The pax experiment p f dalpiaz ferrara
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2 workshop on the QCD structure of the nucleon 12-16 june 2006 Monte Porzio Catone. Polarized Antiproton at FAIR. The PAX experiment P.F.Dalpiaz Ferrara. Transversity. Drell-Yan. Direct mesurament. The most direct probe. valence quarks.

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The PAX experiment P.F.Dalpiaz Ferrara

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The pax experiment p f dalpiaz ferrara

2 workshop on the QCD structure of the nucleon

12-16 june 2006

Monte Porzio Catone

PolarizedAntiproton at FAIR

The PAXexperiment

P.F.Dalpiaz

Ferrara

16 june 2006


The pax experiment p f dalpiaz ferrara

Transversity

16 june 2006


The pax experiment p f dalpiaz ferrara

Drell-Yan

Direct mesurament

The most direct probe

valence quarks

J. Ralston and D.Soper, 1979 J. Cortes, B. Pire, J. Ralston, 1992

Why it works

Elementary LO interaction

LO interaction has no initial gluons

16 june 2006


The pax experiment p f dalpiaz ferrara

The measurament

in polarized proton-antiproton scattering

valence quarks

sea quarks

At GSI-FAIR very large asymmetry expected

16 june 2006


The pax experiment p f dalpiaz ferrara

Intense beam of never produced

Polarized Antiprotons

16 june 2006


How polarize antiproton

Theorethical, never tested

How polarize antiproton?

2006

  • 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

16 june 2006


The pax experiment p f dalpiaz ferrara

How polarize antiproton?

2006

The Spin Filter Method

Experimentally tested in 1992

P.L.Csonka,1968, NIM 63 (1968) 247

16 june 2006


Principle of spin filter method

Principle of spin filter method

Multiple passage of a stored beam in a Polarized Internal Target (PIT)

16 june 2006


The pax experiment p f dalpiaz ferrara

An unpolarized beam has an equal population of spin 

longitudinal case

transverse case

“parallel spin” scatter more often then ” antiparallel spin,” resulting in a polarized (less intense )beam,after passages in a polarized target

Total cross section

Low energy scattering

16 june 2006


The pax experiment p f dalpiaz ferrara

Polarized anti-p beam

Unpolarized anti-p beam

Principle of spin filter method

Polarized H target

16 june 2006

Polarization Staging Signals Timeline


The pax experiment p f dalpiaz ferrara

The filter

16 june 2006


Gas polarized hydrogen target

gas polarized hydrogen target

a short review

16 june 2006


The pax experiment p f dalpiaz ferrara

|1>

e-

p

1

|1>

mj = +1/2

mi=+1/2

|2>

mi=-1/2

mi=-1/2

|3>

mj = -1/2

mi=+1/2

|4>

ABS

Atomic Beam Source

Pz+ = |1> + |4>

Pz- = |2> + |3>

Pe+ = |1> + |2>

Pe- = |3> + |4>

16 june 2006


Hydrogen gas targets densities

Hydrogen gas targets: densities

  • 1970

  • 1985, Novosibirsk,Zurig

  • 1998,HERMES

  • 2004,RHIC

  • 1965 -

  • 1984,W.Haeberli

accumulation cell

16 june 2006


The storage cell

The storage cell

  • Material:75 mm 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)

16 june 2006


The pax experiment p f dalpiaz ferrara

Longitudinal Field (B=335 mT)

Dz

PT = 0.845 ± 0.028

H

Fast reorientation

in a weak field (x,y,z)

Dzz

HERMES

H

PT = 0.795  0.033

HERMES

Performance of Polarized Internal Targets

HERMES: Stored Positrons

PINTEX: Stored Protons

Transverse Field (B=297 mT)

Targets work very reliably (months of stable operation)

16 june 2006

Polarization Staging Signals Timeline

Polarization Staging Signals Timeline


Test experiment on the filter method

Test experiment on the filter method

The TSR experiment with protons 1992

16 june 2006


Experimental setup at tsr 1992

Experimental Setup at TSR (1992)

