Transcript Slide 1

Polarized beam in RHIC in Run 2011.
Polarimetry at RHIC
A.Zelenski, BNL
PSTP 2011, September 13, St.Petersburg
Polarization facilities at RHIC.
32 s-1cm-2 50 < √s < 500 GeV
Design goal - 70% Polarization
RHIC: theL “Polarized”
max = 1.6  10 Collider
RHIC pC “CNI”
polarimeters
Absolute H-jet
polarimeter
RHIC
PHENIX
STAR
Siberian Snakes
Spin Rotators
Pol. H- ion source
LINAC
200 MeV polarimeter
5% Snake
AGS, 24GeV
AGS pC “CNI” polarimeter
20% Snake
Progress in 2011 polarized proton Run.
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–
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Higher polarization out of AGS (jump quads).
Higher polarization at RHIC store (new working point, tune/orbit
feedback on the ramp).
Highest peak luminosity ~1.6∙1032 cm-2 s-1 in RHIC so far (9MHz,
orbit/tune).
–
Orbit feedback works. We have excellent orbit control on the ramp.
9MHz cavity is operational. No indication of intensity limit.
–
10Hz orbit feedback works. Beneficial to luminosity.
–
–
–
Chromaticity feedback works for these ramps. Essential for the
down ramp development.
Tune jump system in AGS
Polarization at injection in RHIC with the
Jump-Quads in operation.
RHIC luminosity in Run-2011
Peak luminosity ~1.5*1032 cm2 s
Bunch intensity
~ 1.6 *1011 proton/bunch
RHIC polarized protons 2000-2011
Run 2011,250 GeV, P-53%
Wolfram Fischer
7
Polarimetry at RHIC
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Faraday rotation polarimeter
Lamb-shift polarimeter
200 MeV - absolute polarimeter
AGS p-Carbon CNI polarimeter
RHIC p-Carbon CNI polarimeter
RHIC - absolute H-jet polarimeter
Local polarimeters at STAR and PHENIX
 Y.Makdisi, A.Poblaguev talks
Faraday rotation polarimeter of Rb vapor.
Linear polarized probe
laser beam at 780 nm.
Θp-optical pumping –on.
Θ0-optical pumping -off.
Rb-cell
PD1
λ/2
PD2
Cr:LISAF
pumping laser
at795 nm
PD1=I0 sin θp
PD2=I0 cos θp
PRb= (θp- θ0)/ θ0
Proton Lamb-shift polarimeter at3-35keV
beam energy. .
H- → H+ → H(2S)
La(10.2eV) -121.6 nm
•
•
•
H(2S)
B=575 G
N+ =N0(1+P) / 2
N- = N0(1-P) / 2
P=2 (N+-N-)/(N+ +N-)
Layout of the 200 MeV proton polarimeter, (2010)
16.2 deg
Proton-Carbon Elastic
Scattering at 200 MeV.
Ay=99.96+/0.02%
Detector and variable absorber setup
for 200 MeV proton beam.
GEANT calculation of pC polarimeter for 200MeV proton beam
Sc1
Collimator
Sc2 Sc3
Absorber
Ep=194.3MeV
inelastic
Ep=198.7MeV
elastic
Measured Analyzing Power vs length of absorber.
Ay(pC) =0.62+/-0.02
AGS CNI Polarimeter 2011
3 different detector types:
1,8
- Hamamatsu, slow
preamplifiers
2,3,6,7 - BNL, fast preamplifiers
Outer
4,5
- Hamamatsu, fast
preamplifiers
Run 2009: BNL, slow preamplifiers
Inner
N L or N L
 or 
16 February 2011
11
Regular
length (30
cm)
A.Poblaguev talk
Carbon target
90º in Lab frame
Polarized proton
Larger
length (50
cm)
N R or N R
Recoil carbon
RHIC Spin Spin
Collaboration
Meeting Meeting
17
Three complimentary pillars
of the RHIC polarimetry.
 p-Carbon CNI polarimeter: relative, fast, polarization
profiles, bunch-by bunch measurements, polarization
decay time.
 Proton-proton H-jet CNI polarimeter: absolute,
integral, about 5-7% statistical accuracy in one store.
 Local polarimeters: relative, fast, integral, bunch-bybunch, polarization decay time.
Polarization facilities at RHIC.
32 s-1cm-2 50 < √s < 500 GeV
Design goal - 70% Polarization
RHIC: theL “Polarized”
max = 1.6  10 Collider
RHIC pC “CNI”
polarimeters
Absolute H-jet
polarimeter
RHIC
PHENIX
STAR
Siberian Snakes
Spin Rotators
Pol. H- ion source
LINAC
200 MeV polarimeter
5% Snake
AGS, 24GeV
AGS pC “CNI” polarimeter
20% Snake
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
Blue
Yellow
Blue
Yellow
Monitors spin direction in PHENIX collision region
Beam polarization. Polarization profiles.
• Polarization measurements for accelerator setup and
monitoring. Depolarization minimization in AGS and RHIC.
Relative (on-line) measurements.
• Polarization loss from intrinsic resonances: polarization
lost at edge of beam → polarization profiles.
• Polarization measurements for experimental data
normalization (off-line absolute values obtained after detail
calibration and normalization). Corrections for polarization
profiles.
Hydrogen Gas Jet and Carbon Ribbon Targets.
Gas Jet Target
p
Carbon Ribbon Target
Beam Cross Section

