate and validate tools, and strengthen confidence in HL-LHC operation under realistic conditions.
Speaker: Carlo Zannini (CERN) -
9
Perspectives on automation and improved efficiency
The Efficient Particle Accelerators (EPA) project, through collaborations across departments, is tackling key efficiency bottlenecks in the accelerator complex - spanning both automated beam production and equipment testing and operation. Progress is increasingly tangible: outcomes range from direct operational value (e.g. dynamic beam scheduling in routine use, deployed autopilots, and pilots for automated equipment testing/operation) to building blocks that feed into the long-term controls and automation strategy and help prepare for future facilities. While some solutions are already in routine use, others are still in prototype validation and need to mature towards operational deployment.
2026 is the final run year before LS3 and therefore a crucial window to consolidate. The priority is to validate prototypes while machines run, quantify their benefit, and close the remaining gaps so that LS3 can enable a structured transition from proofs-of-concept to operations-ready services.
Scaling beyond pilots is essential to unlock the full potential, particularly for equipment automation. Shared software and automation frameworks with common interfaces can lower technical adoption barriers for developers and make deployment repeatable across the complex. This aligns directly with the CTSB long-term controls strategy: coherent, centralised frameworks and interfaces are a prerequisite for sustainable roll-out. Beyond the technical barriers, embedding the required competencies in the relevant groups remains an organisational challenge that also needs to be addressed.
A next key milestone is the EPA project review in October 2026, which will inform post-2027 direction and funding.
Speaker: Michael Schenk (CERN) -
10
LHC beam limitations: protection strategy for the 2026 high-intensity tests
Experience from recent years demonstrates that beam limitations can be handled safely through a structured machine protection strategy combining step-wise intensity increases, dedicated diagnostics and close coordination between OP, MPP/rMPP and equipment teams. The application of the MPP procedure for sparking RF fingers in 2025 showed that local degradation of RF contacts can lead to increased beam-induced heating and vacuum activity without necessarily posing an immediate risk to aperture or device integrity. Important ingredients for operating with such a limitation have been careful monitoring, impedance studies and clearly defined operational limits.
For 2026, the main potential limitations are identified and mitigation paths are in place. The TCLD in IR2 shows recurrent vacuum activity, with a specific sensitivity to certain beam configurations. While the origin is not yet fully understood, simulations and measurements on spare devices indicate a possible degradation of RF finger contacts, but no risk to the device itself. The observations from the planned gap change and studies in the lab will provide important input for a possible modification of the spare TCLDs during LS3. For MDs, an increase of the TCLD vacuum interlock threshold to 2 × 10⁻⁵ mbar is proposed, with a progressive, fill-by-fill relaxation during the high-intensity test under rMPP supervision.
Consolidation of warm RF finger modules is well advanced, with only a limited number of potentially critical modules remaining in 2026. With reliable bunch length control and interlocking, no limitations are expected; replacement scenarios are defined. For the TCDS, operation beyond its specifications during the high-intensity test is considered acceptable by MPP and the respective equipment team, acknowledging a very low-probability risk of local damage in the case of an asynchronous dump.
To identify potential unknown limitations relevant for Run 4, MPP supports a carefully risk-managed programme in 2026, including increased beam-induced heat load during MDs and probing HL-LHC intensities at 3.0 TeV and 6.8 TeV during the high intensity test in the final two weeks of Run 3. This will be done by deliberately stepping beyond the established protection envelope for selected equipment, while maintaining machine safety through incremental intensity increases, selective threshold adjustments and continuous expert support via the rMPP, reinforced by heating and vacuum experts.Speaker: Daniel Wollmann (CERN) -
17:50
Coffee break
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11
LHC plans for high-intensity MDs and 2026 tests
2026 represents the last opportunity to probe HL-LHC operating conditions before LS3 and identify device limitations at HL-LHC intensities, while there is still time to implement mitigations during LS3. For this reason, two weeks at the end of the 2026 run will be dedicated to HL-LHC validation tests. A tentative High-Intensity test program has been defined, consisting of tests at two energies (3 TeV and 6.8 TeV) and using three beam types (STD, BCMS and 8b4e), while respecting present constraints such as e-cloud heat-load limitations. Building on this baseline plan, two proposals are put forward to significantly increase the value of the tests. Proposal "Week 1" advances selected 3 TeV high-intensity tests with single-beam operation into MD1. This allows hard limits to be identified early, reduces the risk of early showstoppers during the dedicated High-Intensity test and preserves time to adapt procedures and recover ahead of the final tests if needed, maximising the overall success probability. To control the risk for the 2026 Physics operation that follows, operational levels in MD1 will be exceeded gradually, with intensity increased in small steps from 25% up to 40% above operational levels. The tests in MD1 will be performed with a single beam, alternating between B1 and B2, to cover a large fraction of the machine while reducing the risk for elements in the common regions. Proposal "Week 2" foresees a controlled exceedance of the TCDS “safe” intensity limits at 6.8 TeV for a short period of time, enabling, for the first time, the validation of HL-LHC baseline conditions at top energy, while providing valuable operational experience under HL-like conditions
Speaker: Sofia Kostoglou (CERN) -
12
RF limitations and mitigation measures in the LHC
This contribution will outline the main limitations of the present and future RF systems in the (HL)-LHC.
With the improvements implemented in RF controls and calibrations and the addition of the HE-klystrons, the main RF system is expected to capture, accelerate and store the HL-LHC beams with 2.3e11 p/b. Some open questions on how to handle the un-captured beam at injection and reliable operation with HE-klystrons have yet to be demonstrated, but no show stoppers are expected.
The 1-turn feedback (aka betatron comb filter) will be implemented as a baseline to achieve the transverse stability requirements for the crabbing mode. Some detailed aspects of the notch filter bandwidth including the differences in the horizontal and vertical plane are being worked out. The implementation of the ultra-low noise feedback system using the crab cavities also as a part of the baseline will ensure the emittance growth budget from the RF noise. However the technical implementation to reach the required specification remains at the edge of the today's technology and the full demonstration including the operational aspects in the HL-LHC still pending.
The longitudinal impedance model indicates some discrepancy with recent MD data hinting to missing impedance sources in the model. A detailed modeling of the impedance is being improved over the last years and implementing new elements in Run 3 and LS3. Nevertheless, predictions for HL-LHC with today's model show no margin for the coupled bunch instabilities with future narrow-band impedances (crab cavities or other). MDs are foreseen in 2026 to probe the narrowband impedance budget. Mitigations should include an impedance reduction campaign on top of improving the model for better predictions. Two options for increasing the thresholds either in the LHC with a 800 MHz harmonic system or with 400 MHz system in the SPS are discussed. Synergies with FCC are highlighted. Present status of the ADT system is mentioned with improvements already implemented and consolidation activities foreseen.Speaker: Rama Calaga (CERN) -
13
Status of the beam screen treatment project
The Beam Screen Treatment (BST) project aims at recovering efficient beam screen surface conditioning in the LHC arcs, to mitigate high beam-induced heat loads developing during beam operation. This will be achieved by coating the beam screens of 120 selected arc half-cells with a 15 nm-thick carbon layer during the Long Shutdown 3.
