Since REDTOP is being designed as a general purpose, hermetic detector with an extremely low sensitivity to hadronic background, is making it ideal to use it with different beam energies and different beam species. At present, four different running phases (one optional) are being considered for REDTOP. Those will extend the lifetime of the experiment by several years and will open the road to new possible discoveries. The list of runs foreseen for REDTOP is presented below, along with the necessary changes required for the experimental apparatus.
- Phase I: η-factory
The beam required for this initial running phase of the experiment are protons with energy between 1.9 and 2.1 GeV. The minimum required intensity is 30 W. The detector configuration is described in some details on the Detector page. The goal is to collect at list 1012 η mesons in one year of running.
- Phase II: η’-factory
The beam required for this running phase of the experiment are protons with energy between 3.5 and 4.0 GeV. The minimum required intensity is about 60. The baseline detector configuration requires a minor change in order to adequate the refractive index of the aerogel to the faster leptons from the η’ decay. The goal is to collect of the order of 1010 η’ mesons in one year of running.
- Phase III (optional): Muon scattering experiment
This running phase will use the hermetic REDTOP detector for exploring the proton radius anomaly with a muon scattering experiment. The experiment will collect a lower statistics than its direct competitor (the MUSE detector at PSI). However, the apparatus and the experimental technique is considerably different, giving to REDTOP the opportunity to contribute to this class of experiments. Such contributions are still under investigation; conequently, this running phase is still considered optional.The beam required for this running phase of the experiment are muons with energy between 0.2 and 0.8 GeV. The baseline detector configuration requires no changes from Phase II. However, a graphite target needs to be added upstream the detector. . The goal is to collect of the order of 1012 muon scattering in one year of running.
- Phase IV: Rare kaon decay experiment
This running phase will explore the K+ -> Pi+ nu nubar CP-violating decay. The beam required for this running phase of the experiment are charged kaons obtained form primary 8 GeV protons impinging on a Platinum target. The detector requires a considerable refurbishing, with the berillium target and the O-TPC being replaced by an active target, a low-mass drift chamber and a range stack. REDTOP will constitute an upgrade of the experiment E949 at BNL, with an expected statistics larger by about two order of magnitude.