Carbon Ribbon:
~ 5-10 µm wide
25nm thickness
~ 5 µg/cm2
mm
FWHM~7
Average Pave
Peak Ppeak and average
polarization
H-Jet polarimeter.
Elastic scattering: Interference between
electromagnetic and hadronic amplitudes in the
Coulumb-Nuclear Interference (CNI) region.
AN t   
 target
Ptarget

 beam
RHIC proton
beam
Pbeam
Forward scattered
proton
H-jet target
t   pout  pin 2  0
recoil proton
Pbeam  Pt arg et
 beam
 t arg et
Pbeam Ptarget  target  beam



<5%
Pbeam
Ptarget
 target
 beam
Ptarget is measured by Breit- Rabi Polarimeter
October 6-10, 2008
A.S. Belov, A. N. Zelenski, SPIN2008, USA
Spin filtering technique. Atomic Beam Sources.
Hydrogen atoms with electron
polarization: mJ=+1/2 trajectories.
Breit-Rabi polarimeter
RHIC beam crossing
RF transition, polarization transfer
from electrons to protons
Electron magnetic moment is 659 times
Larger than proton : e / P ~659.
Focusing strength: ~ (dB/dr) e
permanent magnet
sextupole - 1.7 T
October 6-10, 2008
gradient 5.7 T/cm A.S. Belov, A. N. Zelenski, SPIN2008, USA
H-jet, Blue beam, 250 GeV, Run-2011
H-jet, Yellow beam, 250 GeV, Run 2011
H-jet is an ideal polarimeter !
• High (~4.5%) analyzing power in a wide energy range (23-250
GeV).
• High event rate due to high intensity (~100 mA) circulated
beam current in the storage ring (~6% statistical accuracy in
one 8hrs. long fill). High polarized H-jet density in RHIC ABS.
• Non-destructive.
• No scattering for recoil protons.
• Clean elastic scattering event identification.
• Direct calibration with Breit-Rabi polarimeter.
• Most of the false asymmetries are cancelled out in the ratio:
P beam =( 1/A)Beam asym / Target asym
Problem.
Polarization dilution by H2, H2O and other residual gases.
October 6-10,source
2008
A.S. Belov,
A. N. Zelenski, SPIN2008, USA
Largest
of systematic
error.
H-jet as a luminescence beam intensity monitor.
p-Carbon Polarimetry at RHIC

L
N or N
 or 


L
pC  pC
Carbon target
90º in Lab frame
Polarized proton
N R or N R
Recoil carbon
Measurements with p-Carbon CNI polarimeter.
• Polarization, polarization profile measurements in
the scanning mode.
• Polarization losses during acceleration and store.
• Polarization decay during store.
• Beam intensity profile (emttance) including bunchby-bunch.
• Emittance measurements cross-calibrations.
• Emittance measurements on the ramp.
The RHIC p-Carbon CNI polarimeter.
Elastic scattering: interference between electromagnetic and hadronic
N Interference
or N
amplitudes in the Coulumb-Nuclear
(CNI) region.

