The STAR experiment

Just as was done in the pp2006: longitudinal polarization, I calibrated using the technique described SpaceCharge and GridLeak Calibration How-To Guide. Just a couple notes:

• I did not even attempt to look at the no-calibration data as the pp2006: longitudinal polarization showed this to be of little help. I simply assumed that ZDC east+west would again be the best relevant scaler.
• Again, calibration was done without the beamline constraint with one exception. For the last pass, I used the values predicted by all the previous passes along with the beamline constraint. The result was a new data point which sits almost exactly on the fit curves, not changing the fits, which is good evidence that the fit had indeed converged.
• The fits for the offset parameter were not as good as the other fits, but almost certainly good enough to move forward.
• Spread in the measures of the SpaceCharge ionization did not improve in any significant way with the use of the beamline calibration. This implies that either the beamline calibration is not doing anything useful, or the spread in the sDCA distribution is dominated by something else.

---

Here are the plots and output from my final iterative pass:

---

Gene Van Buren

Additional link to plots:

http://www.star.bnl.gov/~pjakl/xrootdStat/index.html

BeamLine Constraint

• Data from days 73-130 processed (includes first longitudinal polarization period,
  and transverse polarization period, but not second longitudinal period).
  
  

• Studied and verified validity of triggers I used.
• Identified some problem fills, like:
  1. Fill 7697 (day 93): removing some of the data makes point drop back down; will use
     calib from previous fill

  2. Fill 7712 (day 97): that's all the statistics we have; will use
     calib from next fill

  3. Fill 7786 (day 117): two independent subsets of the data show similar calibs;
     will use the calib found for that fill
• Discussed volatility during transverse running with a RHIC operator,
  seems not unexpected.

• Processing of other May longitudinal data progress.

SpaceCharge & GridLeak

• Calibrations using the May longitudinal polarization dataset is done (without using
  BeamLine Constraint) and is in the DB.
  More details are available pp2006: longitudinal polarization.

• Distortion is so large without any calibration that tracking is being affected
  (tracks are being split at the gap between inner and outer TPC sectors).

• Performed checks that BeamLine Constraint does not affect SpaceCharge calibrations,
  and that SpaceCharge does not affect BeamLine calibration.

• Very close to finishing transverse polarization calibration (one more iteration).
• Will need to re-calibrate with different beam polarizations/energies

Short in TPC IFC East

• As You do not have access to view this node, there is a distortion due to an
  electrical short in the TPC IFC East

• Excess current continues to rise and has exceeded the amount which can be
  explained by bridging a 2 MOhm resistance gap, which most probably isolates it
  to one of the patched 3 MOhm resistance gaps.

• Jim Thomas and I have discussed how to handle this varying distortion and
  will work on implementing it in the coming weeks.

• Distortion is not large enough to prevent moving forward with a dEdx calibration.

Gene Van Buren

gene@bnl.gov

On 5/27/2006 14:50, Timothy Hallman wrote:

Dear STAR Collaborators,

The email concerns an upcoming planning exercise related to
STAR's inner tracking detectors. The review, which will take place
just before the Collaboration meeting (July 7-8) at BNL, will place
particular emphasis on understanding how a plan which optimizes our
physics program in the next few years (including planned upgrades
of STAR's capability) informs the question of future utilization of
the SVT and when it should be taken out of the STAR set-up.

The draft charge for the SVT Review Committee is attached below.
The agenda and the membership of the review panel will be announced
in the coming week.

As a final comment, I would like to thank, in advance, Jerome Lauret,
and Spiros Margetis for organizing the necessary effort for this review, as
well as all the members of the STAR software and SVT analysis teams who
have been working steadily behind the scenes for close to a year now to
produce the necessary understanding to inform this important
discussion.



                               Sincerely,

                               Tim Hallman

Charge to the SVT Review Panel: The charge to the committee is to comment on how a plan which optimizes the scientific output of the STAR Collaboration in the next 3-5 years influences the issue of whether and when the STAR Silicon Vertex Tracker should be removed.

The core physics goals of the STAR Collaboration in the next 3-5 years include:

It is rather important to both know where people are, if there are problems seen, have a general status and make an assessment of what we can __really__ do/present and the intent from people to do what analysis. Concrete is needed with for objective to draw an agenda.

Comments / questions: