np Scattering Experiments at ANKE-COSY

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np Scattering Experiments at ANKE-COSY

• Forschungszentrum Jülich

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Outline
COSY (Cooler Synchrotron) at Jülich (Germany)

• Introduction
• Experimental Program
• NN-Scattering Experiments
• ChargeExchange Reaction
• Experimental Facility
• Selected Results
• Outlook
• Summary

• Hadronic probes protons, deuterons
• Polarization beams targets

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ANKE-COSY Program An Overview
Goal
Study of 3-body final states aiming
to extract basic spin-dependent
two-body scattering information
Tools

• Hadronic probes (p,d)
• Double polarization (beam/target)

Topics
NN scattering ? np amplitudes,
nuclear forces Meson production ? NN?
amplitudes (ChPT), FSI Strangeness
production ? YN interaction, OZI rule
Status
?
?
Towards the double polarization measurements (
dp - Nov2009)
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(1) NN Interaction
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NN-Interaction (I) General remarks
pp elastic database

• All labs with appropriate facilities have a duty
  to help to extend the NN database
• Needed to understand the NN forces and to
  interpret the coupling to inelastic channels
• Characterization requires precise data for Phase
  Shift Analyses
• Thanks in large part to EDDA, there is a wealth
  of data for pp system

d?/d?
EDDA
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NN-Interaction (II) The EDDA Legacy

• Ramping mode (Ep lt 2.5 GeV)
• Wide energy angular range
• High precision, consistency
• for pp (I1)-system
• ds/dW PRL 78 (1997) EPJ A 22 (2004)
• AN PRL 85 (2000) EPJ A 23 (2005)
• A PRL 90 (2003) PR C 71 (2005)
• Full characterization of
• elastic pp scattering (PWA)
• ? No dibaryon signal

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NN-Interaction (III) np database

• Current experimental status
• R. Arndt
• Gross misconception within the community that np
  amplitudes are known to a couple of GeV
• np data above 800 MeV is a DESERT for
  experimentalists
• np system poorly known ?ANKE is providing
  high-quality data in forward/backward region

np charge exchange
d?/d?
np forward
np charge-exchange
Ayy
np forward
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NN-Scattering (I) np elastic (small angle)
p
?
d beam
?
?
?
d target
d
? n
p
D
? p
d beam up to 1.1 GeV np d target up to 2.8
GeV pn
? psp
n
dp observables d?/d?, T20, T22, Ay,y, ...
quasi-free
np observables Ay, Ayy
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NN-Scattering (II) np elastic (large angle)
n
?
d beam
?
dp?(pp)1S0n
?
d target
?
?
pd?(pp)1S0n
?
d
? n
p
D
? p
d beam up to 1.1 GeV np d target up to 2.8
GeV pn
? psp
? p
dp observables d?/d?, T20, T22, Ay,y, ...
quasi-free
np observables Ay, Ayy
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np-Scattering (I) Deuteron Charge-Exchange
p
p
In impulse approximation, the pd ? n
pp amplitude corresponding to the figure ?
M ltk,m1,m2,m3f13eiq.r/2d,m,m3gt k pp
relative momentum in final state. q momentum
transfer from p to n. Epp excitation energy in
final pp state.
np charge-exchange amplitudes in cm
with basis vectors in terms of initial and final
cm momenta p and p'
D.V.Bugg C.W., Nucl.Phys.A467 (1987) 575
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np-Scattering (II) Deuteron Charge-Exchange
?
?
dp?(pp)1S0 n
2
over a range in t
In collinear kinematics
Þ
(
)
(
)
(
)
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Characteristics
COSY Facility

• Energy range
• 0.045 2.8 GeV (p)
• 0.023 2.3 GeV (d)
• Max. momentum 3.7 GeV/c
• Energy variation (ramping mode)
• Electron and Stochastic cooling
• Internal and external beams
• High polarization (p,d)
• Spin manipulation

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Exp. Facility (I) ANKE detection system
Spectator detection
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Exp. Facility (II) Polarized Internal Gas
Target

• Main components of PIT
• Atomic Beam Source (ABS)
• H or D
• H beam intensity (2 HFS)
• 8 1016 atoms/s
• Beam size at the IP
• s 2.85 0.42 mm
• Polarization for Hydrogen
• PZ 0.89 0.01
• PZ -0.96 0.01
• Lamb-Shift Polarimeter (LSP)
• Storage Cell (SC) in target chamber

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Selected Results from ANKE-COSY
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np-Scattering (II) Measurements at ANKE

• np system different isospin channel
• via Charge-Exchange deuteron breakup

Measurements

• at Tn up to 1.15 GeV for np
• (Td1.6, 1,8, 2.3 GeV)

Epp lt 3 MeV
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Selected Results (I) Polarimetry reactions
Td 1.2 GeV (Tn585 MeV)
?

