# Presentation: 819032

## Spin Physics with the PHENIX Detector Upgrade

-  **M. Grosse Perdekamp**
** ****University of Illinois **
** ****and RBRC**

**AGS&RHIC Users’ Meeting, BNL, June 20****th****  2007**

-   **Introduction**
- 	Nucleon spin structure at RHIC
- 	Measurements in parallel channels vs DAQ and trigger capabilities
- 	The importance of low-x
- 	PHENIX detector Upgrades
**  ****Physics with the PHENIX detector upgrades**
** **
**	****Δ****G(x) at low x  with photons and heavy quarks**
-                       measurement of ΔG = ∫ ΔG(x)dx.
- 	**Lepton single spin asymmetries in polarized W-production**
-                       precision measurement + flavor separation of Δq(x),** **Δq(x)
- 	**Sivers effect in Drell Yan**
-                       Lz ? , test concepts of factorization + universality in QCD.
- 	**Collins asymmetries**
-                       measurement of quark transversity distributions.
-   **Conclusions**
**      **

## 2005 Complete!

**AGS**

**LINAC**

**BOOSTER**

-   Polarized Source

- Spin Rotators

- Partial Snake

- Siberian Snakes

-   200 MeV Polarimeter

-  AGS Polarimeter

-   Rf Dipole

-  RHIC pC Polarimeters

-  Absolute Polarimeter (H jet)

**P****HENIX**

**P****HOBOS**

**B****RAHMS & PP2PP**

**S****TAR**

- Siberian Snakes

- Helical Partial Snake

- Strong Snake

-  Spin Flipper

**2005 Complete!**

**A novel experimental method****:**   Probing Proton Spin Structure
-   Through High Energy Polarized p-p Collisions

**∫****Ldt ≈    15 pb-1       2007 **
**∫****Ldt ≈    85 pb-1       2008 – 2012, ****√s=200 GeV**
**∫****Ldt ≈   300 pb-1      2008 – 2012, √s=500 GeV**
**∫****Ldt ≈ 1300 pb-1      2013 – 2016, √s=500 GeV**
**Upgrades will be available for most of**
**    ****RHIC spin luminosity!**

## Nucleon Structure at RHIC: Physics Highlights

-         **Physics Goals**
- determine first moment of
- the ***spin dependent gluon***
***distribution***, ∫01ΔG(x)dx.
- measure ***nuclear effects*** on
- the gluon distribution in
- nucleons in nuclei.
- Flavor separation of ***q and anti-quark***
***spin distributions*** in W-production
- measurement of ***trans-***
***versity*** quark distributions.
- Establish magnitude of
- the ***gluon Sivers*** effect.

**Sivers Effect**

## Polarized p-p as a Precision Tool for the Study of Nucleon Structure

** ****Improved theoretical tools: e.g. resummation, NLO perturbative QCD**
** ****Build on experimental results from DIS + unpolarized p-p**
**(C) Consistency: PDFs from DIS + QCD vs cross sections at RHIC**
**(D) Multiple channels which provide access to spin dependent PDFs with **
**      ****independent experimental and theoretical uncertainties.**
**             ****e.g. ****Δ****G  ******** inclusive hadrons**
**                               ******** ****inclusive photons**
**                               ******** ****jet + photon**
**                               ******** ****open heavy flavor**
** **

**Critical: large PHENIX DAQ bandwidth**
**(~ 8kHz) for highest possible rates**
**in multiple channels (including at**
**low p****T****!)**

## Run 5 ALL(): First constraints for ∆G(x)

-  ̈

**standard ****∆G from DIS**

**∆****G =0**

**max ****∆G from DIS**

**min ∆G possible**

**Run 5 A****LL****(************): First constraints for ****∆G(x)**

- Mutiple Channels vs DAQ Bandwidth: Photon Trigger

**~ 1500 Hz**

** ****Photon**
** ****Trigger**

**L=6x10****31****cm****-2****s****-1**

**Photon trigger rate**
**    ****for a threshold at **
**    ****2.1 GeV is ~ 1.5kHz**
**Even at small p****T**** A****LL**
**    ****is statistics limited:**
**         ****Δ****stat****A ~ 2x10****-3****, **
**         ****Δ****sys ****A < 5x10****-4**
**Continue data taking**
**    ****with low threshold!**

## Future ALL(c,b) Projections with VTX   

-  ̈

**Future A****LL****(c,b) Projections with VTX**

- Mutiple Channels vs DAQ Bandwidth: Electron Trigger

**~1500 Hz**

** ****Electron**
**  ****Trigger**

**systematic limit**

**L=6x10****31****cm****-2****s****-1**

**electron rate **
**    ****for a threshold at **
**    ****0.9 GeV is ~ 1.5kHz**
**need ****∫Ldt=320pb****-1**
**    ****before systematics**
**    ****limited at low p****T****!**
**Continue data taking**
**    ****with low threshold!**

## Mutiple Channels and DAQ Bandwidth

**Large bandwidth and trigger capabilities are critical to fully**
**benefit from measurements in multiple channels, e.g. *****Δ******G(x)***** !**
**PHENIX DAQ and trigger are ideal.****	**
**In addition to testing experimental and theoretical**
**    ****uncertainties in independent physics channels**
**    ****this approach leads in PHENIX also to the best**
**    ****statistical precision for results on spin dependent**
**    ****nucleon distribution functions.**
**    ****Final results on spin dependent observables, e.g. *****∫******Δ******G(x) dx***** **
**    ****will come from inclusive Next-to-Leading-Order perturbative**
**    ****QCD analysis of the asymmetries from all experimental**
**    ****channels.**

**   **
*** ******Low x is important******  ***
** **

## Nucleon Structure: 40 Years of Experiment Deep Inelastic Lepton-Nucleon Scattering!

- Nucleon Structure: 40 Years of Experiment Deep Inelastic Lepton-Nucleon Scattering!

******2000**

******2010**

******1995**

******2007**

**ongoing**

**ongoing**

**                ****q(x) -- G(x) -- ∆q(x) – DVCS -- ****δ****q(x) -- Sivers -- ****∆G(x) -- ∆q(x) -- ∆s(x) **
**SLAC      ****DIS, polarized-DIS  **
**CERN                                 ****DIS, polarized-DIS**
**FNAL         ****DIS,        pp**
**DESY                                  ****collider-DIS, polarized-DIS**
**JLAB                                 ****DIS, polarized-DIS**
**RHIC                                                                         ****polarized-pp**

**Polarized p-p scattering is a new experimental technique for**
**the precision study of spin dependent nucleon structure and**
**Has to compete in a well established and advanced field.**
**An important “history lesson” is the central role low-x data**
**   ****have played.**

**1965 **

**2005 **

## The Importance of Low x ,  Example ΔΣ

-  Quark Spin Contribution to the Proton Spin.
-  Measurements at SLAC:   *0.10 < x**SLAC  **<0.7*
-                          vs CERN:   *0.01 < x**CERN **<0.5*

**0.1 < x****SLAC ****< 0.7**

***A******1******(x)***

**x-Bjorken**

**EMC, Phys.Lett.B206:364,1988: 1319 citations in SPIRES**
**EMC, Nucl.Phys.B328:1,1989, 1138 citations in SPIRES **

**0.01 < x****CERN ****< 0.5**

**E130, Phys.Rev.Lett.51:1135,1983: 412 citations.  **

**Evaluation of ****Δ****G=∫****0****1****G(x)dx**
**requires large x coverage**
**in particular towards low x**

** ****QPM expectation !**

##    Overview

**   *****Overview***
***PHENIX Upgrades******  ***
** **

## Physics of the PHENIX Detector Upgrades   

- High T QCD (AA, pA, and pp):
- Electromagnetic radiation (e+epair continuum)
- Heavy flavor (c- and b-production)
- Jet tomography (high pT PID, jet-jet and -jet)
- Quarkonium (J/, ’ , c and (1s),(2s),(3s))
- Spin structure of the nucleon:
- Gluon spin structure G/G (heavy flavor and -jet correlations)
- Quark spin structure q/q (W-production)
- Transverse Spin structure (Collins-jet, Sivers-Drell Yan)
- Low x phenomena
- Nucleon gluon structure in nuclei  saturation?

