Polarized source upgrade

RSC, January 11, 2013

OPPIS

LINAC

Booster

AGS

RHIC

(2.0-2.2) 10∙ 11 p/bunch

0.6mA x 300us→11 10∙ 11 polarized H- /pulse.

(6.0-6.5) 10∙ 11 polarized H- /pulse at 200 MeV

(2.2-2.4) 10∙ 11 protons /pulse at 2.3 GeV

~1.8∙1011 p/bunch, P~60-65% at 100 GeV P ~ 56% at 250 GeV

RHIC Polarized beam in Run 2012

OPPIS with neutral H injector layout.

Atomic H injector

Neutralizer cell

He-ionizercell Rb-cell

Na-jetcell

H+ H0 H+ H0 H-H2 He Rb Na

TMP1CP1

The FABS and new SCS at operational OPPIS bench.

The FABS and new SCS at operational OPPIS bench

“Fast Atomic Beam Source”, BINP 2011

Plasmatron 4-grid protonextraction system

H2 Neutralization cell

~ 3.5 AequivalentH0 beam

FABS produces 200-300 mA equivalent H0 beam intensityWithin the Na-jet ionizer acceptance.

Residual un-polarized H0 beam component suppression by the energy separation.

H+(70%)

H0(7 keV)

H0(3.0keV)

-4.0 kV-4.1 kV -4.1 kV

H0(7.0keV)

He-ionizer cell Rb -cell

H0(30%)

DecelerationH0 + He → H+ + He + e

-2-3 kV +0.1kV

Polarization dilution in the FABS.

H0 (7 keV)

H+ (7 keV)

H+ (3.0keV)

H0 (3.0keV)

H- (3.0keV)

H- (35keV)

Ionization in He-cell~70%

Neutralization in Rb, ~70%

Na-jet, 8.0%

Polarized ~ 4.0 %

H0(7 keV) H-(7 keV) H-(39 keV)40% 2%

H+ (7 keV)H2-cell

0.8 / 4.0 ~ 20% - polarization dilution.4.0 keV energy separation would allow dilution reduction to less than 0.5%.

Losses at Deceleration, ΔE = - 4.0 keV, ???

Acceleration - 32 keV

95%

Un-polarized ~ 0.8 %

He-ionizer cell assembly with electro-dynamic valve and proton deceleration system.

Electro-dynamic valve

Three-gridEnergy-separationsystem

He-ionizer cell assembly with electro-dynamic valve and proton deceleration system.

Grid heater to reduce Rb deposition

Electro-dynamic valve operation principle.

Electro-dynamic valve .

Force to the conducting plate in the (high ~ 3 T) magnetic field.

For I=100 A, L=5 cm, F=15 N).

Electro-dynamic valve.

1 – body, 2 – current vacuum feed-through, 3 – gas supply, 4 – flexible springing plate, 5 – “O” -ring.

Changes in the Low Energy Beam Transport Line.

EL2-replaced with the Quad doublet

Variable collimatorIn DB2 to improveEnergy resolution.

New FC

The LEBT is tuned for 35 keV beamEnergy transport.

Energy separation of decelerated (“polarized”) H- ion beam in LEBT.

0

0.5

1

1.5

2

2.5

3

3.5

20 22 24 26 28 30 32 34 36

Acceleration voltage, kV

H- i

on b

eam

cur

rent

, m

A31.5 + (7.5 – 4.0) = 35 keV

I (He-”on”)/ I(He –”off”) ~50

535 uA in FC after RFQ, Rb-91 deg. I=200 A

Energy separated beam vs. Rb –cell temperature

0

200

400

600

800

1000

1200

1400

1600

0 20 40 60 80 100 120 140

T Rb, C

FC4,

mkA

30 uA- He-off

1400 uA- He-cell“on”

31.5 + (7.5-4.0)= 35 keVE0 =7.5 keV ΔE=4.0 kV

FC4, uA

Beam production and transport vs. Rb-temperature at different primary beam intensities.

