Eric van Herwijnen (Imperial)

SHiP - the Search for Hidden Particles experiment. Why, where, how and when?

Abstract: The Standard Model works well but is incomplete. We do not know how to account for neutrino masses, neither do we know how to explain the asymmetry between matter and antimatter, nor what the nature of dark matter is. The simplest extension of the Standard Model whereby neutrinos become massive is obtained by adding a triplet of right handed, non interacting neutrinos, also called Heavy Neutral Leptons. Neutrino oscillations and the existence of dark matter place constraints on the number of generations and give an indication of the possible mass ranges of these particles. If found, they would also explain the baryon asymmetry of the universe. Via oscillations with active neutrinos, they can leave signals consisting of Standard Model particles. In this context, given the absence of any other hint of physics beyond the Standard Model, the search for right handed neutrinos is one of the highest priority items for research in fundamental particle physics today. The SHiP experiment was designed to do just that. By creating a 0 background environment, it is not only sensitive to HNLs, but also to any particle coupling through a Hidden Portal. The optimal place for such an experiment is behind a beam dump at the CERN SPS. The main components of the detector are a heavy tungsten target, a muon shield (to remove background from muons), a 50m long decay volume and a spectrometer. SHiP aims to start taking data in 2032. After 5 years of data taking, 10^{20} 400 GeV protons on target will be accumulated at the SPS. Assuming a mixing strength |U_{\mu}|^2 \approx 10^{-7} and a HNL mass of 1GeV, several 1000s of HNLs are expected in this dataset.