Research

A central part of our research group's work is the LISA (LIfetime measurements with Solid Active targets) project. The detectors are based on single-crystal diamonds and are arranged in up to 5x5 layers for LISA experiments. We offer thesis topics related to LISA and other research projects, feel free to stop by.

Physics of the atomic nuclei

The coexistence of single-particle and collective degrees of freedom in atomic nuclei gives rise to various exotic phenomena. In nuclei with very asymmetric proton-to-neutron ratios, the strong nuclear interaction drives shell evolution which alters the orbital spacing, and in some cases even the ordering present in stable nuclei. In the absence of large gaps between orbitals, nuclei can take on non-spherical shapes and their excitations proceed through coherent and collective motion of many nucleons. Where and how collectivity emerges from the single-particle dynamics of protons and neutrons is an open question in nuclear structure physics that will be addressed with LISA in a unique way.

The LISA project

The aim of the LISA (LIfetime measurements with Solid Active targets) project is to develop a novel method for lifetime measurements in atomic nuclei. Lifetimes probe the collectivity of a nucleus through its electromagnetic transition properties. The experimental approach is based on active solid targets and will dramatically enhance the scope of measurements of excited-state lifetimes and thus transition probabilities achievable in exotic nuclei.

Here, cooperation at major international research facilities and through international collaborations is equally important. Coupled to state-of-the-art γ-ray tracking detectors such as AGATA, this novel instrument will overcome the present challenges of lifetimes measurements with low-intensity beams of unstable nuclei. LISA will exploit the unique capabilities of FAIR, the future European fragmentation facility set to deliver the most exotic and highest intensity radioactive ion beams. LISA will greatly expand the physics program for nuclear structure studies at FAIR. Through the measurements made possible by LISA, our understanding of key aspects of single-particle and collective structures and their interplay will become much more developed. The results will have significant impact on the theoretical descriptions and modeling of atomic nuclei making their predictions more reliable.

Nuclear Collectivity Across the Nuclear Landscape

Atomic nuclei exhibit diverse collective behaviors depending on their proton–neutron composition, and the evolution of their B(E2) values reveals how shell structure, deformation, and magic numbers shape nuclear excitations.
Lifetimes of excited states

In in-beam γ-ray spectroscopy, the time-dependent Doppler shift—caused by changing ion velocity or emission angle—provides a precise clock to extract lifetimes of excited nuclear states in the picosecond to nanosecond range.
Improving Doppler Correction with Active Targets

LISA enhances lifetime measurements by pinpointing the reaction vertex within stacked active targets, enabling accurate velocity determination and sharper Doppler-corrected γ-ray spectra.
From Passive to Active Targets

By replacing a thick passive target with segmented active layers, LISA overcomes velocity-uncertainty broadening and dramatically improves resolution in experiments using low-intensity radioactive beams.
LISA: Precision Through Reaction-Point Localization

LISA’s ability to identify the exact target layer where a reaction occurs provides the correct the ion velocity β and emission angle α for Doppler correction, boosting both sensitivity and precision in measuring excited-state lifetimes.
Enhancing γ-Ray Resolution with LISA

By reducing effective target thickness and suppressing velocity-related broadening, LISA significantly improves γ-ray resolution in high-performance spectrometers like AGATA and GRETA, greatly boosting sensitivity to lifetimes of exotic nuclei.