Scientific Colloquium Webinars 2021 (past)

Monday, 26/04 (16h, CET): hosted by CENBG
Precision mass measurements for nuclear and neutrino physics studies

Klaus BLAUM (Max-Planck-Institut für Kernphysik, Heidelberg)

Rapidly developing neutrino physics has found in Penning-trap mass spectrometry a staunch ally in investigating and contributing to a variety of fundamental problems. The most familiar are the absolute neutrino mass and the possible existence of resonant neutrinoless double-electron capture / double-beta dacay and of keV-sterile neutrinos. This review provides an overview on the latest achievements and future perspectives of Penning-trap mass spectrometry on short-lived as well as stable nuclides with applications in nuclear structure, neutrino physics and most recently even in dark matter searches where relative mass uncertainties at the level of 10-11 and below are required.
The pdf of the talk is here.

Monday, 12/04 (16h, CET):
From nuclei to neutron stars: Combining nuclear physics and multi-messenger observations
Ingo TEWS (Los Alamos National Laboratory, USA)

Neutron stars contain the largest reservoirs of degenerate fermions, reaching the highest densities we can observe in the cosmos, and probe matter under conditions that cannot be recreated in terrestrial experiments. Throughout the Universe, a large number of high-energy, cataclysmic astrophysical collisions of neutron stars are continuously occurring. These collisions provide an excellent testbed to probe the properties of matter at densities exceeding the density inside atomic nuclei, are an important site for the production of elements heavier than iron, and allow for an independent measurement of the expansion rate of our Universe.
To understand these remarkable events, reliable nuclear-physics input is essential. In this colloquium, I will review how to use state-of-the-art nuclear-physics calculations to provide a consistent and systematic approach to strongly interacting systems from nuclei to neutron stars with theoretical uncertainties.  I will discuss nuclear-physics predictions for the dense nucleonic matter relevant for neutron stars, and discuss how astrophysical multi-messenger observations of neutron stars and their mergers can be used to further elucidate the properties of matter under extreme conditions.
The pdf of the talk is here. LA-UR-21-23129

Monday, 29/03 (16h, CET): hosted by GdR RESANET
Selected topics on heavy and super-heavy nuclei,
Christophe THEISEN (DPhN Saclay)

In this webinar I will review selected aspects of heavy and superheavy nuclei, starting from the discovery of transactinide nuclei in the 40th using neutron « beams ». Then, still with neutrons, I will continue with the question of the superheavy nuclei nucleosynthesis in the r-process: supernovae explosions, neutron star mergers, collapsars. These nucleosynthesis processes are strongly constrained by nuclear structure, and in particular by the fission barriers, for nuclei where no experimental data can be obtained. I will therefore discuss theoretical predictions, both for spherical magic and deformed regions. We will see how we can obtain experimentally information on not-too-heavy nuclei near the deformed shell gap Z=100 N=152. How can we deduce and in some cases measure the deformation or the electric quadrupole moment of the heaviest nuclei (spectroscopy, coulex, laser spectroscopy)? I will also discuss the theoretical difficulties and problems faced in this region. I will conclude with few flagship experimental projects such as S3 and the future NEWGAIN injector at GANIL, the possibility of re-accelerating actinide nuclei, and the synthesis using multi-nucleon transfer reactions. 
The pdf of the talk is here.

Monday, 15/03 (16h, CET): hosted by GdR RESANET
On the tracks of two-proton radioactivity,
Jérôme GIOVINAZZO (CENBG Bordeaux)

The two-proton radioactivity is a very exotic decay mode that can occur for very neutron deficient nuclei located beyond proton drip-line. From theoretical assumptions, it was already predicted in the early 1960’, together with the one-proton radioactivity. Nevertheless, it is only in the years 2000 that a first experimental indication of the phenomenon could be observed, thanks to the development of the facilities that can produce nuclei far from stability.
This process is made possible thanks to very specific quantum effects at the microscopic level: the Coulomb barrier originating in the electric charge of all protons in the nucleus and the gain of stability caused by the coupling of nucleons in pairs. It has been observed in the decay of only 4 nuclei, and 20 years after the first observation, in order to understand this radioactivity, new experimental tools are built to measure the correlations of the protons, and theoretical models are developed to describe both the structure of the emitting nuclei and the dynamics of the emission.
In this presentation will give a brief description of this exotic decay process and explain the major steps of its study, from both theoretical and experimental sides.
The pdf of the talk is here.

Organizers:P. Ascher (CENBG Bordeaux), O. Dorvaux (IPHC Strasbourg), S. Diglio (SUBATECH Nantes), J. Dudouet (IP2I Lyon), A. Fantina (GANIL Caen), G. Henning (IPHC Strasbourg), A. Korichi (IJCLab Orsay), O. Lopez (LPC Caen), J. Margueron (IP2I Lyon), G. Quemener (LPC Caen), O. Sorlin (GANIL Caen), B. Sulignano (IRFU Saclay), J.-C. Thomas (GANIL Caen), L. Thulliez (IRFU Saclay), A. Uras (IP2I Lyon), M. Vandebrouck (IRFU Saclay), P. Van Hove (IPHC Strasbourg), G. Verde (L2IT Toulouse).