Quasi-monoenergetic electron acceleration : the self-modulated multi-bubble regime

[Abstract unavailable

Study of photo-proton reactions driven by bremsstrahlung radiation of high-intensity laser generated electrons

Photo-nuclear reactions were investigated using a high power table-top laser. The laser system at the University of Jena ( I similar to 3-5 x 10(19) W cm(-2)) produced hard bremsstrahlung photons ( kT similar to 2(9 MeV) via a laser-gas interaction which served to induce ( gamma, p) and ( gamma, n) reactions in Mg, Ti, Zn and Mo isotopes. Several ( gamma, p) decay channels were identified using nuclear activation analysis to determine their integral reaction yields

Generation of quasimonoenergetic electron bunches with 80-fs laser pulses

Highly collimated, quasimonoenergetic multi-MeV electron bunches were generated by the interaction of tightly focused, 80-fs laser pulses in a high-pressure gas jet. These monoenergetic bunches are characteristic of wakefield acceleration in the highly nonlinear wave breaking regime, which was previously thought to be accessible only by much shorter laser pulses in thinner plasmas. In our experiment, the initially long laser pulse was modified in underdense plasma to match the necessary conditions. This picture is confirmed by semianalytical scaling laws and 3D particle-in-cell simulations. Our results show that laser-plasma interaction can drive itself towards this type of laser wakefield acceleration even if the initial laser and plasma parameters are outside the required regime

Search for the 6keV isomer excitation and decay in a 181^{181}Ta plasma produced with a high repetition rate laser

The possibility to excite the 6.2 keV, 6.8$\mu$ isomer in $^{181}$Ta within a plasma was studied with the high repetition rate laser available at the CELIA facility at Universite de Bordeaux 1. The laser is a 10mJ, 1kHz, 30fs Tisapphire laser. Excitation of the Ta isomer can be effective through electron excitation or photon absorption by the Ta nuclei inside the plasma produced in the interaction of the laser with solid Ta targets. We have, in a first step characterized the phton production issued from the Bremssttrahlung of electrons for I=1-6 10$^{16}$ W.cm$^{-2}$ laser intensities. The photon spectrum extends up to 500 keV. The plasma expansionwas also studied. We have used several set-ups to optimize the direct detection of the 6.2 keV gamma line which is a definite signature of the Ta de-excitation. This 6.8µs isomer lifetime is short compared to nuclear physic electronic time scales and a special care is to be taken for the detection system in order to observe the gamma-line

Heating of Tantalum plasma for studies on the activation of the 6.238 keV nuclear level of Ta-181

Poster n° P1.152International audienc

Absolute energy distribution of hard x rays produced in the interaction of a kilohertz femtosecond laser with tantalum targets

no abstrac