L
Pbeam  
N
N
pC
N
A
NL  NR

NL  NR
6
1
18cm
2
5
4

L
Carbon
target
Run04
Recoil
carbon
Ultra thin Carbon
ribbon Target
(5 g/cm2)
Si strip detectors
3 (TOF, EC)
Ebeam = 100 GeV
The target ladder.
Carbon ribbon
~5-10 um wide
25 nm thicknes
April 18, 2011, Blue1, H6
Pol. Profile: 250 GeV in Run-2009
Intensity and polarization
profiles:
R=0.280.07
P-Carbon polarimeter upgrade for Run-2009
• Two polarimeters in each
ring.
• Routine polarization profile
measurements in bothvertical and horizontal
planes.
• Beam intensity profile
(emittance) measurements.
• Doubled number of Carbonstrip targets.
• New detectors development.
Pol. Profile: 250 GeV in Run-2009
• Polarization loss from intrinsic resonances: polarization lost at
edge of beam → polarization profile.
• Impact of polarization profile on beam polarization at collisions:
2 +x'2
2
2s x,P
-
-x
P(x,x',y,y') = P0 e
P =P
1
0 (1+RH )(1+RV )
e
y2 +y'2
2
2s y,P
; I(x,x',y,y') = I 0 e
; Pcoll. = P0
2 +x'2
2
2s x,
I
-x
1
1+ 12 RH 1+RH 1+ 12 RV 1+RV
-
e
y2 +y'2
2
2s y,
I
= P
s x,2 I
s y,2 I
x,P
y,P
; RH = s 2 ; RV = s 2
1+RH 1+RV
1+ 12 RH 1+ 12 RV
For RH ≈ RV and small: P0 = <P> (1+<R>)2;
Pcoll. = <P> (1+½<R>)
There is a
Polarization evolution in AGS and RHIC.
Note that P0, the polarization of the core particle, should
be equal to the maximum achievable polarization.
<P>
<R>
AGS extr.
67.6 ± 1.0
RHIC inj., B
Pcoll.
P0
Pmax.
0.02 ± 0.02
70.3 ± 1.0
80.0
65.7 ± 0.3
0.08 ± 0.02
76.6 ± 0.4
76.6
RHIC inj., Y
66.3 ± 0.3
0.08 ± 0.02
77.3 ± 0.4
79.3
RHIC 250 GeV, B
52.2 ± 0.3
0.17 ± 0.02
56.6 ± 0.3
71.5 ± 0.4
76.6
RHIC 250 GeV, Y
54.5 ± 0.3
0.16 ± 0.02
58.9 ± 0.3
73.3 ± 0.4
79.3
There is a possibility of an additional longitudinal polarization profile.
Polarization profiles Run 9, Injection
Polarization profiles at 100GeV, Run 2009
Polarization profiles at 250GeV, Run 2009
Run-2009, polarization profiles.
Polarization profiles at injection, Run-2011
May 3, 2011
A. Poblaguev
Spin Meeting
24 GeV, Blue-2, Horiz profiles, Run-2011
May 3, 2011
A. Poblaguev
Spin Meeting
24 Gev, Blue-1, Horiz target, Vert profiles
May 3, 2011
A. Poblaguev
Spin Meeting
Run-2011, 250 GeV, Blue-2, Horiz profiles
May 3, 2011
A. Poblaguev
Spin Meeting
Run-2011,250 GeV, Yellow-1, Vert.profiles
May 3, 2011
A. Poblaguev
Spin Meeting
Polarizaion profiles in Run-2011
May 3, 2011
A. Poblaguev
Spin Meeting
Polarization decay during the store.
Yellow ring, Vert.target, 0.72+/-0.18%/hr
Blue-1, 250 GeV, Run-2011
Blue-2,Vertical target, 250 GeV
Yellow-2, 250 GeV, Run-2011
P-Carbon /H-jet for different targets.
Ribbon target orientation.
Target strip orientation
Yellow, Vertical-15pi, Horiz-13 pi
Summary of RHIC polarimetry
Source, Linac, AGS-injector polarimetrs.
Absolute H-jet polarimeter:
Absolute polarization measurements
Absolute normalization for other RHIC Polarimeters
Proton-Carbon polarimeters:
Separate for blue and yellow beams
Normalization from H-Jet
Polarization vs. time in a fill
Polarization profiles
Fill-by-fill polarizations for experiments
PHENIX and STAR Local Polarimeters:
Monitor spin direction (through transverse spin
component) at collision
Polarization vs time in a fill (for trans. pol. beams)
Polarization vs bunch (for trans. pol. beams)
Summary
AGS horizontal tune jump system operational: P +5% with
high intensity.
Acceleration near Qv = ⅔ in RHIC: P +25%
Polarization at end of 250 GeV ramp: 53 %
With incremental improvements <P> = 55 - 60% possible
for next run:
Changes in source/LEBT/MEBT: + 6% in <P>
Smaller emittance growth (24 → 18 p mm): + 8% in <P>
Small change in store energy: no P decay during store: +
5% in <P>.
Vertical/horizontal beam motion decoupling.