Ferrara 8 june 2004M.Savrié1 Production Readiness Review Ferrara MWPC Production Site.
The PAX experiment P.F.Dalpiaz Ferrara
description
Transcript of The PAX experiment P.F.Dalpiaz Ferrara
P.F.Dalpiaz 16 june 2006 1
PolarizedPolarized Antiproton Antiproton at at FAIRFAIR
The PAXThe PAX experimentexperiment
P.F.DalpiazP.F.Dalpiaz
FerraraFerrara
2 workshop on the QCD 2 workshop on the QCD structure of the nucleonstructure of the nucleon
12-16 june 200612-16 june 2006
Monte Porzio CatoneMonte Porzio Catone
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TransversityTransversity
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The most direct probe elXllpp , ,
Drell-Yan
q
1xq
2xq
Why it works
Elementary LO interaction
J. Ralston and D.Soper, 1979 J. Cortes, B. Pire, J. Ralston, 1992
Direct mesurament
* eeqq
LO interaction has no initial gluons
valence quarksvalence quarks
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The measurament
At GSI-FAIR very large asymmetry expected
in polarized proton-antiproton scattering
TTA
TTA
Xeepp
valence valence quarksquarks
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Polarized Antiprotons
Intense beam of never producedp
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How polarize antiproton?
Polarized pbar from antilambda decay (1987-90) Pbar scattering off liquid H2 target (1995)
(Niinikoscki and Rossmanith 1985) Stern-Gerlach separation of a stored beam Very recently :(Th. Walcher et al) polarized electron beam
350 ;1051 15 . P s. I -
20 ;102 13 . P s I -
2006
Theorethical, never tested
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How polarize antiproton?
The Spin Filter MethodThe Spin Filter Method
Experimentally tested in 1992
2006
P.L.Csonka,1968, NIM 63 (1968) 247
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Multiple passage of a stored beam in a Polarized Internal
Target (PIT)
Principle of spin filter Principle of spin filter methodmethod
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“parallel spin” scatter more often then ” antiparallel spin,” resulting in a polarized (less intense )beam,after passages in a polarized target kQkPQPtot
210
Total cross section targetbeam pp
Low energy scattering tottot
Qtot 10 Qtot 210
An unpolarized beam has an equal population of spin
longitudinal case
transverse case
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Principle of spin filter Principle of spin filter methodmethod
Unpolarized anti-p beam
Polarized H target
Polarized anti-p beam
Polarization Staging Signals Timeline
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The filter
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gas polarized hydrogen target
a short review
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Atomic Beam Source ABS
2H
ep
ep
H ep
mmjj = = ++1/21/2
mmjj = = --1/21/2
mmii=-1/2=-1/2
mmii=-1/2=-1/2
mmii=+1/=+1/22
mmii=+1/=+1/22
1|1>|2>
|3>|4>
ep
ee-
pp|1>
Pz+ = |1> + |4>
Pz- = |2> + |3>Pe+ = |1> + |2>
Pe- = |3> + |4>
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Hydrogen gas targets: densities
1970
1985, Novosibirsk,Zurig
1998,HERMES
2004,RHIC
1965 -
1984,W.Haeberli
210 /10 cmatomsI
211 /102 cmatomsI 211 /104 cmatomsI
211 /108.7 cmatomsI
accumulation cellaccumulation cell
214 /10 cmatomsI
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The storage cellThe storage cell
•Material:75 m Al with Drifilm coating•Size: length: 400mm, elliptical cross section (21 mm x 8.9 mm)•Working temperature: 100 K ( variable 35 K – 300 K)
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Performance of Polarized Internal Performance of Polarized Internal TargetsTargets
PT = 0.795 0.033
HERMES
HTransverse Field (B=297 mT)
HERMES
Dz
Dzz
PT = 0.845 ± 0.028
Longitudinal Field (B=335 mT)
HERMES: Stored Positrons PINTEX: Stored Protons
H
Fast reorientation in a weak field (x,y,z)
Targets work very reliably (months of stable operation)
Polarization Staging Signals TimelinePolarization Staging Signals Timeline
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Test experiment on the Test experiment on the filter methodfilter method
The TSR experiment with protons The TSR experiment with protons 19921992
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Experimental Setup at TSR (1992)Experimental Setup at TSR (1992)
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mmjj = = ++1/21/2
mmjj = = --1/21/2
mmii=-1/2=-1/2
mmii=-1/2=-1/2
mmii=+1/=+1/22
mmii=+1/=+1/22
1|1>|2>
|3>|4>
ee-
pp|1>The FILTEX
experiment has runned with state 1
hydrogen
~80% of electronic
polarization
~80% of nuclear
polarization
Transverse target Transverse target polarizationpolarization
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Experimental SetupExperimental Setup ResultsResults
F. Rathmann. et al., PRL 71, 1379 (1993)
1992 Filter Test at TSR 1992 Filter Test at TSR with protons, with protons, T=23 MeV
213 /106 cmatomsI
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SPIN filtering works! but how?