• dp ? dp ? Pz, Pzz
• np ? dp0 ? Pz
• dp ? 3Hep0 ? Pzz

?
?
Pz75 Pzz 60 with EDDA and LEP
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Selected Results (II) Beam polarization
dp ? dp
ANKE
ANKE
dp ? 3Hep0
np ? dp0
dp ? (pp)n
SAID
(Tn 585 MeV)
ANKE
ANKE
Depolarization less then 4
D. Chiladze et al. Phys. Rev. STAB , 9 (2006)
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Selected Results (III) Polarization export

• Experiments at higher energies uses polarization
  export technique
• Data has been taken at Td 1.6, 1.8, and 2.23 GeV

Result
by I -0.213 0.005
by III -0.216 0.006
byy I 0.057 0.003
byy III 0.059 0.003
Time
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Selected Results (IV) Analysing powers, Cross
sec.
?
D.Chiladze et al. PLB 637, 170 (2006)
dp?pp1S0 n
Axx (T22)

• Transition from deuteron to pp1S0 pn ? np
  spin flip
• np spin-dependent amplitudes
• Results
• Method works at Tn 585 MeV
• Application to higher energies
• Td1.6, 1.8, 2.23 GeV (in progress)

Td 1170 MeV
Ayy (T20)
D.Chiladze et al. EPJA,40, 23 (2009)
New !
Tn 585 MeV ? SAID np amplitudes
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Selected Results (V) Spin amplitudes
?
dp?pp1S0 n
Epp lt1 Mev

• Transition from deuteron to pp1S0 pn ? np
  spin flip
• np spin-dependent amplitudes
• Results at q0

t20 (q0) 0.37 0.02

SAID prediction 0.58
D.Chiladze et al. EPJA,40, 23 (2009)
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Selected Results (VI) Spin correlations
?
D.Chiladze et al. PLB 637, 170 (2006)
dp?pp1S0 n
Axx (T22)

• Transition from deuteron to pp1S0 pn ? np
  spin flip
• np spin-dependent amplitudes
• Results
• Method works at Tn 585 MeV
• Application to higher energies
• Td1.6, 1.8, 2.23 GeV (in prog.)
• Next step
• Double polarized ? Cy,y, Cx,xgt relative phases

Td 1170 MeV
Ayy (T20)
Cy,y
Cx,x
Production run for double polarization
measurements Nov.2009
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Outlook Double polarization

• High target polarization Qy 80
• by nuclear reaction np ? dp0
• Online monitoring of ABS polarization
• by Lamb-shift polarimeter
• Silicon Tracking Telescope as a tool
• for Polarimetry operating with storage cell

?
?
dp test experiment at ANKE
L 2 x 1029 s-1cm-2 achieved at COSY
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Summary

• COSY - unique opportunities for hadron physics
  with polarized hadronic probes (beam target)
• Deuteron breakup reaction successfully used as a
  method to study np charge-exchange amplitudes -
  proof of principal is achieved !
• The method suggests that measurements at higher
  energies will provide useful information in
  regions where the existing np database is far
  less reliable
• ANKE equipment has been commissioned and it ready
  for extraction of spin correlation parameters
• Use of inverse kinematics with a polarized proton
  incident on a polarized deuteron will extend
  study up to max. COSY energy 2.9 GeV

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The END

• Thank you very much for your attention
• Many thanks to the
• organizers !

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np-Scattering Deuteron Charge-Exchange
Unpolarized np ? pn differential cross section
As first approximation, consider data with Epp lt
3 MeV 1S0 dominance. There are two form factors
from the integral over the Fermi momenta
S and S- are longitudinal (?0) and transverse
(? ?1) form factors. In terms of the wave
functions of the deuteron S- and D-states, u and
w, and the 1S0 pp wave function ?k,
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np-Scattering Deuteron Charge-Exchange
Define a ratio of form factors by unpolarized
intensity depends only upon spin-flip amplitudes
Terms can be separated by measuring with
polarised beams/targets
unpolarized cross section ?
d,p vector analysing powers ?
d tensor analysing powers ?
d-p vector spin correlations ?
d-p tensor spin correlation ?
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Bugg, Wilkin, NP A467(1987) 575
(
)
b
0


15
.
0
86
.
1
(ANKE)
(
)
e
0
(
)
b
0


79
.
1
(SAID)
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.
0
(
)
e
0
Value from SAID WI00 Error from R. Arndt
SE-Solution
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COSY-Hardware (III) Silicon Tracking Telescope

• Features
• Three layers (double sided)
• 1st 60 ?m
• 2nd 300 ?m
• 3rd 5 mm
• Ekin2 MeV (60 MeV/c)
• 800 Channels
• Self-triggering
• On-board electronics
• UHV compatible
• Large Acceptance
• 10 per telescope
• 30 mm from the beam

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Future plans Experiments with polarized
probes
2005-2009
2010-2014
COSY proposal 152 ArXivnucl-ex/0511028