Population of the 2(ms)(+) mixed-symmetry state of Ba-140 with the alpha-transfer reaction
2015 (English)In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 92, no 4, 044324Article in journal (Refereed) Published
Background: Identification of proton-neutron mixed-symmetric one-quadrupole phonon excitations (the 2(ms)(+) states) of atomic nuclei provides information on the isovector part of the residual nucleon-nucleon interaction. It was predicted that the 2(ms)(+) state of particular nuclei close to the U(5) limit of the interacting boson model, in particular Ba-140, should be considerably populated by alpha-transfer reactions [C. E. Alonso et al., Phys. Rev. C 78, 017301 (2008)]. Purpose: We aim at the identification of the 2(ms)(+) mixed-symmetry state (MSS) of radioactive Ba-140 and investigate its population by the alpha-transfer reaction as a suitable tool to selectively populate MSSs and as a potential new signature for its mixed-symmetric character. Method: A gamma-ray spectroscopy experiment was performed in inverse kinematics in order to populate the 2(ms)(+) state of Ba-140 by alpha-transfer from a C-nat target on Xe-136 beam ions. The population of the candidate for the 2(ms)(+) state of Ba-140 was measured relative to the population of the 2(1)(+) state. Results: The candidate for the 2(ms)(+) state of Ba-140 was populated by a transfer three times weaker than predicted. Another 2(+) state that can be ruled out as the MSS was in turn as strongly populated by the a transfer as predicted for the MSS. Conclusions: The relative population of 2(+) states by alpha-transfer cannot serve as a new signature for MSSs, since other 2(+) states are also strongly populated. Nevertheless, the substantial population of the MSS candidate of Ba-140 by alpha transfer qualifies this type of reaction as suitable tool to excite MSSs and study their electromagnetic decay properties.
Place, publisher, year, edition, pages
2015. Vol. 92, no 4, 044324
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:uu:diva-267196DOI: 10.1103/PhysRevC.92.044324ISI: 000363524900001OAI: oai:DiVA.org:uu-267196DiVA: diva2:872545
FunderEU, European Research Council