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121006.024.1 hdt
dP
fQd
ttP
t1
1
1
1 ;tanh
mb8.55.721
ObservedObserved polarization build-up:polarization build-up:
beampp 1ObservedObserved cross-sectioncross-section beampp 1
PIT areal thickness
PIT polarization
Revolution frequency
FILTEX RESULTSFILTEX RESULTS
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Two interpretations of FILTEX Two interpretations of FILTEX resultresult
1994. Meyer and Horowitz: three distinct effects1. Selective removal through scattering beyond θacc=4.4 mrad (σR=83 mb)
2. Small angle scattering of target prot. into ring acceptance (σS=52 mb)
3. Spin-transfer from pol. el. of target atoms to stored prot. (σE=-70 mb)
σ1= σR+ σS + σE = 65 mb
2005. Milstein & Strakhovenko + Nikolaev & Pavlov: only one effect
1. Selective removal through scattering beyond θacc=4.4 mrad (σR=85.6 mb)
No contribution from other two effects
(cancellation between scattering and transmission)
σ1 = 85.6 mb
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Spin-filtering: Present Spin-filtering: Present situationsituation
Spin filtering works, but:
• controversial interpretations of TSR result
• no experimental basis for antiprotons
Experimental tests:- Protons (40-800 MeV) (COSY)- Antiprotons (5MeV-3GeV)(AD)
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How to disentangleHow to disentangle
hadronic and hadronic and electromagnetic electromagnetic contributions?contributions?
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… only had
- elm. + had.
TSR
A measurement of with 10 % precision is needed.
Polarization measurement with P/P = 10% requested.
Polarizing cross-section for the two Polarizing cross-section for the two modelsmodels
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How to disentangle had. and elm How to disentangle had. and elm contributions?contributions?1: Injection of different combination of hyperfine
states
Inj. states Pe Pz Interaction Holding field
|1> +1 +1 Elm. + had. Transv. + Long.
Weak (20 G)
|1>+|4> 0 +1 Only had. Long. Strong. (3kG)
|1>+|2> +1 0 Only elm
Experiment at AD will require both transverse and longitudinal (weak)field.
Different combinations of elm. and hadronic contributions:
Strong field can be applied only longitudinally (minimal beam interference)
Target polarimetry difficult for pure electron polarization.
Null experiment (elm. component = 0) possible in strong holding field
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Spin-transfer
1 10 100 1 103
1 104
1 105
0.01
0.1
1
10
100
1 103
181.621
0.022
etr T
1.5 1045 T
10 100 1000 T (MeV)
elm
(mba
rn)100
10
1
Hadronic
2: Use of different energy dependence of the processesMeasurement at different energies
How to disentangle had. and elm How to disentangle had. and elm contributions?contributions?
(Transverse case)
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Spin-filtering studies at COSY Spin-filtering studies at COSY
Goal: deeper understanding spin-filtering mechanismDisentangle between two interpretations of TSR result.
•Electromagnetic + hadronic contributions
(20-120MeV 175-2880 MeV)(20-120MeV 175-2880 MeV)
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Experimental setupExperimental setup
• Low-beta section • Polarized target (HERMES)• Detector• Snake• Commissioning of AD setu-up
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• x,ynew=0.3 -> increase a factor 30 in density respect ANKE
•Lower buildup time, higher rates•Higher polarization buildup-rate due to higher acceptance
•Use of HERMES target (in Jülich since March 2006)
Low beta sectionLow beta section
S.C. quadrupole development applicable to AD experiment
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Detector conceptDetector concept•Reaction:
•p-p elastic (COSY)•p-pbar elastic (AD)
•Good azimuthal resolution (up/down + left/right asymmetries)•Low energy recoil (<8 MeV)
•Teflon cell requested
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Teflon cell (IUCF – 2002)Teflon cell (IUCF – 2002)
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Detector conceptDetector concept•Reaction:
•p-p elastic (COSY)•p-pbar elastic (AD)
•Good azimuthal resolution (up/down asymmetries)•Low energy recoil (<8 MeV)
•Teflon cell•Silicon tracking telescope
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The ANKE silicon tracking telescope
3 silicon detector layers➔ 69 µm silicon➔ 300/500 µm silicon
128 x 151 segments51 x 66 mm (≈400 µm pitch)
➔ >5 mm Si(Li)96 x 96 strip64 x 64 mm (≈666 µm Pitch)
COSY beam
cluster beam
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Detector conceptDetector concept•Reaction:
•p-p elastic (COSY)•p-pbar elastic (AD)
•Good azimuthal resolution (up/down asymmetries)•Low energy recoil (<8 MeV)
•Teflon cell•Silicon tracking telescope
•Angular resolution on the forward particle for p-pbar•AD experiment will require an opening-cell
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ANKE vs new interaction pointANKE vs new interaction point
Acceptance @ ANKE
Cross sections
Acceptance @ new-IP
… elm + had
- only had.
