# Presentation: 601442

## Status of Reaction Plane Detector 

- Eric Richardson for RXNP Group
- University of Maryland
- PHENIX Collaboration Meeting
- 7/12/07

## All plots provided by Shinlchi Esumi and his graduate students

## Detector Components

- Detector has North and South halves
- Each half divided into quadrants
- Each quadrant contains:
- 1 Pb converter
- 3 inner & 3 outer scintillators
- 6 fine mesh PMT’s 	(Hamamatsu R5543)

## Detector Components

## Historical Time Line

- Only 20 months from conception to data taking

|  | Winter | Spring | Summer | Fall |
| --- | --- | --- | --- | --- |
| 2005 |  |  | Conceived | Design & Simulations |
| 2006 |  | Improved Detector Design | Testing & Assembly,
Installed Aug. | Electronics & Software |
| 2007 |  | Finished Commissioning |  |  |

## Detector Performance during Run 7

- 47 of 48 PMT’s operational for entire run
- RXNP collected data on all Physics runs
- Efficiency of RXNP compared to BBC is 100% except for the most peripheral collisions [95%]

## Detector Performance

**z-vertex cuts by BBC**

**[-40,40] cm**
**[-30, -20] cm**
**[-5,5] cm**
**[20,30] cm**

**RXNP south charged mult. (a.u.)**

**RXNP north charged mult. (a.u.)**

- Behavior wrt. to z-vertex

- RXNP

- Nosecone

- Nosecone

- BBC Vertex Cuts

- Beam Pipe

- [-30,-20]   [-5,5]   [20,30]

- _South_

- _North_

- _PHENIX Central Region_

## Detector Performance

******south**** (rad)**

******north**** (rad)**

**mid-central **
**collisions**

- Counts

- Agreement of Determined RP Angle

## Detector Resolution

- Max Resolution
- RXNP ~0.75
- MPC ~0.52
- BBC ~0.40
- RXNP resolution about a factor of 2 higher than BBC
- Combined resolution of BBC+MPC+RXNP is ~0.8

- <cos 2(E.P.{2}-true)>

**R.P. resolution**

- 0%		           100%
- Centrality

- RXNP

- MPC

- BBC

## v2 comparison of Run 7 to Run 4

| Resolution | Statistics |
| --- | --- |
| Run 4 - 0.40 
Run 7 - 0.75 | Run 4 - 1.5B
Run 7 - 5.1B  |
| Equivalent to ≈3.5x statistics | 3.4x actual statistics |

## Possible J/ v2

- _Possible J/____ v__2_

- Calculations by Tony Frawley

- Run 7
- 0.813/nb

## Detector Performance

- Saw some aging effects on PMT’s

## RXNP as a Trigger

- Wrt centrality RXNP behaves similarly to BBC
- Use for low energy Au+Au run
- Expected to increase trigger efficiency from ~15% with BBC to ~96%.
- During Run 7 timed in RXNPLL1 with respect to BBCLL1, but further testing needed to see if it will be a viable trigger for low energy Au+Au, d+Au, and p+p

**Charged Multiplicity in RXN (a.u.)**

**Centrality cuts are given**
**by BBC charged multiplicity**

**total**
**[<500]**
**[500~1500]**
**[1500<]**

- Counts

- Behavior wrt. to Centrality

## Summary

- RXNP successfully commissioned for Run 7
- Detector is working well
- Resolution of ~0.75  (BBC ~0.4)
- v2 measurement in Run 7 equivalent to ~12x statistics of Run 4
- Further testing needed to ensure the success of RXNPLL1

## Slide 15

## Backup

## Combining Detectors

- Combining RXNP, MPC, and BBC yields an even higher resolution

- RXNP(S) - RXNP(N)
- MPC(S) - MPC(N)
- BBC(S) - BBC(N)

- RXNP(SN) - MPC(SN)
- RXNP(SN) - BBC(SN)

- BBC+MPC+RXNP  (S - N)
- BBC+MPC               (S - N)

- <cos 2(A-B)>

**< cos 2(********A+B**** - ********true**** ) >**

**RXNP**

**BBC**

**< cos 2(********A**** – ********B**** ) >**

**RXNP+**
**MPC+BBC**

- 0%	                  100%
- Centrality

- 0%	                    100%
- Centrality

- 0%	                    100%
- Centrality

## Uncorrected v2

- <cos 2(CNT-E.P.{2})>

- <cos 2(CNT-E.P.{2})>

- Un-corrected v2

- Un-corrected v2

- RXN(SN)
- MPC(SN)
- BBC(SN)

- RXN(SN)
- MPC(SN)
- BBC(SN)

- 0       1       2       3        4     5
- pT [GeV/c]

- 0%		        100%
- Centrality

## Corrected v2

- corrected v2

- corrected v2

- v2 (charged particle (||<0.35)

- v2 (charged particle (||<0.35)

- 0     1      2       3      4
- pT [GeV/c]

- <cos 2(E.P.{2}-true)>

- R.P. resolution

- RXN(SN)
- MPC(SN)
- BBC(SN)

- 0%	          100%
- Centrality

- 0%	           100%
- Centrality

## RXNP_DST

-      TRxnpRawScint
-      TRxnpScint
-      TRxnpRawXang

- BbcReco

- RpSumXYReco

- CNT/PWG/EWG/nDst/pDst
-      RpSumXYObject
-      PHGlobal
-      central/muon tracks

- ZdcReco

- MpcReco

- RxnpReco

**programs executed during production**

**calibration and analysis with ReCal**

- centrality calibration

- r.p. flattening calibration
- run by run calibration with M.B. CNT (~6 segments: ~300K events) to make ascii constants, which are being uploaded to the database after verification of the quality

**output DSTs from production**

- r.p. re-calibrator
- using RpSumXYObject and the database calibration constants, r.p. angle will be created on fly and available as ReactionPlaneObject with turning on master-re-cal-reco...

- Masahiro Konno
- Kentaro Miki

- Hiroshi Masui
- Yoshimasa Ikeda
- Kengo Watanabe