414 research outputs found
Search for the eta-mesic nuclei by means of COSY-11, WASA-at-COSY and COSY-TOF detector systems
We review status and perspectives of the search for the light eta-mesic
nuclei using COSY-11, WASA-at-COSY and COSY-TOF detector systems.Comment: Invited talk at the International Symposium on Mesic Nuclei, Krakow,
16 June 201
Search for eta-mesic helium using the WASA-AT-COSY detector
We conduct a search for the 4He-eta bound state with the WASA-at-COSY
facility via the measurement of the excitation function for the reaction
dd->3Heppi-. In first experiment performed in June 2008, we used COSY deuteron
beam with a slowly ramped beam momentum corresponding to a variation of the
excess energy for the 4He-eta system from -51.4 MeV to 22 MeV. Here we report
on the status of the measurement and the data evaluation.Comment: Presented at Symposium on Meson Physics: extended COSY-11
collaboration meeting, Cracow, Poland, 1-4 Oct 2008, 8 pages, 5 figures
Study of the Low Energy Dynamics in the ppK+K- System with the Cosy-11 Magnetic Spectrometer
The near threshold production of K+K- pairs in proton-proton collisions has
been investigated at the cooler synchrotron COSY below and above the threshold
for the \phi meson production. The experimental excitation function determined
for the pp-->ppK+K- reaction differs from theoretical expectations including
proton-proton final state interaction. The discrepancy may be assigned to the
influence of K+K- or pK interaction. In this article we present distributions
of the cross section for the pp-->ppK+K- reaction as a function of the
invariant masses of two and three particle subsystems at excess energies of
Q=10 MeV and 28 MeV.Comment: Presented at the Symposium on Meson Physics, Cracow, 01-04 October
200
Search for eta-mesic Helium with the WASA-at-COSY detector
A search for the 4He-eta bound state via exclusive measurement of the
excitation function for the dd->3Heppi- reaction, was performed at the Cooler
Synchrotron COSY-Juelich with the WASA-at-COSY detection system. The data were
taken during a slow acceleration of the beam from 2.185 GeV/c to 2.400 GeV/c
crossing the kinematic threshold for the eta production in the dd -> 4He-eta
reaction at 2.336 GeV/c. The corresponding excess energy in the 4He-eta system
varied from -51.4 MeV to 22 MeV. The shape of the excitation function for the
dd -> 3Heppi- was examined. No signal of the 4He-eta bound state was observed
in the excitation function.Comment: 4 pages, 5 figures, to appear in proceedings of MESON201
Near threshold eta meson production in dp collisions
Preliminary results of recent measurements of the near threshold eta meson
production in the dp-->dp eta reaction are presented. The experiment was
performed at the COSY-Juelich accelerator with the use of the COSY-11 detection
system. Data were taken for three values of deuteron beam momenta corresponding
to excess energies of 3.2, 6.1 and 9.2 MeV. The energy dependence of the total
cross section confirms a strong effect of the final state interaction.Comment: Talk given at 9th International Workshop on Meson Production,
Properties and Interaction, Cracow, Poland, 9-13 June 2006. 5 pages, 3
figure
Determination of the eta'-proton scattering length in free space
Taking advantage of both the high mass resolution of the COSY-11 detector and
the high energy resolution of the low-emittance proton-beam of the Cooler
Synchrotron COSY we determine the excitation function for the pp --> pp eta'
reaction close-to-threshold. Combining these data with previous results we
extract the scattering length for the eta'-proton potential in free space to be
Re(a_{p eta'}) = 0+-0.43 fm and Im(a_{p eta'}) = 0.37(+0.40)(-0.16) fm.Comment: 5 pages, 3 figures, accepted for publication in Phys. Rev. Let
Monitoring of the accelerator beam distributions for internal target facilities
We describe a direct method for monitoring the geometrical dimensions of a
synchrotron beam at the target position for internal target installations. The
method allows for the observation of the proton beam size as well as the
position of the beam relative to the target. As a first demonstration of the
technique, we present results obtained by means of the COSY-11 detection system
installed at the cooler synchrotron COSY. The influence of the stochastic
cooling on the COSY proton beam dimensions is also investigated.Comment: 7 pages, 8 figures, Submitted to Nucl. Inst. & Meth.
Search for Low Mass Exotic mesonic structures. Part I: experimental results
Recently, several papers discussed on the existence of a low mass new
structure at a mass close to M=214.3 MeV. It was suggested that the
disintegration: pP, P
proceeds through an intermediate particle P having such mass. The present
work intends to look at other new or available data, in order to observe the
eventual existence of small narrow peaks or shoulders in very low mesonic
masses. Indeed narrow structures were already extracted from various data in
dibaryons, baryons and mesons (at larger masses that those studied here).Comment: 7 pages 11 figure
An analysis of the reaction pp --> pp\eta near threshold
It is shown that most of the available data on the reaction,
including the invariant mass distributions in the reaction
recently measured at COSY, can be understood in terms of the partial-wave
amplitudes involving final and states and the meson s-wave.
This finding, together with the fact that results within a meson--exchange
model are especially sensitive to the details of the excitation mechanism of
the resonance, demonstrates the possibility of investigating the
properties of this resonance in collisions. The spin correlation function
is shown to disentangle the - and -wave contributions. It is
also argued that spin correlations may be used to help constrain the
contributions of the amplitudes corresponding to the final Comment: 10 pages, 7 figures, minor revision with one additional figur
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