computing

pp2006: transverse polarization

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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:

* Constraint on SC x GL = 7.32e-07
* Guesses on SC = 8.73e-08 , 4.39e-08 , 8.63e-08 , 4.39e-08
* Guesses on GL = 8.39 , 11.3 , 8.48 , 11.3
* Guesses on SO = 3.27e+04 , 3.26e+04

*** FINAL CALIBRATION VALUES: ***
SC = 8.63e-08 * ((zdce+zdcw) - (3.27e+04)) with GL = 8.48

Gene Van Buren

SVT/SSD Review Coordination meeting 7

-00-00
Thursday, 1 January 1970
, at 00:00 (GMT), duration : 00:00
Previous meetings are available at
  1. [node:1297]
  2. [node:1540]
  3. [node:1568]
  4. [node:2299]
  5. [node:2298]
  6. [node:2300]
Attendance: Jamie, Lidia, Gene, Maxim, Rene, Christina, Yuri, Victor and Thomas
Phone: Spiros



TimeTalkPresenter
17:00Review charges reminder, logistic ( 00:10 ) 0 filesMyself (BNL)
17:10Data set status and location summary ( 00:10 ) 0 filesLidia Didenko (BNL)
17:20Planned analysis and who is going to make presentations ( 00:30 ) 0 filesAll (All)

Pedestals / Status Tables

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Code for the calculation of the BTOW & BSMD status tables has been made publicly accessible. BTOW status code is in StRoot/StEmcPool/CSMStatusUtils.

Calibrations

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Here you'll find links to calibration studies for the BEMC:

BTOW

2006

pp2006: longitudinal polarization

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Using the calibration technique described SpaceCharge and GridLeak Calibration How-To Guide, I made several passes on data from the longitudinal polarization running. This was the first dataset from the 2006 running which I calibrated, and there were a few items to note during this calibration process:
  • No beamline constraint was yet available while I did the calibration. Instead, a beamline fixed to the z-axis was used. This should bias the vertex positions, but as long as tracks used in this calibration come from all azimuth angles, there should only be a smearing of the DCA distributions, not a bias.
  • Distortions were larger than ever before, so histogram ranges needed expanding.
  • Spread in the measures of the GridLeakage and SpaceCharge ionization were larger than I found when calibrating CuCu22 from last year, so I had to open the cuts used in the Calib_SC_GL.C macro (from 0.005 and 0.0003 respectively for CuCU22, to 0.015 and 0.0015 for this data). The SpaceCharge cut in particular had to be significantly widened. I though that this might be because of the uncalibrated beamline constraint, which introduces a smearing of a few mm into the primary vertex DCA distribution used to determine SpaceCharge, but a later test using the beamline constraint did not significantly narrow this distribution.
  • For the first pass of this calibration, I used Fast Offline data which had no SpaceCharge and GridLeak corrections. While the first pass was somewhat useful to suggest where to start with SpaceCharge and GridLeak correction parameters, I had to remove the first pass data points from the eventual iterative pass fits because the distortion is so strong that without correction we actually lose tracks with large GridLeak gaps, biasing our measure of the distortion. This can be seen in the following plot of measured distortion gap versus the amount of GridLeak correction used (as expressed by SC*GL), where the no-correction points significantly alter the straight-line fit:

    It may also be true that the StMagUtilities code used to correlate distortions to the ionization has issues when the GridLeak gap is large. Work is in progress to improve this particular code.


Excluding the no-correction data, here are the plots and output from my final iterative pass (after enough iterations to stabilize the fits):

* Constraint on SC x GL = 7.31e-07
* Guesses on SC = 8.9e-08 , 3.95e-08 , 8.96e-08 , 3.95e-08
* Guesses on SO = 4.68e+04 , 4.72e+04

*** FINAL CALIBRATION VALUES: ***
SC = 8.96e-08 * ((zdce+zdcw) - (4.7e+04)) with GL = 8.2

Gene Van Buren

Useful Documents

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 A full list of attached documents is available below, but I wanted to highlight a few here:

BEMC Technical Design Report (PDF)

Miscellaneous TPC calibration notes

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The log file for automated drift velocity calculations is at ~starreco/AutoCalib.log.

Log files for fast offline production are at /star/rcf/prodlog/dev/log/daq.

The CVS area for TPC calibration related scripts, macros, etc., is StRoot/macros/calib.

ExB (twist) calibration procedure

In 2012, the procedure documentation was updated, including global T0 calibration:

Web Access

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STAR web organization at BNL

  • The STAR home page URL is http://www.star.bnl.gov/ .

GatedGrid polarity test for GridLeak

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On May 9-10, 2006, a test was performed where we reversed the polarity of the Gated Grid as shown in the top of Fig.3 in the GridLeak Simulations ["inverted" mode] for the west side of the TPC. Here are the results of that test.

