H-Jet Polarimeter Upgrades & Status 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

DISSOCIATOR

6-POLE MAGNETS

RECOIL DETECTORS

TARGET MAGNET COILS

RHIC BEAMS

BRP POLARIMETER

RF TRANSITIONS

ASSEMBLED JET

The Jet Polarimeter

x

y

jet

targetNtarget

beamNbeam

PA

PA

targettarget

beambeam PP

96 silicon strips:(6 x 2 x 8)

geometry reflectskinematics of elastic ppscattering

displacement of beams

~ 80 cm

8 cm

5 c

m

Oleg Eyser

Atomic beam intensity and density measurements in the collision region

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

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+ = 0.957±0.001 and Pˉ = -0.959±0.001• Intensity 12.4 x1016 Atoms/sec• Thickness along the beam1.3±0.2 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.

H2 and H2O dilution• Sample Jet with 600 eV Electron Beam

• Extract Ions and Momentum analyze

•Correct for cross-section

H2 dilution is (2.3±1.2)% during normal running conditions

H2O dilution is small but measurable: (0.15±0.05)%

Mass 1

0

500

1000

1500

2000

2 2.5 3 3.5 4

magnet current (Amperes)

Mass 2

Total target polarization

ATOMS ARE DILUTED BY:

(2.3±1.2)% H2 and

(0.15±0.05)% H2O

P+JET = 0.933±0.013

P-JET = 0.935±0.013

Assume only the H in H2O contributes because of Fermi motion of oxygen nuclei

Instability and problems determining the proper cross sectionsThus still use the QMA results. 92.4% +/- 0.2 %

MirrorBox

PrimaryLens

UpperBox

RHIC Jet Beam Profile Imaging SystemS. Bellavia, D. Gasner, D. Trbojevic, T. Tsang, A Zelenski

Camera

Filter Wheel

Secondary Lens Doublet

MotionStage

Mirror box

If successful, could provide in situ H and H2 monitoring

Beam in the Cage

Camera Focus on Near Wires

Camera Focus on Far Wires

Camera Focus on Beam

FWHM (y) = 1.9 mm

FWHM (x) = 4.5 mm

σ(y) = 0.8 mm

σ(x) = 1.91 mm

FWHM (x) = 6.4 mmσ(x) = 2.7 mm

•486 nm filter: H-β linegives 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 camerasensitive to far IR to detect this!

}H-jetWidth

RHICbeam}

RHIC Yellow beam profile

after 656 nm red filter

Data of Feb 28, 2006

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 6ּ10-3 what was achieved is 5 ּ10-3

Jet Vacuum With RHIC Beam Intensity2004 W/ 60 bunches

`06 Jet VacuumW/ NEG coating

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.

Waveforms(new H-Jet data format this year)

Fit

Half maximum

Baseline = 8

Snap shot of online Monitoring

Yellow Beamhitting the jet

Blue Beambackground

Online Time vs Energy Cuts

Energy Distributions

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.

Data Collected @ 100 GeV

Fills Dates Beam Events7630-7652 3/18-25 B 2.5M7662-7697 3/26-4/4 Y 2.8M7718-7745 4/4-11 B 1.6M4/11 Lost Si detector # 3 7780-7802 4/12-5/2 Y 3.8M7810-7858 5/3-15 B 4.2M7887-7946 5/19-6/1 Y 2.5M6/2 Si detector #1 acted up: reduced the bias from 200 – 175 V.

7949-8002 6/3-5 B 2.0M

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.

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.

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 R&D effort, T. Wise, Wisconsin is building two

RF cavities to allow a polarized deuteron jet beam.

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 HFT’s (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 HFT’s and the polarization of the beam by comparing the detector signals while running different HFT’s, e.g.:

•ABS SFT•ABS WFT•ABS SFT + ABS WFT•BRP HFT’s for calibration

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:B/B=6ּ10-3

achieved 5ּ10-3

No depolarizationwith 60 bunches inRHIC

Toms theoretical values to be added

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.

Operations continued

• Failed to take data with two beams at the same time: a) Requirement that the two beams be separated by 4-6 mm.b) 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.