Upgraded DIRAC spectrometer at CERN PS for the investigation of pi pi and pi K atoms

0466587 - ÚJF 2017 RIV NL eng J - Journal Article
Adeva, B. - Benelli, A. - Čechák, T. - Doškářová, P. - Hons, Zdeněk - Klusoň, J. - Lednický, Richard - Martinčík, J. - Průša, P. - Smolík, J. - Trojek, T. - Urban, T. - Vrba, T. … Total 70 authors
Upgraded DIRAC spectrometer at CERN PS for the investigation of pi pi and pi K atoms.
Nuclear Instruments & Methods in Physics Research Section A. Roč. 839, DEC (2016), s. 52-85. ISSN 0168-9002. E-ISSN 1872-9576
R&D Projects: GA MŠMT(CZ) LG13031
Institutional support: RVO:61389005 ; RVO:68378271
Keywords : upgraded DIRAC spectrometer * CERN PS * pi pi and pi K atoms * Life-time measurement * long-lived excited states of pi pi atoms
Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders; BF - Elementary Particles and High Energy Physics (FZU-D)
Impact factor: 1.362, year: 2016

The DIRAC spectrometer installed at CERN PS was upgraded in order to study simultaneously A(2 pi) and A(pi K) atoms, namely the bound states of two pi mesons, and of pi and K mesons, respectively. The detector system can now accept a high intensity beam of 2-6 x 10(11) primary protons per second. The electronics and the data-acquisition system can handle a very large amount of data to identify pi, K, p, e and mu, allowing the selection of pi pi and pi K pairs in the offline analysis. The resolution of the longitudinal and transverse components of the relative momentum Q of each meson pair in their center-of-mass system with respect to the direction of the pair was substantially improved. The analysis of their distributions allowed an reliable separation between the meson pairs originating from hadronic atoms and the backgrounds permitting the measurement of the lifetimes of hadronic atoms in the ground state and pi-pi, pi-K s-wave scattering lengths. The upgraded setup also allowed the study of the long-lived excited states of pi pi atoms.
Permanent Link: http://hdl.handle.net/11104/0264853