Measurement of high-dynamic range x-ray Thomson scattering spectra for the characterization of nano-plasmas at LCLS.

The Review of scientific instruments

PubMedID: 27910491

MacDonald MJ, Gorkhover T, Bachmann B, Bucher M, Carron S, Coffee RN, Drake RP, Ferguson KR, Fletcher LB, Gamboa EJ, Glenzer SH, Göde S, Hau-Riege SP, Kraus D, Krzywinski J, Levitan AL, Meiwes-Broer KH, O'Grady CP, Osipov T, Pardini T, Peltz C, Skruszewicz S, Swiggers M, Bostedt C, Fennel T, Döppner T. Measurement of high-dynamic range x-ray Thomson scattering spectra for the characterization of nano-plasmas at LCLS. Rev Sci Instrum. 2016;87(11):11E709.
Atomic clusters can serve as ideal model systems for exploring ultrafast (~100 fs) laser-driven ionization dynamics of dense matter on the nanometer scale. Resonant absorption of optical laser pulses enables heating to temperatures on the order of 1 keV at near solid density conditions. To date, direct probing of transient states of such nano-plasmas was limited to coherent x-ray imaging. Here we present the first measurement of spectrally resolved incoherent x-ray scattering from clusters, enabling measurements of transient temperature, densities, and ionization. Single shot x-ray Thomson scattering signals were recorded at 120 Hz using a crystal spectrometer in combination with a single-photon counting and energy-dispersive pnCCD. A precise pump laser collimation scheme enabled recording near background-free scattering spectra from Ar clusters with an unprecedented dynamic range of more than 3 orders of magnitude. Such measurements are important for understanding collective effects in laser-matter interactions on femtosecond time scales, opening new routes for the development of schemes for their ultrafast control.