Developments carried out in a full-scale beam line mock-up have now concluded on the best coating implementation recipe. A series of 4 coating trains (carrier of the graphite target being sputtered in the beam screen) is assembled in the half-cell beam line. A system of spools actuated by external motors ensure the independent powering of the plasma discharge for each train via in-vacuum electrical cables, while the train displacement along the beam line is ensured by a mechanical cable. A carbon coating performed with this scheme efficiently conditions at 15K, i.e. its Secondary Electron Yield is reduced below the multipacting threshold of 1.1, as confirmed by laboratory measurements. Similar coatings have proven to condition over at least 3 cycles of electron irradiation / 3 months storage in saturated humid atmosphere. Despite a visible reduction of the carbon concentration over cycles, this confirms the surface robustness against the future venting(s). Preparation for LS3 campaign, including integration and procurement of coating systems, is on-going according to this implementation scheme.
In parallel, a strong need persists for measuring heat loads with HL-LHC beam at 6.8 TeV, to refine the heat load predictions for Run 4, in particular for un-coated half-cells, and, within planning and resources constraints, adjust the BST half-cell selection, if relevant.
Finally, the management of the beam vacuum system during warm-up and PIM buckling detection phases are being revised to limit the exposure of the beam screens to uncontrolled atmosphere.Speaker: Valentine Petit (CERN) -
14
Backgrounds and operational impact of forward physics at the LHC
The Run 3 LHC forward‑physics program for proton operation comprises FASER and SND (placed in side tunnels on each side of IP1) and the PPS (CMS) and AFP/ALFA (ATLAS) roman‑pot systems. FASER and SND faced a sharp rise in high‑energy muon background in 2024 when the inner‑triplet polarity in IR1 was reversed; after restoring the nominal polarity, 2025 rates remained elevated (≈ 1.1‑1.4 ×) due to horizontal crossing angle. FLUKA + Geant4 simulations reproduced the data within 10‑30 %. Mitigations through orbit bumps were tested with low intensity. They reduced the muon flux by 10‑20 % but were not adopted for 2026 operation.
For Run 4 (HL‑LHC), AFP and ALFA will be removed, PPS will be upgraded to PPS2 and FASER and SND will continue operation with upgraded detectors. Simulations predict a 7‑8‑fold increase in muon flux at SND in Run 4, driven mainly by the higher luminosity and larger triplet aperture, and similar factors could be expected at FASER. Consequently, SND will replace emulsion plates with an electronic detector that can handle the high muon rates without need for accesses. FASER considers using emulsions only if the background can be kept near 2023/2025 levels, in which case 2‑3 accesses of 4 h each would be requested each year for emulsion exchanges, with very small operational impact. Unless mitigations can be found for Run 4, the predicted muon backgrouns will be too high, and FASER will in that case not use emulsion detectors and instead switch to an electronic detector.
In Run 4, PPS will be upgraded to PPS2 and operate as a standard CMS sub‑detector. The operational impact will be similar to Run 3, with beam-based alignment each year. PPS2 is compatible with present HL-LHC baseline optics and collimator settings and has to go through the standard approval process for LHC installations. No special high‑β* runs are requested.
Speaker: Dr Roderik Bruce (CERN)
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8
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Session 3: LS3 injectors & Expt Facility Readiness for Run 4Conveners: Claudia Ahdida, Johannes Bernhard (CERN)
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15
Nuclear dismantling activities in LS3
While LS3 is primarily driven by large-scale upgrades, consolidations, and preparations for future physics programs, it is also characterized by a significant increase in nuclear dismantling and decommissioning activities. These projects are no longer peripheral tasks but have become strategic prerequisites for the installation of new facilities, the reuse of existing infrastructure, and the long-term sustainability of CERN operations.
Several major dismantling projects are planned (or already ongoing) during the LS3 period and they represent a major technical, organizational, and radiological challenge for CERN.
CNGS Target Area Dismantling (CTD) is an on-going operation and is a prerequisite for AWAKE Run 2c.
The dismantling and replacement of the current beam dumps of ISOLDE is necessary for the long term operation of the facility.
In the North Area, the TCC2 and TCC8 dismantling are major milestones for NA-CONS and HI-ECN3 project.
These dismantling operations require expertise, careful preparation, dedicated resources, and strong coordination across many groups. When properly planned and executed, these activities directly support CERN’s long-term operation, sustainability, and future scientific ambitions.Speaker: Nicolas Quinquis -
16
ISOLDE Upgrade and Plans for Run4 and beyond
ISOLDE is a unique CERN facility using GeV protons from the PS Booster to deliver low-energy and post-accelerated radioactive ion beams (RIBs). It serves a large and diverse user community, exploiting 15 state-of-the-art instruments to conduct a rich and diverse scientific programme. The ISOLDE Improvement Programme is a coordinated effort capitalising on planned CONS activities, dedicated MTP allocations, and a contribution from the ISOLDE collaboration to increase the capability and capacity of the facility and address the backlog of planned experiments.
LS3 has started for ISOLDE, driven by the need to replace the beam dumps, an activity requiring a two-year intervention. A major upgrade of the ventilation system is well underway, with most of the work anticipated during the last two years and in parallel with operation. The BTY line modifications for 2 GeV operation, the RILIS upgrade, and several consolidation and improvement activities on the low-energy beam lines will secure and enhance the quality and diversity of beams for Run 4.
For the REX/HIE-ISOLDE linac, the key activity is the refurbishment of Cryomodule 1 (CM1), which is essential to recover the nominal accelerating gradient. CM1, which must be reinstalled in the linac by the end of 2027, will be removed from the machine in April 2026 to reduce schedule pressure and mitigate the risks inherent to a period such as LS3, when teams are also committed to other CERN projects.
For the post-LS3 period, the roadmap will be driven by the outcome of a feasibility study to design and operate next-generation Frontends (target stations) compatible with remote handling and capable of sustaining higher instantaneous and average proton intensities. A similar approach, complemented by the continuation of machine development studies with high-intensity beams, will be pursued for targets. These activities are required to address future beam-sharing constraints with HI-ECN3 and to fully exploit the maximum beam intensity available from the PS Booster. In parallel, the construction of a spare cryomodule (CM5), with a target horizon around 2030, is required to allow routine cryomodule maintenance and preserve the nominal accelerating gradient of the REX/HIE-ISOLDE linac. Maintaining this gradient is essential, as reduced performance would directly impact the ISOLDE experimental programme by reducing the number of deliverable experiments and degrading the quality of the physics results.Speaker: Joachim Vollaire (CERN) -
17
North Area Experiments in Run 4
The Run 4 North Area physics programme is ambitious but achievable, with the infrastructure readiness aligned with the evolving experimental landscape. Demand continues to grow across fixed-target experiments, test beams, and irradiation facilities, with increasing pressure for higher intensities, greater flexibility, and faster changeovers. New flagship programmes and proposals add to an already rich portfolio of running and planned experiments, while test-beam and irradiation activities remain highly subscribed and critical for HL-LHC and future FCC detector R&D. In this context, CERN will remain a unique worldwide facility capable of delivering the full range of beam types, intensities, and energies required by these communities.