**Physics requires **
**highest AA, pA or**
**pp luminosity**

- Measurements are based on existing detector capabilities + upgrades

## PHENIX Detector Upgrades at a Glance

- Central arms:
-       Electron and Photon measurements
-          o Electromagnetic calorimeter
-          o Precision momentum determination
- Hadron identification
- Muon arms:
- Muon measurements
-     o Identification
-     o Momentum determination

-   + Dalitz/conversion rejection – **HBD **
-   + Precision vertex tracking – **VTX  **
-           + PID (k,,p) to 10 GeV  - **Aerogel/TOF**
-   + High rate trigger - ****** trigger**
-   + Precision vertex tracking - **FVTX**
- Electron and photon measurements
- +  Muon arm acceptance - **NCC**
- +  Very forward - **MPC**

**C**
**F**
**C**
**F**
**P**
**P**
**C**

- C: complete F: funded P: proposal stage

## PHENIX Upgrades Physics Capabilities 

**X****  upgrade critical for success**
**O **** upgrade significantly enhancements program**

**PHENIX upgrades designed for optimum **
**physics output with RHIC II luminosity**
**spin channels require the highest ∫Ldt**

## Upgrades: Future PHENIX Acceptance  

**-3              -2             -1                 0                1               2               3    rapidity**

**(i)  ********0**** and direct ******** with combination of all electromagnetic calorimeters**
**(ii) heavy flavor with precision vertex tracking with silicon detectors **
**     ********combine (i) and (ii) for jet tomography with ********-jet **
**(iii) low mass dilepton measurments with HBD + PHENIX central arms**

- Upgrades: Future PHENIX Acceptance

## PHENIX Upgrades Schedule

|  | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Aerogel |  |  |  |  |  |  |  |  |  |  |
| TOF-W |  |  |  |  |  |  |  |  |  |  |
| HBD |  |  |  |  |  |  |  |  |  |  |
| VTX-barrel |  |  |  |  |  |  |  |  |  |  |
| FVTX-endcap |  |  |  |  |  |  |  |  |  |  |
| NCC |  |  |  |  |  |  |  |  |  |  |
| MuTrigger |  |  |  |  |  |  |  |  |  |  |
| DAQ |  |  |  |  |  |  |  |  |  |  |

**R&D Phase**

**Construction Phase**

**Ready for Data**

##    ΔG = ∫01ΔG(x)dx  

**   *****Δ******G = ******∫******0******1******Δ******G******(x)dx  ***
** **

## RHIC: Measurement of ΔG = ∫01ΔG(x)dx  ?

## NLO QCD Analysis of DIS A1 + ALL(π0) 

- M. Hirai, S. Kumano, N. Saito, hep-ph/0603212
- (Asymmetry Analysis Collaboration)

**DIS A****1**** + A****LL****(****π****0****)**

**ACC03**

***x***

## PHENIX π0 ALL vs GSA-LO and GSC-NLO

**A****LL**

**p****T****[GeV]**

**GSA-LO**

**GSC-NLO**

**PHENIX-2005-PPG063**

**GSA-LO: *****Δ******G = ∫******Δ******G(x)dx = 1.7***
**     **

**GSC-NLO: *****Δ******G = ∫******Δ******G(x)dx = 1.0***
***  ***
** **

**Large uncertainties resulting**
**from the functional form used**
**for ****Δ****G(x) in the QCD analysis!**

- GSA-LO and GSC-NLO
- courtesy Marco Stratmann
- and Werner Vogelsang

## ΔG(x) A, B and C from Gehrmann Stirling

**present **
**x-range**

**Much of the first moment**
***Δ******G = ******∫******Δ******G(x)dx***** might **
**emerge from low x!**
**Some theoretical **
**guidance:**
***     ******Δ******G(x) ******≤****** ******x G(x)***
**but***** G(X) *****diverges faster**
**than***** x******-1 ******!***
***NEED TO EXTEND***
***MEASUREMENTS TO***
***LOW x !!***

## Next Steps for ΔG(x) in PHENIX  

- Extend measurements to low x
**           ** Di-hadron Production extends                           (2008)
-                 measurements to x  0.01
-                 NLO treatment available:
-                 Marco Stratmann -- INPC 2007
-                 (EMC forward calorimeters available
-                  in STAR and PHENIX!)
- Forward detector upgrades for direct                 (2011)
- photons and heavy flavor + highest luminosity
-              reach x  0.001

**Next Steps for ****Δ****G(x) in PHENIX  **

## Direct Photons (NCC) + Heavy Flavor (VTX+FVTX)

- NCC direct photons

##    Δq(x), Δq(x)  

**   *****Δ******q(x), ******Δ******q******(x)  ***
** **

## Semi-Inclusive DIS:  e+p  e+ h +X Quark & Anti-Quark Helicity Distributions

- Semi-Inclusive DIS:  e+p  e+ h +X Quark & Anti-Quark Helicity Distributions

- u quarks large positive polarizationd quark have negative polarizationsea quarks (u, d, s ,s) compatible with 0in the measured x-range 0.02 < x < 0.6.

