38th Meeting of the ESS Council (4-5 June 2024)

ESS Council June 2024
Members of the ESS Council and ESS Management in the office atrium at the 38th Council Meeting. Image: Jo Lewis/ESS

The 38th meeting of the governing body of the European Spallation Source ERIC, the ESS Council, was held at the Lund site on 4-5 June. 


Remembering Mats Lindroos

Mats Lindroos

Mats Lindroos in the ESS Accelerator tunnel.

The ESS Council, ESS Management Team, and In-Kind Partners acknowledged the extremely sad passing of Mats Lindroos, former Head of the ESS Accelerator Division. Many Member State delegates paid tribute to Mats’s invaluable contributions to the Accelerator project, both for his technical skills and for the fruitful collaboration with In-Kind partners. 
Capturing the feelings and thoughts of all attendees, Director General Helmut Schober remarked how "Mats was among the first to join the ESS initiative in 2009, bringing his expertise in accelerators together with an abiding passion for science to the service of the organisation and the many colleagues that he has led and worked with over the last 15 years. Mats was relentlessly working for ESS, a job that he embraced with his mind and his heart."

Update from the Director General

Director General Helmut Schober updated the Council on the project progress since the last Council meeting held in February 2024. 

In the Accelerator, the extensive preparations for beam commissioning, with the license to operate the Superconducting Linac, was received from SSM, the Swedish Radiation Safety Authority. Regarding the installation of components, one cryomodule and two Linac Warm Units are left to be installed to achieve the 2MW capability required for the Beam on Dump and Beam on Target scope. Beam instrumentation is also being installed. The majority of the gallery power systems have been energised and are being soak tested. The last modulator is in place and is getting ready for energisation.

Superconducting Linac

The superconducting linac, with 26 of the 27 cryomodules needed for BoD in place.

A2T Accelerator

The Accelerator to Target (A2T) section.

Klystron Gallery

Power sources in the Klystron Gallery.

G04 backup compressor

Backup compressor in place.

In the Target systems, major components, including the Target wheel and drive unit, moderator and moderator cap, and helium rotary union are installed, with electrical infrastructure and piping getting in place. Vacuum leak tests of the entire Monolith vessel confinement are underway and preparations to receive the helium circulators are being made, with FAT tests performed on both options.
The majority of the cooling and process systems in the utility building are installed and under commissioning. The first round of commissioning of the Cryogenic Moderator System was completed. Manufacturing of the Casks Assemblies continues, including seven casks and ancillary equipment.

Target connection cell

The Target connection cell.

D02 Utility system test

Radiolysis gas handling system under commissioning in the utility building.

Radiolysis system test

Radiolysis gas handling system under commissioning in the utility building.

Cryogenic Moderator System

The Cryogenic Moderator System.

Installation of the scientific instruments has also progressed with detector modules and all in-bunker components, including choppers, heavy chopper, and neutron guide for DREAM, ESTIA’s in-bunker components, bunker wall inserts, BIFROST’ detector modules onto the spectrometer tank and tested. The LOKI collimation installations proceeded, with the selector now in place and in-bunker chopper now in place. The MAGIC cave was structurally completed, NMX hutch installations, including ventilation, sprinkler, and lighting, were completed. Shielding for the SKADI collimator started. Infrastructure for the Test beamline is getting in place.

DREAM detector

Detector installation for DREAM.

ESTIA and SKADI in-bunker

In-bunker components in place for ESTIA and SKADI.


Ongoing works in the LOKI cave and with the Test Beamline infrastructure.

Bunker wall inserts

Bunker wall inserts getting in place in the west sector.

MAGIC cave

MAGIC cave constructed.

BIFROST detectors

Detectors installed under the BIFROST spectrometer tank and under testing.

The integrated Control Systems are also making significant progress, in view of the upcoming project milestones. The Personnel Safety System (PSS) for the entire Accelerator has completed site integration tests while PSS for LOKI and more instruments are getting in place. Machine Protection System (MPS) units are installed throughout the tunnel, with MPS for vacuum systems under testing. A testing sequence for cold operation of the cryomodules has been implemented.

HEBT access station

Site Integration Tests of the Accelerator Personnel Safety System (PSS).


Machine Protection System for the linac magnets in place.

LOKI cave roof

PSS cabinets installed on the LOKI cave roof.

CM testing sequence

A logic testing sequence for the cryomodule cooldown process has been implemented.

"The Council congratulated ESS on approval of the license for Beam on Dump (BoD)”, commented Council Chair Robert McGreevy. “This is a significant step forward, and BoD itself should be achieved around the end of the year. ESS can then start commissioning the whole accelerator, albeit at low power, but also move into a mode of regular operation for a major part of the facility. So this is the first step towards operation of the whole facility.”

The Council meeting hosted a talk by Ken Andersen, Director General at the Institut Laue-Langevin (ILL) in Grenoble, France, and former Head of Instruments at ESS. The talk provided an update of the ILL current activities including collaborations with ESS scientists.

Towards Future Operations

The ESS DG also updated the Council on progress in the plan to transition the ESS project to a user facility Steady State Operations (SSO).

The process for defining the budget for Steady State Operations is now underway, and discussions on sharing of the funding are progressing”, said Robert McGreevy. “The fact that this is a long-term, multi-decade commitment is emphasised by the inclusion of discussion about decommissioning. But in the much shorter term, we note that the joint ESS-ILL user meeting in Grenoble in December will be the last one where ESS does not have its own users with experiments to report – at the following meeting, after Beam on Target, it will!"

"Thanks to the excellent progress, as construction approaches completion, significant work lies ahead of us to achieve the technical and scientific readiness necessary to operate our facility in a high-performing way, meeting the expectations of the user community that ESS will serve to enable excellent science”, concludes Director General Helmut Schober. “We thank the Council for their support in governing the ESS organisation through this exciting transition from construction project to an operating scientific infrastructure.

The next ESS Council meeting will be held on 3-4 December 2024.