On 12 June, the new schedule for the activities of Long Shutdown 2 (LS2) was unveiled. The first test beams will circulate in the LHC at the end of September 2021, four months after the date planned before the COVID-19 crisis.

The rest of CERN’s accelerator complex will restart gradually from December 2020 onwards. The various ISOLDE experiments and the experiments at the PS-SPS complex will therefore be able to start data taking as of summer 2021.

The COVID-19 lockdown phase, which resulted in a shutdown of activities on the CERN site and the closure of many partner institutes, is now being followed by a gradual restart, all of which has naturally had an impact on the LS2 schedule. For example, it is now impossible for several activities to take place simultaneously in the same location, which is causing delays to the schedule. The main LHC experiments, which are international collaborations, are facing particular difficulties, since they are waiting for equipment and collaborators to arrive from all over the world.

To allow them to complete their upgrade programmes, Run 3 of the LHC will therefore start in March 2022, provided that the current plan, which includes the installation of the second small wheel of ATLAS, is confirmed. If this is not the case, physics running will instead be brought forward to November 2021. “Initially, ATLAS had planned to install its second small wheel during the 2021-2022 year-end technical stop (YETS),” recalls José Miguel Jiménez, head of CERN’s Technology department. “But, under the new schedule, it might be possible – if the assembly process proceeds without any issues – to install it during LS2.” The schedule will be confirmed by the ATLAS collaboration in November.

In order to keep to the schedule, around 500 additional people – mainly those involved in LS2 – have been returning to their activities on the CERN site every week since the start of Phase I of the restart plan on 18 May. “We have been able to plan the restart precisely and optimally thanks to the excellent documentation work done by all the teams before the machines were put into safe mode in March,” emphasises Jiménez. This has made it possible to resume activities rapidly since May, although often in a different order: “It hasn’t always been possible to simply pick up where we left off,” he adds. “Many institutes are still closed, not to mention the fact that many of our collaborators and contractors are unable to come to CERN.”

No changes have been made to the schedule beyond 2022. Provided that ATLAS completes its upgrades during LS2, the 2023/2024 YETS will be a normal shutdown. LS3 will start at the beginning of 2025.

Closure of accelerators – current schedule:

The commissioning of the accelerators will begin this summer, starting with gradual hardware commissioning. The first beams from Linac 4 are expected in December this year.

• Closure of the PS Booster: 3 July 2020
• Closure of Linac 4: 3 July 2020
• Closure of the PS injection area: 28 August 2020
• Closure of Linac 3: 9 October 2020
• Closure of the PS extraction area: 23 October 2020
• Closure of the SPS: 4 December 2020
• Closure of the LHC: 19 February 2021
• Closure of LEIR: 21 May 2021

Between now and the end of 2020, seven of the LHC’s eight sectors will be cooled down. Electrical quality tests, powering tests and a long campaign of quench training for the magnets will follow.

A week of tests with low intensity beams will take place at the LHC at the end of September 2021.

Restart of physics runs – current schedule:

• ISOLDE: end of June 2021
• North Area and HIE-ISOLDE: July 2021
• AD/ELENA: end of August 2021
• n_TOF: end of September 2021
• East Area: October 2021
• LHC: February 2022

According to the new schedule, all of the LHC experiment halls will be closed on 1 February 2022.

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Special COVID-19 occupational health and safety measures

Special health and safety measures have been put in place at CERN to help in the fight against COVID-19 (see full details on the HSE unit website).

In particular, we remind you that:

• It is compulsory to wear a mask indoors when other people are present (shared workspaces) or might be encountered (public areas). It is also compulsory to wear a mask outdoors if physical distancing of two metres cannot be observed. The mask must cover your mouth AND nose (we remind you that infection occurs principally via the nasal mucous membrane).
• Physical distancing of at least two metres must be observed.
• You should wash your hands regularly, in particular after the use of sanitary facilities or other communal facilities (cash machines, vending machines, access control devices, etc.), before and after handling a mask, and after coughing or sneezing.
• Tools, workstations and CERN vehicles must be cleaned regularly by the person who uses them, in accordance with the instructions provided.
• PPE (mask, protective face visor, gloves) must be worn and the applicable work procedures and instructions for use must be followed.

We invite you to consult all the special COVID-19 occupational health and safety measures on the HSE unit website.

These exceptional measures must be followed in addition to the usual safety and radiation protection rules, which remain in force come what may.