HJet Polarimeter Upgrades

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H-Jet Polarimeter Upgrades Status

• Yousef Makdisi
• Collider-Accelerator Department, BNL
• Spin 2006

BNL A. Bravar, G. Bunce, R. Gill, Z. Li. A.
Khodinov, A. Kponou, Y. Makdisi, W. Meng, A.
Nass, S. Resica, A. Zelenski, V.
Zubets WISCONSIN T. Wise, M.A. Chapman, W.
Haeberli Kyoto H. Okada, N. Saito ITEP-Moscow
I. Alekseev, D. Svirida IUCF E.
Stephenson Rikkyo U. K. Kurita Data analysis
H.Okada, O. Eyser, K. Boyle
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ASSEMBLED JET
DISSOCIATOR
6-POLE MAGNETS
RF TRANSITIONS
TARGET MAGNET COILS
RHIC BEAMS
RECOIL DETECTORS
BRP POLARIMETER
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The Jet Polarimeter
Oleg Eyser
96 silicon strips (6 x 2 x 8) geometry
reflectskinematics of elastic ppscattering
5 cm
displacement of beams
8 cm
80 cm
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Atomic beam intensity and density measurements in
the collision region

• H-beam intensity and density vs. H2 flow in
  dissociator.

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Jet Operating Parameters

• Stable behavior over the 04, 05 runs, 06 run
  is similar
• 06 we ran typically with 55 sccm H2, .25 sccm O2
• P 0.9570.001 and P -0.9590.001
• Intensity 12.4 x1016 Atoms/sec
• Thickness along the beam1.30.2 x 1012Atoms/cm2
• Added A/C to the RF and Power Supplies for
  stability
• After a nozzle cleaning, the intensity starts at
  0.5-.6 of maximum, rises to maximum in about 1
  day, flat for 12 days, and decreases slowly to
  blockage in 2 weeks.
• Changed the beam beta from 5 to 10 meters in an
  attempt to reduce background.

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H2 and H2O dilution

• Sample Jet with 600 eV Electron Beam
• Extract Ions and Momentum analyze
• Correct for cross-section

PRELIMINARY
Mass 1
H2 dilution is (2.31.2) during normal running
conditions
H2O dilution is small but measurable (0.150.05)
Mass 2
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Total target polarization
Assume only the H in H2O contributes because of
Fermi motion of oxygen nuclei
ATOMS ARE DILUTED BY (2.31.2) H2
and (0.150.05) H2O
PRELIMINARY
PJET 0.9330.013 P-JET 0.9350.013
Instability and problems determining the proper
cross sections Thus still use the QMA results.
92.4 /- 0.2
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RHIC Jet Beam Profile Imaging SystemS. Bellavia,
D. Gasner, D. Trbojevic, T. Tsang, A Zelenski
Camera
Filter Wheel
UpperBox
Secondary Lens Doublet
MotionStage
MirrorBox
PrimaryLens
Mirror box
If successful, could provide in situ H and H2
monitoring
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Beam in the Cage
Camera Focus on Far Wires
Camera Focus on Beam
Camera Focus on Near Wires
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FWHM (x) 4.5 mm
RHIC Yellow beam profileafter 656 nm red
filterData of Feb 28, 2006
s(x) 1.91 mm
FWHM (x) 6.4 mm

H-jet Width
s(x) 2.7 mm

• 486 nm filter H-ß line
• gives similar result
• Expect to see molecular
• hydrogen in a broad band
• around 350 nm.
• A 320 nm filter shows no
• jet image.
• Tsang May need a camera
• sensitive to far IR to detect this!

FWHM (y) 1.9 mm
RHIC beam

s(y) 0.8 mm
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Depolarizing Resonance Scan with 112 bunches

• Nass reported (Spin 2004) no depolarizing
  resonance effects on the Jet polarization with 60
  bunches in the RHIC beam.
• We conducted a resonance scan using the "flip in"
  method.Conditions ABS SF transition ON BRP WF
  transition ONBeam intensity total 120x1011
  protons, 1.1x1011/bunch
• The scan took about 1 hour and during that time
  blue beam decayed to 103x1011 protons.
• Scanned the Inner and Outer holding field coil
  currents from 319.8 inner/252.0 outer to
  356.6/281.0 amps respectively in 69 steps.This
  range guarantees at least one 1-2 resonance but
  most likely two resonances (harmonic numbers 59
  and 60)
• We observed no resonances across the entire scan
  at a level 1x10-3
• The JET required a field uniformity over a 3 cm
  gap of
• 6?10-3 what was achieved is 5?10-3

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Jet Vacuum With RHIC Beam Intensity2004 W/ 60
bunches
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06 Jet Vacuum W/ NEG coating
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Jet operations in 06

• New code to readout the full waveform along with
  a new versatile monitoring program. (Alekseev and
  Svirida)
• Daily PC and DAQ technical support and monitoring
  (Gill)
• Jet oversight and maintenance (Zelenski and
  Makdisi)
• The SFT RF acted up (Wise rescue increase gain)
• Replaced the dissociator nozzle midway.
• MCR Operators took full responsibility and saw to
  it that data were collected in each fill.
• Attempted to collect data with both beams
  vertically separated failed due to loss of
  acceptance.
• Horizontally separated beams not acceptable as
  the beams have to cross and exacerbate the
  beam-beam problem.

