Systematic investigation of the collective structure of neutron-rich even-even nuclei with 50 < Z < 82 via recoil-distance Doppler shift lifetime measurements of excited nuclear states using the two neutron transfer reaction.

• Applicant: Professor Dr. Jan Jolie
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 529851512

We plan to perform two-neutron transfer reactions in the 50 < Z < 82 region of the nuclear chart to investigate different nuclear structure phenomena. The nuclei of interest are 152Nd, 156Sm, 160,162Gd, 178Yb, 182Hf, 188W, 194Os and 200Pt which will be populated in a two-neutron transfer reaction using a 18O beam. The beam is provided by the Cologne 10 MV Tandem accelerator with the beam energy around the Coulomb barrier of the corresponding reaction. The Cologne Plunger spectrometer, equipped with 25 high purity germanium (HPGe) detectors and eight LaBr(Ce) detectors, will be used to measure lifetimes. Additionally, solar cells will be placed at backward angles to gate on the recoiling beam-like particles. This feature will allow to measure particle gated gamma-ray spectra which can be used to employ the recoil distance Doppler shift (RDDS) method. Further, the installation of LaBr(Ce) detectors will allow to measure lifetimes using the electronic fast timing in combination with the generalized centroid difference (GCD) method. Both methods are reliable and established method to measure lifetimes in the pico to nanosecond regime. With the resulting lifetimes, reduced transition strengths can be obtained to study the structure of the nuclei. The 152Nd and 156Sm nuclei lie close to the so-called "octupole magic" number N = 88 and are therefore interesting cases to study octupole deformation in this region. The 160,162Gd, 178Yb and 182Hf isotopes are located around the gamma-soft region with low-lying 0+ states. New data on these nuclei will further improve the gamma-soft model which is an analytical solution of the Bohr-Hamiltonian. The higher mass isotopes 188W, 194Os and 200Pt show evidences of triaxiality and especially gamma-softness. The reduced transition strength are important signatures to understand this phenomenon in this region. Lastly, all of these results will be compared to the mean field based proton-neutron interacting boson model to verify and understand the underlying structure.

• DFG Programme: Research Grants
• International Connection: Japan
• Cooperation Partner: Professor Dr. Kosuke Nomura