# Presentation: 661187

## Proposal for a polarized target p-p Polarimeter 

- Robert Hobbs
- University of New Mexico
- for the RHIC Spin Collaboration
- RSC Brookhaven meeting – July 29, 2002

**Notes:**
Thanks to the Collaboration for all the drawings!

## Outline

- Motivation
- Principle
- Setup
- Monte Carlo
- Rates

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Motivation 1

- Spin physics based on polarization
- a=AP, we use A to measure P
- Only have A(24 GeV) with large uncertainty
- Solution
- Solution gas-jet target (2004)
- Better A uncertainty (2003)

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## p-p polarimeter

- p-C polarimeter

- p-C polarimeter

- N. Bruner       Univ. of New Mexico

- April 30, 2000

**Notes:**
The thirteen PHENIX Countries and the full list of PHENIX Institutions is:
Brazil:         Sao Paolo
Canada:      	McGill
China:         	CIAE
France:       	SUBATECH
Germany:    	Munster
India:          BARC, Banaras Hindu University 
Israel:         Weizmann Institute
Japan:  CNS, Hiroshima, KEK, Kyoto, Nagasaki, RIKEN, TITech., Tokyo, Tsukuba, Waseda
Korea:         	Korea, Myongji, Yonsei
Russia:        	IHEP Protvino, JINR Dubna, Kurchatov, NPI, St. Petersburg STU
Sweden:	Lund
Taiwan:    	Academica Sinica
U.S. National Labs:    BNL, LANL, LLNL, ORNL
U.S. Universities:  Alabama-Huntsville, California-Riverside, Columbia, Florida State, Georgia State, Iowa State, New Mexico, New Mexico State, SUNY-Stony Brook, Tennessee, Vanderbilt
NOTE:  The total number of Institutional Units participating in PHENIX is 45, but you will count only 43 listed above.  The RIKEN/BNL Research Center (RBRC) and Chem./Phys. split for Stony Brook make up the other two.

Spin run = 10 weeks/year, 250 GeV
Au-Au at 100 A GeV

## p-p polarimeter

*South*

- p-C polarimeter

- p-C polarimeter

- N. Bruner       Univ. of New Mexico

- April 30, 2000

**Notes:**
6 MuID panels/gap for a total coverage=12.59.8 m2.
Absorber:
nosecones are symmetric
59cm thick central magnet yoke
a copper piston plug next to the beamline

## 	p  on polarized target

-    +   p  on polarized target
-    =   p on polarized p
- 	Lorentz boost to obtain A(p-p)
-  	measure P from a=PA

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Ideas

- Compare results with PISA
- Ancestry, depth of first interaction
- Parametrization with number
-        neutral particles

- p-C polarimeter

- p-C Polarimeter

- Polarized target

- a=

**P**

- A'

- a=

**P**

- A

- N. Bruner       Univ. of New Mexico

- April 30, 2000

**Notes:**
MVD will be 1/2 installed this year. 
Year 2 improvements:
- P-p collisions begin.
- Au-Au have increased luminosity.
- MVD completely installed.
- Remaining EmCal and TEC electronics installed.
- Triggers for RICH and EmCal.

Octant test complete		mid-May
Order production boards		May-Aug.  (may be shorter)
Install Mech. Support Structure	Aug. 2
Install Platform and Racks		Aug. 9
Test boards			Aug
Assemble chassis, CRAs		Aug-Nov
Install chassis, CRAs		Aug-Nov
FEE Installation complete		Nov. 10
Activities to follow FEE Installation:
Roll-in
Connections to counting house, plumbing, etc.
Replacement of beam pipe
Installation of “collar”
Installation of Magnet Buss

## Compare results with PISA

- Vacuum                 Copper                   Iron                                                    Vacuum

- Pion+ (10 GeV)

- Ancestry, depth of first interaction
- Parametrization with number
-        neutral particles

- p-C polarimeter

- p-C Polarimeter

- Polarized target

- a=

**P**

- A'

- a=

**P**

- A

- a=

**P**

- A

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## More accurate but still wrong energy

- Acceleration/deceleration
- Map of A: fit to models

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Motivation 2

- Understand loss of polarization
- From 75% (200MeV) to 40% (200GeV)