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Waveforms(new H-Jet data format this year)
Fit
Half maximum
Baseline 8
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Snap shot of online Monitoring
Blue Beam background
Yellow Beam hitting the jet
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Online Time vs Energy Cuts
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Energy Distributions
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Click on Info to get statistics
With 112 bunch fills and high intensities per
bunch on average the jet collects enough
statistics (online) to measure the beam to jet
polarization ratio to better than 10 per 7-8
hour fill. Offline analysis is required to see
how much data are lost to attain The signal to
background ratio.
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Data Collected _at_ 100 GeV

• Fills Dates Beam Events
• 7630-7652 3/18-25 B 2.5M
• 7662-7697 3/26-4/4 Y 2.8M
• 7718-7745 4/4-11 B 1.6M
• 4/11 Lost Si detector 3
• 7780-7802 4/12-5/2 Y 3.8M
• 7810-7858 5/3-15 B 4.2M
• 7887-7946 5/19-6/1 Y 2.5M
• 6/2 Si detector 1 acted up reduced the bias
  from 200 175 V.
• 7949-8002 6/3-5 B 2.0M

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Data Collected at 31.2 GeV

• Fills Dates Beam Events
• 8005-8054 6/9-17 B 3.6M
• 8055-8061 6/18-20 Y 2.6M
• The Fills were relatively shorter durations.
• The statistics will allow a good calibration of
  the p-CNI polarimeters near injection.

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Data Analysis

• The 2004, 100 GeV data AN and ANN were published
  H. Okada et al. PLB 638 (2006).
• The 2004, 24 GeV analysis (15 hours) AN and ANN
  is complete (Hiromi Okada). Calibration of the
  Blue pC polarimeter at injection.
• The 05 data is complete (Oleg Eyser).
• The 31.2 GeV data a good statistical sample taken
  in conjunction with the polarimeters (Oleg
  Eyser).
• The 100 GeV 06 to be analyzed (Kieran Boyle).
• The Jet has met its goal to provide the necessary
  polarimeter calibration to the desired level of
  3
• A remaining issue is the ability to process the
  data off line on a timely basis.

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What is next?

• Determine the cause of the silicon failure.
• Replaced the failed detectors with existing
  spares. We are experiencing high currents in the
  new detectors.
• Placed an order with Hamamatsu for 12 new
  detectors.
• Started the procurement of spare 25 Wave Form
  Digitizer units for jet and polarimeters.
• Look into increasing the acceptance to be able to
  measure both beams simultaneously (not so easy)
• As and RD effort, T. Wise, Wisconsin is building
  two RF cavities to allow a polarized deuteron jet
  beam.

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Setup of the JET

• Atomic beam produced by expansion of a
  dissociated H beam through a cold nozzle into
  vacuum chamber
• Nuclear polarization achieved by HFTs (SFT, WFT)
  after focusing with sextupole magnets
• After passing RHIC beam BRP sextupoles focus the
  atomic beam into the detector
• Determination of the efficiencies of these HFTs
  and the polarization of the beam by comparing the
  detector signals while running different HFTs,
  e.g.

• ABS SFT
• ABS WFT
• ABS SFT ABS WFT
• BRP HFTs for calibration

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Depolarizing Effects

• Beam induced depolarization due to bunched
  structure of p-beam ? transient magnetic fields
  transverse to the beam direction
• Closely spaced depolarizing resonances in the
  usable range of the surrounding target holding
  field
• High uniformity of the target holding field
  necessary

• Required at JET
• DB/B6?10-3
• achieved 5?10-3
• No depolarization
• with 60 bunches in
• RHIC

Toms theoretical values to be added
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Operational issues

• Nozzle blockage frequency every two weeks. It
  takes 3 hours to warm up, ½ hour beam down, and
  two hours to cool down and back online.
• Slower intensity ramp up than before. 3-4 days to
  reach full intensity, plateau for a few days and
  then a slow decrease to blockage.
• Midway replaced the nozzle which improved matters
  somewhat.
• The SFT phase became unstable for a period. Fixed
  by T. Wise by increasing the gain.
• Lost some precious time due to memory full
  condition.
• Lost one silicon detector, and another acted up.

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Operations continued

• Failed to take data with two beams at the same
  time
• Requirement that the two beams be separated by
  4-6 mm.
• The vertical collimation occluded the silicon
  acceptance.
• Determined no polarization loss with 112 bunch
  operation and 1.1011 p/bunch implying the holding
  field uniformity is adequate.
• Installed a CCD camera to look at light emitted
  as the beam hits the jet. This serves as another
  vertical beam emittance device. Our interest is
  to measure the molecular hydrogen contamination.
• No pump failure this run.