BDF – Project Description

The proposed SPS beam dump facility (BDF) is a fixed-target facility foreseen to be situated at the North Area of the SPS (see blow). Beam dump in this context implies a target aimed at absorbing all incident protons and containing most of the cascade generated by the primary beam interaction. The aim is a general purpose fixed target facility, which in the initial phase is aimed at a general Search for Hidden Particles (SHiP) including heavy neutral leptons, as well as tau neutrino physics.

The facility would be served by a ~1 second duration slow resonant extraction from the SPS of 400 GeV/c protons via the existing extraction system at LSS2. The extracted beam would be transferred along the existing TT20 line to a splitter, which would direct the beam into a new short section of beam-line, which in turn would transport the beam to the target complex. The 400 GeV/c switch out of TT20 to the new beam line is challenging. A possible solution is to the replace the existing splitter magnets with an upgraded splitter that allows negative polarity powering.

The facility would require the construction of a target that has the two-fold objective of producing charged mesons as well as stopping the primary proton beam. The production target is one of the most challenging aspects of the proposed facility due to the very high energy and power density. The target complex would be located underground with the production target at a depth of about 10 m. The target is designed to contain most of the cascade generated by the primary beam interaction. It is embedded in a massive iron shielding absorbing the remaining primary protons and produced hadrons emerging from the target. The hadron absorber is followed by an active muon shield and an experimental hall.

As the facility aims at pushing the primary proton beam to a power of around 355 kW, radiation protection considerations strongly determine the design of the facility. In particular high prompt and residual dose rates call for considerable shielding and remote interventions in the target area. Also the risk and environmental impact from releases of radioactivity by air and water as well as the soil activation heavily influence the design.

The induced radioactivity in the SPS extraction region will increase in proportion to the total number of protons extracted per year. The expected increase of the activation levels should be further investigated. Since the dedicated beam line branches off at the top of the existing TT20, in the TDC2 cavern, further studies on prompt dose rates during beam operation in TT20 and TDC2 as well as the expected level of ground activation around TT20 and TDC2 should be conducted.

The aim of the project is to complete key technical feasibility studies in time for the ESPP update foreseen around 2019-2020. This is in conjunction with the recommendation by the Research Board to the SHiP experiment to prepare a comprehensive design study as input to the ESPP.

The four main areas of the foreseen BDF feasibility studies are:

  • Extraction, beam-line and splitter
  • Target and target complex
  • Radiation protection
  • Safety engineering

Project management foresees the creation of separate working groups to drive activities in these four areas.

Foreseen location at North Area of SPS

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