Polarized Protons in RHIC at 500 Polarized Protons in RHIC at 500 GeVGeV

Mei BaiC-A Dept. BNL

RHIC pp design parameterRHIC 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 forPhysics Runs

Luminosity performanceLuminosity performanceNeed 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 performancePolarization performanceAchieved 100% polarization

transmission efficiency from injection to 100 GeV

Much stronger spin depolarzing resonances from 100 GeV to 250 GeV

RHIC intrinsic spin resonance RHIC intrinsic spin resonance spectrumspectrum

Intr

insi

c sp

in r

eso

nance

Qx=

28.7

3,

Qy=

29.7

2,

em

it=

10

AchievedPhysics Run

Design goal

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

Power supply preparations: 2 shiftsRamp and polarization development: 8

shiftsDedicated polarization studies: 2

shiftsDedicated luminosity studies: 2

shiftsContingency 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 lifetimeTotal intensity limits

Overview of RHIC pp 250 GeV Overview of RHIC pp 250 GeV developmentdevelopment

ps workWeather related down time

Quench

reco

very

Boost

er

pro

ble

m

Boost

er

pro

ble

m,

ps

pro

ble

m

ps

pro

ble

m,

acc

ess

contr

ol pro

ble

m

Ps

pro

ble

m,

acc

ess

contr

ol pro

ble

m

Fix t

he r

f ri

ng t

o r

ing s

yn

chro

Yello

w p

s le

ad fl

ow

pro

ble

m

Boost

er

pro

ble

m

What have been What have been achieved?achieved?Blue beam was first accelerated

up to 250 GeV at the end of FY2006 pp RUN

250 GeV

inje

ction

Pola

rizatio

n a

t inje

ction

Polarization at 250 GeV

pp in blue accelerated to 250 GeV with 45% pp in blue accelerated to 250 GeV with 45% polarizationpolarization

What have been What have been achieved?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 RHIC pp polarization ramp measurementmeasurement

0

0.002

0.004

0.006

0.008

0.01

0.012

20 40 60 80 100 120 140 160 180 200 220 240

Beam Energy [GeV]

Asy

mm

etry

d

Resonance around 138 GeV

Remaining issues of RHIC pp 250 GeV Remaining issues of RHIC pp 250 GeV developmentdevelopment

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 Polarized proton development planplan

Luminosity: Non-linear chromaticity correction:

implemented in the current Au-Au Run: Tepikian, Nikolay, Yun

Polarized proton development Polarized proton development planplan

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 Polarized proton development planplan

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 Polarized proton development planplan

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 feedback10 Hz orbit feedback

feedback OFF Feedback ON

Courtesy of Christoph and Angelika

Polarized proton development Polarized proton development planplan

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