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

Underwater detection of dangerous substances: status the SABAT project

The Neutron Activation Analysis (NAA) plays an exceptional role in the modern nuclear engineering, especially in detection of hazardous substances. However, in the aquatic environment, there are still many problems to be solved for effective usage of this technique. We present status of SABAT (Stoichiometry Analysis By Activation Techniques), one of the projects aiming at construction of an underwater device for non-invasive threat detection based on the NAA

Measurement of the invariant mass distributions for the pp -> ppeta' reaction at excess energy of Q = 16.4 MeV

The proton-proton and proton-eta' invariant mass distributions have been determined for the pp -> ppeta' reaction at an excess energy of Q = 16.4 MeV. The measurement was carried out using the COSY-11 detector setup and the proton beam of the cooler synchrotron COSY. The shapes of the determined invariant mass distributions are similar to those of the pp -> ppeta reaction and reveal an enhancement for large relative proton-proton momenta. This result, together with the fact that the proton-eta interaction is much stronger that the proton-eta' interaction, excludes the hypothesis that the observed enhancement is caused by the interaction between the proton and the meson

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

Kaon pair production close to threshold

The total cross section of the reaction pp->ppK+K- has been measured at excess energies Q=10 MeV and 28 MeV with the magnetic spectrometer COSY-11. The new data show a significant enhancement of the total cross section compared to pure phase space expectations or calculations within a one boson exchange model. In addition, we present invariant mass spectra of two particle subsystems. While the K+K- system is rather constant for different invariant masses, there is an enhancement in the pK- system towards lower masses which could at least be partially connected to the influence of the Lambda(1405) resonance.Comment: accepted for publication in Phys. Lett.

A method to disentangle single- and multi-meson production in missing mass spectra from quasi-free pn --> pn X reactions

The separation of contributions from multi- and single-meson production in the missing mass spectrum of the quasi-free pn --> pnX reaction constitutes a~challenging task when the reaction is studied close to threshold. This is especially true if the resolution of the mass determination is comparable with the excess energy and if the investigated signal appears close to the kinematical limit. In this article we outline a method which permits the extraction of the signal originating from the creation of a single meson without the necessity of conducting model-dependent simulations. For the pd --> pnXp(spectator) reactions, the method allows one to combine events corresponding to multi-meson production at various excess energies with respect to the pn --> pn meson process, and hence leads to an increase of the statistics needed for the determination of the shape of the multi-meson background. As an example of the application of the method, we demonstrate that the evaluation of the data from the pd --> pnXp(sp) process according to the described technique enables one to extract a signal of the pn --> pn eta reaction whose shape is consistent with expectations, supporting the correctness and usefulness of the method introduced.Comment: 14 pages, 10 figure

Drift chamber with a c-shaped frame

We present the construction of a planar drift chamber with wires stretched between two arms of a c-shaped aluminium frame. The special shape of the frame allows to extendthe momentum acceptance of the COSY-11 detection system towards lower momenta without suppressing the high momentum particles. The proposed design allows for construction of tracking detectors covering small angles with respect to the beam, which can be installed and removed without dismounting the beam-pipe. For a three-dimensional track reconstruction a computer code was developed using a simple algorithm of hit preselection.Comment: submitted to Nucl. Instr. & Meth