In a recent experimental campaign, we used laser-accelerated relativistic hot electrons to ensure heating of thin titanium wire targets up to a warm dense matter (WDM) state EPL114, 45002 ...(2016)10.1209/0295-5075/114/45002. The WDM temperature profiles along several hundred microns of the wire were inferred by using spatially resolved X-ray emission spectroscopy looking at the Ti K
characteristic lines. A maximum temperature of ∼30 eV was reached. Our study extends this work by discussing the influence of the laser parameters on temperature profiles and the optimisation of WDM wire-based generation. The depth of wire heating may reach several hundreds of microns and it is proven to be strictly dependent on the laser intensity. At the same time, it is quantitatively demonstrated that the maximum WDM temperature doesn't appear to be sensitive to the laser intensity and mainly depends on the deposited laser energy considering ranges of 6×10
-6×10
W/cm
and 50-200 J.
Taking benefit of the R3B/SOFIA setup to measure the mass and the nuclear charge of both fission fragments in coincidence with the total prompt-neutron multiplicity, the scission configurations are ...inferred along the thorium chain, from the asymmetric fission in the heavier isotopes to the symmetric fission in the neutron-deficient thorium. Against all expectations, the symmetric scission in the light thorium isotopes shows a compact configuration, which is in total contrast to what is known in the fission of the heavier thorium isotopes and heavier actinides. This new main symmetric scission mode is characterized by a significant drop in deformation energy of the fission fragments of about 19 MeV, compared to the well-known symmetric scission in the uranium-plutonium region.
We report a laser-plasma experiment that was carried out at the LMJ-PETAL facility and realized the first magnetized, turbulent, supersonic ( Maturb ≈ 2.5 ) plasma with a large magnetic Reynolds ...number ( Rm ≈ 45 ) in the laboratory. Initial seed magnetic fields were amplified, but only moderately so, and did not become dynamically significant. A notable absence of magnetic energy at scales smaller than the outer scale of the turbulent cascade was also observed. Our results support the notion that moderately supersonic, low-magnetic-Prandtl-number plasma turbulence is inefficient at amplifying magnetic fields compared to its subsonic, incompressible counterpart.
X-ray phase contrast imaging (XPCI) is more sensitive to density variations than X-ray absorption radiography, which is a crucial advantage when imaging weakly-absorbing, low-Z materials, or steep ...density gradients in matter under extreme conditions. Here, we describe the application of a polychromatic X-ray laser-plasma source (duration ~0.5 ps, photon energy >1 keV) to the study of a laser-driven shock travelling in plastic material. The XPCI technique allows for a clear identification of the shock front as well as of small-scale features present during the interaction. Quantitative analysis of the compressed object is achieved using a density map reconstructed from the experimental data.
The inverse kinematics technique, applied to radioactive beams and combined to the Coulomb excitation method, is a powerful tool to study low-energy fission. A novel experimental setup was developed ...within the R3B/SOFIA (Reactions with Relativistic Radioactive Beams/Studies On FIssion with Aladin) collaboration to identify in mass and atomic numbers both fission fragments in coincidence. These new data provide elemental, isobaric, and isotonic yields for the fission along the thorium isotopic chain. Results are also compared to previous measurements using either the same reaction mechanism or thermal-neutron induced fission. This latter comparison permits to probe the influence of the excitation energy in the fission process.
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