Key pressure points have been identified, notably competition for shared beamline infrastructure, long changeover times (particularly in M2), target and radiation-protection limits on delivered intensity, and finite access and resources during LS3. To address these a list of upgrades have been proposed for the M2 and H4 beamlines which promises to be the most subscribed for fixed target experiments and electron beam users respectively. A first optimisation exercise has been performed, based on known experiment running timelines, to structure the upgrade scope into LS3-critical and post-LS3 activities. This enables a realistic alignment with LS3 resource constraints. LS3-critical upgrades focus on changes required at the beginning of Run 4 and aim to improve flexibility, beam quality, and changeover times, while additional improvements are staged post-LS3 to avoid blocking Run 4 start-up. The LS3 critical upgrades are also flexible in terms of the installation schedule within LS3 and shall be planned with the shutdown activities as a priority. For NA60+, a staged approach is recommended, with LS3 dedicated to studies and preparation and major infrastructure changes implemented post-LS3.
Overall, LS3 decisions will directly determine Run 4 performance. Early prioritisation, protection of the NA-CONS and HI-ECN3 critical paths, timely completion of implementation studies, and sustained cross-group collaboration are essential to convert physics ambition into reliable delivery. Looking beyond Run 4, supporting a coherent and sustainable roadmap for fixed-target and test-beam programme into Run 5 and beyond is critical.Speaker: Dipanwita Banerjee (CERN) -
10:00
Coffee break
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18
NA-CONS Readiness for LS3
The North Area Consolidation Project (NA-CONS) is overall on track and demonstrates a high level of readiness for LS3 and the subsequent start of Run 4. All planned activities, including the full renovation of TCC2 and TDC2, the required beamline upgrades for HI-ECN3 and the major consolidation works in BA80, are fully integrated into the NA-CONS planning. Project execution is closely monitored through resource-loaded planning, float tracking, milestone control and regular work-package reviews.
The current planning confirms that the full scope can be executed within the LS3 timeframe. However, schedule margins are very limited, in particular for TCC2 and BA80, resulting in a strong dependency on parallel activities and tight coordination, especially with cabling and infrastructure works.
Several critical topics are being actively managed. These include procurement and cost risks related to POLARIS and BOREAL power converters, the challenging procurement of radiation-resistant cables, the potential need to replace under-rated DC cables, and the availability of approximately 850 m² of storage space for highly radioactive components, which is indispensable for the TCC2 renovation. For all identified risks, mitigation measures are in place, dedicated task forces have been appointed, and planning optimizations are ongoing. Nevertheless, unresolved issues could still impact the Cost to Completion and the start of NA physics if not resolved in time.
In summary, NA-CONS is technically and organizationally well prepared for LS3, with strong project governance and close monitoring in place. Successful execution will critically depend on continued proactive risk management, supply-chain stability, and very strict coordination across all involved stakeholders.
Speaker: Thomas Zickler (CERN) -
19
HI-ECN3
The HI-ECN3 project has made strong progress over the past year and is now converging on its Facility Technical Design Report. Extensive work across accelerator systems, infrastructure, civil engineering and safety has clarified requirements and translated them into concrete designs and LS3-ready activities. HI-ECN3 and the SHiP experiment work in close coordination, and SHiP’s staged implementation strategy, endorsed by the SPSC, will enable commissioning and background validation in Run 4.
The project is now entering a milestone-driven phase with Work Package Descriptions to be available shortly for scrutiny by the Group Leaders. The Facility TDR will be reviewed and published in 2026, followed by a Cost, Scope and Schedule Review to establish a project baseline. This step will be essential to align priorities with CERN’s available resources and to formalise commitments ahead of LS3 execution and Run 4 operation.
NA-CONS Phase 1 upgrades are being integrated into LS3 planning, while extensive preparation is underway to ensure safe and coordinated dismantling activities, in particular for NA62. Civil engineering studies have matured substantially, including the integration of the B754 service building and its Class A service cell, which is now approaching the start of procurement following dedicated design, regulatory and safety reviews.
On the beam side, developments in slow-extraction beam-loss reduction show promise and may already reach the performance required for BDF/SHiP before LS3. Prototype beam-dump target tests performed in 2025 are reassuring, and preparations for a high-power helium-cooled target test in 2026 are well advanced. These results provide growing confidence in the technical robustness of the baseline design.
The coming period will be decisive, with the launch of major procurements and the establishment of a consolidated project baseline, positioning HI-ECN3 for LS3 execution and subsequent Run 4 operation.
Speaker: Matthew Alexander Fraser (CERN) -
20
ACC-CONS overview
CERN’s Accelerator Consolidation Programme is all about keeping its ageing accelerator complex reliable, safe, and high-performing while working with tight budgets and growing demands. The focus is clear: complete the HL-LHC by 2030 and prepare for the future, like the FCC-ee. But with a 42% cut on the consolidation budget over the past eight years and theoretically only 4.9 MCHF left to approve new consolidation requests until 2035, the challenge is real.
The current situation:
- 231 ongoing projects (175.2 MCHF total) are spread across departments, with most 2026 funding going to SY, EN, and TE.
- 2025’s arbitration round saw 31 priority requests (37.5 MCHF), but pre-only a fraction were approved. Many were postponed, and over-costs are adding pressure.
- Non-collider physics (like ISOLDE and AD/ELENA) remains a priority, but it needs a long-term roadmap to avoid piecemeal fixes and missed opportunities.The way forward?
We need a smarter, more strategic approach: a long-term roadmap that balances immediate needs with future goals, avoids redundant requests, and ensures every Swiss franc is spent where it matters most.Bottom line: The clock is ticking. To stay ahead, we must align resources, priorities, and vision or risk falling short when it matters most.
Speaker: Rende Steerenberg (CERN)
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15
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16:00
Coffee break
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Session 4: HLConveners: Davide Bozzini (CERN), Susana Izquierdo Bermudez (CERN)
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21
QXL Cryogenic Lines: Technical Challenges, Installation Status, and Path to Full Deployment
The HL-LHC cryogenic system will include two new refrigerators and associated infrastructure, a new control system, and new Cryogenic Distribution Lines (QXL) replacing part of the existing LHC cryogenic distribution line (QRL) on each side of Points 1 (P1) and 5 (P5). The QXL will connect HL-LHC components to a new cold compressor box in a cavern near the LHC tunnel and to the existing cryogenic distribution. Each QXL is ~750 m long and will be installed in two phases: Phase 1 in the underground service galleries and Phase 2 in the LHC tunnel.
Phase 1 installation was delayed in 2025 after corrosion was discovered in the process pipes, requiring repair of 24 delivered pipe elements (PE) and those already in production. At Point 1, installation of Phase 1A1 using repaired segments started in October 2025 and was completed in January 2026. All 48 affected segments were repaired and delivered to CERN by the end of 2026.
In parallel, the contractor faced difficulties in design execution and component procurement. Procurement of compensation bellows (Phase 1) and cryogenic valves (Phase 2) was internalized. Despite corrective actions in early 2025, design progress remained incompatible with delivery of Phase 2 components by end of 2027, which are on the LS3 critical path. After an initial de-scoping of the Phase 2 preliminary design in June 2025, the detailed design and production of all 44 cryogenic modules were internalized, while the remaining 40 pipe elements stayed with the original contractor.
A major joint effort has been launched by the TE-CRG and EN-MME groups to ensure the design and production of the modules by the end of 2027. Additional personnel has been recruited, and a joint QXL design team is now operational to progressively deliver the required studies and drawings by June 2027. In parallel, procurement of the 44 cryogenic modules has been initiated, with the aim of placing production contracts by March 2026.