- N. Bruner       Univ. of New Mexico

- April 30, 2000

**Notes:**
MVD: Two concentric barrels of 300 m Si strips, two end-plates of Si pads, -2.5 <   < +2.5
Beam-beam:  timing of the collision, 2 arrays of 64 Cerenkov radiators + PMT’s, 50ps resolution, located within the CM poletips to measure time-of-flight of forward particles.
Zero Degree Calorimeters : small transverse area hadron calorimeters which will be located
downstream of the DX dipole magnets in each of the heavy ion experiments at RHIC.
Central tracking - 3 sub-systems:
  Drift Chamber 
  Pad Chambers (pixels)
  Time Expansion Chamber
Particle Identification for hadrons:
  Measure time difference between Beam-Beam counters and TOF wall or EmCal elements.
  Time-of-Flight  wall: ~ 2000 PMT’s reading out ~1000 slats,  ~ 80 ps  EmCal:  Both PbSc and PbGl have timing capability, (PbSc) ~ 300 ps, (PbGl) ~ 400 ps
Particle Identification for electrons = RICH, dE/dx;  contamination in identified e=10-4
“The central arms consist of a drift chamber providing charged particle tracking in the r-f plane, a set of three pixel pad chambers providing tracking in the r-z plane, a Ring Imaging Cherenkov Counter providing electron identification up to p~3 GeV/c, a Time Expansion Chamber providing simultaneous tracking in the r-f plane and electron identification up to p~ 2
GeV/c via dE/dx measurements, an Electromagnetic Calorimeter providing e/g measurements and further electron identification, and a Time-of-Flight system providing hadron identification and p /K separation up to 2.4 GeV/c. ”

## ?

- OK

- OK

- OK

- 3Gev

- 24Gev

- P

- AGS Polarization

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## 75%

- 40%

- ?

- ?

- ?

- ?

- N. Bruner       Univ. of New Mexico

- April 30, 2000

**Notes:**
Sensitive to many signatures of the quark-gluon plasma.

2 central spectrometers (East and West)
2 forward spectrometers  (north and south)
2 global detectors

## Extracted beam polarized target polarimeter, in conjunction with AGS p-C polarimeter
Use own Analyzing power to provide polarization.
P-C polarimeter measures A (p-C)
Have map (3Gev-24GeV) of A (p-C)

- Use own Analyzing power to provide polarization.
- P-C polarimeter measures A (p-C)
- Have map (3Gev-24GeV) of A (p-C)

- In short

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## ~ 80 events

- GeV

- cm

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## GeV

- cm

- Elastic scattering

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## cm

- Hits in Forward detectors 100M p  ~  500k hits

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Kinematics

-      t : 0.22 – 0.38 GeV2
- R : 13 – 15 degrees
- Tkin : 110 – 170 MeV
-   pR : 470 – 590 MeV

- R; ER

- R and *t*

-          measure position and energy of recoil 

- Essentially only 1 free parameter: t (+ ) 
- 	       elastic *pp* kinematics fully constrained by recoil proton !

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Setup

- Polarized Ammonia target in 2.5T magnetic field
- Recoil (x2) silicon detectors or hodoscopes
- Use  x (angle) vs. Ke (momentum transfer)
- Collimators

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Setup

- 1-2 m distant

- Silicon? or

- Ammonia target in 2.5T B-field

- Collimator

- Hodoscope

- N. Bruner       Univ. of New Mexico

- April 30, 2000

- Requirements
-  good energy resolution
- E < 0.1 MeV
-  handle large statistics
-  space resolution
- x ~ few mm
-  time resolution
- t ~ 1 (2) ns

- horizontal segmentation ~ 4 mm (16 ch.)
- vertical segmentation ~ 8 mm (8 ch.)   ~ 10 mrad
- thickness: 0.5 mm  stops up to 8 MeV protons
- 	  veto for faster protons?
- under development (Inst. Div. @ BNL)

- Detectors?

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## elastic

- inelastic

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Understanding Background

- GeV

- cm

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Elastic events

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Nitrogen

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Collimated

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Binning

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## Time of flight

- ns

- Next bunch 330ns

- N. Bruner       Univ. of New Mexico

- April 30, 2000

## RATES

**L** =1.2 1010  **** 2.0 1023 = 2.4 1033 cm-2s-1
- N = **L** ********(5.0 10-27)*acc *(0.01) *eff* (50%) = 20000 evt s-1
- in 8 hours can collect 1.4 108 events (M.C: 24000 evt s-1 )

| BEAM | TARGET |
| --- | --- |
| 1.21010 p / spill
1 spill/ 4 sec | 2.0 1023 atoms / cm2 |

- N. Bruner       Univ. of New Mexico

- April 30, 2000