# Presentation: 488468

## STAR Calibrations

**STAR Calibrations**

***Gene Van Buren***
***Brookhaven National Lab***

***STAR Collaboration Meeting***
***BNL - Feb. 23, 2005***

## Outline

- 2003 issues
- SpaceCharge in dAu
- 2004 issues
- GridLeak
- 2005 issues
- Preparing for CuCu production
- Future?

## dAu Issues (2003)

**dAu Issues (2003)**

- SpaceCharge effect observed in dAu via physical-signed DCAs. Is it a problem?

## dAu Issues (2003)

- Strangeness showed no conclusive evidence that correcting this data helps low-PT issues for K0s.
- Contact me if you want to learn/study more.

- Mark Heinz

## pp Issues (2004)

**pp Issues (2004)**

- Notable SpaceCharge!
- Correcting via scaler-based measures of luminosity.

## SpaceCharge: E-by-E

- Fluctuations on the seconds time scale
- E-by-E handles this, but is problematic for ‘gaps’

- Run 5044026: productionHigh

## SpaceCharge: E-by-E

- Run 5044026: productionHigh

- Fluctuations on the seconds time scale
- E-by-E handles this, but is problematic for ‘gaps’

**Notes:**
E-by-E does well to correct this
Prepass gets us started and helps with gaps as a fallback value.
Started production with this but....

## TPC GridLeak distortion

- Dependence on field, track charge, location, luminosity consistent with ion leakage at gated grid gap

## TPC GridLeak distortion

- Dependence on field, track charge, location, luminosity consistent with ion leakage at gated grid gap

**Notes:**
...there was a new problem.

## Understanding the Distortion

**Understanding the Distortion**

- “Gap” goes with luminosity - allows scaling with SpaceCharge (measure of lum.)
- Somewhat worse for half field

## Understanding the Distortion

**Understanding the Distortion**

- “Gap” varies ~linearly with z

## Understanding the Distortion

**Understanding the Distortion**

- “Gap” varies ~linearly with z
- No observed dependence on GG-opening rate!

## Understanding the Distortion

**Understanding the Distortion**

- “Gap” goes (qualitatively, not quantitatively) with anode gains

## TPC GridLeak distortion

- Correcting for the gap leaves some residual even smaller effects (still under study - a testament to the TPC that we can see them!)

## GridLeak Distortion Correction

- Is the GL correction even worth doing?
- In January, several PWGs started reporting issues with the (at the time) current production.
- Ran a test production using data under different fields and luminosities.
- PWGs indicated that most issues were improved.
- There appear to be some remaining issues (K0s mass in half field data).
- Re-calibrated dE/dx and going again.

**Notes:**
Which brings us to 2005 issues and readiness...

## 2005 Non-tracking detectors

**BEMC** focus is on 2003 & 2004 data calib.
**EEMC** gains done.
**TOF** doing their own thing this year.

## 2005 Tracking Detectors

**SVT**
- Calibration that don’t need tracking done.
- Alignment needs to be redone (cone was removed during the break) - awaits fully-calibrated TPC
**SSD**
- Developing methods for gaincalibrations and alignment(much to be done)
**FTPC**
- Calibs that don’t need TPC vertexdone (Gains, T0, d.v.)
- Alignment/rotation needs fully-calibrated TPC

**Notes:**
FTPC did a lot of work on insuring temperature calibrations this year, and automating insertion into DB.

## 2005 TPC drift velocity

**2005 TPC drift velocity**

- Initially done using lasers, a process now automated, including insertion into DB (Javier & Jerome)
- Gets double-checked with vertex-matching from two TPC halves
- Still eventually want to use SVT (best)

- DV from east lasers
- before outlier removal

- Javier Castillo

## 2005 SpaceCharge + GridLeak

**2005 SpaceCharge + GridLeak**

- SpaceCharge & GridLeak distortions comparable to what we had in AuAu

## 2005 TPC calibrations

- Second TPC short for 1.5 weeks
- Twist distortion calibration
- SpaceCharge vs. Scalers
- Now have Scalers with higher sampling rates stored in the data stream.
- GridLeak vs. SpaceCharge
- dE/dx calibration
- Provide good tracking for SVT, good vertex for FTPC

## 2005 TPC calibrations

- Second TPC short for 1.5 weeks
- Twist distortion calibration
- SpaceCharge vs. Scalers
- Now have Scalers with higher sampling rates stored in the data stream.
- GridLeak vs. SpaceCharge
- dE/dx calibration
- Provide good tracking for SVT, good vertex for FTPC

## Future TPC

- Higher-than-design luminosities brought issues we did not expect (and have yet to fully understand)
- Can we be surprised again at higher luminosities?
- Lesson: **fine details can become coarse!**
- Are there issues in the current data of which we’re unaware? no measures?
- Beating design spec despite!
- Guarantee that a TPC replacement won’t harbor surprises?

## Summary

**Summary**

- Same old thing:always seems to be something new...
- Working to get calibrations to the point where they make great physics possible!

## Extras

## SpaceCharge : Zerobias

- Run 5047041, Fill 4547

## GridLeak Gap

**GridLeak Gap**

- There is some remaining azimuthal dependence

## psDCA vs. phi

**psDCA vs. phi**

- Something going on versus phi

- Run 5046043

- Run 5058060