A new target to probe unknown

BDF target prototype assembly
Assembly of the target prototype before installation.
(Image: Julien Ordan/CERN)

The Physics Beyond Colliders programme encompasses several new projects and experiments that aim to use CERN’s infrastructure for new explorations. One of these projects, which is currently awaiting approval and is being discussed in the context of the European Strategy for Particle Physics, is a facility that will use the beams of the Super Proton Synchrotron (SPS). This facility, known as the Beam Dump Facility (BDF), is a high-intensity fixed target beam dump.

The target, located 15 metres underground, will stop the main proton beam and produce mainly charmed mesons to enable physicists to carry out research on dark matter and the hidden sector. The aim is to produce very weakly interacting hypothetical particles.

The 1.5 metre thick target will be capable of absorbing all the energy of the SPS beam which should reach an average power of 355 kW. This is why the BDF set-up is more like a beam dump than a traditional target. Furthermore, the target will be very dense in order to produce heavy hadrons while also stopping lighter particles.

The BDF will be significantly more sophisticated than the existing targets and will therefore need a complex shielding and handling system. The target will be surrounded by approximately 3,700 tonnes of cast iron and stainless steel shielding. The target and the shielding will be handled by robots and cooled.

How will the facility work? A proton beam produced by the SPS will be sent along the existing line through a separator that will then direct the beam towards the new target. A new junction cavern and an extraction tunnel will be built to house the new line.

The BDF project will inter alia feed into the Search for Hidden Particles (SHiP) project which is designed to look for extremely weakly interacting particles within the hidden sector as well as black matter particles. If the SHiP project is approved it will enter a technical design phase followed by a five-year construction phase and should produce its first data in 2028.

Last year, the BDF team tested a prototype target to gauge the feasibility of the project. The target resisted the impact of the beam and behaved as expected during the simulation. The team is now carrying out design studies. The construction of the facility will then begin.

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