# Presentation: 122317

## Reaction Plane Resolution in 200 GeV Cu+Cu Collisions 

-  Shusu Shi
-  11/05/2007

## Overview

- Event and Track Selection
- FTPC and TPC reaction plane
- FTPC and TPC reaction plane resolution
- Summary and outlook

## Event and Track Selection

| Trigger Setup Name | Day number | Vertex Cut | Trigger ID | No. of Events |
| --- | --- | --- | --- | --- |
| cuProductionMinBias | 048-053 | |Vz|<30cm | 66007 | 3.5 M |

**Used events:**

**1. Reactionplane from FTPC can decrease the non-flow correlation and auto correlation effects.**
**2.Comparing the v2 results from FTPC reactionplane with TPC reactionplane can help us understand the non-flow effects.**

**              ****Tracks used for FTPC reaction plane**
**                                  ****Primary tracks**
**     ****5 =< nFitHits < 11 **
**       ****0.52 < gnHitsFit/gnHitsPoss < 1.05**
**     ****0.1 < pT < 2.0 GeV/c **
**       ****2.5<|eta| < 4.0**

**Tracks used for TPC reaction plane**
**                 ****Primary tracks**
**                  ****nFitHits >= 16**
**        ****gnHitsFit/gnHitsPoss > 0.52 **
**             ****0.15 < pT < 2.0 GeV/c **
**                       ****|eta| < 1.0**
**                       ****gDca<2.0**

**Centrality bins **
** ****10%  20%  30%  40%  50%  60%:**
** ****140   103    74     53     37     25**

**a.     Eta distribution for primary tracks.        b.   NHitsFit distribution for primary tracks.**
**c.     NHitsFit distribution for FTPC tracks     d.   NHitsFit distribution for TPC tracks.**** **
**     **

**(a)**

**(b)**

**(c)**

**(d)**

## Weighting Corrections

**West**
**FarWest**
**East**
**FarEast**

**Phi weight corrections are done day by day, centrality by centrality**

**Phi distributions**

**We remove the**
**detector bias by **
**applying phi weights**
**to the tracks.**** **
**Phi weights are generated by inverting the**
**normalized phi distributions of detected tracks for**
**a large event sample.**

**(a)**

**(b)**

**(c)**

**(d)**

## Shifting Corrections

**If the detector has only minor inefficiency, both of east reaction plane and west reaction plane will be flat. In the reality, they are not  because of  the severe loss of acceptance at some places in FTPC**
**Then we need step 2. ****Apply shifting method on east reaction plane and west reaction plane. The shifting method will force any distribution to be flat. So both of them will become perfectly flat if you do it correctly.****  **

-     (n=1,2,3,4...... )

**J.Barrette et al. Phys. Rev. C56 (1997)3254 **

**(1)**

**(2)**

**Equation (1) and (2) define the event flow vector Q****2**** and the event plane**
**Angle ****Ψ****2 ****(The subscript 2 means we use the second harmonic): **

## Reaction plane distribution

**Correction term up to n = 8**

**Red line stands for distributions after weight correction**
**Black line stands for distributions after shift correction**

**(a) West Shift + East Shift then shift.**

**(b) West**

**(c) East**

**(d) TPC**

## Reaction plane resolution for FTPC

**Fig1. Distribution of **
**for ****FTPC**
**Fig2. ****Upper****: Reaction plane resolution for**** FTPC**** **
**         ****Lower****: Reaction plane resolution for ****TPC**** **
** ****(The first bin stands for the resolution of  0-60% centrality)**

**Resolution of 0-60% ****centrality**
**FTPC : ****0.171 +/- 0.004**
** ****(Using West and East as sub-events).**
**TPC:    ****0.552 +/- 0.001**

**Fig1**

**Fig2**

## Summary and Outlook

**Summary**
**We reconstructed CuCu 200 GeV FTPC and TPC reaction plane.**
**We calculated CuCu 200 GeV FTPC and TPC reaction plane resolution.**
**Outlook**
**Full data Strange hadron v2 for CuCu 200 Gev will be done.**

## Thank you for your attention!