Long term life time and future of the STAR TPC

In an effort to better understand the future of the TPC in the high luminosity regime, several meetings were held and efforts carried through.

Present at the meeting(s) were: myself (Jerome Lauret), Alexei Lebedev, Yuri Fisyak, Jim Thomas, Howard Wiemann, Blair Stringfellow, Tonko Ljubicic, Gene van Buren, Nikolai Smirnof, Wayne Betts (If I forgot anyone, let me know).

It is noteworthy to mention that the TPC future was initially addressed at the Yale workshop in (Workshop on STAR Near Term Upgrades) where Gene van Buren gave a presentation on TPC - status of calibration, space charge studies, life time issues. While the summary was positive (new method for calibration etc...) the track density and appearance of new distorsions as the lumisoity ramped up remained a concern. As a reminder, we include here a graph of the initial Roser luminosity projection.

Roser luminosity
which was build from the following data  

 200220032004200520062007 20082009201020112012 20132014
Peak Au Luminosity 4 12 16 24 32 32 32 32 32 48 65 83 83
Average Au Store Luminosity 1 3 4 6 8 8 8 8 16 32 55 80 80
Total Au ions/ring [10^10] 4 8 10 11 12 12 12 12 12 12 12 12 12

An update summary of the status of the TPC was given by Jim Thomas at our February 2005 collaboration meeting (A brief look at the future evolution of TPC track distortions ; see attachement below) to adress ongoing GridLeak issues. Slide 19 summary for teh future is added here:
Will the TPC Last Forever?

  1. Dynamic distortions driven by L
    1. 2x increase is feasible and this takes us to 2010 and (probably) beyond.
  2. Some static distortions need work
    1. e.g. Central Membrane is not flat
      Probably of academic interest
    2. Unlikely that any of these static unresolved issues will affect the useful lifetime of the TPC
  3. Beam backgrounds and ghost beams may be a problem
    1. PHENIX put up shielding
    2. Gene see’s some bad runs
  4. TPC replacement parts will eventually be a problem
  5. TPC replacement people will definitely be a problem

Questions arose as per the liability of the detector itself i.e., aging issues (including shorts and side effects) were raised along with increasing concerns related to grid leak handling. Alexei Lebedev proposed a serie of hardware modification in May 2005 to account for those issues (see What we can do with TPC while FEE are in upgrade attachement).

Relevant to possible software and hardware solutions for the grid leak are GridLeak Simulations of the fields and particle paths in the region near the inner/outer TPC sector gap.

Extensive analysis are also available from the pages SpaceCharge and GridLeak and especially (for AuAu) this page QA: High Luminosity and the Future.

Anode wire aging

 See the attached file: RD51-Note-2009-002.pdf