RHIC Polarimetry status and plan May 26 2010

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RHIC Polarimetry: status and plan May 26, 2010 20+10 min

RHIC Polarimetry: status and plan May 26, 2010 20+10 min

RHIC and Polarimetry Absolute Polarimeter (H jet) RHIC p. C Polarimeters Siberian Snakes BRAHMS

RHIC and Polarimetry Absolute Polarimeter (H jet) RHIC p. C Polarimeters Siberian Snakes BRAHMS & PP 2 PP (p) RHIC PHENIX (p) STAR (p) Siberian Snakes Spin Rotators Solenoid Snake LINAC Pol. Proton Source 500 m. A, 400 ms BOOSTER AGS 200 Me. V Polarimeter Warm Snake AC Dipole AGS p. C CNI Polarimeter Cold Snake

Polarization Measurements H-Jet Absolute polarization p-Carbon Polarization profile Polarization vs time in a fill

Polarization Measurements H-Jet Absolute polarization p-Carbon Polarization profile Polarization vs time in a fill Bunch-by-bunch polarizations Fill-by-fill polarizations Local Polarimeters (PHENIX and STAR) Monitor spin direction at collision regions (Used to tune Spin Rotators and to confirm the long. polarization) Capable to monitor polarization decay vs time in a fill and bunch-by-bunch polarization

HJet Left-right asymmetry in elastic scattering: Interference between electromagnetic and hadronic amplitudes in the

HJet Left-right asymmetry in elastic scattering: Interference between electromagnetic and hadronic amplitudes in the Coulumb-Nuclear Interference (CNI) region Beam and target are both protons RHIC proton beam Forward scattered proton H-jet target recoil proton <5% Ptarget is provided by Breit Rabi Polarimeter

HJet: Identification of Elastic Events Forward scattered proton To. F vs Energy proton beam

HJet: Identification of Elastic Events Forward scattered proton To. F vs Energy proton beam proton target recoil proton Energy vs Channel # YELLOW beam BLUE beam Array of Si detectors measures TR & To. F of recoil proton. Channel # corresponds to recoil angle R. Correlations (TR & To. F ) and (TR & R ) the elastic process 5

HJet: Example from Run 6 εtarget εbeam Polarization vs fill Measures average over beam

HJet: Example from Run 6 εtarget εbeam Polarization vs fill Measures average over beam profile polarization with fillby-fill stat. uncertainty ~10% Data accumulated for a few fills provide normalization for p. C polarimeter with uncertainty <<5%

Hjet: Two Beam Mode Yellow beam on target Blue beam on target Both beams

Hjet: Two Beam Mode Yellow beam on target Blue beam on target Both beams on target Successfully tested in Run 2008 and routinely used in Run 2009 ü Background level only slightly increased compared to single beam mode ü Will allow to monitor both beam polarizations by HJet simultaneously in all fills

Hjet: AN Used for polarization measurements 24 Ge. V: PRD 79, 094014(2009) 31 Ge.

Hjet: AN Used for polarization measurements 24 Ge. V: PRD 79, 094014(2009) 31 Ge. V: Preliminary 100 Ge. V: PLB 638 (2006) 450 250 Ge. V: Preliminary pp-CNI Weak (if any) energy dependence pp elastic scattering in CNI region is ideal for polarimetry in wide beam energy range

p. C: Left-right asymmetry in elastic scattering: Interference between electromagnetic and hadronic amplitudes in

p. C: Left-right asymmetry in elastic scattering: Interference between electromagnetic and hadronic amplitudes in the Coulumb-Nuclear Interference (CNI) region Carbon target Polarized proton 6 1 18 cm 5 4 Ultra thin Carbon ribbon Target (5 mg/cm 2) 2 3 Si strip detectors (TOF, EC) Recoil carbon

