The iTPC was developed into a proposal. The technical design report is available as a STAR note SN0644.

Historical remarks:

We propose to upgrade the inner sectors of the STAR TPC to increase the segmentation on the inner pad plane and to renew the inner sector wires which are showing signs of aging. The upgrade will provide better momentum resolution, better dE/dx resolution, and most importantly it will provide improved acceptance at high rapidity to |eta|<1.7 compared to the current TPC configuration of |eta|<~1.0. In this proposal, we demonstrate that acceptance at high rapidity is a crucial part of STAR’s future as we contemplate forward physics topics such as p-A, e-A and the proposed phase II of the Beam Energy Scan program (BES II). Unlike the outer TPC sectors, the current inner TPC pad row geometry does not provide hermetic coverage at all radii. The inner pads are 11.5 mm tall yet the spacing between rows is variable but always greater than 5 cm, resulting in "missing rows". Approximately, only 20% of the path length of the charged particle traversing the TPC inner sector has been sampled by the electronics readout.

https://drupal.star.bnl.gov/STAR/event/2014/02/10/star-rd-2014-and-itpc-review  

internal review: 
https://drupal.star.bnl.gov/STAR/event/2015/02/05/itpc-internal-review