Réunion de lancement du projet LICORNE

12 oct. 2015, 15:00 → 14 oct. 2015, 12:30 Europe/Paris

salle Nord (Nançay)

A natural lightning flash is a powerful phenomenon, still not totally understood. Lightning mapping techniques, like difference of time-of-arrival technique in the VHF domain, provide key characterization of the development of both Intra-Cloud (IC) and Cloud-to-ground (CG) lightning flashes. Combined to cloud remote sensing observations, the lightning flash can be replaced in its environmental context. However questions remain on the physical processes that trigger a lightning flash, as the ambient macroscopic electric field inside the cloud is typically one order of magnitude less than that required for dielectric breakdown. One hypothesis currently considered by the community is that a lightning flash can be triggered by an avalanche of runaway electrons created by cosmic ray-induced extensive air showers with energy in excess of 1016 eV (Gurevich et al, 1992). On the other hand, it has been evidenced that terrestrial gamma-ray flashes may be produced in association with natural lightning flashes (e.g. Cummer et al., 2005; Splitt et al., 2010). Consequently further investigations are required to not only document but also to understand the complex physical processes involved here through a multi-disciplinary study that will require both observations and modeling exercises. The LIghtning and COsmic Rays in Natural Environment project (LICORNE) aims at gathering French Scientists working in High-energy Particle and Atmospheric Sciences on a common project dedicated to the study of the impact of natural cosmic rays on the occurrence of natural lightning flashes and on the characterization of high-energy particles radiated during natural lightning flashes. In its first year, the LICORNE project will: i) perform a rather exhaustive literature review on the interaction between cosmic rays and lightning flashes, ii) identify strengths and weaknesses of the Consortium in its current composition, iii) explore available lightning and air shower observations above the CODALEMA site during the recent years to help define a realistic Science Plan that will drive the development phase of the project, including an observational strategy combining relevant instrumentation, and a modeling strategy in preparation for the interpretation of the observations. A preliminary approach could be based on long-term collection of detailed records of air showers and lightning flashes for storms passing above a single state-of-the-art instrumental site - already existing or to build - and on the analysis of temporal and spatial correlations in the observations to provide key inputs for modeling investigations coupling high-energy particle physics and lightning phenomenology. The LICORNE project includes physicists of the Terrestrial Gamma-ray Flashes (TGFs) French community for shared analysis using lightning and cosmic rays data but no gamma imager is foreseen in this project.

lundi 12 octobre

15:00 → 18:00 Visite du site

Tour des instruments de CODALEMA/EXTASIS

mardi 13 octobre

09:30 → 09:50 Introduction

but de la réunion, objectifs du projet, quelle observable d’une corrélation RC/éclairs ? 10 kE+2 kE disponibles : mesureur de champ ? autre ? tour de table 2 possibilités : corrélation éclair/passage d'une gerbe (temps/espace) et modification du champ électrique des gerbes en conditions orageuses

Orateur: Benoît Revenu (subatech)

Transparents reunion_lancement.pdf

09:50 → 11:00 Théorie

09:50 Les rayons cosmiques

très bref sur : spectre en énergie, source description de la gerbe atmosphérique : particules secondaires, distribution en énergie, géométrie reconstruction des paramètres du primaire : cœur, triangulation, résolutions

Orateur: Benoît Revenu (subatech)

Transparents rcs_gerbes.pdf

10:10 Emission radio dans les gerbes

Orateur: Benoît Revenu (subatech)

Transparents mecanisme_emission.pdf

11:00 → 11:15 café

11:15 → 11:45 Instrumentation

11:15 Instruments à Nançay (1/2)

présentation générale puis : scintillateurs : description, signaux, identification des gerbes, trigger stations autonomes 10-200 MHz : description, trigger, transitoires, identification des gerbes

Orateur: Lilian Martin (subatech)

Transparents InstrumentsSC.pdf PNHEGrandsInstruments.pdf

11:45 → 12:15 Discussions

12:15 → 13:25 Pause repas

13:25 → 14:30 Théorie

13:30 Orages et éclairs

comment ça marche ? physique de l'éclair, quelles mesures ? Données Météorage.

Orateur: Stéphane Pedeboy

Transparents LICORNE-2015.pptx

14:00 Lien orages/rayons cosmiques

modèle de Gurevich

Orateur: Éric Defer

Transparents licorne_kom_defer_20151013.pdf

14:30 → 15:10 Instrumentation

14:30 Instruments à Nançay (2/2)

stations basse fréquence 1-10 MHz : description, trigger, allure des données antenne tripole 10-200 MHz : description, trigger, allure des données station météo

Orateur: M. Richard Dallier (SUBATECH)

Transparents bfTripoleMeteoRD.pdf

15:00 Mesureur de champ

Orateur: Benoît Revenu (subatech)

Transparents moulin_a_champ.pdf

15:10 → 15:30 Mesures infrason

Orateur: Thomas Farges

Transparents KOM_LICORNE_Farges.pdf

15:30 → 17:00 Data & analyse

17:00 → 17:15 café

17:15 → 19:30 Data & analyse

mercredi 14 octobre

09:30 → 11:00 Data & analyse

09:30 Data

accès à la DB, tables disponibles : préparer un slide avec tous les paramètres de connexion Météorage : LIF comparaison ciel clair/orage pour SA, sci

Orateur: Lilian Martin (subatech)

Transparents Data.pdf

11:00 → 11:15 café

11:15 → 12:15 Discussions et conclusion