p. C: AN Used for polarization measurements p. C-CNI Weak energy dependence p. C

p. C: AN Used for polarization measurements p. C-CNI Weak energy dependence p. C elastic scattering in CNI region is good for polarimetry in wide beam energy range

p. C: goals/strategy Polarization measurements for experiments Target Scan mode Provides polarization at beam

p. C: goals/strategy Polarization measurements for experiments Target Scan mode Provides polarization at beam center, polarization profile, average polarization over profile 20 -30 sec per measurement For stat. precision 2 -3% 4 -5 measurements per fill (every 2 -3 hours), per ring Controls polarization decay vs time in a fill Polarization profile, both vertical and horizontal Normalized to HJet measurements over many fills Knowledge on polarization profile in one transverse direction is required Fill-by-fill polarization Knowledge on polarization profile in both transverse directions is required Feedback for accelerator experts Beam emittance measurements, bunch-by-bunch Polarization profile, both vertical and horizontal Polarization (and polarization decay in a fill) Polarization at injection (and polarization loss in transfer) Polarization on the ramp (and polarization loss during ramp)

Pol. Profile and Average Polarization H-Jet p. C Collider Experiments ~1 mm 6 -7

Pol. Profile and Average Polarization H-Jet p. C Collider Experiments ~1 mm 6 -7 mm x=x 0 P(x, y) – polarization profile, I(x, y) – intensity profile

Pol. Profile and Average Polarization Scan C target over the beam cross: Polarization Intensity

Pol. Profile and Average Polarization Scan C target over the beam cross: Polarization Intensity p. C With uniform C-target scan: I P Run 9: s=200 Ge. V: R~0. 1 5% correction s=500 Ge. V: R~0. 35 15% correction Target Position

p. C+HJet: Polarization vs Fill Run-2009 results ( s=200 Ge. V) ü Normalized to

p. C+HJet: Polarization vs Fill Run-2009 results ( s=200 Ge. V) ü Normalized to Hjet ü Corrected for polarization profile P/P < 5% Dominant sources of syst. uncertainties: ~3% - HJet background ~3% - p. C stability (rate dependencies, gain drift) ~2% - Pol. profile s=500 Ge. V: P/P ~ 10% Due to higher rates and sharper pol. profile

p. C for beam set up and tune Run 9 s=500 Ge. V Resonance

p. C for beam set up and tune Run 9 s=500 Ge. V Resonance around 140 Ge. V Polarization loss on the ramp between 100 and 250 Ge. V Intensity vs pol. Profiles (arb. units) Sharper pol. profile for 250 Ge. V beams compared to 100 Ge. V beams Studied for different beam tunes Fill 10486 Fill 10373 No pol. profile change from AGS to RHIC 100 Ge. V

6 1 18 cm 5 4 Ultra thin Carbon ribbon Target (5 mg/cm 2)

6 1 18 cm 5 4 Ultra thin Carbon ribbon Target (5 mg/cm 2) p. C in Run-2009 2 3 Si strip detectors (TOF, EC) Significantly upgraded: Two independent polarimeters in each ring (but using the same DAQ) ü Improved vacuum chamber ü New target holders Better target positioning 6 vertical and 6 horizontal targets in each polarimeter – enough for long Run ~Simultaneous measurements of vertical and horiz. polarization profiles ü 6 detectors in each polarimeter Slots to test new detectors

p. C+Hjet: Path Forward Towards P/P<3% HJet: ü New type of detectors with possibly

p. C+Hjet: Path Forward Towards P/P<3% HJet: ü New type of detectors with possibly extended acceptance (larger statistics better precision) 24 Ge. V: PRD 79, 094014(2009) 31 Ge. V: Preliminary 100 Ge. V: PLB 638 (2006) 450 250 Ge. V: Preliminary ü Better control of molecular (and other) background (becoming a dominant source of syst. uncertainties) p. C: ü New type of detectors (radiation hard, uniform, better resolution, less sensitive to background) ü New FEE (faster peramplifiers) ü DAQ upgrade (from CAMAC to VME, possibly from WFD to ADC/TDC) ü Slow control / Monitoring ü Develop online (provide more information and tools for machine experts)

