Precise scan of the dp 3Hp 3Hep 0 cross section ratio at the h production threshold

1
Precise scan of the dp? 3Hp / 3Hep 0
cross section ratio at the h production
threshold
COSY-11-meeting, Cracow, June 2004

• J. Smyrski
• Jagellonian University

Measurement of ds/dW ( dp? 3H p )
ds/dW ( dp? 3He p0 )
Objective
Determination of sign of Re(a( 3He ? ))
2
Structure at the ? threshold
3
Coupled channel effectsconnected with ?
production
dp ? 3He X
p- p elastic scattering
4
Coupled channel effectsconnected with ?
production
Ay (pd? 3H p )
T20 (dp? 3Hep 0 )
5
Experiment
deuteron beam ramped from 3.099 GeV/c to 3.179
GeV/c
3H and ? measured in coinc.
3He registered with COSY-11 ?0 identified via
miss. mass
Luminosity monitored using p-p quasielastic and
d-p elastic scattering
COSY-11 facility
6
Angular acceptance
dM2/dt (dp ? 3He p0)
3H p
7
Results from dp ? pdh run in January 2003
dp ? 3He X
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dp ? 3He X threshold excitation curve
SATURNE results
Proposed measurement
Spectrometer momentum acceptance
h
N-counts
missing mass
Dm
9
stot(dp ? 3He h)
COSY-11 acceptance
( Sibirtsev, J. Haidenbauer, C. Hanhart and J.
A. Niskanen, nucl-th/0310079 )
Scattering length a4.30.3i(0.50.5) fm
For bound state Re(a)gtIm(a)gt0
10
Beam time request
Beam momentum range from 3.099 to 3.179 GeV/c
(divided into 20 bins 4 MeV/c wide)
Luminosity 4x1030cm-2 s-1 (number of stored
deuterons 5x1010, target density 5x1013cm-2 )
Expected cusp 10, Statistical accuracy of 3
per bin in 3 weeks
aR iaI (3.8i1.6)fm
Requested 3 weeks