Speaker: Antonio Perin (CERN) -
22
HL-LHC Crab Cavities: Production status, Installation Plans & Contingencies
Superconducting RF Crab cavities (WP4 of the HL-LHC project) are complex equipment developed in close collaboration among several groups at CERN and within a large international collaboration including institutes from the UK, US, Canada and Japan. This novel concept of SRF cavities will allow reducing the crossing angle and maximize the luminous regions at the interaction regions in ATLAS and CMS.
Double Quarter Wave (DQW) cavities will crab the beam in the vertical plane, and 8 of them will be installed around the CMS experiment (4 on each side of the experiment). Radio Frequency Dipole (RFD) cavities will crab the beam in the horizontal plane and 8 of them will be installed around Atlas. The cavities are grouped by 2 into a cryomodule (CM). So, in total 4 DQW cryomodules and 4 RFD cryomodules will be installed in the LHC. One additional DQW cryomodule and one RFD cryomodule will be produced as spare equipment.
The SPS prototype testing program will conclude in June 2026. The successful installation and operation of both DQW and RFD cryomodules have de-risked both technical and operational aspects. The program has also provided valuable operational experience for Run 4 start-up.
DQW series production is progressing according to plan. 4 fully qualified DQW cavities were delivered to UK-STFC. UK cryostating activities are well streamlined to deliver CM #2–5 on schedule. Assembly of CM #1 will start at CERN this year.
The first series RFD cavity from US-AUP has been successfully delivered to TRIUMF. The activities at TRIUMF are ramping up. The mitigation plan presented at Chamonix last year has been fully implemented at CERN and TRIUMF to maintain the installation of the full system during LS3.
All major contracts for High Power RF & Controls are launched. The current delivery schedule is compatible with the installation timeline.Speaker: Ofelia Capatina (CERN) -
23
HL-LHC Magnets – Manufacturing, Retrofitting, Testing, and Installation Readiness
Superconducting magnets for the HL-LHC fall under Work Package 3, which covers the new Nb₃Sn triplet quadrupoles, and the Nb-Ti dipoles and correctors. A complete set of triplet and D1 cryo-assemblies was completed and installed in the IT String in 2025.
Q2 cryo-assemblies are the most advanced in terms of readiness for LS3 installation: six of the eight units have been tested horizontally, five of them fully configured for tunnel installation and ready for beam-screen installation. All Q1 and Q3 magnets have been qualified through vertical tests; two corresponding cryo-assemblies have undergone horizontal testing and are currently being cryogenically configured. All four D1 magnets have been vertically tested, with one complete cryo-assembly finished and fully qualified. Two D2 magnets have been tested, and a third is in the final stages of cryostating.
With most magnet production now complete, the success of the programme increasingly depends on cold testing and cryostat assembly, and therefore on the efficient use of the SM18 and SMI2 facilities. This will be critical in 2026 as production and qualification of new cryo-assemblies continue, and in 2027 when LHC Q4, Q5 and Q10 magnets are removed from the tunnel for refurbishment. In SM18, the 1.9 K pumping capacity is shared between magnet tests, the IT String, and superconducting cavity testing, requiring close coordination and sustained collaboration between teams. In SMI2, constraints are driven by the limited space under the 40 tonne overhead crane and by specialised cryostating tooling, which, while adequate for the planned schedule, leave little margin for logistical inefficiencies or unexpected technical issues. Maintaining focus and fully leveraging the experience gained so far will be essential to meet the challenges ahead.
Speaker: Delio Ramos (CERN) -
18:00
Coffee break
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24
HL-LHC IT String: Lessons Learned and the Road Towards the Validation Program
After a pivotal year in 2025 for the HL-LHC Inner Triplet (IT) String facility, and as preparations for the cool-down and powering tests of the installation intensify, this presentation reviews the major achievements of the past year and provides an overview of the organization of the IT String team and HL-LHC WP16 in view of the upcoming challenges.
The presentation also describes the vacuum leak non-conformity encountered in the HL-LHC IT String, which was discovered in July 2025. The timeline leading to a full understanding of the non-conformity, as well as the definition and implementation of the repair strategy, are discussed. These actions enabled the final closure of the magnet interconnections and the start of the insulation vacuum pumping of the repaired system, during the first days of 2026.
With the cool-down of the IT String facility scheduled for February 2026, the progress and methodology for the preparation of the required safety documentation are presented, with particular emphasis on the safety clearance and the cool-down permit.
The updated timeline of the IT String validation program, aligned with the announcement of the HL-LHC Cost and Schedule Review 2025, is presented, and the major steps towards a successful program are described. The required documentation and the software and control infrastructure for the validation program, are also detailed, highlighting the robust preparation for the next phase of the IT String.
Finally, in line with the progress of the String Validation Program, which represents a cornerstone for the Hardware Commissioning (HWC) of the HL-LHC magnet circuits and related systems, the next steps and organizational aspects of the HL-LHC HWC are outlined. The completion of a high-level HL-LHC HWC document defining the scope, content, and responsibilities is targeted for the end of 2026.
Speaker: Samer Yammine (CERN) -
25
From IT-String Nonconformity to HL-LHC Solution: Redesigning the N-Lines Busbars Layout
Following the nonconformity identified after the insertion of the N-lines busbars in the IT-String, a revised busbar system layout and updated components have been proposed for the HL-LHC installation. The redesign introduces a reduced-diameter cable for the trim circuits of the main quadrupole and the orbit corrector magnets. This design change relaxes mechanical integration constraints, improves the clearance required for inserting the N-lines inside the cryostat, and significantly eases the integration of all splices at each cryostat interconnection.
The proposed busbar layout foresees the insertion of the busbars inside the cryostat during the cryostating phase, followed by splicing at each interconnection. This approach eliminates the need for N-line pulling operations in the tunnel and simplifies the management of the extra-length budget required to accommodate thermal contraction of the busbars.
The design updates have been formalized through an Engineering Change Request (ECR), which is currently under review and has been presented during a design review to a panel of senior advisors. Cable requirements related to circuit operation and protection are presented, together with the methods foreseen for cable fabrication and preparation.
Most of the key features of the proposed busbar layout have already been implemented during the IT-String repair and are expected to be validated through the ongoing IT-String validation program. In parallel, development activities and tests on mock-ups are currently ongoing. Busbar production is planned to start in 2026, alongside updates of the assembly procedures and quality assurance controls.Speaker: Lucie Baudin (CERN) -
26
HL-LHC Cold Powering: Insights from Assembly & Tests and the Challenges Ahead for Installation
The HL-LHC Cold Powering Systems connect the power converters in the newly dug Service Galleries at Point1 and Point5 to the Inner Triplets and Matching Sections magnets located in the LHC tunnel. In total, eight systems plus two spares are produced and qualified at the surface by end 2027, and eight will be installed in the underground galleries between Q2-2028 and Q2-2029. The assembly of the fourth Inner Triplets System is close to completion. Two systems were cold tested in 2024 and 2025 and demonstrated identical electrical, mechanical and thermal performance, fully compliant with specifications. These results bring confidence in the robustness and repeatability of the systems to come. Concerning the Matching Sections Cold Powering systems, the first assembly, presenting a total length of about 130 meters, is in progress. It uses tooling and QA plan of the Inner Triplets. The completion of the cold test of this first unit is expected by summer 2026.
