Observation of a highly directional γ-ray beam from ultrashort, ultraintense laser pulse interactions with solids

Abstract

A tuneable ultra-compact high-power, ultra-short pulsed, bright gamma-ray source based on bremsstrahlung radiation from laser-plasma accelerated electrons Novel measurements of electromagnetic radiation above 10 MeV are presented for ultra intense laser pulse interactions with solids. A bright, highly directional source of ␥ rays was observed directly behind the target. The ␥ rays were produced by bremsstrahlung radiation from energetic electrons generated during the interaction. They were measured using the photoneutron reaction ͓ 63 Cu(␥,n) 62 Cu͔ in copper. The resulting activity was measured by coincidence counting the positron annihilation ␥ rays which were produced from the decay of 62 Cu. New measurements of the bremsstrahlung radiation at 10 19 W cm Ϫ2 are also presented.

Petawatt class lasers worldwide

“…This was extended into the keV regime using petawatt power pulses focused to 10 21 W cm −2 intensities [24] by 2007, and into the attosecond region [25] using even shorter few femtosecond optical driving pulses. The production of high currents of MeV electrons [26] and associated gamma-ray production [27] brought significant attention to the scale length of the interaction. At such intensities, any illumination of the target above the ionization threshold (10 11 -10 12 W cm −2 ) can generate a pre-plasma which expands and dramatically changes the scale length of the interaction.…”

Multiphoton radiative recombination of electron assisted by a laser field

“…[1,2]). The laser stimulated bremsstrahlung plays the very important role in plasma physics, see recent experimental [3,4] and theoretical [5,6] works.…”

Sources X : du multi-keV-ns au multi-MeV-ps

“…Les expériences effectuées sur un grand nombre d'installations laser sur le laser P102 du CEA/LV [14], sur NOVA [15], sur VULCAN [16,17], au LOA et au LULI [18] ont produit une grande quantité de rayonnement X dans la gamme multi-MeV et permis de radiographier des objets divers [19]. Les études expérimentales et théoriques menées à la DIF dans ce domaine ont permis de préciser les caractéristiques des sources X multi-MeV obtenues en fonction de celles du laser et des conditions d'interaction, passant de quelques centaines de TW dans les années 80 aux lasers PW actuels.…”