title: Femtosecond dynamics of energetic electrons in high intensity laser-matter interactions.
abstract: Highly energetic electrons are generated at the early phases of the interaction of short-pulse high-intensity lasers with solid targets. These escaping particles are identified as the essential core of picosecond-scale phenomena such as laser-based acceleration, surface manipulation, generation of intense magnetic fields and electromagnetic pulses. Increasing the number of the escaping electrons facilitate the late time processes in all cases. Up to now only indirect evidences of these important forerunners have been recorded, thus no detailed study of the governing mechanisms was possible. Here we report, for the first time, direct time-dependent measurements of energetic electrons ejected from solid targets by the interaction with a short-pulse high-intensity laser. We measured electron bunches up to 7 nanocoulombs charge, picosecond duration and 12 megaelectronvolts energy. Our 'snapshots' capture their evolution with an unprecedented temporal resolution, demonstrat- ing a significant boost in charge and energy of escaping electrons when increasing the geometrical target curvature. These results pave the way toward significant improvement in laser acceleration of ions using shaped targets allowing the future development of small scale laser-ion accelerators.
authors.affiliation: Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Pompili
authors.affiliation: Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
authors.forename: M P
authors.initials: MP
authors.lastname: Anania
authors.affiliation: Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Bisesto
authors.affiliation: Racah Institute of Physics, Hebrew University, 91904 Jerusalem, Israel.
authors.forename: M
authors.initials: M
authors.lastname: Botton
authors.affiliation: Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Castellano
authors.affiliation: Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Chiadroni
authors.affiliation: University of Rome Tor Vergata, 00133 Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Cianchi
authors.affiliation: Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Curcio
authors.affiliation: Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Ferrario
authors.affiliation: Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Galletti
authors.affiliation: Racah Institute of Physics, Hebrew University, 91904 Jerusalem, Israel.
authors.forename: Z
authors.initials: Z
authors.lastname: Henis
authors.affiliation: University of Rome Sapienza, 00185 Rome, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Petrarca
authors.affiliation: Racah Institute of Physics, Hebrew University, 91904 Jerusalem, Israel.
authors.forename: E
authors.initials: E
authors.lastname: Schleifer
authors.affiliation: Racah Institute of Physics, Hebrew University, 91904 Jerusalem, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Zigler