PHENIX Local Polarimeter Utilizes spin dependence of very forward neutron production discovered in RHIC

PHENIX Local Polarimeter Utilizes spin dependence of very forward neutron production discovered in RHIC Run-2002 (PLB 650, 325) ZDC (energy) + SMD (position) ü Controls spin vector in runs with trans. polarized protons ü Controls residual trans. polarization in runs with long. polarized protons ü Capable to precisely monitor polarization decay vs time in a fill and bunch-bybunch polarization (in trans. pol. runs) SMD ZDC

STAR Local Polarimeter Utilizes spin dependence of hadron production at high x. F: BRAHMS,

STAR Local Polarimeter Utilizes spin dependence of hadron production at high x. F: BRAHMS, s=62 Ge. V PRL 101, 042001 (2008) x. F Beam-Beam Counters 3. 3<|h|< 5. 0 (inner tiles) p x. F Asymmetry vs bunch # STAR BBC Counts Minimum Ionizing Particles (Left-Right, Up-Down) in BBC acceptance: AN~0. 7% at s=200 Ge. V Also in Run-2009, ZDC-based polarimeter commissioned (higher AN at higher beam energy)

Summary RHIC Polarimetry consists of several independent subsystems Hjet: p. C: Absolute polarization measurements

Summary RHIC Polarimetry consists of several independent subsystems Hjet: p. C: Absolute polarization measurements Absolute normalization for other RHIC Polarimeters Separate for blue and yellow beams Normalization from HJet Polarization vs time in a fill Polarization profile Fill-by-fill polarizations for experiments PHENIX and STAR Local Polarimeters: Monitor spin direction (through trans. spin component) at collision Polarization vs time in a fill (for trans. pol. beams) Polarization vs bunch (for trans. pol. beams) Reliably provides RHIC beam polarizations With relative uncertainty better than 5% Continuously developing p. C: , Target system, Detector, FEE and DAQ upgrade to deal with high beam intensities, and to improve efficiency and reliability

Backups

Backups

H-jet system target • Height: 3. 5 m • Weight: 3000 kg Recoil proton

H-jet system target • Height: 3. 5 m • Weight: 3000 kg Recoil proton RHIC proton beam IP 12 • Entire system moves along x-axis 10 ~ +10 mm to adjust collision point with RHIC beam.

HJet target system H = p+ + e |1> |2> |3> |4> Hyper fine

HJet target system H = p+ + e |1> |2> |3> |4> Hyper fine structure H 2 desociater Separating Magnet (Sextuples) |1> |2> P+ OR |1> |3> P |2> |4> |1> |2> Ion gauge  RF transitions (WFT or SFT) Holding magnet Separating magnet Ion gauge Atomic Beam Source Scattering chamber Breit-Rabi Polarimeter 2 nd RFtransitions for calibration

HJet: Ptarget Source of normalization for polarization measurements at RHIC Nuclear polarization of the

HJet: Ptarget Source of normalization for polarization measurements at RHIC Nuclear polarization of the atoms measured by BRP: 95. 8% 0. 1% Correct for H 2, H 2 O contamination. 1 day Polarization cycle (+/ 0/ ) = (500/50/500) seconds Very stable for entire run period ! Ptarget = 92. 4% 1. 8%

