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Transcript of The Relativistic Heavy Ion Collider high-intensity polarized H - ion source The Relativistic Heavy...
The Relativistic Heavy Ion Collider high-intensity polarized H- ion source
The Relativistic Heavy Ion Collider high-intensity polarized H- ion source
A.Zelenski, G.Atoian, D.Raparia, J.Ritter, D.Steski Brookhaven National Laboratory
ICIS 2015, August 28, 2015
• Optical pumping polarization technique• Charge-exchange collisions• High-brightness atomic beam source• He-ionizer cell• Sodium-jet ionizer cell• Summary
Summary
• The old RHIC OPPIS based on ECR primary proton source retired after successful operation in Runs 2000-2012.
• The new source with atomic beam hydrogen injector and He-ionizer was developed in 2010-12 and commissioned for operation in Run-2013.
• It produces significantly higher brightness primary proton beam which resulted in higher polarized beam intensity and polarization delivered for injection to Linac-Booster-AGS-RHIC accelerator chain.
• Practically all OPPIS systems were modified (in addition to the ECR-source): a new superconducting solenoid; new He-ionizer cell with a pulsed He-injection and new pulsed electro-magnetic gas valve; beam energy separation system developed for un-polarized residual beam suppression; new vacuum system with turbo-molecular pumps for He-pumping; laser control, diagnostics and transport systems.
The RHIC OPPIS upgrade with atomic hydrogen injector, Run-2013-15
BNL - BINP, Novosibisk -INR, Moscow collaboration
STARPHENIX
AGS, 24GeVLINAC
BOOSTER, 2.5 GeV
Pol. H- ion source
Spin Rotators Siberian Snakes
200 MeV polarimeter
RHIC pC “CNI” polarimeters
RHIC
Absolute H-jet
polarimeter
L max = 1.6 1032 s-1cm-2 50 < √s < 510 GeV
AGS pC “CNI” polarimeter
Polarization facilities at RHIC
OPPIS
LINAC
Booster
AGS
RHIC
(2.0-2.5) 10∙ 11 p/bunch
1.0 mA x 300us→18 10∙ 11 polarized H- /pulse.
9.0 10∙ 11 polarized H- /pulse at 200 MeVroutinely in Run-15
(2.5-3.0) 10∙ 11 protons /pulse at 2.3 GeV
~1.8∙1011 p/bunch, P~60-65% at 100 GeV P ~ 58% at 255 GeV
RHIC Polarized beam in Run 2013-15
It is expected, that use of Electron Lenswill allow increase of the bunch intensity to ~2.5∙1011 p/bunch.
What can we learn about “swiss” watches from watches collisions?
Actually a lot!In particular, if protons are polarized!
Intermediate bozons W± - can be produced directly in electroweak processes in collisions of polarized proton beams of a 250 GeV energy at RHIC.
In this case parity-violation can be as large as 50% and spin-correlation can be used for studies of different flavor quark contribution to the proton spin.
SPIN -TRANSFER POLARIZATION IN PROTON-Rb COLLISIONSSPIN -TRANSFER POLARIZATION IN PROTON-Rb COLLISIONS
Rb+
H+ H+Proton source
Proton source
Laser-795 nmOptical pumpingRb: NL(Rb) ~1014 cm-2
Sonatransition
Sonatransition
Ionizercell
Ionizercell
H-
Laser beam is a primary source of angular momentum:
10 W (795 nm) 4•1019 h/sec 2 A, H0 equivalent intensity.
Supperconducting solenoid 25 кГс
1.5 kG fieldCharge-exchange
collisions: ~10-14 cm2
Na-jet ionizer cell:
NL(Na)~ 3•1015 cm-2
Electron to proton polarization transfer
ECR-29 GHz
Н+ source
~50 mA, 2.8keV
Rb+
Optical Pumping polarization technique. A. Kastler, Nobel prize 1966
5S1/2
5P1/2
λ = 795 nm
Circularly
Polarized lig
ht
MJ = -1/2 MJ = +1/2
Spontaneous
decays.
nLJ
~ 100% polarized Rb
atoms!
1.56 eV
relaxation
Optical pumping application is limited by available laser power!?Recent progress in laser technology is very promising for new applications.
MJ = +1/2MJ = -1/2
Pulsed OPPIS with the atomic hydrogen injector at
INR, Moscow, 1982-1990. First generation
Atomic H0 injector
Helium ionizer cell~80% ionizationefficiency.
Lamb-shift polarimeterH- current- 0.4mA
H+ current- 4.0 mA, P=65%, 1986
New generation OPPIS with atomic H0 injector
Atomic Hinjector He-cell
H-
High-brightness proton beam inside strong 2.5 T solenoid field produced by atomic H beam ionization in the He-gas ionizer cell
The proton beam intensity is about 1.0 A !
Hydrogen atomic beam ionization efficiency in the He- cell
Hydrogen atomic beam ionization efficiency in the He- cell
10 keV
80%
H0 + He → H+ + He + e
“Fast Atomic Beam Source”, BINP, Novosibirsk, 2012
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.
FABS 4-grid spherical Ion Optical System
3-5 A of proton beamAt 6-8 keVenergy
1820 holes , 1.0 mm in diameter
FABS and neutralizer cell.
Neutral hydrogen beam intensity profile at 250 cm distance from the
source.