Regarding the installation during LS3, the preparation is advancing according to plan. Challenges are properly identified and action plans are established to ensure timely qualification of procedures, tooling and personnel, in due time for the execution.Speaker: Yann Leclercq (CERN)
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Session 5: LS3 HL and LHC SystemsConveners: Hector Garcia Gavela (CERN), Joao Batista Lopes (CERN)
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MME workload prior and during LS3
The presentation highlights the contributions of the EN-MME Group to the preparation and execution of LS3 activities, with a particular emphasis on how MME capabilities and services, spanning engineering, design, fabrication, subcontracting and materials science, are mobilised to provide transversal support to critical deliverables across the Organization. It also recalls the organization of the EN-MME Group and the distribution of its resources across different personnel categories.
The current LS3-related contributions of EN-MME are reviewed, including deliverables for the HL-LHC work packages, LHC projects, interventions and technical support to the LHC experiments, as well as major activities for the SPS and PS complexes and related facilities. In addition, non-LS3 activities and ongoing work in support of future projects are briefly addressed.
The presentation then outlines the EN-MME workload currently expected over the coming years for both LS3 and non-LS3 activities, based on the present planning baseline and informed by the experience gained during LS3. On this ground, the group’s expected capacity margins to accommodate unforeseen requests is derived. The potential impact of such requests, and of their timing, on existing commitments and priorities are also recalled.Speaker: Alessandro Bertarelli (CERN) -
28
HL-LHC Vertical Cores
The High-Luminosity LHC (HL-LHC) project requires the construction of 28 vertical linkage cores to connect new service galleries with the LHC tunnel at Points 1 and 5. These cores, 1m in diameter and approximately 7m long, are critical for housing powering and control equipment. Following the IT-5063 tender in 2025, a Swiss joint venture was selected based on technical merit and a competitive schedule that reduced the LHC intervention window from 8.5 to 5.5 months.
To optimise time spent in the LHC, since this activity is on the critical path of LS3, a two-phase methodology is presented, transitioning first from HL-LHC galleries intervention into a later LHC tunnel intervention. A key focus of this presentation is the validation through field tests conducted first at the ISR surface area and subsequently at UA17. These tests were essential to verify the compatibility and efficiency of the drilling methodology in a real-world environment.
The experience gained from these trials has allowed for the immediate identification of technical improvements and logistical optimisations. By integrating these lessons learned, the project will increase the robustness of the solution, ensuring a high level of operational readiness and disciplined delivery for the LS3 intervention.Speaker: David Rodriguez Gomez (CERN) -
29
(De-)cabling and other EN-EL core activities in LS3
The LS3 period remains the most demanding phase ever for EN-EL cabling and de-cabling activities, with volumes comparable to those presented in at Chamonix Workshop 2025 but now transitioning from planning into full execution readiness.
In addition to (de-)cabling, EN-EL will also execute a wide range of other LS3-critical activities, including electrical network consolidation, substation upgrades, protection systems, secured power networks, fibre infrastructure deployment and large-scale commissioning, all requiring tight coordination with machine and experiment schedules.
Since last year, major progress has been achieved in schedule optimisation, execution tools and organisational readiness. The HL-LHC signal patch-panel strategy has been technically validated, prototyped and costed, allowing more than 250 km of cabling to be anticipated during Run 3 and reducing LS3 critical-path exposure by several weeks. In parallel, automation solutions for de-cabling and cable bunching are being industrialised to reduce workforce pressure and improve productivity in large campaigns.
Execution robustness is reinforced through a dedicated LS3 quality framework, systematic issue tracking and reinforced site inspections. A group-wide planning tool (EL Planner) is now used as the single source of truth for coordinating projects, internal teams and contractor resources, enabling workload levelling and contingency scenario analysis. Contracting strategies have been adapted with a second installation contractor to protect LS3-critical activities, while procurement and stock management remain closely monitored.
In conclusion, while LS3 remains an exceptional challenge, EN-EL is now very close to having a consolidated execution plan, strengthened organization and concrete risk-mitigation measures in place. The focus is shifting from preparation to disciplined delivery, positioning the group to enter LS3 with a high level of operational readiness.Speaker: Jan De Voght (CERN) -
10:00
Coffee break
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30
ATLAS updates and readiness for LS3
The presentation will describe the status of the ATLAS detector and infrastructure upgrades with focus on the readiness of infrastructure upgrades for LS3. The remaining risks for deliverables on the critical path will be highlighted and possible mitigation strategies will be discussed.
Speaker: Martin Aleksa (CERN) -
31
CMS updates and readiness for LS3
The presentation highlights the status of the CMS experiment upgrades and the readiness of the global infrastructure for the execution of the LS3 program. Focus is given to highlight progress with respect to critical deliverables presented in Chamonix 2025 and areas of still open concerns.
Speaker: Paola Tropea (CERN) -
32
Some contributions to the experiments (Beryllium, CO2 Cooling Transfer Lines,...) from the accelerator sector
This contribution presents some of the most relevant deliverables from the ATS sector to the LHC experiments, with a primary focus on activities supporting the production of beryllium beam pipes and CO₂ cooling transfer lines.
The motivation for constructing the Be facility is recalled, highlighting the strategic need for in-house beryllium processing, qualification, and R&D capabilities. The project scope, achieved milestones, and next steps are described, together with possible additional uses of the facility for wider CERN needs.
The status of the CO₂ cooling technology project is reported, including milestones reached and planned LS3 activities.
An overview of other ATS activities is provided to illustrate the broader support and strong commitment to the success of the CERN experiments.Speaker: Isabel Bejar Alonso (CERN)
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16:00
Coffee break
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Session 6: LS3 Common TopicsConveners: Andreas Herty (CERN), Maria Barberan Marin (CERN)
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Run3 and LS3 safety related topics
The CERN Safety Policy is the cornerstone of Safety at CERN, and the challenges in matters of Safety at CERN, due to its unique nature, can be overcome thanks to a specific organisation in Safety.
In line with the learnings from LS2 and incident data, a focus has been made to highlight and remind CERN’s population on a number of topics across various Safety domains. This has also led to the establishment of the LS3 Safety Objectives, which will be ratified by the Executive Board in March 2026.
Attention is also made on the risk of normalisation of deviance in daily behaviours, with keeping a focus on Safety over schedule, alongside a view to protecting mental health.
The continuous improvement journey of CERN’s Safety Culture is also presented, alongside the need for clear communications on matters of Safety, that are properly disseminated to everyone down through the hierarchical chains of responsibility.
Continuous improvement and a healthy feedback culture are key to ensuring CERN is a Safe place to work for all its personnel in all respects, under the mantra of:
Stop. Think. Act.
Safety first. Safety always.Speaker: Simon Marsh (CERN) -
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Electrical Safety Project and its rollout
The Electrical Safety project (ESP) was launched by the Accelerators and Technology Sector (ATS) to improve the management of electrical risks in the CERN accelerators complex by establishing a robust regulatory framework and ensuring comprehensive understanding of the electrical risk across all locations.
Significant progress was achieved during the period 2024-2025, resulting in the development of a methodology and associated processes clarifying, simplifying and harmonising practices within ATS.
The stagged implementation of ESP methodology is foreseen to start in 2026 with the third Long Shutdown (LS3). Before deployment, a few prerequisites need to be fulfilled, namely ATS approval of the methodology, HSE confirmation of its compatibility with the future CERN Electrical Safety Rule and allocation of the necessary resources.
