Exclusive measurtement of two-pion production in the dd->4Heππ reaction
2009 (English)In: Nuclear Physics A, ISSN 0375-9474, Vol. 825, no 1-2, 71-90 p.Article in journal (Refereed) Published
The results from the first kinematically complete measurement of the reaction are reported. The aim was to investigate a long standing puzzle regarding the origin of the peculiar ππ-invariant mass distributions appearing in double pion production in light ion collisions, the so-called ABC effect. The measurements were performed at the incident deuteron energies of 712 MeV and 1029 MeV, with the WASA detector assembly at CELSIUS in Uppsala, Sweden. We report the observation of a characteristic enhancement at low ππ-invariant mass at 712 MeV, the lowest energy yet. At the higher energy, in addition to confirming previous experimental observations, our results reveal a strong angular dependence of the pions in the overall centre of mass system. The results are qualitatively reproduced by a theoretical model, according to which the ABC effect is described as resulting from a kinematical enhancement in the production of the pion pairs from two parallel and independent NN→dπ sub-processes.
Place, publisher, year, edition, pages
2009. Vol. 825, no 1-2, 71-90 p.
Nuclear reactions, 2H(d, 2π0), (d, π+π−), E=712, 1029 MeV, measured, σ(θ), invariant mass spectra, energy spectra, other reaction observables, Comparison with simplified ΔΔ model and earlier results
Research subject Nuclear Physics
IdentifiersURN: urn:nbn:se:su:diva-32609DOI: 10.1016/j.nuclphysa.2009.04.008ISI: 000267188500004OAI: oai:DiVA.org:su-32609DiVA: diva2:281091
Totalt 49 författare2009-12-142009-12-142011-09-13Bibliographically approved