Real-photon scattering experiments, also called Nuclear Resonance Fluorescence (NRF) experiments, are a well-established tool for investigating the low-lying dipole response in atomic nuclei due to the low-momentum transfer of photons [1,2]. By studying the angular distributions of the emitted photons during the decay of the previously excited nucleus, spin and parity quantum numbers can be...
For the neutron number N = 60, a sudden onset of the deformation has been observed in Y isotopes at the ground state, which is manifested by the presence of rotational bands (e.g. [1]). On the other hand, the occurrence of shape coexistence in nuclei with N = 58 and 59, in this region (e.g. [2]), suggests that the evolution of the deformation is a more gradual process. Our recent research has...
In the compound process of neutron-induced nuclear reactions, the parity symmetry (P-violation) is violated due to the effect of the weak interaction. It has been experimentally found that the helicity dependence of the reaction cross section due to the P-violating nucleon-nucleon interaction is enhanced by up to six orders of magnitude compared to the bare effect observed in few-nucleon...
Shape coexistence is a fundamental phenomenon found in atomic nuclei. It consists in some states displaying different intrinsic deformations while having relatively similar excitation energies [1].
Neutron-rich nuclei belonging to the A≃100 region of the nuclear chart are known to show a large degree of deformation [2]. In particular, the limit N = 60 is well known for showing a dramatic...
The A$\approx$100 region is a diverse region of the nuclear chart with the occurrence of different nuclear structure phenomena. For example the well known sudden onset of collectivity in the neutron-rich Sr and Zr isotopes [1,2], the multiple shape coexistence in the neutron-rich stable Cd isotopes [3,4] or the evidences for $\gamma$-softness in the Mo, Ru and Pd isotopes. Lifetimes of excited...
Nuclear level lifetimes are important properties of the atomic nucleus, as they yield information about transition strengths and nuclear wave functions. An established method to determine lifetimes in the sub-picosecond regime is the particle-γ coincidence Doppler-shift attenuation method (pγ-DSAM) [1]. As opposed to most DSAM approaches, the additional coincident detection of emitted γ-ray...
The Recoil Distance Doppler-Shift (RDDS) method for measuring the lifetime of excited nuclear states relies on the detection of gamma rays. In cases where the internal conversion coefficient (ICC) becomes large, e.g. for low energy transitions in heavy nuclei, the intensity of $\gamma$-ray emissions may be small and the RDDS method becomes impractical. To overcome this difficulty, a charge...
Although nuclear fission has been discovered more than eight decades ago, the scenario related to the involvement of excitation energy (E$_{ex}$) and angular momentum (L) in controlling the reaction dynamics of a fissioning system has not been clearly understood. The potential energy surface of a fissioning system gets modified due to an enhancement in either one of the two or both the...
Calcium nuclei between doubly closed shells, i.e. N=20 and N=28, offer a unique opportunity to investigate the evolution of nuclear structure from symmetric to neutron-rich systems. Along this isotopic chain, spherical configurations at shell closures are expected to be overcome by deformed structures in mid-shell nuclei, already at low excitation energy. This will significantly affect the...
Experimental and theoretical studies of the germanium isotopes point increasingly toward exotic combinations of nuclear-structure effects, with indications of triaxiality, configuration mixing, and shape coexistence. Studies of the $E0$ strengths, which can provide a direct measure of the amount of configuration mixing, are lacking along the Ge chain. Thus, an experimental determination of...
With very few exceptions, direct measurements of neutron capture cross sections on radionuclides have not been possible. A number of indirect methods have been pursued such as the surrogate method [1], the γ-ray strength function method [2,3], the Oslo method [4-7] and the β-Oslo method [8]. Substantial effort has been devoted to quantify the usually large systematic errors that accompany the...
The major challenge in the Shell Model framework is the diagonalization of the effective (generally two-body) Hamiltonian in the model space. Indeed, this is a huge task for open shell nuclei as the model space dimension grows combinatorially with the number of particles. In this talk, I will present our recent work aiming to tackle this problem in a deformed Hartree-Fock (HF) basis conserving...
$\gamma$-ray spectra following the radiative capture on well-isolated s-wave neutron resonances of $^{167}$Er were measured with the Detector for Advanced Neutron Capture Experiments (DANCE) located at Los Alamos National Laboratory. This highly-segmented calorimeter is an ideal tool for detecting complete $\gamma$ cascades due to its efficiency and solid angle coverage.
Information on...
We report on the first direct measurement of the bound-state beta decay [1] of $\mathrm{^{205}Tl^{81+}}$ ions, an exotic decay mode, in which an electron is directly created in one of the empty atomic orbitals instead of being emitted into the continuum. One of the most awaited and pioneering experiments was realized in the spring beamtime at GSI, Darmstadt in 2020, wherein the entire...
Nuclei from the regions of doubly-closed shells may be considered an excellent ground for studying both a) the couplings between valence nucleons - this provides information on the effective nucleon-nucleon interaction and, b) couplings of the valence nucleons with core excitations, what may be used as a unique test of various effective interactions (Skyrme, Gogny, etc.) employed in mean-field...
The Th-U fuel cycle, in which the $^{233}$U plays an important role, has been proposed as an alternative to the U-Pu fuel cycle due to its reduced amount of transuranium elements. The experimental $^{233}$(n,γ) cross section data available in the literature are scarce and were measured decades ago [1, 2, 3]. An accurate measurement of the $^{233}$(n,γ) cross section is required by the NCSP...
