Observation of W Decay in 500 GeV p+p Collisions in the PHENIX Experiment at RHIC
Polarized Protons in RHIC at 500 GeV
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Polarized Protons in RHIC at 500 Polarized Protons in RHIC at 500 GeVGeV
Mei BaiC-A Dept. BNL
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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
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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
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Polarization performancePolarization performanceAchieved 100% polarization
transmission efficiency from injection to 100 GeV
Much stronger spin depolarzing resonances from 100 GeV to 250 GeV
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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
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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
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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
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What have been What have been achieved?achieved?Blue beam was first accelerated
up to 250 GeV at the end of FY2006 pp RUN
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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
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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
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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
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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
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Polarized proton development Polarized proton development planplan
Luminosity: Non-linear chromaticity correction:
implemented in the current Au-Au Run: Tepikian, Nikolay, Yun
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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, …
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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
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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
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10 Hz orbit feedback10 Hz orbit feedback
feedback OFF Feedback ON
Courtesy of Christoph and Angelika
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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
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Need polarized proton to continue the RHIC pp 500 GeV commissioning