Z-dependence

Below are plots of the distortion gap (as measured by track residuals) as a function of Z for normal runs (71290[234]*, 57 files) and test runs with the west GG reversed (71290[56]*, 39 files). Here one can see the slight improvement caused by reversing the polarity. At this time I have no explanation for why the distortion seems to abate near the central membrane (the distorting field should abate because of the boundary conditions, but the distortion is an integral in Z over this field).

Normal:
West reversed:

West/East Ratio

Using a linear fit to the distortion as a function of |Z| as a measure of the amount of leaked ions (distortion scales linearly with Z and with leaked current), I can take the ratio of the west side to east side to see if anything changed with the test. I find that the test appears to show a visible decrease of about 2-3% in the ion leakage, as seen in the following (normalized) histograms. I had more files available when I made this plot (70 normal, 69 reversed test files), and only fit over the range 25cm<|Z|<150cm.


Gene Van Buren
gene@bnl.gov

pp200 (2006)

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SVT/SSD Review Coordination meeting 6

-00-00
Thursday, 1 January 1970
, at 00:00 (GMT), duration : 00:00
Previous meetings available at
  1. [node:1297]
  2. [node:1540]
  3. [node:1568]
  4. [node:2299]
  5. [node:2298]
TimeTalkPresenter
15:00Status and readiness of the code ( 00:10 ) 0 filesAll
15:10Calibration adjustment and recent changes ( 00:10 ) 0 filesYuri Fisyak
15:20Self-alignment and how to move forward ( 00:10 ) 0 filesVictor, Christine, all
15:40Production samples, statistics, time etc ... ( 00:10 ) 0 filesJerome Lauret

SVT/SSD Review Coordination meeting 4

-00-00
Thursday, 1 January 1970
, at 00:00 (GMT), duration : 00:00
Previous meeting reference
  1. [node:1297]
  2. [node:1540]
  3. [node:1568]

This meeting was restricted to discuss technical issues and show stoppers we may have had still. Topics included

  • Self-alignment progress / where are we (Victor)
  • Drift velocity (Yuri)
  • track ID issue ? Vertex issue ? (All)
  • Overview of other activities (Spiros)

SVT/SSD Review Coordination meeting 5

-00-00
Thursday, 1 January 1970
, at 00:00 (GMT), duration : 00:00
Previous meetings are available at
  1. [node:1297]
  2. [node:1540]
  3. [node:1568]
  4. [node:2299]
TimeTalkPresenter
14:30Geometry and Drift calibration status ( 00:10 ) 1 fileSpiros Margetis (KSU)
14:40Self-Alignement discussion ( 00:10 ) 0 filesChristine Nattrass (Yale)
14:50Self-Alignement discussion ( 00:10 ) 0 filesVictor Perevoztchikov (BNL)
15:00Progress forward, missing code components ( 00:10 ) 0 filesAll

CuCu200 (2005)

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This is a quick look at the performance of SpaceCharge & GridLeak corrections performanc in a test production sample of CuCu200.

Metrics and Accounting

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Lets try to post the grid metrics and accounting info here.

SVT/SSD Review Coordination meeting 3

-00-00
Thursday, 1 January 1970
, at 00:00 (GMT), duration : 00:00
Previous meetings are listed below
  1. [node:1297]
  2. [node:1540]
Today's agenda will be focused on getting a few action item from [node:1540 "two weeks ago"] sorted out.
TimeTalkPresenter
15:00Feedback summary from the PWGC ( 00:10 ) 0 filesJames Dunlop (BNL)
15:10Library status and chain readiness ( 00:10 ) 0 filesLidia Didenko (BNL)
15:20Simulation sample summary ( 00:10 ) 1 fileMaxim Potekhin (BNL)
15:30Analysis progress ( 00:10 ) 0 filesAll (All)
15:40Self-alignement technique progress ( 00:10 ) 0 filesVictor Perevoztchikov (BNL)
15:50SSD / TPC alignment status, drift velocity ( 00:10 ) 0 filesYuri Fisyak (BNL)

Hardware and Software status

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The link below points to a document detailling the current (April 2006) status of the SSD hardware and software.

End of the migration

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The SSD web server is now fully transferred from Lyon to BNL.
The "phototheque" for instance is now accessible.
I have change several pages but some pages may still point to the old location.

SVT/SSD Review Coordination meeting 2

-00-00
Thursday, 1 January 1970
, at 00:00 (GMT), duration : 00:00
Previous meetings listed below
  1. [node:1297]
We are planning to discuss the following items:
  • We would review the requests for data and infrastructure and the past week action items
  • We will go over the remaining technical details if any
  • I would like for the core team to read and review the document attached in [node:1502 "here"] and plots attached by Maxim (thanks) in [node:1501] so we can have a fruitful discussion on this as well.