16 june 2006


The pax experiment p f dalpiaz ferrara

|1>

e-

p

1

|1>

mj = +1/2

mi=+1/2

|2>

mi=-1/2

mi=-1/2

|3>

mj = -1/2

mi=+1/2

|4>

The FILTEX experiment has runned with state 1 hydrogen

~80% of electronic polarization

~80% of nuclear polarization

Transverse target polarization

16 june 2006


The pax experiment p f dalpiaz ferrara

1992 Filter Test at TSR with protons, T=23 MeV

Experimental Setup

Results

F. Rathmann. et al.,

PRL 71, 1379 (1993)

16 june 2006


Spin filtering works but how

SPIN filtering works! but how?

16 june 2006


The pax experiment p f dalpiaz ferrara

FILTEX RESULTS

Revolution frequency

PIT areal thickness

PIT polarization

Observedcross-section

Observedpolarization build-up:

16 june 2006


The pax experiment p f dalpiaz ferrara

Two interpretations of FILTEX result

1994. Meyer and Horowitz: three distinct effects

  • Selective removal through scattering beyond θacc=4.4 mrad (σR=83 mb)

  • Small angle scattering of target prot. into ring acceptance (σS=52 mb)

  • 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

  • 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 = 85.6mb

16 june 2006


The pax experiment p f dalpiaz ferrara

Spin-filtering: Present situation

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)

16 june 2006


The pax experiment p f dalpiaz ferrara

How to disentangle

hadronic and electromagnetic contributions?

16 june 2006


The pax experiment p f dalpiaz ferrara

Polarizing cross-section for the two models

… only had

- elm. + had.

TSR

A measurement of s with 10 % precision is needed.

Polarization measurement with DP/P = 10% requested.

16 june 2006


The pax experiment p f dalpiaz ferrara

Strong field can be applied only longitudinally (minimal beam interference)

Target polarimetry difficult for pure electron polarization.

How to disentangle had. and elm contributions?

1: Injection of different combination of hyperfine states

Different combinations of elm. and hadronic contributions:

Null experiment (elm. component = 0) possible in strong holding field

Experiment at AD will require both transverse and longitudinal (weak)field.

16 june 2006


The pax experiment p f dalpiaz ferrara

How to disentangle had. and elm contributions?

  • 2: Use of different energy dependence of the processes

    • Measurement at different energies

Spin-transfer

Hadronic

100

10

selm (mbarn)

1

10

100

1000

T (MeV)

(Transverse case)

16 june 2006


Spin filtering studies at cosy

Spin-filtering studies at COSY

  • Goal: deeper understanding spin-filtering mechanism

    • Disentangle between two interpretations of TSR result.

      • Electromagnetic + hadronic contributions

(20-120MeV 175-2880 MeV)

16 june 2006


Experimental setup

Experimental setup

  • Low-beta section

  • Polarized target (HERMES)

  • Detector

  • Snake

  • Commissioning of AD setu-up

16 june 2006


The pax experiment p f dalpiaz ferrara

Low beta section

  • bx,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)

S.C. quadrupole development applicable to AD experiment

16 june 2006


The pax experiment p f dalpiaz ferrara

Detector 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

  • 16 june 2006


    The pax experiment p f dalpiaz ferrara

    Teflon cell (IUCF – 2002)

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    Detector 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

  • 16 june 2006


    The anke silicon tracking telescope

    3 silicon detector layers

    • 69 µm silicon

    • 300/500 µm silicon

    128 x 151 segments

    51 x 66 mm (≈400 µm pitch)

    • >5 mmSi(Li)

    96 x 96 strip

    64 x 64 mm (≈666 µm Pitch)

    The ANKE silicon tracking telescope

    cluster beam

    COSY beam

    35

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    Detector 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

  • 16 june 2006


    The pax experiment p f dalpiaz ferrara

    … elm + had

    - only had.

