For last five years STAR has used magnetic field from agufld (== mfldgeo, P.L.Nevski) from STAR GEANT3 application. Coming upgrade STAR simulation and reconstruction based on VMC (ROOT Virtual Monte Carlo) requires to have GEANT/ZEBRA independent method for calculation of magnetic field.
J.Thomas created in StMagUtilities method to calculate magnetic field based on the same magnetic field map as agulfd.
The missing part of the above method is parameterization of magnetic field in region out of the STAR magnetic field map.
The separated package StarMagField was created from StMagUtilities.
In this package parameterization of STAR mag.field outside of the mapped region was taken from Nevski's extrapolation
(mfldgeo) which includes also mag.field of the nearest to STAR RHIC dipoles.
StarMagField will be only package which provides the STAR magnetic field.
This directory contains contains root- and png-files with
2D magnetic field maps for new (StarMagField == DEV2) and old (mfldgeo == DEV)
parameterizations for Bx and Bz and their differences
( new - old == StarMagField - mfldgeo ).
The main difference is at Z = 0 and R ~250 cm due to requirement (for new mag.filed) for Br component to be zero.