- [HERMES, PRL92(2004), PRD71(2005)]

**x**

**Future:**
**Precision DIS at JLAB-12 and at a**
**possible electron – ion collider!         **

***x******Δ******u(x)***

***x******Δ******d(x)***

***x******Δ******u(x)***

***x******Δ******d(x)***

***x******Δ******s(x)***

**How well do we know hadron                 **
**fragmentation functions ?**
**      ******** ****new analysis of e+e- data,**
**           ****Hirai, Kumano, Nagai, Sudo**
**           ****hep-ph/0612009, INPC 2007****       **

**Possible Improvements**
**      ******** ****include e-p, p-p and e+e-  in fragmentation**
**            ****function analysis ******** done!**
**            ****De Florian, Sassot, Stratmann**
**            ****hep-ph/0703242**
**    **

****** “****add data” from b-factories e+e- ******** hadrons**

## Possible Impact on the Knowledge of 

- Belle MC

- <1% of data sample           work in progress

- Possible Impact on the Knowledge of
- Hadron FFs from Analysis of b-Factory Data

- FF

- FF

- Compilation of data
- available for the char-
- ged hadron FF

- Belle MC: Charged h+/-, pions, kaons, protons

- precision
- at high z!

-   h+,-
-   pions
-   kaons
-   protons

-  Input for precision
-  measurements of quark
-  helicity distributions in
-  SIDIS, with JLab-12 and
-  a possible future electron-
-  polarized proton collider.

## Another Alternative:

**Another Alternative:**
**W-production at RHIC**

**SIDIS:**
** ****large x-coverage**
** ****uncertainties from**
** ****knowing fragmentation**
** ****functions**
**Ws in polarized p-p:**
** ****limited x-coverage **
** ****high Q****2 ******** theoretically **
**                  ****clean**
** ****no FF-info needed**
**Background:**
**Absorber (S/B 3:1),**
**isolation using FVTX/NCC**
**additional factor 3-5**** **

**Hermes – 243 pb****-1**

**PHENIX – 800 pb****-1**

##    Transverse Spin    

**   ****Transverse Spin*****    ***
** **

##   Sivers Asymmetries in Drell Yan 

**0**

-   **Sivers Asymmetries in Drell Yan **

- RHIC II  Drell Yan Projections

**Muon trigger**
**+**
**   ****FVTX for heavy flavor**
**   ****background rejection**

## Nucleon Spin Structure: Physics Impact ofVTX, FVTX, NCC and Muon Trigger Upgrades 

-    ** ****Present vs ****with upgrades**
- Inclusive hadrons + photons
- heavy flavor, photons, photon-jet
-           increase x-range
-           parton kinematics
- not possible without upgrades
- ,
*A**N ** *for inclusive hadronen
- AT  in Interference-Fragmentation
- AT  Collins FF in jets
- AN    for back-to-back hadronen
- AN,T  jets, Ds, DY

-         **Physics Goals**
- determine first moment of
- the spin dependent gluon
- distribution, ∫01ΔG(x)dx.
- flavor seperation of quark
- and anti-quark spin distri-
- butions
- measurement of trans-
- versity quark distributions.
- Measurement of the
- Sivers distributions

- Nucleon Spin Structure: Physics Impact ofVTX, FVTX, NCC and Muon Trigger Upgrades

**Sivers Effect**

## Summary

**RHIC and it’s experiments are the world’s first facility capable of colliding**
**high energy polarized protons with high polarization and luminosity.**
**The planned detector upgrades significantly strengthen PHENIX’**
**capabilities to study nucleon structure:**
**    ****(1) Measurement of the gluon spin contribution ****∫****Δ****G(x)dx**
**                 ******** ****large x-range**
**                 ******** ****event-by-event kinematics**
**                 ******** ****heavy flavor + photon jet are new channels with**
**                      ****independent experimental and theoretical uncertainties**
**    ****(2) First measurements with spin dependent W-production! **
**    ****(3) Transverse spin: Collins fragmentation and Gluon Sivers in **
**                                        ****multiple channels. Test fundamental prediciton**
**                                        ****on non-universality of the Sivers function in Drell Yan!**