Status of the South Magnet Mapping Analysis (Christos Velissaris)
Full field map
Full map of the PHENIX magnetic field (Ralf Prigl)
The Central Magnet
The Central Magnet is an axial field magnet energized by two pairs of concentric coils, which can be run separately, together, or in opposition.
The Central Magnet is 9m tall and weighs nearly 500 tons.
It covers a rapidity interval of ±0.35 units.
The Int(B.dl) at 90 degrees is 0.78 Tesla-meters.
The CM single particle resolution is better than 1% between 200MeV and 1GeV.
Keeping the magnetic field low in the active volume of the RICH was a major design constraint. This was required to minimize the distortion of the particle tracks and therefore preserved the shape of the Cerenkov rings. The final design achieved an Int(B.dl) of 100 gauss-m from a radius of 2.4 meters to 4.0 meters.
The field is minimized in the region near the RICH phototubes. Btot≤200 gauss in this region.
The field near the EM Cal phototubes is less than 10 gauss.
The pole faces of the CM serves as the primary absorber of hadrons for the Muon arm spectrometers. This required careful optimzation of the CM poles and the neutron and gamma ray absorbers that are attached to the CM.
Muon Magnet North
The Muon Magnet uses two solenoidal coils to produce a radial magnetic field. The coils are wound around a tapered piston and the flux propagates out to the lampshade and returns via a 30 cm thick endplate.
It is 10m tall and weighs more than 400 tons.
The MM covers a rapidity interval of 1.1 to 2.4 units (10 degrees to 37 degrees).
It has large acceptance in PHI (angle) for low cross section measurements.
The average Pt kick in the magnet is 200MeV.
The Int(B.dl) along a line at 15 degrees from the beam axis is 0.72 Tesla-meters.
The MM spectrometer has sufficient resolution to resolve the PSI prime from the J/PSI and the Upsilon(1S) from the Upsilon(2S+3S).
The Muon Magnet piston is notched to hide the frames of the muon tracking chambers.