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| LHC Long Shutdown 2 | |
|---|---|
| Name | LHC Long Shutdown 2 |
| Date | 2018–2021 |
| Location | CERN, Geneva |
| Type | Planned maintenance and upgrade |
LHC Long Shutdown 2 Long Shutdown 2 was a scheduled multi-year maintenance and upgrade period for the Large Hadron Collider at CERN between major running periods. It aimed to prepare the accelerator complex for higher-luminosity operation and to install upgrades across injector chains, magnets, cryogenics, and detectors to support future experiments such as High-Luminosity Large Hadron Collider, ATLAS experiment, and CMS experiment.
The shutdown followed earlier interventions such as Long Shutdown 1, and was planned amid developments in projects like High-Luminosity LHC project, European Strategy for Particle Physics, and coordination with member states including France and Switzerland. Goals included increasing integrated luminosity for experiments like LHCb experiment and ALICE experiment, enabling searches related to Higgs boson properties, beyond-Standard-Model signatures studied at Tevatron and LEP, and aligning infrastructure with roadmaps from organizations such as CERN Council and collaborations including ATLAS Collaboration and CMS Collaboration.
Major works encompassed accelerator hardware from the Super Proton Synchrotron to the Proton Synchrotron Booster, installation of superconducting elements similar in heritage to Tevatron superconducting magnets, and enhancements to cryogenic systems influenced by designs from ITER and Fermilab. Scope included refractory and radiation-hard components developed with partners like Siemens and Thales, logistical coordination with agencies such as European Investment Bank, and compliance with safety frameworks like those overseen by International Atomic Energy Agency.
Detector upgrades were implemented across ATLAS experiment, CMS experiment, ALICE experiment, and LHCb experiment, including new tracking systems influenced by technology from CERN Microstrip Tracker prototypes, calorimeter refurbishments drawing on CALICE R&D, and trigger/DAQ overhauls taking cues from HL-LHC design studies. Injector chain work included upgrades to the Linac4, refurbishments at Proton Synchrotron and Super Proton Synchrotron to support higher beam brightness, and reliability enhancements informed by operational experience from ISOLDE and AD facility.
The planned timeline aligned with multi-institutional calendars involving CERN Council decisions, vendor deliveries from companies like ABB and Thales, and coordination with national labs including DESY, Fermilab, and KEK. Milestones tracked installation windows for superconducting quadrupoles, RF cavities, and cryogenics, with commissioning phases intended to link to running periods designated by the LHC schedule and international conference deadlines such as ICHEP and EPS-HEP.
Upgrades were expected to increase instantaneous and integrated luminosity for experiments including ATLAS Collaboration, CMS Collaboration, LHCb Collaboration, enabling precision measurements of the Higgs boson, searches for supersymmetry, and investigations of dark matter candidates that build on results from Run 1 (LHC) and Run 2 (LHC). Improvements to the injector chain and beam instrumentation influenced studies from beam physics groups that had collaborated with institutions like University of Oxford, University of Geneva, and MIT.
Workstreams faced risks related to supply chains, cryogenic commissioning, and magnet training derived from experiences at Tevatron and RHIC. Mitigations included contingency planning with contractors such as Siemens and Thales, cross-checks with test facilities like the Superconducting Test Facility and reliance on expertise from partner laboratories including DESY, Fermilab, and RAL. Health, safety, and environmental issues were managed through CERN Safety Policy frameworks and engagement with national regulators in France and Switzerland.
The shutdown delivered upgrades that laid groundwork for the High-Luminosity Large Hadron Collider era, improved detector capabilities for collaborations like ATLAS Collaboration and CMS Collaboration, and strengthened partnerships among research centers such as DESY, Fermilab, KEK, and European universities. Technological advances in superconducting magnets, cryogenics, and detector electronics had spillovers to projects including ITER, European XFEL, and medical imaging initiatives promoted by institutions like CERN Medical Applications. Category:Large Hadron Collider