First Measurement of a Long-Lived pi(+) pi(-) Atom Lifetime

0503671 - ÚJF 2020 RIV US eng J - Článek v odborném periodiku
Adeva, B. - Afanasyev, L. - Anania, A. - Aogaki, S. - Benelli, A. - Čechák, T. - Doškářová, P. - Hons, Zdeněk - Klusoň, J. - Lednický, Richard - Martinčík, J. - Průša, P. - Smolík, J. - Trojek, T. - Urban, T. - Vrba, T. … celkem 60 autorů
First Measurement of a Long-Lived pi(+) pi(-) Atom Lifetime.
Physical Review Letters. Roč. 122, č. 8 (2019), č. článku 082003. ISSN 0031-9007. E-ISSN 1079-7114
Grant CEP: GA MŠMT(CZ) LG13031
Institucionální podpora: RVO:68378271 ; RVO:61389005
Klíčová slova: CERN * DIRAC experiment * scattering
Obor OECD: Nuclear physics; Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) (FZU-D)
Impakt faktor: 8.385, rok: 2019
Způsob publikování: Open access
https://doi.org/10.1103/PhysRevLett.122.082003

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogenlike pi(+)pi(-) atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96 mm between the target and a 2.1 pm thick platinum foil, in which most of them dissociated. Analyzing the observed number of atomic pairs, n(A)(L) = 436(-61)(+157)vertical bar(tot) the lifetime of the 2p state is found to be QED tau(2p) = (0.45(-0.30)(+1.08) vertical bar(tot)) x 10(-11) s, not contradicting the corresponding QED 2p state lifetime r., -P 1.17 x 10(-11) s. This lifetime value is three orders of magnitude larger than our previously measured value of the pi(+) pi(-) atom ground state lifetime r = (3.15(-0.26)(+0.28)vertical bar(tot)) x 10(-15) s. Further studies of long-lived n-+ atoms will allow us to measure energy differences between p and s atomic states and so to discriminate between the isoscalar and isotensor Kin scattering lengths with the aim to check QCD predictions.
Trvalý link: http://hdl.handle.net/11104/0295479