2011/10/05 by P. Papakonstantinou, H. Hergert, V. Yu. Ponomarev +2 · 24 citations
Physics and Astronomy · #Advanced Chemical Physics Studies #Astronomical and nuclear sciences #Atomic physics #Dipole #Isoscalar #Isotope #Isovector #Neutron #Nuclear physics #Nuclear physics research studies #Nucleon #Oscillation (cell signaling) #Physics #Quantum mechanics #Random phase approximation #nucl-ex #nucl-th
paper · pdf · doi:10.1016/j.physletb.2012.02.024
published in Physics Letters B 709(3), 270-275 (Elsevier BV) · 7 pages, incl. 3 figures; PLB submitted
arxiv created 2011/10/05 · openalex publication_date 2012/02/11 · arxiv updated 2012/03/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Recent theoretical work has not led to a consensus regarding the nature of the low-energy E1 strength in the 40,44,48Ca isotopes, for which high-resolution (gamma,gamma') data exist. Here we revisit this problem using the first-order quasi-particle random-phase approximation (QRPA) and different interactions. First we examine all even Ca isotopes with N=14-40. All isotopes are predicted to undergo dipole transitions at low energy, of large and comparable isoscalar strength but of varying E1 strength. Provided a moderate and uniform energetic shift is introduced to the results, QRPA with the Gogny D1S interaction is able to account for the (gamma,gamma') data, because, up to N=28, it yields a rather pure isoscalar oscillation. A neutron-skin oscillation is anticipated for N larger or equal to 30. This contradicts existing predictions that 44,48Ca develop a neutron-skin mode. Which theoretical result is correct cannot be resolved conclusively using the available data. We propose that alpha-scattering, possibly followed by an electroexcitation experiment, could resolve the situation and thereby help to improve the different models aspiring to describe reliably the low-energy dipole strength of nuclei.