First-hand information for everyone
The SHiP/NA67 project is a new experiment approved in 2024 to run in the ECN3 hall at CERN’s Super Proton Synchrotron. Over about 15 years it will send 6×10^20 protons onto a dense target to make a very large sample of short‑lived particles. The main goal is to look for “feebly interacting particles” (FIPs) with masses around 100 MeV to a few GeV. These include proposed particles such as heavy neutral leptons, dark photons, dark scalars, axion‑like particles, and light dark matter.
The experiment uses a beam‑dump layout. A 400 GeV proton beam hits a tungsten target to produce many heavy‑flavour hadrons. SHiP expects roughly 4×10^19 protons on target per year and, over the programme, fluxes on the order of 10^18 charmed hadrons and 10^16 beauty hadrons. Those hadrons can produce rare new particles that travel some distance before decaying back into ordinary particles. SHiP is built to find those rare decays in a long, instrumented decay region downstream of the dump.
A main technical challenge is the very large muon and neutrino spray coming out of the dump. SHiP plans to cut the muon flux by about six orders of magnitude with a magnetic active muon shield. The experiment surrounds the decay volume with background taggers. An upstream tagger and a surrounding tagger together use trackers, scintillators and liquid scintillator cells (about 780 cells with ~145,000 litres total) read out by wavelength‑shifting modules and silicon photomultipliers. The collaboration reports >99% tagging efficiency and sub‑nanosecond timing for these systems. The decay spectrometer includes high‑precision straw trackers in front of a dipole magnet, a fast timing system with ≲50 picosecond resolution, and electromagnetic and hadron calorimeters that can reconstruct neutral and charged final states.
SHiP also includes a dedicated scattering and neutrino detector (SND@SHiP). It combines a silicon‑tungsten target and a magnetised iron‑scintillator calorimeter to record neutrino interactions of all flavours and to reject backgrounds. The collaboration gives numbers ranging from order 10^3 tau neutrinos per year (noted in the project summary) to an expectation of order 10^4 tau‑neutrino and antineutrino interactions in the scattering detector sample. That data could enable the first measurements of certain structure functions that are accessible only with tau neutrinos, studies of parton (quark and gluon) distributions at low momentum fraction, and a probe of strange quarks via charm production in neutrino interactions. The SND can also search for light dark matter scattering off electrons.
Why this matters: many ideas for physics beyond the Standard Model predict new light particles that are extremely weakly coupled and so far escaped detection. High‑intensity beam‑dump searches are well suited to find them because they rely on producing huge numbers of parent particles and watching for rare decays. SHiP claims world‑leading sensitivity in much of the 100 MeV–few GeV mass range and aims to operate in an essentially background‑free regime. Important caveats are that the project is still in its design phase. The collaboration is preparing a Technical Design Report, with outputs expected in roughly two years, and the new Beam Dump Facility is foreseen to be commissioned with beam by 2033. The stated sensitivities and the zero‑background goal depend on successful implementation of the muon shielding, background tagging, and other detector systems, and so remain projections until the facility and detectors are built and operated.