Theory Days 2020

Following the tradition of the previous successful meetings that have started in 2009, the Theory Days workshop aims at stimulating constructive discussions, collaborations, and knowledge exchange among a selected group of theoreticians. This year, the twelfth edition will be dedicated to multiscale approaches for the description of irradiation processes.

Since the discovery of radioactivity and X rays in the late 19th century, understanding the interactions and effects of radiation (from photons, electrons or heavier particles such as protons and heavy ions) has been of tremendous importance in a large variety of scientific fields. The aim is either to minimize radiation damage for example in electronic devices, or, on the contrary, to use radiation effects, for instance for therapeutic purposes.

Modeling of the effects of radiation on systems has been continuously evolving for decades in many domains : material science, electronics, chemistry, biology and, of course, medicine. Each of these fields has developed its own tools and methodologies, and even its own units of measure. This produces the tendency to complexify a topic that is by essence complex and at crossroads of scientific fields with very different histories and cultures. Even though the elementary processes at play are of the same nature (matter-particle interactions) and thus call for similar expertise (physics, mathematics, computing, electronics, biology, etc.), there is a clear need of convergence of the methods and the approaches specifically developed in this or that field.

Effects of atomic displacement due to irradiation have been studied since long in many devices (diodes, image sensors, etc.) or in systems of biological interest (DNA strands, proteins, etc.). However, the understanding at a fundamental level of the link between the modifications of the atomic structure and the consequences of their presence on the electronic response of the irradiated systems is not achieved yet. Nowadays, the existing numerical tools, most of them being macroscopic, do not allow one to make reliable predictions because atomistic and quantal effects are not accounted for.

We here mainly focus on components and electronic devices, either from an academic point of view or in an industrial context. Indeed, the size reduction of electronic devices now invading our all day life makes a deep understanding and control of radiation effects a major pressing scientific and industrial issue.

The effects of irradiation in nanosystems are however extremely complex since the players (electrons and ions) respond to the excitation with very different time scales (from fs up to ps, or even ns) and can imply very different length scales. During the past few decades, various approaches dedicated to a specific length and/or time scale have been developed. The development of multiscale theoretical tools (sub-fs / 100 fs / 10 ps and 0.1 nm / 10 nm) addressing electronic excitation and ionization in nanodevices represents a key challenge in this context. The objective of this workshop is to review the existing methods at different scales, to question the consistency between them and to possibly address a methodology to establish a continuum from microscopic to macroscopic descriptions.

We plan to gather people from various groups working in this domain, mostly in western Europe. The workshop is intended to be a working forum, thus rather informal. The format will consist in a series of long detailed talks, typically 1 hour (40 mn talk + 10 mn for questions) focusing in particular on ongoing problems and open issues. We thus urge participants to prepare their talks in this spirit. Ultimately a most efficient organization would consist in having a limited number of talks per representative group in order to avoid doublings.

If a consensus is reached during the workshop it would be highly profitable to envision a sequel to this workshop in order to possibly establish, at best collaborative links between the various groups with possible exchange of researchers and students, at worst an ongoing follow up of progress in the field.

Scientific program

Exceptionally, and due to the special circumstances of the Covid-19 pandemic, this year’s venue (workshop) will entirely be organized through Zoom visio conferencing and last three half-days (instead of the usual four), from Wednesday November 25th afternoon to Thursday November 26 afternoon. The Zoom links are provided below soon.

Wed Nov 25th 2020

• 14:00 : V. Goiffon (ISAE-Supaero, Toulouse, France), "Experimental study of semiconductor irradiation defects by the use of image sensors"

https://univ-tlse3-fr.zoom.us/j/83206602891?pwd=d0pzS0tqZmhVbDFIcS9aYzFjeE1pZz09

Meeting ID : 832 0660 2891

Password : ThDays

• 15:00 : C. Villagrasa, (Laboratoire de dosimétrie des rayonnements ionisants, Fontenay- aux-Roses, France), "Modelling Biological response to radiation with Geant4-DNA Monte carlo code"

https://univ-tlse3-fr.zoom.us/j/89321384481?pwd=SEhwakpSYmpoZ1p4c1hKNTZYNEVVQT09

Meeting ID : 893 2138 4481

Password : ThDays

• 16:00 : E. Artacho (CICnanoGUNE, Bilbao, Spain), tba

Thu Nov 26th 2020

• 09:00 : L. Martin Samos (CNR-IOM/Democritos National Simulation Center, Istituto Officina dei Materiali, Trieste, Italy), "Challenges in modeling defects : multi-scaling and linking theory to experiments"

https://univ-tlse3-fr.zoom.us/j/89824802575?pwd=S3I3R1V6ZmliRzl3NUZqckJXUkdSZz09

Meeting ID : 898 2480 2575

Password : ThDays

• 10:00 : P.-G. Reinard (Institute for Theoretical Physics, University Erlangen, Germany), tba

• 11:00 : J. Kohanoff (School of Mathematics and Physics, Queen’s University of Belfast, UK), tba

• 14:00 : F. Da Pieve (Belgian Institute For Space Aeronomy, Brussels, Belgium), tba

• 15:00 : T. Jarrin (CEA-DAM, Arpajon, France), "Multiscale simulation of displacement damage in semiconductors : Molecular Dynamics, Activation Relaxation Technique and ab initio methods"

https://univ-tlse3-fr.zoom.us/j/86118270581?pwd=NmVadURVdkZHd3l5dC9xK082SHNudz09

Meeting ID : 861 1827 0581

Password : ThDays

• 16:00 : N. Dray (TRAD Tests&Radiations Company, Labège, France), tba