The rollout will be carried out along three independent lines: ‘Activities management’ (with clearer processes and responsibilities); ‘Systems compliance’ (with homogeneous approach); ‘Responsibilities within the powering chains’ (with identification of roles and responsibilities).
Introducing the ‘Activities management’ module at LS3 start is expected to deliver immediate operational benefits. The other two modules, while important, can be deployed later in 2026 or during LS3 once groups’ resource needs are established. The initial deployment scope (at LS3 start) will match the current available resources (with the objective of covering all ATS facilities as early as possible).
Several challenges remain for the first half of 2026, including finalisation of prerequisites (with an initial approval phase in March 2026). The contribution of HSE and ATS experts, and the support of management will be essential for a successful transition to the operational phase of ESP.Speaker: Anne-Laure Perrot (CERN) -
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Outcome of the Logistics and Storage Space Review
The LS3 Space Management & Logistics Review, conducted on 10 December 2025, evaluated CERN’s preparedness for the logistical, storage, and transport challenges associated with the Long Shutdown 3 (LS3), with a particular focus on radioactive components. The review identified both strengths and critical areas requiring immediate attention to ensure the shutdown proceeds efficiently and safely.
Current Status & Strengths
The review confirmed that logistics and storage strategies for non-radioactive materials are well-established and compliant with CERN’s operational and safety standards. The TREC system continues to provide robust traceability, and the roles and responsibilities of key stakeholders—including HSE, EN, SY, and TE—are generally clear. These elements form a solid foundation for LS3 operations.
However, the review highlighted remaining challenges in the management of radioactive materials, which pose the most substantial risk to the shutdown’s success.Key Challenges
Insufficient Radioactive Storage Capacity
The demand for storage space in Buildings B954 and B955 exceeds present availability, necessitating urgent solutions such as repurposing alternative locations or optimising existing space possibly through stacking methods.Improving Workflows in Temporary Buffer Zones
The logistics processes within temporary buffer zones require further attention, particularly regarding radiation protection (RP) measurements, traceability recording in TREC, and the division of responsibilities between EN-HE and SCE for handling. Without clarification, these zones risk becoming bottlenecks, leading to congestion and operational delays.Radioactive Transport Risks
The Internal Transport Module (ITM), critical for managing radioactive transport, is still under development. Delays in its completion or inadequate testing could disrupt transport operations. Additionally, uncertainty in dose estimates for transport personnel risks exceeding annual radiation limits, potentially leaving transport teams understaffed during peak periods.Unaccounted Experimental Materials
Materials from ATLAS and CMS, not fully integrated into current logistics planning, may introduce unforeseen demands on resources, further straining the system.Critical Recommendations
To mitigate these risks, the review committee issued eight actionable recommendations:R1: Establish a task force to address radioactive storage shortages and define clear acceptance criteria for storage buildings.
R2 & R3: Develop and document standardised workflows for temporary buffer zones, including RP measurements, traceability, and responsibility assignments.
R4: Deploy additional personnel to buffer zones during the initial 3–6 months of LS3 to ensure smooth operations.
R5: Collect detailed information on experimental materials to prevent resource shortages.
R6: Resolve potential conflicts with Category 1 construction areas that may impact buffer zone operations.
R7: Prioritize the completion and testing of the ITM module, including a 3-month validation phase before LS3 commencement, and ensure ongoing support throughout the shutdown.
R8: Refine dose estimates for transport personnel to enable accurate resource planning and prevent workforce shortages.Conclusion
While the logistics framework for conventional materials is robust, the management of radioactive components presents the most significant challenge for LS3. Success hinges on proactive planning, clear communication, and swift execution of the recommendations outlined above.
The anticipation of potential issues, whether in storage, transport, or workflow management, will be critical to maintaining the shutdown’s timeline and ensuring compliance with safety standards. With focused effort and collaboration across departments, CERN can navigate these challenges and achieve a safe, efficient, and successful LS3.Speaker: Rende Steerenberg (CERN) -
18:05
Coffee break
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Overview on Injector planning and schedule drivers
The Injectors Complex (LINAC4, PSB, PS and SPS) will stop operations the 31st August 2026 to enter the challenging Long Shutdown (LS3). Given the scale and diversity of interventions in the different machines and the dependencies for resources availability across all CERN groups, a thorough preparation is key to ensure a feasible LS3 schedule.
This presentation provides an overview of the LS3 schedule in the different machines, the main works and the evolution since Chamonix 2025. The talk will highlight certain activities which are on the critical path, that are impacting the draft master schedule, and which require a decision on the direction to take. Different aspects that are essential to reduce the risks, and how to make sure the LS3 in the injectors can be performed successfully are also addressed in this talk.Speaker: Fernando Baltasar Dos Santos Pedrosa (CERN) -
37
Overview on LHC planning and schedule drivers
The Large Hadron Collider (LHC) will stop operations on 29 June 2026 to enter a four-year Long Shutdown (LS3). Given the scale and diversity of interventions requiring resources from across all CERN groups, extensive preparation is mandatory to ensure LS3 schedule feasibility.
This presentation provides an overview of the LS3 schedule and its evolution since Chamonix 2025. It describes the optimisation activities carried out to reduce the beam-to-beam duration from 51.5 months to 47 months, including the anticipation of selected activities into YETS 2025–26. The planning assumptions underpinning the schedule are detailed, together with their current validation status and associated constraints, highlighting the uncertainties and risk exposure. The talk outlines the roadmap towards LS3, emphasising the next milestones. The critical and near-critical path is addressed to clarify the chain of activities with no or limited contingency in the whole duration of the LS3, and the buffer periods identified. The presentation covers the main schedule drivers and the interfaces with the new HL-LHC galleries and the experiments.
No showstoppers have been identified for the start of LS3 in summer 2026; the LS3 schedule is well advanced and consolidated, and thorough preparation together with robust coordination will be essential for the successful execution of LS3 and for addressing unforeseen events.
Speaker: Estrella Vergara Fernandez (CERN) -
38
Priorities, rescoping, reprofiling
LS3 Priorities, Rescoping, Reprofiling and resources
J.-Ph. Tock on behalf of the LS3 Coordination
The Long Shutdown 3 (LS3) programme has entered its execution phase and will largely ramp up in 2026 with the LHC and the rest of the accelerators complex entering into shutdown mode respectively at the end of June and August this year. Considering this and the CERN reorganisation, the LS3 coordination team is being adapted and reinforced. The presentation recalls briefly the scope of LS3, highlighting the many projects with limited or even no contingency.
To address these challenges, a structured approach to prepare alternative scenarios and potential rescoping/reprofiling is presented. Groups are already strongly engaged with the LS3 works in AWAKE and ISOLDE and the HL-LHC galleries, as well as for the finalisation of the preparation of the LS3 in the LHC and injectors, and last but not least in the YETS 2025-26 interventions to ensure the success of the 2026 physics run. It was therefore decided to limit the workload to the groups for this exercise by targeting those with the highest number of contributions and the greatest occupancy of the critical path.
LS3 high-impact risk scenarios are being identified with them and ranked according to defined criteria, enabling the preparation of targeted mitigation measures, limited to a maximum of three per group. To prepare for necessary descoping or reprofiling, decision points will be defined with groups and projects.
