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Review of Scientific Instruments 77 (2006) 093302
Absolute energy distribution of hard X-rays poduced in the interaction of a kHz femtosecond laser with tantalum targets
F. Gobet1, F. Hannachi1, M.M. Aléonard1, J.F. Chemin1, G. Claverie1, M. Gerbaux1, G. Malka1, J.N. Scheurer1, M. Tarisien1, F. Blasco2, D. Descamps2, F. Dorchies2, R. Fedosejevs2, C. Fourment2, S. Petit2, V. Méot3, P. Morel3, S. Hanvey, L. Robson, B. Liesfeld

Previous reports have indicated the anomalous excitation rate for the 6.2 keV nuclear level of 181Ta in a plasma produced with a femtosecond laser. A detailed characterization of the electrons and x-ray sources produced in such a plasma is required to interpret these results. In a preliminary work, the continuous energy distribution of hard x rays 10–500 keV produced in the interaction of a kilohertz femtosecond laser beam with a tantalum solid target is investigated in the 31015–6 1016 W/cm2 range of intensity. A sodium iodide detector with appropriate shielding is used. Strong collimation and absorption filters are used to avoid the pileup of photons in the detector. The response function of this setup is calculated with the GEANT3 simulation code. We demonstrate the necessity to quantify the Compton scattered events in the raw spectra in order to restore the absolute x-ray energy distribution.
1 :  CENBG - Centre d'Etudes Nucléaires de Bordeaux Gradignan
2 :  CELIA - Centre d'Etudes Lasers Intenses et Applications
3 :  SERVICE DE PHYSIQUE NUCLéAIRE - Service de Physique Nucléaire
Physique/Physique/Physique des plasmas
tantalum – plasma X-ray sources – plasma production by laser – high-speed optical techniques – plasma diagnostics – plasma light propagation – plasma simulation – Compton effect