# Presentation: 080345

## Integrated Tracker(progress, status, plans)

- Y. Fisyak

## December Status

**Claude Pruneau in his December report gave** (_[http://www.star.bnl.gov/STAR/comp/meet/AM200411/StarMeetDec4-04.ppt](http://www.star.bnl.gov/STAR/comp/meet/AM200411/StarMeetDec4-04.ppt)_) **history, overview of problems  and** s**tatus of Integrated Tracker.  He concluded with following actions list: **
**“...****Code review + some further bug fixes in progress ...**
**Further performance checks ...**
**Is the SVT geometry OK, or Sti problem only?**
**Some tuning - insure tracking parameters are optimal**
**Large scale test and review (again?) “**

## Summary of the Progress for last three months

**Major players in code review, debugging and tests are: Victor, Claude, Manuel, Marco, +Andrew**
**Some principal changes have been made (list of changes on next slides)**
**Bugs have been found and fixed**
**This step has been complete last week**
**IT gets better but we still don’t know:        Is it good enough ?**

## Principle Changes

- 1. **To reduce correlation with ****Curv**** variable**
**     ****eta = Xc*Curv = -sin(Psi) +  x*Curv****      **
**    ****has been replace by **
**     ****eta = -sin(Psi)**
**2. To keep sign of ****cos(alpha)**** (where ****alpha**** is track direction in local system) new argument ****fitDirection**** was added to  a lot of methods.   **
**3. In many places it was a mess between ****NormalRefAngle**** and ****LayerAngle.**
**4. Each node now is initiated with infinite ****chi2**** and changed only if fit is successful. This blocks penetrating garbage to track parameters.**

## Principle Changes (cont.)

**5**. **In refit covariance matrix has been reset.**
**6. Alice propagation formula has been corrected for big angles.**
**7. Added debugging tools on different levels:**
**Added numerical verification of derivative matrices.**
**Added verification of all matrix manipulation.**
**8. Added dead material (mainly for SVT) using Virtual Monte Carlo geometry.**

## Modification required (next step)

- The main limitation in IT now is the geometry model:
- It is essentially 2D + 1 geometry which is the first of all suited for ideal TPC (Global to Local coordinate transformation => rotation around Z)
- This creates troubles with alignment and including new detectors.
- The solution is to use VMC geometry.
-     The concern was that VMC could affect performance. There is proof (from Victor’s test) that this is not the case. VMC is a factor of ~3 faster in geometrical node search with respect to Sti tracking.

## Status

- After all above there are certain improvements, especially for tracks with no. of TPC points > 15 but
- The overall status of IT is still unclear.
- Test production has been run (“no SVT” runs are still in processing)
- We have not finished evaluation yet..
- More news later

## Dead material

**After adding dead material there is no more offset in energy measurement seen before**

** ****Reconstructed - Simulated energy versus 1/pT**

**Before adding dead material: 3 MeV offset**

**After adding dead material: no offset**

## SVT matching

**Possible/ found hits**
**                ****0          1           2         3          4 **
**0      1.000**
**1      0.163   0.837                            eff. ~ 70%**
**2      0.063   0.483   0.453**
**3      0.041   0.221   0.329   0.409**
**4      0.034   0.208   0.243   0.456   0.059**

## No. of Primaries versus no. of Globals

- Two band shape is due to tracks with No.TPC hit points < 15

## Plans

**Evaluation of present IT with test productions (with and without SVT)**
**Performance with respect to tpt**
**Possible IT parameters tuning**
**Bring IT to level of PWG evaluation by ****April 1, 2005.**
**Check possibility to use VMC **
**Proof of principle (very tentatively) by ****April 1, 2005**
**By August 1, 2005**
**Add Smoother (IT hit self consistency check) **
**Primary vertex fit has to be revisited to use track parameters errors, multiple primary vertex option.**
**Alignment**
**New detectors**