All LS3 risk scenarios cannot realistically be exhaustively covered; building on the detailed preparatory work and the derived fine understanding of dependencies and criticalities, it must be possible to ensure effective and timely reactions to emerging issues, as was the case during LS2 with the Covid19, for example.
The definition and coherent application of CERN priorities between the numerous concurrent projects, as defined at the Directorate level is a must.Speaker: Jean-Philippe Tock (CERN)
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Session 7: FCCConveners: Jacqueline Keintzel (CERN), Malika Meddahi (CERN)
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The FCC integrated program in the CERN strategySpeaker: Mark Thomson (CERN)
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Delivering the FCC: workforce
Delivering the FCC: workforce
M.Capeans, B.GoddardThe delivery of the FCC-ee poses a major workforce and organisational challenge for CERN, requiring sustained effort over several decades while maintaining excellence in existing programmes. This contribution examines the workforce needs for the design, construction, and operation of FCC-ee.
The analysis, grounded in LHC benchmarks, confirms an overall workforce requirement of about 20 000 FTE·years over the period 2026–2045, with the majority concentrated in the construction phase. It also highlights the potential to operate FCC-ee with a significantly lower OPEX-to-CAPEX ratio than previous large accelerators, if new operating models, automation, and digital technologies are well prepared and timely integrated in the design and operation of FCC-ee.
Different workforce scenarios are discussed, ranging from a continuation of current practices to a strategic re-attribution of resources. The latter enables a substantial reduction in additional costs but requires a coordinated, CERN-wide transformation over the coming decade, including a shift to a target-driven operating framework, and changes in planning and skills deployment.
The FCC-ee workforce challenge is therefore not only a question of scale, but an opportunity to modernise CERN’s delivery model, align resources more effectively with long-term goals, and enhance sustainability for future large research infrastructures.
This work paved the way for a structured process to forecast workforce needs at the organisational level, explicitly dependent on technology choices, the appetite to embrace change, and the willingness to invest in new technologies that support more efficient operational models. This process should be consolidated into a baseline and be regularly updated as the FCC-ee cost class, design maturity, and technical choices continue to evolve.Speaker: Mar Capeans Garrido (CERN) -
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Delivering the FCC: organisation and interfaces
The objective is to make the new FCC organisation operational and unambiguous as the project towards the Technical Design Phase.
The FCC becomes an embedded CERN project with the FCC activities delivered in CERN’s sectors in a matrix model, with a small central coordinating team in a new FCC Project Office, The FCC Project Leader defines strategy and priorities reporting to the Director General. The Project Office is accountable for integration, planning, baselines, cost, schedule, and transparency. Departments and groups retain full authority over execution. The project defines what and when, the line organisation defines how and who.
The FMIC is established as the single ATS-level coordination interface. Its role is coordination, coherence, and arbitration, not command or project management. FMIC protects line management while ensuring accelerator-wide consistency and structured feedback to FCC leadership.
ATS coordinators are mandated by the FCC Project Leader. They coordinate scope, milestones, and interfaces. Execution authority remains with departments and group leaders.Not all FCC activities can be handled through classical work packages. Several competences, including scheduling, configuration, system integration, finance, socio-economic and environmental studies, require continuous service-level interaction with the Project Office to deliver a TDR.
A single Product Breakdown Structure (PBS) and Master Schedule is being established as the master reference. From it derive the cost centres, requirements, and baseline parameters. The PBS will be mirrored in EDMS and reporting tools to ensure transparency and traceability, following the practise of the LIU and HL-LHC project management. Longer-term the required set of Digital Tools will be revisited CERN wide including FCC needs under the guidance of the CIO.
External collaborations are welcome and will be aligned and will be screened by the FMIC accelerator-related collaborations to ensure strategic alignment, technical coherence, and fairness.
The conclusion is that clarity, transparency, and disciplined coordination and role mandates are essential to progress on the maturity of the FCC design within CERN.Speaker: Dr Florian Sonnemann (CERN) -
10:00
Coffee break
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The FCC-ee baseline concepts
The FCC-ee collider parameters are mainly driven by considerations of beam-beam effects and the assumption that synchrotron radiation losses of about 50 MW, a very tight focusing of the beam at the interaction point down to a vertical beta-star of about 1 mm and a beam-beam parameter ranging from 0.09 to 0.14 per each of the four interaction points are feasible.
The resulting set of parameters aims at maximizing the luminosity, but at the other hand makes FCC-ee a very difficult machine for many beam dynamics and technology domains with several possible performance limitations. Thorough studies, many of them well beyond what has been possible in preparation of past projects, are undertaken by several teams across CERN and by outside collaborators to assess the feasibility of the resulting concepts and to identify possible performance limitations. Still, a significant amount of effort is needed to complete these challenging studies with the aim to obtain a sound machine design with parameters and specifications discussed and agreed with all contributors. A few examples on the present state of the study, highlighting potential performance limitations, are discussed. A proposal on an improved work organization of the FCC-ee collider design, aiming at clarifying responsibilities, tasks and interfaces, is made.Speaker: Christian Carli (CERN) -
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FCC-ee injector complex
This presentation focuses on organization and preliminar roadmap of the FCC-ee injector complex as it transitions from the feasibility phase into the TDR stage.
The current technical baseline, established in the Feasibility Study Report, centers on a high-efficiency system comprising three linacs and a damping ring. This configuration is designed to meet in particular the Z-pole operation while prioritizing power and cost optimization. The preferred siting assumes the "Prevessin option" as the working hypothesis. This plan aims to house the entire injector complex within the existing CERN site to leverage proximity to established infrastructure and the North Area, though it necessitates careful management of tight spatial and environmental constraints.
A significant portion of the report details the new project structure. To streamline the 2025–2028 TDR transition, the project has implemented a "Pillar" framework. This organizational model integrates existing CHART-III project tasks into specialized Work Packages (WPs). A RACI matrix is been introduced to define clear accountability between CERN groups and external partners, fostering a unified approach to global requirements.
The project includs the CHART-III collaboration—a consortium involving CERN, PSI, IJCLab, CERN, and INFN LNF. This partnership is dedicated to validating technical parameters and testing key technologies, with the CHART organization now fully embedded within the new "Pillar" structure.
Finally, the presentation outlines the 2026 roadmap. This pivotal year will focus on securing approval for the Work Breakdown Structure (WBS), defining key deliverables and workforce requirements, and finalizing the baseline reference documentation. These organizational efforts will run in parallel with technical advancements in beam physics studies and technical designs with the integration of critical experimental results, such as the P3 positron yield studies at PSI. These organizational milestones are essential to remain aligned with the broader FCC project schedule, targeting the start of civil construction in the early 2030s and beam commissioning in the early 2040s.
Speaker: Dr Simone Gilardoni (CERN) -
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FCC-hh studies: improving and ensuring continued compatibility with FCC-ee
The FCC-hh studies are strongly focused on improving the lattice design, always ensuring compatibility with the layout of the FCC-ee rings. Since the CDR milestone, the Feasibility Study introduced major changes, such as a reduction of the circumference length and of the field of the main magnets. This required a full re-design, which was based on the choice of pushing the energy reach of the new lattice, and the study converged to a solution that is discussed in the FS report and represents the new baseline. Since then, further optimisation has been performed opening also to a non-baseline option, such as the use of combined-function magnets.
