Page History

August 27, 2009

Phone bridge number 617 452 2163
Time 2:00 pm to 3:30 pm, people 10

Agenda

1. Evaluation of SL09b production
   • Matt - electrons in BTOW
   • Gene - TPC accuracy
   • Rosi - vertex finder
   • Jan - misc plots
2. W analysis: who is working on it? What is your strategy? Do you need help?
   • Ross
   • Jan : wants to use default jet finder (for isolation and away side veto cuts) and has 0 experience.
   • anyone else ?

...

1. Production status
   • pilot production has been QAed . No major problems were found and Lidia is most likely executing production now.
   • expect St-W muDst to be ready in few days.
   • identified problems to be fixed before next production
     • explain why PPV sees no tracks crossing TPC CM
     • why 7-bit bXing has no abort gap for the fill on page 19 top plot ?
2. ETOW absolute calibration to compensate for incorrect TCD phase used during data taking. Two alternative methods are used:
   • Justin is comparing ratio of slopes for correct & incorrect TCD phase from regular minB events from pp200 data:http://drupal.star.bnl.gov/STAR/blog/stevens4/2009/aug/05/run-9-eemc-tcd-phase-and-effective-gains^{Image Removed}
     Fig 1.1 show example for 1 tower
     Link http://drupal.star.bnl.gov/STAR/system/files/ETOW_SlopeSet0vSet1234.pdf^{Image Removed}
     shows slopes (top) and the deduced gain correction (bottom) for all towers and all crates.
   • Scott is analyzing slopes from calibration pp500 data taken and various TCD phases and predicts similar gain correction for the TCD phase value used during W-data taking. The comparison is here
     

     PDF
     name scott-08-20-2009-all_ETOW-crates.pdf

     In particular pages 4-6 show error bars. Both methods lead to the same gain correction.
   • The plan is to compute weighted average gain correction and upload it to DB with a different flavor. So user will get non-sense gains for the default 'ofl' and needs to request those. (Very good plan, Jan)
3. Status of Vernier scan was presented by Ross:http://drupal.star.bnl.gov/STAR/blog/rcorliss/2009/aug/20/absolute-cross-section-notes-5^{Image Removed}
   The rate of STAR events vs. time (fig 1) is described by the product of 2D gauss functions representing X,Y spread of ions in both (identical?) beams. We know from Angelika the relative displacement of both beams for every time period of Vernier scan. Ross fits 2 params: sigX, sigY - the width of gauss.
   Fig 3 ('counts vs. steps') shows anticipated result. The value of 'skfNN' is absolute cross section of STAR BHT3 trigger in units TBD and assuming no hot tower correction is needed.
   Ross add constant background to better describe the observed rate , yet still peaks are under-predicted.
   He will continue to try to model vernier scan better and is awaiting for muDst from 6 Vernier scan runs from ongoing production to be able to assess how stable is the value of skfNN.
4. run QA : Hal will do QA of the first week of pp500 data within next 30 days, backward in time. (Thanks^2, Hal)

...

1. TPC, Gene:
   • non-linear SC(lumi) should provide TPC track accuracy of 2 mm at both ends of the track. We hope Joe will work on this next week, should take a week.
   • We could also use Gene's PCA method of finding a linear combination of scalers (each at first order).
   • since linear SC(lumi) was tuned to lumi equivalent to ZDC base rate of 70kHz, any pp500 run taken at the ZDC rate has current best TPC calibration. Jan: I'll use it for beam line constrain study, see below.

   • Wiki Markup

     *beam line constrain* : plan A is Rosi & Jan succeed with 3D beam line fit to global tracks w/o intermediate vertex finding. Here are \[[Media:Beamline-v3.pdf |details of the algo]\] as intended and not implemented. If this works Gene needs a \~day to produce beam line constrain for all 39 fills. Plane B is to use Minuit vertex finder which may require significant stats to overcome jitter due to pileup tracks. In such case we would need to provide manpower for \~week long job, Gene would only supervise it. Jan: lets go for plan A.

   • conclusion: once both items are resolved we can ask for production, perhaps 2 weeks from now.
2. BTOW, ETOW gains - no progress.

3. Wiki Markup
   BSMD : Willie is working '''slopes for individual strips'''. He run over 10k VPD-minB events and got this \[[Media:BSMD-strips-Picture 16.png|2D plot of module 119]\] and spectra \[[Media:BSMD-strips-Picture 15.png |individual strips]\]. The available 1.5M vpd-minB events should be enough to fit every strip. If not we will merge strips.

4. Wiki Markup

   BSMD geometry: Scott asked how well we know '''relative position of BSMD vs. TPC'''. It is [followed up on emc2-hn |http://www.star.bnl.gov/HyperNews-star/get/emc2/3250/1.html]. <p> Scott once did \[[Media:Conversions-distace-Scott.pdf | simple calculation for photons that convert to e+/e- pairs]\] in the SVT, attached. <br>The relevant equation is on the bottom left. For the W -> e, we have r_1 = 0, r_2 = 2.3 m (approximate radius of BSMD planes), and B = 0.5 T. With these numbers, you get the simple relation<br> dPhi (cm) = 40 / pT (GeV)<br>For example, an electron of 40 GeV pT will deflect in the phi direction by 1 cm relative to the same e- of infinite pT. This is probably good to better than a few %.

5. run QA : Scott is working on his fills.

...