Study of the Pygmy Dipole Resonance in (p,p’γ) and (d,pγ) experiments with SONIC@HORUS

Institute for Nuclear Physics, Zülpicher Str. 77, D-50937 Cologne, Germany

^a e-mail: pickstone@ikp.uni-koeln.de

Published online: 28 May 2015

Abstract

Last year, the new silicon-detector array SONIC with up to 8 silicon-detector positions was installed inside the existing γ-ray spectrometer HORUS consisting of 14 HPGe detectors. The combined setup SONIC@HORUS allows for a coincident detection of γ-rays and light charged particles in the exit channel of inelastic scattering and transfer reactions. As a first physics case, the Pygmy Dipole Resonance (PDR) in ⁹²Mo has been investigated in a (p,p’γ) experiment at E_p = 10.5 MeV. Since specific excitation energy can be chosen offline in the coincidence data, the sensitivity to weak decay branchings of PDR states is increased. Additionally, a second reaction mechanism for the excitation of PDR states has been tested with the new setup. In a ¹¹⁹Sn(d,pγ) transfer reaction at E_d = 8.5 MeV, PDR states in ¹²⁰Sn could be excited. Since this one-neutron transfer reaction is sensitive to the neutron single-particle structure, it could reveal new information on the microscopic structure of the PDR.