proton polarimetry at rhic k. oleg eyser for the cni polarimeter group newport news, va, october 25,...
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Proton Polarimetry at RHIC
K. Oleg Eyserfor the CNI polarimeter group
Newport News, VA, October 25, 2013
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@ RHIC
AGSAGSLINACLINACBOOSTERBOOSTER
Polarized Source
Spin Rotators
200 MeV Polarimeter
Absolute Polarimeter (H jet)
PHENIX
BRAHMS & PP2PP
STAR
Siberian Snakes
Siberian Snakes
Spin Flipper
RHIC pC Polarimeters
Rf Dipole AGS Internal Polarimeter
AGS pC Polarimeter
Strong SnakePartial Snake
Helical Partial Snake
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RHIC Luminosity
Beam momentum100 GeV250 GeV
Consistent luminosity improvement over the years
255 GeV in 2013
Significance: Figure of Merit
or
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Polarization and Asymmetries
π΄π=ππ ππππ‘βππ hπππ π‘
ππ ππππ‘+ππ hπππ π‘
S
x
y
NP
Polarization:
π=π΄π βπ=π πΏβππ
π πΏ+ππ
ππ=π΅
π=π³
left
right
scattering plane
π π§=Β±12βπ=πββπβ
πβ+πβ
(proton)
(proton)(Carbon)
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Polarimeters in RHIC
Carbon polarimeters
Two per ring
Fast measurement
Beam polarization profile
Hydrogen jet
Polarized target
Continuous operation
per fill
normalization
Carbon polarimeters
Hydrogen jet
beam
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Elastic Signal Identification
πΈπππ=12ππ£2=1
2π(ππ‘ )
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ADC/TDC waveform readout
normalized to peak
ADCmax
TDC0
V10BASELINE
Elastic signal
β Energy calibration
β Time offset
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Energy Calibration
π β π΄=πΈππππ =πΈπππββπΈ
βπΈπΌ(π΄π )=0.72ββπΈπΌ (πΊπ)
Two different Ξ±-sources
Stopping power forΞ±-particles and protons from NIST database
βπΈπ=0.44 ββπΈπΌ (πΊπ) βπΈ[πππ ]β0.64
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Elastic Signal and Background
5 MeV
1 M
eV
signal region background region
atomic jet target
proton beam
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Asymmetry and Polarization
β
π=ππππβπ βπππ1βπ
What if
π π΅πππ=βππ΅ππππππππππ‘
πππππππ‘π π΅=
ππ΅ππππππ=
ππππππ
Polarization independent background
Polarization dependent background
background fraction
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abort gaps
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Polarimeter PerformanceKinematic distributions for consistency checks
Fast feedback to RHIC operations
Target P=92%
1 Fill
over 150 RHIC fills in 2013
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Summary
Polarization in RHIC is measured with fast p+C targets for monitoring, polarization profiles,
and polarization decay, a polarized atomic hydrogen jet for normalization.
The 2013 data provides unprecedented possibilities to use the jet polarimeter for background studies.
The jet polarimeter provides fast feedback to RHIC operations.
Final analysis and systematic studies are on-going.
https://wiki.bnl.gov/rhicspin/RHIC_Spin_Group
BACKUP
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Polarization Profile
πππππ=β«ππ₯ππ¦π (π₯ , π¦ ) πΌπ΅ (π₯ , π¦ ) πΌπ (π₯ , π¦)
β«ππ₯ππ¦ πΌπ΅ (π₯ , π¦ ) πΌπ (π₯ , π¦ )
π πππ‘=β«ππ₯ππ¦π (π₯ , π¦ ) πΌ π΅ (π₯ , π¦ )
β«ππ₯ππ¦ πΌπ΅ (π₯ , π¦ )
ππ π€πππ=β«ππ¦π (π¦ ) πΌπ΅ ( π¦ )
β«ππ¦ πΌ π΅ ( π¦ )
jet target polarization is flat
vertical and horizontal Carbon targets available
For Gaussian profiles
Profile parameter