TPC survey instructions

Survey results can be obtained from the STAR Technical Support Group:

http://www.bnl.gov/STAR/STSG/survey.asp

Contact Ralph Brown or Frank Karl if the results you need are not yet posted.

The procedure used to determine the position of the center of the TPC in Magnet coordinates and two rotation angles (rotation about the z axis is not done) is described in this web page

http://www.star.bnl.gov/STAR/tpc/docs/SurveyTPC/SurveyTPC.html  [Link is not working]

for the survey of 2003. For 2004 there is not a webpage but the relevant plots are at RCF: /star/u/startpc/tpcAlignment/SurveyTPC04

The macros used to produce those plots are alignTPC.C and alignTPC_0804.C in that directory.

The measured positions of the targets are hard coded in the macro, and only a few of the targets are used for this analysis. The names in the macro are the same as the names in the survey. It is straightforward to modify the macro and run it to get the new values, which go into the tpcGlobalPosition table. However, note that the ExB (twist) parameters are also in this table so the standard procedure is to not update the table until the PhiXZ and PhiYZ parameters from the ExB (twist) calibration procedure are also available.