Rb-91 deg, T9-current-525 uA, I=200A

T9-current-600 uA, Rb-96 deg, I=200 A,

Superconducting Solenoid Sona transition

Ionizersolenoid

LargeCorrectionCoil

OPPIS magnetic field, Sona-transition field shape control.

InternalCorrection Coils

Higher residual field with the new solenoid. Use of iron shield and four correction coils allowed of field

gradients control to the required level.Still there is a room for improvements.

80 %

Laser system upgrade. New wavelength meter.

Optical pumping of Rb-85 (72.7%), Rb-87(27.8%) natural

mixture..Effective width of Rb 85-87 natural mixture including hyperfine Splitting and Doppler broadening is ~ 3.2 GHz

Δν ~ 8 GHz

Laser frequency scan. 200 MeV polarization vs. laser frequency.

~ 12 GHz

Spin “up”

Spin “down”

Dec.16, T9-current 220 uA, Pol-78.7+/-0.7%

Polarization vs. Rb –temperature.

90 deg

80 %

Polarization measurements in Lamb-shift polarimeter.

Rb-cell vapor thickness

OPPIS current and polarization vs. Rb –cell vapor thickness.

5∙1013

Rb-cell thickness, atoms/cm^2

X 1013

Higher ~105 deg Rb cell temperature

Recent progress.• The new solenoid works well.• Both atomic H sources are in operation. Plasmatron operation is quite

stable and reliable. • High –intensity H- ion beam production, acceleration to 35 keV,

transportation in LEBT were studied.• 4 mA H- ion beam was obtained out of Linac.• He-ionizer cell works well with a new pulsed magneto-dynamic He gas

valve. • Reliable deceleration of proton beam was demonstrated.• Very good beam energy separation (Suppression of the “wrong” energy

un-polarized beam component) was demonstrated.• A 600-800 uA energy separated H- ion beam was produced for injection to

RFQ. • Beam polarization measurement are in progress in 200 MeV polarimeter.• 75-80 % polarization was obtained so far.

Recent tests at 200 MeV.

• Goals:• Reliability studies.• Polarization and intensity optimization.• MCR operator training.

Reliable operation

Intensity

Polarization

Results so far.

• Reliable long-term ∙operation of the source was demonstrated.• Very good suppression of un-polarized beam component was demonstrated.• Small beam emittance (after collimation for energy separation) and high

transmission to 200 MeV.• 500-600 uA beam intensity was obtained at 200 MeV (9.0-10.8) ∙1011 H-/pulse at Rb –vapor thicknes ~6 ∙10 13 atoms/cm2, (90 deg. cell temperature).~ 78-80% polarization was measured in 200 MeV polarimeter at beam intensity

200-250 uA.~ 80-82% polarization at 150 uA.~ 74-76% at intensity 300-500 uA. After a new set of magnetic field measurements the Rb-cell position was moved ~ 100 mm upstream in a field flattop part. Hopefully, it will improve

polarization.

Summary

It looks like the source reliability is acceptable for the use in the RHIC Run 13.

The beam intensity and polarization is comparable with the best ECR-based OPPIS operation.

Beam intensity of ~10 ∙1011 was obtained (Booster input).

Polarization measurements and optimization will be continued. There is a room for improvements.

LINAC (T9) H- beam current 4.0 mA at 200 MeVE inj = 4 + 31 kV=35 keV, May 14, 2012.

4.0/0.03 ~33 Suppressionfactor for Un-polarized beam component

4.0 mA

Linac current vs. Rb vapor thickness.

400 uA at 200 MeV7.4∙1011 H- /pulseat Rb thickness13∙1013 Rb/cm2

Ratio of the target to the emitter current density vs spherical grids focal length.

Fig. 8. Ratio of the target current to the emitter current vs focal distance: 1 – without magnetic field, 2 – with magnetic field.

5A, H+ → 200mA, H0→ 16 mA, H-