News

The first shipment of 10 CVD single-crystaline diamond samples for the full 5x5x5 LISA array has arrived at GSI. Over the next year, we will receive about 10 samples a month to complete the array. The samples will be measured, tested, and mounted into layers for the LISA experiment in May 2025.

Our paper Triaxial deformation of neutron-rich Zr nuclei explored by high-resolution in-beam γ-ray spectroscopy was published in Physics Letters B. Lifetimes of excited states in the very exotic nuclides ¹⁰⁸Zr₆₈ and ¹¹⁰Zr₇₀ were measured for the first time applying high-resolution in-beam γ-ray spectroscopy at relativistic energies. Emitted γ rays from the excited states were measured by the High-resolution Cluster Array at RIBF (HiCARI) and lifetimes were extracted from the observed line shapes caused by relativistic Doppler-shift effects. Various physical quantities were compared with theoretical models to investigate the collectivity in Zr isotopes towards N=70. Together the experimental and theoretical results point at a reduction of the axial deformation while triaxial collectivity increases.

Hannah Werner joins us for a three month internship. She will test the newly arriving diamond detectors and characterize their response. This is crucial for our acceptance tests toward a full 5x5x5 LISA setup. First task was to visit the viewing platform for the FAIR construction site.

The first full LISA experiment at GSI has just finished. The two-layer prototype was installed at the S2 focal plane of the FRS and tested with ¹⁰⁰Mo beam. The detectors were tested under various conditions of the beam and the high-voltage supplies and also used our own development of pre-amplifiers for the first time. The experiment was very successful, we were able to demonstrate the proof-of-principle of the active target method. Congratulations to the whole teams.

A new paper on isospin symmetry in the T=1, A=62 triplet has been published in Physics Letters B. The study presents a combination of in-beam γ-ray spectroscopy experiments done at the RIBF with projectile fragmentation and at JYFL-ACCLAB using a fusion evaporation reaction. The first excited states in ⁶²Ga and ⁶²Ge were identified, resolving discrepant interpretations in the literature. In comparison with shell-model calculations, we can conclude that the radius of the proton and neutron p orbits shrink when they are occupied by at least one nucleon.

During the engineering runs at GSI, we have performed the first in-beam test of LISA detectors. A single diamond detector (named "Tokyo") was inserted at the S2 focal area and tested with heavy ions.

This is a huge step forward in the project, congratulations to the whole team!

Martha Reece joined us recently as a PhD student in the LISA team. Together with the rest of the team she just completed a vacuum test of newly delivered equipment. It seems to work, everybody is happy ;-)

Our paper on the nature of axial and triaxial deformation in ⁷²Zn was published in Physics Letters B. This paper is based the PhD work of S. Hellgartner. It discusses the results of a Coulomb excitation experiment performed at REX-ISOLDE. The differential excitation cross sections allowed us to draw conclusions on the shape of ⁷²Zn. The results were compared with shell model and beyond mean field calculations which corroborate the large deformation in the γ degree of freedom, while pointing to a more deformed state. These experimental and theoretical findings establish the importance of the γ degree of freedom in the ground state of ⁷²Zn, located between the ^68,70Ni nuclei that have spherical ground states, and ⁷⁶Ge, which has a rigid triaxial shape.

Our experiment to study nuclei toward the N=20 Island of Inversion has been successfully completed at National Laboratories of Legnaro. Using the AGATA γ-ray spectrometer and PRISMA for the detection of ions, we employed multi-nucleon transfer reactions of a ²²Ne beam onto a ²³⁸U target. Excited states in various Ne, F, and O isotopes were observed in the on-line analysis.

With help of the GSI detector lab, we have measured the energy resolution of SC-CV diamond detectors. All detectors show excellent performance and wait to be tested with beams this fall.

Jelena Bardak and Bellona Bles are two PhD students from the University of Novi Sad who join us for the next six month. Already in their first week, they were working hard cutting and sanding parts of the support structure in the workshop.