Shape Coexistence Near Neutron Number N=20: First Identification of the E0 Decay from the Deformed First Excited J(pi)=0(+) State in Mg-30
2009 (English)In: Physical Review Letters, ISSN 0031-9007, Vol. 103, no 1, 012501- p.Article in journal (Refereed) Published
The 1789 keV state in Mg-30 was identified as the first excited 0(+) state via its electric monopole (E0) transition to the ground state. The measured small value of rho(2)(E0,0(2)(+)-> 0(1)(+))=(26.2 +/- 7.5)x10(-3) implies within a two-level model a small mixing of competing configurations with largely different intrinsic quadrupole deformation near the neutron shell closure at N=20. Axially symmetric configuration mixing calculations identify the ground state of Mg-30 to be based on neutron configurations below the N=20 shell closure, while the excited 0(+) state mainly consists of two neutrons excited into the nu 1f(7/2) orbital. The experimental result represents the first case where an E0 back decay from a strongly deformed second to the normal deformed first nuclear potential minimum well has been unambiguously identified, thus directly proving shape coexistence at the borderline of the much-debated "island of inversion."
Place, publisher, year, edition, pages
2009. Vol. 103, no 1, 012501- p.
IdentifiersURN: urn:nbn:se:uu:diva-128371DOI: 10.1103/PhysRevLett.103.012501ISI: 000267697900016OAI: oai:DiVA.org:uu-128371DiVA: diva2:331435