# Presentation: 696608

## Polarized Protons in RHIC at 500 GeV

- Mei Bai
- C-A Dept. BNL

## RHIC pp design parameter

| Parameter | Unit | p-p |
| --- | --- | --- |
| relativistic , injection | ... | 25.9 |
|  relativistic , store | ... | 266.5 |
| no of bunches, nb | ... | 112 |
| ions per bunch, Nb | 1011 | 2.0 |
| emittance eN x,y 95% | mm-mrad | 20 |
| average luminosity | 1030 cm-2s-1 | 150 |
| polarization,store | % | 70 |

| p-p |
| --- |
| 25.9 |
| 106.6 |
| 111 |
| 1.3 |
| 20 |
| 20 |
| 60~65 |

- Achieved performance for
- Physics Runs

## Luminosity performance

- Need a factor of 3 to achieve the design luminosity goal
- Current luminosity limit
- Beam-beam interaction
- Cause emittance growth through non-linear resonance and other effects.
- Current pp workpoint at (0.695,0.685) hits the limit by 3Qx resonance and 10Qx,y
- E-cloud: possibly an additional source  of emittance growth

## Polarization performance

- Achieved 100% polarization transmission efficiency from injection to 100 GeV
- Much stronger spin depolarzing resonances from 100 GeV to 250 GeV

## RHIC intrinsic spin resonance spectrum

- Intrinsic spin resonance
- Qx=28.73, Qy=29.72, emit= 10

- Achieved
- Physics Run

- Design goal

## FY 2006 RHIC pp 250 GeV development(one week)

- Power supply preparations:		 2 shifts
- Ramp  and polarization development:	 8 shifts
- Dedicated polarization studies: 		 2 shifts
- Dedicated luminosity studies: 		 2 shifts
- Contingency shifts:  		            2.5 shifts
- Total required:	16.5 shifts or  ( 5 days +1.5 shifts)

- Explore polarization transmission to a beam energy of 250 GeV
- Inspect the luminosity aspects (witn 2 collisions)
- Store lifetime
- Total intensity limits

## Overview of RHIC pp 250 GeV development

- ps work

- Weather related down time

- Quench recovery

- Booster problem

- Booster problem, ps problem

- ps problem, access control problem

- Ps problem, access control problem

- Fix the rf ring to ring synchro

- Yellow ps lead flow problem

- Booster problem

## What have been achieved?

- Blue beam was first accelerated up to 250 GeV at the end of FY2006 pp RUN

## pp in blue accelerated to 250 GeV with 45% polarization

- 250 GeV

- injection

- Polarization at injection

- Polarization at 250 GeV

## What have been achieved?

- Blue beam was first accelerated up to 250 GeV at the end of FY2006 pp RUN
- Polarization measurement as a function of beam energy identifies the location of polarization loss

## RHIC pp polarization ramp measurement

## Remaining issues of RHIC pp 250 GeV development

- Exam the polarization transmission efficiency in Yellow
- Systematic study of polarization along the energy ramp as function of orbit distortion and beam tunes at depolarization resonances beyond 100 GeV
- Establish collisions to study the luminosity aspects at 250 GeV
- Study the polarization lifetime as a function of beam tunes at 250 GeV

## Polarized proton development plan

- Luminosity:
- Non-linear chromaticity correction: implemented in the current Au-Au Run:  Tepikian, Nikolay,  Yun

## Slide 14

## Slide 15

## Polarized proton development plan

- Luminosity:
- Non-linear chromaticity correction: implemented in the current Au-Au Run
- 3Qx resonance correction: under study by Johan,  Yun,  Rama, Mei, ...

## Polarized proton development plan

- Luminosity:
- Non-linear chromaticity correction: implemented in the current Au-Au Run
- 3Qx resonance correction:  under study
- Explore new working points
- (0.92, 0.93): Christoph
- (0.08, 0.07): Wolfram
- DA tracking: Christoph and Yun
- Spin tracking: Mei, Alfredo
- Gradient error correction is also under development by Todd, Jen and Mei during the current Au run
- This will be first commissioned during the 2008 pp 100GeV run

## Polarized proton development plan

- Luminosity:
- Non-linear chromaticity correction: implemented in the current Au-Au Run
- 3Qx resonance correction:  under study
- Explore new working points
- (0.92, 0.93): Christoph
- (0.08, 0.07): Wolfram
- DA tracking: Christoph and Yun
- Spin tracking: Mei, Alfredo
- This will be first commissioned during the 2008 pp 100GeV run
- Triplet 10 Hz vibration
- 10 Hz orbit feedback
- Rebuild tripplet assembly to reduce the 10Hz

## 10 Hz orbit feedback

- feedback OFF

- Feedback ON

- Courtesy of Christoph and Angelika

## Polarized proton development plan

- Polarization:
- Improve the orbit control to achieve an orbit distortion of 0.3mm or better during the acceleration from 100 GeV to 250 GeV
- Improve the betatron tune and coupling control: Tune/coupling feedback
- Snake current setting: spin tune measurement

## Need polarized proton to continue the RHIC pp 500 GeV commissioning