Ultrafast laser-driven microlens to focus and energy-select mega-electron volt protons.

We present a technique for simultaneous focusing and energy selection of high-current, mega-electron volt proton beams with the use of radial, transient electric fields (10(7) to 10(10) volts per meter) triggered on the inner walls of a hollow microcylinder by an intense subpicosecond laser pulse. Because of the transient nature of the focusing fields, the proposed method allows selection of a desired range out of the spectrum of the polyenergetic proton beam. This technique addresses current drawbacks of laser-accelerated proton beams, such as their broad spectrum and divergence at the source.

Practicability of protontherapy using compact laser systems.

Protontherapy is a well-established approach to treat cancer due to the favorable ballistic properties of proton beams. Nevertheless, this treatment is today only possible with large scale accelerator facilities which are very difficult to install at existing hospitals. In this article we report on a new approach for proton acceleration up to energies within the therapeutic window between 60 and 200 MeV by using modern, high intensity and compact laser systems.

Self-diffusion and collective diffusion in a model viscoelastic system.

We use dynamic light scattering (DLS) and fluorescence recovery after pattern photobleaching (FRAPP) to investigate the dynamics of a model transient network made of an oil-in-water droplet microemulsion to which small amounts of a telechelic polymer are added. The DLS correlation functions exhibit three relaxation modes. The two first modes can be interpreted quantitatively in the frame of the classical De Gennes-Brochard theory of DLS in viscoelastic system.