Lifetimes
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PIT Filter. time Polar. Total rate Meas. Time (P/P=10%)
ANKE 2= 16 h 1.2 % 7.5x102 s-1 44 min
5 = 42 h 3.5 % 5x10 s-1 26 min
New IP 2= 5 h 16 % 2.2x104 s-1 1 s
5= 13 h 42 % 1.5x103 s-1 < 1 s
ANKE vs new interaction pointANKE vs new interaction point
Polarization
T=40 MeV Ninj=1.5x1010
New IP
ANKE
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Antiproton polarization build-up
Test at AD
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ANKE
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Commissioning of ANKE PITCommissioning of ANKE PIT
Goal: installation of a storage cell with a polarized target in COSY
Electron-cooling at injection with storage cellStochastic cooling at 700 MeVCooler stacking to increase particles in the ring
Propedeutical studies to spin-filtering experiments
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Storage Cell Setup (coll. Ferrara – Storage Cell Setup (coll. Ferrara – FZJ)FZJ)
COSYbeam
XY-table Frame with storage cell and aperture
Target chamber
Feeding tube: l = 120 mm, Ø = 10 mmExtraction tube: l = 230 mm, Ø = 10 mmBeam tube : l = 400 mm, 20x20 mm2
400mm
400mm
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Storage cell and stochastically cooled Storage cell and stochastically cooled beambeam
Cooling off
Cooling on
Tp=831 MeV
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Target Thickness (from Target Thickness (from pp→dpp→dππ+)+)
Jet Storage Cell
Method Jet [atoms/cm2] Storage Cell [atoms/cm2]
ABS flux (+ cell geometry) (1.6±0.1)·1011 (1.9±0.1)·1013
Rates (pp→dπ+) (1.5±0.1)·1011 (2.1±0.1)·1013
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Cooler Stacking into the Storage CellCooler Stacking into the Storage Cell
28 stacks followed by • 2s electron cooling • after 58s acceleration toTp=600 MeV
Cooler Stacking allows for higher polarized beam intensities with cell.
2.5·1010 protons have been injected in the ring
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Ferrara is building an ion-deflector
Next step: Installation of the Lamb-shift Next step: Installation of the Lamb-shift polarimeterpolarimeter
October 2006
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Antiproton polarization build-up
AD
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Measurements at AD at CERN (2009-2010)Measurements at AD at CERN (2009-2010)
Target Snake
E-cooler
T:5 MeV÷2.8 GeV
Np = 3·107
study of spin-filtering in pp scattering
Measurement of effective polarization cross-section.Both transverse and longitudinal.Variable ring acceptance.
First measurement at all for spin correlations in pp (not pure text experiment!)
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TimelineFall 2006 Submission of Technical Proposal for COSY
Spring 2007 Submission of Technical Proposal for AD
2006-08 Design and construction phase COSY
2008 Spin-filtering studies at COSY Commissioning of AD experiment
2009 Installation at AD
2009-2010 Spin-filtering studies at AD
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VERY PRELIMINARY
Polarization build-up implemantation at HESR,FAIR
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PAX ACCELERATOR SETUPPAX ACCELERATOR SETUP
EXPERIMENT: Asymmetric collider: s=210GeV2
polarized antiprotons in HESR (p=15 GeV/c) polarized protons in CSR (p=3.5 GeV/c)
Physics: Transversity
preliminary!
Internal polarized target with 22 GeV/c polarized antiproton Internal polarized target with 22 GeV/c polarized antiproton beam. beam. s=30GeV2s=30GeV2
Valence region x>0.5
4<Q2<100GeV2
ATT>0.3
L2x1030 1000 events by day
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http://www.fz-juelich.de/ikp/pax
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THE ENDTHE END
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0.1
0.2
0.3
0.4B
eam
Pola
riza
tion P
(2·τ
beam)
10 T (MeV)100
EM only
5
10
30
20
40
Ψacc=50 mrad
0
1
Filter Test: T = 23 MeV Ψacc= 4.4 mrad
Electron Transfer Electron Transfer PolarizationPolarization
Polarization Staging Signals Timeline
??
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Polarization with hadronic Polarization with hadronic pbar-p interactionpbar-p interaction
Model A: T. Hippchen et al. Phys. Rev. C 44, 1323
(1991)
P
Kinetic energy (MeV)10 100 100
01
0.05
0.10
0.15
0.20
Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360
(1995)
P
Kinetic energy (MeV)
10 100 1000
1
0.05
0.10
0.15
0.20
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pp Elastic Scattering from ZGSpp Elastic Scattering from ZGSSpin-Spin-dependence at dependence at large-Plarge-P (90°90°cmcm):):
Hard Hard scattering scattering takes takes place only place only with spins with spins ..
D.G. Crabb et al., PRL 41, 1257 (1978)
T=10.85 GeV
Similar Similar studies in studies in pbar p pbar p elastic elastic scatteringscattering
dtddtd
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