The next study to be addressed is that of the injection energy, for which the CDR is still the reference. This has major implications in the characteristics of the high-energy booster (HEB, the FCC-hh injector). In the CDR, several scenarios had been envisioned: the next studies should help to down-select the most promising option. The general criterion should be based on the optimisation of the FCC-hh performance.
The fact that the HEB is the last ring of a long chain of hadron accelerators suggests that a global approach is required to define the future of the entire CERN hadron complex. The current strategy is based on a vision at 25 years (established in 2010), whereas the FCC-hh sets a much longer time scale, until the end of the century. Even disregarding the FCC-hh, approved physics programmes require a chain of hadron accelerators delivering top-quality beams up to 2050s. The global strategy should include an assessment of the consolidation options, of the physics opportunities, and of the capabilities of the hadron complex. The outcome of these analyses should be combined into a coherent approach and vision for the CERN hadron complex.
Speaker: Massimo Giovannozzi (CERN)
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12:00
Lunch (Majestic)
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Session 8: ESPP & Longer Term ATS StrategyConveners: Rhodri Jones (CERN), Yannis Papaphilippou (CERN)
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Conclusions of the ESPP comparative project study & way forward for CERNSpeaker: Mike Lamont (CERN)
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Impact of the proposed LHCb and ALICE Phase II Upgrades on the Accelerator complex
Major upgrades are proposed for the ALICE and LHCb experiments to be implemented during LS4, enabling operation at significantly higher luminosities in Run 5 for proton or ion collisions and allowing the experiments to fully exploit the HL-LHC potential for ion, QGP, and flavour physics. These upgrades require an ambitious and challenging R&D programme, involving the development of new detector technologies, tight production schedules, and installation activities concentrated in LS4. Their successful implementation will rely on strong support for experimental infrastructure within a Host Lab framework, involving multiple groups across the ATS sector.
In Run 5, LHCb is expected to operate at a luminosity of 1.0 × 10³⁴ cm⁻² s⁻¹, a factor five increase over Run 4, leading to significantly higher radiation levels and power deposition in nearby machine elements and electronics, particularly cryogenic systems in the service galleries. A feasibility study has identified mitigation measures that would enable safe Run 5 operation. Resources should now be allocated to complete the study, select the most effective protection options for electronics, define a robust solution, and prepare the project—including resource estimates and planning—for the necessary works before and during LS4.
With Upgrade II, LHCb aims to collect a total integrated luminosity of 300 fb⁻¹ over the full LHC programme. The baseline optics with round beams meet this requirement with minimal impact on ATLAS and CMS, while flat-beam optics provide a viable fallback option. Both solutions require further validation studies, and MD time during Run 4, particularly to assess the impact of the additional high-intensity interaction point at IP8.
For ALICE3 in Run 5, operation is foreseen at a Pb–Pb luminosity of 1.2 × 10²⁸ cm⁻² s⁻¹, targeting 30 nb⁻¹ accumulated over the full Run 5, or alternatively using an ion species with A ≫ 100 at equivalent luminosity. Current estimates based on Run 3 experience and injector performance suggest that the Pb–Pb target is challenging, while it could be achieved in optimistic scenarios using Xe or In ions. Further simulations and studies of beam optics, collimation, beam losses, and backgrounds at the LHC, as well as studies and optimization at the injectors, are required to validate the predicted performance for Pb and Xe/In. These studies and associated hardware upgrades require additional resources beyond those presently foreseen within the HL-LHC project scope.Speaker: Ilias Efthymiopoulos (CERN) -
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ATS Roadmap for Common Accelerator Controls Hardware and Software Development
CERN has a powerful control system that is collectively provided by groups from across ATS. Although Controls has been highly available over the last 5 years, it comes at a non-negligible personnel cost. With overlapping & duplicated solutions at many levels (HW & SW), growing maintenance challenges, emerging needs that can’t yet be satisfied (increasing data rates / volumes, automation (EPA), AI, etc.), the workforce cannot scale with the current approach. Left unchecked there is a strong risk hitting a wall.
Over the last five years, the ATS Common Technology Strategy & Technical Boards (CTSB & CTTB) have worked to contain the situation and promote common and collaborative approaches. In 2025, a 2-part CTSB workshop was launched to bootstrap an ATS-wide effort to look at future Controls needs in a proactive and strategic manner. Ten Task Forces have studied distinct aspects of Controls to propose a roadmap for common development on specific topics which serve as input to formulate a global roadmap as part of the strategy for future Controls.
Looking ahead, a holistic, systems-thinking approach is proposed, in the form of a “Next Gen Controls” project with multiple phases to integrate FCC requirements and establish a common control system for CERN's entire complex. Appropriate organization with clearly defined responsibilities will be essential for success.
Speaker: Chris Roderick (CERN) -
14:30
Coffee break
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Options for accelerator magnet technology, with a focus on high field
This talk provides a perspective on accelerator magnet development. The focus is on high field, covering the activities of the HFM programme as well as developments in related areas. After an initial look at ongoing initiatives, such as the delivery of HL-LHC hardware and consolidation campaigns, studies for FCC-ee resistive magnets and development of superferric and curved canted cosine theta superconducting demonstrators, the main part of the presentation will focus on high field. This will start by putting the current targets in context, by comparing with other superconducting accelerators (Tevatron, HERA, RHIC, LHC and HL-LHC) and considering advances in other communities (e.g. nuclear magnetic resonance, fusion). Examples of recent test results for both LTS (Nn$_3$Sn) and HTS (REBCO) dipole demonstrators built at CERN are given, together with a discussion on fresh ideas and future options. Opportunities to optimize and refocus the high field magnet initiatives – as a balance between parallel technology developments and focused down-selection and scale-up in length – are mentioned, considering synergies with other programmes, the involvement of industry, and the foreseen timeline.
Speaker: Attilio Milanese (CERN) -
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Development roadmap for RF technologies
The RF technology roadmap for FCC-ee defines a plan to develop the key RF components and systems while meeting ambitious performance, cost, and sustainability targets. Between 2026 and 2031, the main goals are to build two cryomodule demonstrators at 400 MHz and 800 MHz, develop a 400 MHz tristron prototype, establish RF infrastructures, and pursue R&D for future upgrades. Industrialization is scheduled to begin in 2032, followed by large-scale fabrication, installation, and commissioning, with beam operations planned for 2047.
The project aims to exceed current machine performances by doubling cavity accelerating gradients and quality factors and increasing RF power source efficiency from 60% to 90%, enabling major reductions in power consumption, cooling needs, and environmental impact.
The program is coordinated through multiple funded projects and international collaborations. The 400 MHz activities are on the critical path, with cavity qualification and the new SRF building expected by 2029, a cryomodule ready for assembly in 2030 and for testing in 2031. Development of a new high efficiency tristron prototype is done in-house and is expected in 2028. Development of the 800 MHz systems relies more on external partners and remains partially funded, although cavity procurement is secured via German contribution.
Good progress has been achieved in niobium coated cavities performance and gridded cathode development for the tristron. Novel ideas to test power couplers with reduced investments are proposed. New infrastructures, including the SA18 building and additional RF test stations, will support surface preparation and assemblies in clean environment as well as high-power qualifications at cryogenic temperature. Achieving the targeted RF performances is vital to limiting investment, operational costs, and carbon footprint of the future collider at CERN.Speaker: Franck Peauger (CERN) -
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Future CERN contributions to the fixed target physics landscapeSpeaker: Urs Wiedemann (CERN)
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