In the present paper, results of experimental studies of
near-threshold meson production in the reactions
pp->d pi+,
pp->pp eta',
pp->pK+Lambda, and
pp->ppK+K-
are presented.
The experiments were performed at the new cooler synchrotron
COSY-Jülich.
The first of the above reactions was measured by using the
external magnetic spectrometer
BIG
KARL, and the three remaining reactions were studied at the internal
COSY-11
facility, resulting in the first world data on near-threshold
cross sections in these reactions.
In both experiments, the magnetic field of dipole magnets was
used for separating the ejectiles from the beam and for
reconstructing their momentum vectors at the target
point.
This experimental method allowed measurements with high
detection acceptance very close to threshold, at excess
energies of the order of 1 MeV.
At higher energies, detection efficiency was drastically
limited by the height of the gaps in dipole
magnets.
Particle trajectories were measured with built in Cracow
drift chambers and, in the off line analysis, they were
traced back through the magnetic field to the target which
allowed us to determine the momentum vectors at the target
point.
Particle identification proceeded via the time-of-flight
measurement combined with the information on particle
momenta.
The missing-mass method was applied to identify unobserved
ejectiles.
High missing-mass resolution, achieved thanks to precise
particle momenta reconstruction, allowed us to extract
signals of the measured reaction from the background of
other possible processes, even for reaction cross sections
at the level of 1 nbarn.
Report in PostScript-Format (~7.2MB)