First experimental results of the COSY-11 collaboration concerning
total cross sections for pp-induced strangeness production
will be presented.
The COSY-11 installation (see Ref.1) is an internal target experiment
at the cooler synchroton COSY, designed for meson production studies
close to threshold.
A COSY machine dipole is used here as a magnetic separator.
In front of the COSY dipole a hydrogen cluster target is installed
pro ducing densities of about
1014 atoms/cm2 (Ref.2).
The reaction products are separated from the proton beam by the
magnetic field.
Positively charged particles are detected using a system of drift
chambers and scintillators and for negatively charged particles a
Si-pad detector is installed in the dipole gap.
Although the gap height limits the acceptance in the laboratory
system the full acceptance is achieved in the CM system close to
threshold.
At COSY-11 threshold measurements for the channels
ppK+K- and
pp->pK+Lambda has been done.
For the reaction channel
pp->ppK+K- the momentum components
of the two protons and the K+ are reconstructed
by tracking back to the target with the measured
directions.
The particle identification results from an additionally time of
flight measurement.
For the channel
pp->pK+Lambda the analysis is similar.
The momenta of the charged ejectiles p and
K+ are reconstructed from which the 4-momentum
components of the unobserved Lambda particle result.
The resolution of the detection system is sufficient for a clear
separation of pions, kaons and protons in the particle
identification.
In the K+K- channnel as well as in
the pK+Lambda channel the background is very low
which allows a clear separation of these events.
1. S.Brauksiepe et al., Nucl.Inst.& Meth. A 376 (1996) 397-410
2. H.Dombrowski et al., Nucl.Inst.& Meth. A 386 (1997) 228-234
Complete
document in Postscript format (4.3MB)
Conference
abstract in Postscript format (35kB)
Publication:
Nucl.Phys. A
631
(1998)
262c-275c