FWHM
~ 20 mm
Residual un-polarized H0 beam component suppression by the energy separation
H+(70%)
H0(6.5 keV)
H0(2.5 keV)
-4.0 kV-4.1 kV -4.1 kV
H0(6.5keV)
He-ionizer cell Rb -cell
H0(30%)
DecelerationH0 + He → H+ + He + e
-2-3 kV +0.1kV
He-ionizer cell and 3-grid energy separation system.
He-pulsedvalve
3-grid beamdecelerationsystem
“Electro-magnetic” valve operation principle.
Force to the conducting plate in the (high ~ 3 T) magnetic field.
For I=100 A, L=5 cm, F=15 N).
I
B
F
New OPPIS with atomic H0 injector layout, 2013
Rb-cell
H+H0 H+ H0 H-
H2 He Rb Na
CP1
Na-jetcell
Atomic Hinjector
He-ionizercell
Neutralizer H2-cell
TMP1
Rb-cell Sonatransition
H- yield vs. H0 beam energy.
0
1
2
3
4
5
6
7
8
9
10
0 2 4 6 8 10 12
Beam energy, keV
H-
ion
yie
ld,
%
Sodium-jet ionizer cellSodium-jet ionizer cell
Reservoir– operational temperature. Tres. ~500 оС.Nozzle – Tn ~500 оС.Collector- Na-vapor condensation: Tcoll.~120оСTrap- return line. T ~ 120 – 180 оС.
Transversal vapor flow in the N-jet cell.Reduces sodium vapor losses for 3-4 ordersof magnitude, which allow the cell aperture increase up to 3.0 cm .
Transversal vapor flow in the N-jet cell.Reduces sodium vapor losses for 3-4 ordersof magnitude, which allow the cell aperture increase up to 3.0 cm .
Nozzle500deg.C
Collector~150 deg.C
Reservoir~500 deg.C
NL ~2·1015 atoms/cm2
L ~ 2-3 cm
H- beam acceleration to 35 keV at the exit of Na-jet ionizer cell
H- beam acceleration to 35 keV at the exit of Na-jet ionizer cell
Na-jet cell is isolated and biased to – 32 keV. The H- beam is accelerated in a two-stage acceleration system.
-32 kV
H-
35 keV
39 keV
-28 keV -15 keV
3 keV7 kev
H0
H- beam acceleration to 35 keV at the exit of Na-jet ionizer cell.
H- beam acceleration to 35 keV at the exit of Na-jet ionizer cell.
Na-jet cell is isolated and biased to – 32 keV. The H- beam is accelerated in a two-stage acceleration system.
-32 kV
H-
35 keV
-28 keV -15 keV
Low Energy Beam Transport line.
Variable collimatorIn DB2 to improveEnergy resolution.
Lamb Shift Polarimeter
FC435.0 keV
FC-Tk1,750keV
OPPIS
23.7 deg bender
RFQ
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-
ion
be
am
cu
rre
nt,
mA
31.5 kV
31.5 + (7.5 – 4.0) = 35 keV
1400/30=47
06 Dec, 2013Note#31,page75
BeamEnergy=6.5keV; IONZ=220A; Polarized H-current at 750 keV energy(after RFQ) vs. Rb-cell temperature
NL~10×1013
atoms/cm2
Rb cell temperature, deg. C
1.0 mA × 300 us =18×1011 ions/pulse
12uA
Polarized H- current-1.05 mA, after RFQ 750 keV Rb-98º
100 us/div
200 uA/div
Rb-90, 200 MeV, T9-620uA
600 µA × 400 µs →14.4 ∙1011 protons/pulse
Polarization (at 200 MeV) vs. SCS magnetic field in He and Rb-cells
Magnetic field ,kG
Source intensity and polarization.
Rb-cell thickness-NL 4.5 5.5 7.5 10.4
Linac Current, μA 500 560 680 750
Booster Input ×1011 9.0 10.0 12.2 13.5
Pol. %, at 200 MeV 84 83 80.5 78
• Reliable long-term operation of the source was demonstrated. ∙• Very high suppression of un-polarized beam component was
demonstrated.• Small beam emittance (after collimation for energy separation)
and high transmission to 200 MeV.
Rb-cell thickness ,NL ×1013 atoms/cm2
H- beam current and polarization at 200 MeV vs. Rb vapor thickness
Rb-vapor thickness –nL –atoms/cm2
H- ion beamcurrent (mA)
Polarization in 200 MeV polarimeter
Equal 12 deg and 16 deg polarization numbers
Polarization at 200 MeV -85.2%
Long-term polarization stability, April 14-23, 2014
86%
Polarization in AGS, 23 GeV
Polarization measurements at 255 GeV in H-jet polarimeter, Run-2013, April-25-30
<
~ 62% in collisions
High intensity polarized proton sources makes feasible the high luminosity RHIC operation to study:
spin proton structure,
fundamental tests of QCD and electro-weak interaction.
Summary
• The old RHIC OPPIS based on ECR primary proton source was retired after successful operation in Runs 2000-2012.
• The new source with atomic beam hydrogen injector and He-ionizer was developed in 2010-12 and commissioned for operation in Run-2013.
• It produces significantly higher brightness primary proton beam which resulted in higher polarized beam intensity and polarization delivered for injection to Linac-Booster-AGS-RHIC accelerator chain.
• Practically all OPPIS systems were modified (in addition to the ECR-source): a new superconducting solenoid; new He-ionizer cell with a pulsed He-injection and new pulsed electro-dynamic gas valve; beam energy separation system developed for un-polarized residual beam suppression; new vacuum system with turbo-molecular pumps for He-pumping; laser control, diagnostics and transport systems.