Feasibility study of {\eta}-mesic nuclei production by means of the WASA-at-COSY and COSY-TOF facilities

Despite the fact that existence of {\eta}-mesic nuclei in which the {\eta} meson might be bound with the light nucleus by means of the strong interaction was postulated already in 1986, it is still not experimentally confirmed. Discovering of this new kind of an exotic nuclear matter is very important as it might allow for better understanding of {\eta} meson structure and its interaction with nucleons. The search of the {\eta}-helium bound states is carried out at the COSY accelerator in the Research Center Juelich in Germany, by means of the WASA detection system. The search are conducted with high statistic and high acceptance for the free production of the 4He-{\eta} bound states. It is also considered to search for {\eta}-tritium in quasi free reaction which might be realised with COSY-TOF facility. In this thesis the results of the Monte Carlo simulations of the {\eta}-helium bound states and {\eta}-tritium bound state are presented and discussed. The acceptances of the WASA-at-COSY and COSY-TOF detectors for the free and quasi-free {\eta}-mesic nuclei production reactions were determined, respectively. Furthermore acceptances were compared for three different models of nucleon momentum distribution inside atomic nuclei and three different values of width of a considered bound states. In case of COSY-TOF detector it was established that the most effcient measurement of quasi-free dd --> p_sp (T-{\eta})_bs --> p_sp dp{\pi}- reaction can be done at beam momentum of p_beam =3.1GeV/c.Comment: Master Thesis prepared in the Instytute of Physics of the Jagiellonian University; 55 page

Search for the manifestation of the mesic-nuclei on the dd-->3HeNpi excitation function measured with WASA-at-COSY

We search for an evidence of eta-mesic 4He with the WASA-at-COSY detector. Two dedicated experiments were performed at the Cooler Synchrotron COSY-Juelich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: dd-->3Heppi- and dd-->3Henpi0, where the outgoing N-pi pairs originate from the conversion of the eta meson on a nucleon inside the He nucleus. In this contribution, the experimental method is shortly described and preliminary excitation functions from the 2010 data are presented.Comment: 8 pages, 12 figures, Presented at International Symposium on Mesic Nuclei, Krakow, Sept. 20, 201

Search for eta-mesic nuclei with WASA-at-COSY

We search for an evidence of eta-mesic He with the WASA detector. Two dedicated experiments were performed at the Cooler Synchrotron COSY-Juelich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: dd->3Heppi- and dd->3Henpi0, where the outgoing N-pi pairs originate from the conversion of the eta meson on a nucleon inside the He nucleus.In this contribution, the experimental method is shortly described and the current status of the analysis is presented.Comment: 5 pages, 2 figure

Status and Perspectives of the Search for Eta-Mesic Nuclei

In this report the search for eta-mesic nuclei is reviewed. The brief description of the experimental studies is presented with a focus on the possible production of the eta-nucleus bound states for light nuclei like 4He and 3He.Comment: Conference Proceedings: The 11th Latin American Symposium on Nuclear Physics and Applications (XI LASNPA), 30.11-04.12.2015, Medellin, Columbi

Luminosity determination for the proton-deuteron reaction using pd -> 3He eta channel with WASA-at-COSY detector

In this report one of the methods used for the luminosity determination for the experiment performed by WASA Collaboration to search for 3He-eta mesic nuclei is presented. The method is based on the analysis of pd -> 3He eta process

Luminosity determination for the proton-deutron reactions using quasi-free reactions with WASA-at-COSY facility

The scientific aim of our research is experimental confirmation of the existence of mesic-nucleus: a new exotic kind of nuclear matter consisting of nucleons and mesons. In this report we present the method of luminosity determination for experiment performed atWASA-at-COSY detector dedicated to search for 3He-η bound state. This method is based on analysis of quasi-free $pd \to ppn_{{\rm{spec}}}$ reaction

Updating spin-dependent Regge intercepts

We use new high statistics data from CLAS and COMPASS on the nucleon's spin structure function at low Bjorken x and low virtuality, Q^2 < 0.5 GeV^2, together with earlier measurements from the SLAC E-143, HERMES and GDH experiments to estimate the effective intercept(s) for spin dependent Regge theory. We find alpha_{a_1} = 0.31 \pm 0.04 for the intercept describing the high-energy behaviour of spin dependent photoabsorption together with a new estimate for the high-energy part of the Gerasimov-Drell-Hearn sum-rule, -15 \pm 2 mu b from photon-proton centre-of-mass energy greater than 2.5 GeV. Our value of alpha_[a_1} suggests QCD physics beyond a simple straight-line a_1 trajectory.Comment: 4 pages, 1 figure, to appear in Physical Review

Perspective of CP violation search by modular J-PET detector in the ortho-positronium decay

The positronium atom, a bound state of electron and positron, is a suitable leptonic test site for Charge-Parity (CP) discrete symmetry research. According to the Standard Model, the photon–photon interaction in the final state due to the vacuum polarization may mimic CP violation of the order of 10$^{-9}$, while weak interaction effects lead to a violation of the order of 10$^{-14}$. So far, the experimental limits on CP symmetry violation in the decay of o-Ps are set at the level of 10$^{-3}$. The J-PET detector can be used to explore discrete symmetries by looking for probable non-zero expectation values of the symmetry-odd operators, constructed from spin of ortho-Positronium (o-Ps) and momentum, and polarization vectors of gamma (γ) quanta resulting from o-Ps annihilation. The upgraded version of the J-PET detector, with an additional fourth layer of detection modules increases signal acceptance, which allows to triple the efficiency of γ quanta detection for CP discrete symmetry studies