# Presentation: 472901

## RHIC Polarimetry

- Status and Plans for 2005 run
- 	JET
- 	RHIC pC Polarimeters
- 	AGS Polarimeter

## RHIC Polarimeters

**BRAHMS **
**& PP2PP**

**STAR**

**PHENIX**_*** ***_

**AGS**

**LINAC**

**BOOSTER**

- Pol. Proton Source

**Spin Rotators**

- 20% Snake

**Siberian Snakes**

- 200 MeV polarimeter

- AGS quasi-elastic polarimeter

- Rf Dipoles

- RHIC pC “CNI” polarimeters

**PHOBOS**_*** ***_

**RHIC**

**absolute pH**
**polarimeter**

**Siberian**
**Snakes**

- AGS pC “CNI” polarimeter

- 5% Snake

## What we do

- recoil proton
- or Carbon

- (polarized)
- proton beam

- scattered
- proton

- polarized
- proton target
- or Carbon target

- Pbeam = Ptarget . Nbeam / Ntarget
****
- ANpC  = NpC / Pbeam
****
- Pbeam = NpC / ANpC

- elastic
*pp* and *pC*
- scattering

## JET Target

- Basically ready to install
- 	will be moved to IP12 on March 30th
- JET “composition” measurements with Electron Gun done
- Installed shutters for calibration  sources
- New set of Silicon detectors installed and tested
- JET running smoothly with high and stable polarization ~ 96 %
- Much more work done than in this short list
- STILL TO DO:
- Some more work on the dissociator
- Install Front End Electronics
- Complete shaping electronics (new design)
- Online software (develop further `04 programs)

## 2005 running

- measure both beams
- 	*t* range of 1  10–3 < **-***t* < 1.0  10–2 GeV2
- 	<AN> = 4 %
- same detector will cover both beams
- 	(recoil arms off set by ~50 mm)
- 	all detector read out at all times
- 	both beams measured at the same time ?
-  Pbeam / Pbeam < 5 % measurement in ~ 1 week
- 	(based on `04 rates, assuming 60  1011 protons, ...)
- 	4 “Blue” and 4 “Yellow” independent Pbeam
- 	measurements & ANpC calibrations during `05 run
- GOAL: reduce systematic error by 2
- 	more background running (at least 10 % of data)

## RHIC pC Polarimeters

- 2 72 channels read out with Wave Form Digitizers (2  48 in 2003)
- very large statistics per measurement (~ 20  106 events)  detailed analysis
- bunch by bunch analysis
- channel by channel (each channel is an “independent polarimeter”)
- 45o detectors: sensitive to vertical and radial components of  Pbeam
-  unphysical asymmetries

- Ultra thin Carbon ribbon Target
- (3.5g/cm2 ,10m)

- beam
- direction

- 1

- 3

- 4

- 5

- 6

- RHIC  2 rings

- 2

- Si strip detectors
- (ToF, EC)

- ~ 37 cm

- inside RHIC ring @IP12

## 2005 Upgrades for pC

- New grounding scheme
- 	hopefully will suppress / eliminate the beam induced pickups
- 	(believed to be the major source of systematic effects)
- New Front End electronics
- 	will solve all oscillation problems
- New shaper boards
- 	calibration measurements much simpler (and therefore more frequent)
- Target “upgrade”
- 	better alignment & new frames
- 	new controls
- Additional information: orbit numbers  event builder (already end of `04)
- complete time stamp for each event
- although independent, all channels can be correlate
-  spin tune measurements and spin flipping
- however 120 bunch mode operation still difficult this year

## DAQ

- 2 independent WFD / DAQ systems for Blue and Yellow ring
- 	JET still coupled to one of the pC polarimeter readout
- Much faster compared to 2004 using USB Camac controllers:
- ~ 8 **** faster with 12 MB / sec data transfer rate already achieved
- 	(need debugging)
- 	typical measurement < 15 sec (vs. 2 min in `04)
- 	readout of a ramp measurement < 2 min (vs. ~ 30 min in `04)
- expect even faster (2 ****) with new firmware (doesn’t work yet !)
- Several automated tasks developed / being implemented
- new interfaces for operators (target, DAQ, online QA, ...)
- target scans
- polarization profiles
- New FPGA algorithms being developed
- better Timing & Energy resolution
- address / solve some problems encountered in previous years

## Running in 2005

- Yellow and Blue beam polarimeters fully decoupled (2 independent systems)
- JET coupled to Yellow polarimeter
- (in the future will procure more readout electronics to fully decouple also the JET)
- alternate measurements with *pp* CNI (JET) and *pC* CNI polarimeters each 1 – 2 hours
*pp* measurement: 	only fraction of whole statistics, requires ~ 1 week
*pC* measurement:	> 2  107 events (full measurement)

- share the same set of
- WFDs (total 96 ch.)

*pp* JET

*pC* CNI

- multiplexer

- WFD

- DAQ PC

*pC* CNI

- WFD

- DAQ PC

## RHIC polarization profile

- Polarization Profiles observed during `04 run
- Evidence however inconclusive at this stage
- Will be studied in detail during 2005 run
- Suggestions on additional measurements welcome ....

- Polarization
- Beam Intensity
- H Scan --horizontal scan with vertical target
- V Scan – vertical scan with horizontal target

## AGS pC polarimeter

- No more beam induced pickups !
- solved all intensity related issues
- works reliably up to and above 2  1011 p / bunch
- Almost ready to restart operations
- RF clock still to be solved
- new AGS cycle  redo timing
- Later during the run will install also 450 detectors
- 	(relevant for cold snake)
- all hardware already in place or available
- Polarimeter chamber realigned during `04 shutdown
- observed acceptance asymmetries indeed due to “bad” alignment
- 	Detectors moved ~5 mm forward to work also at injection energies
- Develop more automated procedures for ramp measurements

## Summary

- significant developments / upgrades from `04
- 	will address several “open” issues and
- 	(hopefully) solve some pending “problems”
- much faster DAQ
- 	Yellow & Blue independent readout
- 	detailed polarization studies
- AGS polarimeter almost ready to start operating
- RHIC pC polarimeters “upgrade” & JET installation
- 	on March 30 – 31