HJet Target asymmetry vs TR Run 4 Blue Run 5 Yellow Run 6 Blue

HJet Target asymmetry vs TR Run 4 Blue Run 5 Yellow Run 6 Blue Run 6 Yellow

HJet: AN in pp PLB 638, 450 100 Ge. V: calculations with no hadronic

HJet: AN in pp PLB 638, 450 100 Ge. V: calculations with no hadronic spin flip amplitude contribution are consistent with data 24 Ge. V: calculations with no hadronic spin flip amplitude contribution are not consistent with data AN almost constant vs beam energy Reliable polarimetry in wide range of beam energies PRD 79, 094014(2009)

p. C: AN Elastic scattering: interference between electromagnetic and hadronic amplitudes in the Coulumb-Nuclear

p. C: AN Elastic scattering: interference between electromagnetic and hadronic amplitudes in the Coulumb-Nuclear Interference (CNI) region p. C Analyzing Power Run 04 zero hadronic spin-flip With hadronic spin-flip (E 950) Phys. Rev. Lett. , 89, 052302(2002) Ebeam = 21. 7 Ge. V unpublished Ebeam = 100 Ge. V

p. C: polarization in a fill Example from Run-2006 Blue 60% Fill 7622 40%

p. C: polarization in a fill Example from Run-2006 Blue 60% Fill 7622 40% Yellow 62% 57% 70% Fill 7820 80% 60% 10 hours Some fills may show polarization decay vs time Run 6: average polarization drop during a fill 0. 3 -0. 4% per hour

Average Polarization H-Jet If target positioned at beam peak intensity/polarization p. C Collider Experiment

Average Polarization H-Jet If target positioned at beam peak intensity/polarization p. C Collider Experiment If I 1= I 2= I Corrections due to polarization profiles are different when normalizing p. C to H-Jet and when propagating p. C measurements to experiments Polarization profile in both trans. directions (X, Y) required

p. C: Polarization Profile Rate Polarization Examples of p. C measurements in Run-2005 Target

p. C: Polarization Profile Rate Polarization Examples of p. C measurements in Run-2005 Target Position Beam polarization profile is different for different beams, different fills Correction for average polarization depends on beam/fill

p. C: Polarization Profile R=0. 29 0. 07 Scan C target over the beam

p. C: Polarization Profile R=0. 29 0. 07 Scan C target over the beam cross: Intensity p. C I I 2. Obtain R directly from the P(I) fit: P Polarization 1. Directly measure I and P : P Target Position Precise target positioning is NOT necessary

p. C: Run-2009 issues Measurements for 100 Ge. V and 250 Ge. V beams

p. C: Run-2009 issues Measurements for 100 Ge. V and 250 Ge. V beams Sizable rate dependencies ( 3 higher rates than previously) Targets appeared to be wider than expected Higher beam intensity for 100 Ge. V (1. 7 1011 /bunch in 109 bunch pattern) Smaller beam size for 250 Ge. V Substantial p. C-system upgrade is being considered: Better (thinner and uniform) target production More robust detectors, smaller acceptance Faster preamps Replace WFD with simple ADC/TDC scheme?

PHENIX Local Polarimeter Asymmetry vs φ Spin Rotators OFF Vertical polarization Spin Rotators ON

PHENIX Local Polarimeter Asymmetry vs φ Spin Rotators OFF Vertical polarization Spin Rotators ON Current Reversed Radial polarization Spin Rotators ON Correct Current ! Longitudinal polarization! Blue Yellow Monitors spin direction in PHENIX collision region

PHENIX Local Polarimeter Run-2009 Yellow beam 5 min data ! Asymmetry vs bunch #

PHENIX Local Polarimeter Run-2009 Yellow beam 5 min data ! Asymmetry vs bunch # (in scaler mode) Blue beam Left-Right Up-Down Precisely monitors bunch-by-bunch polarization and polarization vs time in a fill (for transversely polarized beams)

PHENIX Local Polarimeter: energy dependence See M. Togawa talk at PST-09 next week d

PHENIX Local Polarimeter: energy dependence See M. Togawa talk at PST-09 next week d /dx. F is nearly energy independent <p. T>ZDC ~ Beam_Energy (or s) AN ~ p. T AN ~ s in fixed ZDC geometry polarimetry is less efficient for lower beam energy