The pygmy quadrupole resonance and neutron-skin modes in 124Sn

Research output: Contribution to journalArticlepeer-review


  • M. Spieker
  • N. Tsoneva
  • V. Derya
  • J. Endres
  • D. Savran
  • M.N. Harakeh
  • S. Harissopulos
  • R.-D. Herzberg
  • A. Lagoyannis
  • H. Lenske
  • N. Pietralla
  • Lucia-Ana Popescu
  • M. Scheck
  • F. Schlüter
  • K. Sonnabendl
  • V.I. Stoica
  • H.J. Wörtche
  • A. Zilges

Institutes & Expert groups

  • Institut für Kernphysik der Universität zu Köln
  • FIAS - Frankfurt Institute for Advanced Studies
  • JLU - Justus-Liebig-Universität Gießen - Institut für Theoretische Physik
  • INRNE - Institute for Nuclear Research and Nuclear Energy
  • University of Groningen
  • EMMI - ExtreMe Matter Institute
  • NCSR Demokritos - National centre for Scientific Research, Institute for Nuclear Physics - Greece
  • University of Liverpool
  • Technical university Darmstadt
  • UWS - University of the West of Scotland
  • Goethe Universität Frankfurt am Main - Institut für Angewandte Physik

Documents & links


We present an extensive experimental study of the recently predicted pygmy quadrupole resonance (PQR) in Sn isotopes, where complementary probes were used. In this study, (α, α'γ ) and (γ , γ') experiments were performed on 124Sn. In both reactions, Jπ = 2+ states below an excitation energy of 5MeV were populated. The E2 strength integrated over the full transition densities could be extracted from the (γ , γ') experiment, while the (α, α'γ ) experiment at the chosen kinematics strongly favors the excitation of surface modes because of the strong α-particle absorption in the nuclear interior. The excitation of such modes is in accordance with the quadrupole-type oscillation of the neutron skin predicted by a microscopic approach based on self-consistent density functional theory and the quasiparticle-phonon model (QPM). The newly determined γ -decay branching ratios hint at a non-statistical character of the E2 strength, as it has also been recently pointed out for the case of the pygmy dipole resonance (PDR). This allows us to distinguish between PQR-type and multiphonon excitations and, consequently, supports the recent first experimental indications of a PQR in 124Sn.


Original languageEnglish
Pages (from-to)102-107
Number of pages6
JournalPhysics Letters B
Publication statusPublished - 10 Jan 2016


  • Pygmy quadrupole resonance, neutron skin

ID: 1383609