Conveners
Symmetries of interacting boson and/or fermion systems
- Piet Van Isacker
- Jan Jolie
Symmetries of interacting boson and/or fermion systems
- Piet Van Isacker
- Jan Jolie
The phenomena of shape phase transitions and shape coexistence are prominent aspects of nuclear structure. Experiments using radioactive-ion beams have allowed to study these phenomena in thus far unknown nuclei, and stimulate timely systematic and reliable theoretical predictions. This presentation will review recent theoretical studies on the shapes and the related collective excitations in...
Delayed 𝛾 rays from neutron rich A=97 fission fragments were measured using the Lohengrin spectrometer at the reactor of the Institut Laue-Langevin in Grenoble [1]. Several lifetimes of excited states in 97 Sr were measured using the fast-timing technique [2]. The rapid change in ground-state deformation between the spherical 96 Sr (N=58) and the deformed 98 Sr (N=60) is well known [3, 4]....
The spectrum of odd-mass medium and heavy nuclei involving multiple shell model configurations have rarely been calculated by theoretical models thus far due to their demanding computational aspect or, for some models, the lack of an adequate framework. The evolution of structure of such odd-mass nuclei with varying number of nucleons is hence difficult to investigate. In this talk I will...
I will present some of our later results on the $^{213}$Pb neutron-rich nucleus [1] studied using the unique availability of a primary 1 GeV $A$ $^{238}$U beam and of the FRS-RISING setup at GSI. The products of the uranium fragmentation were separated in mass and atomic number and then implanted for isomer decay $\gamma$-ray spectroscopy. A level scheme from the decay of the $21/2^+$ isomer,...
The well-known near-X(5) nucleus $^{150}$Nd is the mother nucleus of a two-neutrino double beta ($2\nu\beta\beta$) decay and therefore also a candidate for neutrinoless double beta ($0\nu\beta\beta$) decay with the daughter being $^{150}$Sm. $0\nu\beta\beta$-decay is a process only allowed if the neutrino were a Majorana particle and recently gained much attention with numerous experiments...
Symmetries of the IBFFM will be discussed and Spectroscopic Amplitudes (SA) in the Interacting Boson Fermion Fermion Model (IBFFM) are necessary for the computation of $0\nu\beta\beta$ decays but also for cross-sections of heavy-ion reactions, in particular, Double Charge Exchange reactions for the NUMEN collaboration, if one does not want to use the closure limit. We present for the first...
Lifetimes of low-energy states in $^{211}$At have been measured using the recoil-distance Doppler shift, Doppler-shift attenuation, and fast-timing methods at the University of Cologne. The obtained reduced transition probabilities have been compared to two shell-model calculations, a large-scale shell-model calculation using the Kuo-Herling residual interaction and a calculation using a...
The nuclei with few proton and neutron particles (holes) away from doubly-magic nuclei are the simplest nuclear systems in which both nuclear collectivity and the two-fluid nature of the nuclear matter can simultaneous be manifested. The relatively small number of valence particles (holes) allows the low-lying collective states in these nuclei to be described in the shell-model framework. The...
Mixed-symmetry states have proven their sensitivity to the shape evolution across quantum phase transitions. Especially the electromagnetic transitions between the $1^+$ scissors mode and the $0^+_2$ state are strongly affected by the amount of nuclear deformation. Also the elusive $E2$ properties of mixed-symmetry states can be established as novel signatures for phase-transitional behavior....
The nucleus $^{152}$Sm is well known to be located at the $N=90$ quantum shape-phase transition (QSPT) boundary. Since the scissors mode (SM) is a collective, isovector excitation, its decay characteristics depend on the proton-neutron residual interactions and are sensitive to the QSPT. The SM is known for its large $M1$-excitation strength, however, data on isovector $E2$ properties are...