    Acceptance @ ANKE

    Acceptance @ new-IP

    ANKE vs new interaction point

    Cross sections

    Lifetimes

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    New IP

    ANKE

    ANKE vs new interaction point

    Polarization

    T=40 MeV Ninj=1.5x1010

    16 june 2006


    Antiproton polarization build up

    Antiproton polarization build-up

    Test at AD

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    ANKE

    16 june 2006


    Commissioning of anke pit

    Commissioning of ANKE PIT

    Propedeutical studies to spin-filtering experiments

    Goal: installation of a storage cell with a polarized target in COSY

    Electron-cooling at injection with storage cell

    Stochastic cooling at 700 MeV

    Cooler stacking to increase particles in the ring

    16 june 2006


    Storage cell setup coll ferrara fzj

    Storage Cell Setup (coll. Ferrara – FZJ)

    XY-table

    Target chamber

    Frame with storage cell and aperture

    400mm

    COSY

    beam

    Feeding tube: l = 120 mm, Ø = 10 mm

    Extraction tube:l = 230 mm, Ø = 10 mm

    Beam tube : l = 400 mm, 20x20 mm2

    16 june 2006


    Storage cell and stochastically cooled beam

    Storage cell and stochastically cooled beam

    Cooling off

    Tp=831 MeV

    Cooling on

    16 june 2006


    Target thickness from pp d

    Target Thickness (from pp→dπ+)

    Storage Cell

    Jet

    16 june 2006


    Cooler stacking into the storage cell

    Cooler 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

    16 june 2006


    Ferrara is building an ion deflector

    Next step: Installation of the Lamb-shift polarimeter

    Ferrara is building an ion-deflector

    October 2006

    16 june 2006


    Antiproton polarization build up1

    Antiproton polarization build-up

    AD

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    Target

    Snake

    E-cooler

    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!)

    Measurements at AD at CERN (2009-2010)

    study of spin-filtering in pp scattering

    T:5 MeV÷2.8 GeV

    Np = 3·107

    16 june 2006


    Timeline

    Timeline

    Fall 2006 Submission of Technical Proposal for COSY

    Spring 2007 Submission of Technical Proposal for AD

    2006-08Design and construction phase COSY

    2008 Spin-filtering studies at COSY

    Commissioning of AD experiment

    2009Installation at AD

    2009-2010Spin-filtering studies at AD

    16 june 2006


    Very preliminary

    VERY PRELIMINARY

    Polarization build-up implemantation at HESR,FAIR

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    PAX ACCELERATOR SETUP

    preliminary!

    Valence region x>0.5

    4<Q2<100GeV2

    ATT>0.3

    L2x1030 1000 events by day

    Physics: Transversity

    EXPERIMENT:

    Asymmetriccollider: s=210GeV2

    polarized antiprotons in HESR (p=15 GeV/c)

    polarized protons in CSR (p=3.5 GeV/c)

    Internal polarized target with 22 GeV/c polarized antiproton beam.

    s=30GeV2

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    http://www.fz-juelich.de/ikp/pax

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    THE END

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    Ψacc=50 mrad

    EM only

    0.4

    40

    30

    0.3

    20

    Beam Polarization P(2·τbeam)

    10

    0.2

    5

    0.1

    0

    1

    10

    100

    T (MeV)

    Electron Transfer Polarization

    ?

    Filter Test: T = 23 MeV

    Ψacc= 4.4 mrad

    16 june 2006

    Polarization Staging Signals Timeline


    The pax experiment p f dalpiaz ferrara

    Polarization with hadronic pbar-p interaction

    Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995)

    P

    0.20

    0.20

    0.15

    0.15

    0.10

    0.10

    0.05

    0.05

    1

    1

    10

    10

    1000

    1000

    100

    100

    Kinetic energy (MeV)

    Model A: T. Hippchen et al. Phys. Rev. C 44, 1323 (1991)

    P

    Kinetic energy (MeV)

    16 june 2006


    Pp elastic scattering from zgs

    pp Elastic Scattering from ZGS

    Spin-dependence at large-P (90°cm):

    Hard scattering takes place only with spins .

    D.G. Crabb et al.,

    PRL 41, 1257 (1978)

    T=10.85 GeV

    Similar studies in pbar p elastic scattering

    16 june 2006


    The pax experiment p f dalpiaz ferrara

    16 june 2006


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