Title :  Xperimenting  Xploring  Xperiencing down to the Femtoscale  

일시 : 2022년 11월 29일(화), 17시

Speaker : Alahari Navin(프랑스 GANIL의 전 director)


Abstract : The existence of the atomic nucleus as we know it, was demonstrated around 100 years ago by scattering of alpha particles from a radioactive source on a gold foil - the Rutherford experiment - and subsequently studied using accelerated beams of stable elements. Today it has become possible to create and accelerate beams of short lived (~msec) designer nuclei in the laboratory and to study their properties. These exotic nuclei are produced from stable nuclei by altering the neutron/proton ratio, exhibit new phenomena like halos, skins, new ‘magic numbers’, exotic radioactivities, etc., different from those seen near the valley of beta stability. Facilities differing in methodologies and capacities for exploring these exotic nuclei have been setup worldwide to study their unusual properties and their influence on nuclear reaction mechanism. The RAON facility being built in South Korea will be addressing many related interesting questions.

 

Key questions in the field can be summarized as i) understanding of how regular and simple patterns emerge in the intrinsic structure of nuclei ii) identifying the degrees of freedom, which govern the dynamics of their collisions.

 

In this talk, after a brief historical review, I will present recent progress in this field and will use the Grand Accélérateur National d'Ions Lourds (GANIL) facility as a typical laboratory to illustrate part of the recent progress in this field.  The various studies that we will discuss use ion high intensity (~1012 particles/s) stable ion beams (12C to 238U) up to 95 MeV/nucleon and exotic beams of nuclei (which live for a very short time with lifetimes ranging from ~ msecs to msecs). The intensities of these exotic beams range from a few particles/s to ~107 p/s.  More recently, a new very high intensity superconducting LINAC  has also been commissioned that will  also provide intense neutron beams. These numerous types of beams are coupled to versatile detection facilities (active targets, powerful spectrometers, 4p charged particle detectors, g-ray tracking detectors, etc.) built by various international collaborations. These tools help us explore the behavior of nuclei under various conditions of excitation energy (heating to different temperatures), angular momentum (spinning), and isospin (different composition in terms of neutrons and protons).  

 

In this talk, we will make a virtual visit of the laboratory and explore details at the femtometer scale using the available microscopes at GANIL to address some aspects of these key questions.