In order to increase  magnetic field in endcap reagion it has been considered a possibility to remove STAR magnet pole tips and 
to insert a thin superconducting solenoid (~5 T) inside of TPC inner field cage (R ~ 40 cm).
The calculation has been done using opera with advices from Wuzheng Meng (CAD).
The standard STAR magnetic field is presented in
https://drupal.star.bnl.gov/STAR/blog/fisyak/2013/dec/20/asymmetry-star-magnetic-field-due-adding-back-west-pole-tip-extra-magnetic-material 

We consider 3 options:

1. Removed pole tips (b).
2. 4 m long solenoid (a).
3. 2 m long solenoid (c).

Below plots for Bz and Br versus Z and R are shown f 

BL integrals versus Theta

   |B|L integrals were calculated at the surface of cylinder with R = 2m and half length Z = 2m.

|BL^2| 

After these plots it looks that we need to try to move solenoid forward  in region 1 m < Z < 2m.