[en] This accident prevention provision has come into force in August 1977 for a trial period to end on March 31, 1980, which has been prolonged up to the end of 1984. A new, revised version is under way. This provision has been set up so as to leave enough room for innovations of safety and plant engineers to be taken into account. (HP)

[en] The Sandia ACRR (a Hazard Category 2 Nuclear Reactor Facility) was defueled in June 1997 to modify the reactor core and control system to produce medical radioisotopes for the Department of Energy (DOE) Isotope Production Program. The DOE determined that an Operational Readiness Review (ORR) was required to confirm readiness to begin operations within the revised safety basis. This paper addresses the ORR Process, lessons learned from the Sandia and DOE ORRS of the ACRR, and the use of the ORR to confirm authorization basis implementation

[en] In_2S_3 thin films deposited using chemical methods always contain residual elements from the precursors, which modify their properties. As buffer layers in solar cells, the residual elements in the In_2S_3 layer affect the performance of these devices. The stoichiometry of In_2S_3 thin films deposited by spray ion layer gas reaction (ILGAR) was studied as a function of the residual Cl from InCl_3 precursor by varying the deposition parameters. The chemical formula was deduced from the elemental composition determined using Rutherford backscattering (RBS). Incomplete sulfurization of the precursor implies that residual Cl"− remains bonded to the In"3"+ ions while some occupy interstitial and/or antisite positions in the In_2S_3 matrix. This results in thin films with different stoichiometry, described by the formula In_4S_6_−_xCl_2_x_+_2_y. This changes the local bond configuration and geometry and underpins the influence of residual Cl on the physical properties of In_2S_3 thin films.

[en] The origin of the accident prevention regulation - ''Thermal Power Stations'' is attributable mainly to two tragic accidents. It has made organizational changes and interventions in the operational process necessary in thermal power stations. Emphasis is laid upon the consistent issue of written permits-to-work on plant components carrying a heating medium and operating under pressure and on written operating licences for the operation of boilers. The paper describes additional ways in which regulation influences the daily practices of the power station operator. Brief references is made to the draft of the revised regulation. (orig./HP)

[en] We present a time and space resolved emission spectroscopy technique that enables a full characterisation in three dimensions density of emitting species generated by femtosecond pulsed laser ablation. Applied to Al neutral atoms, it reveals a population that, at the lowest fluences used, can be roughly described by a half range Maxwell-Boltzmann function. This simple configuration evolves towards a more complex population as the energy density increases. Specificities connected to the measured emitted spectral rays are evidenced and taken into account

[en] We study the time of flight optical emission from titanium and tungsten nanosized particles, generated through femtosecond laser-matter interaction in vacuum, in the wavelength spectral range from 300 to 900 nm. Typical spectra consist of broadband structureless signals similar to black body emission from a macroscopic object. Nanoparticles temperature, deduced from their emission spectra, decreases drastically as a function of their time of arrival at a given distance from the target. This behaviour is seen to be independent of individual particle velocities

[en] We present a new nonlinear solid-state technique for temporal femtosecond pulses cleaning. This technique called cross-polarized wave generation (XPW) is a 4-wave mixing process governed by the anisotropy of the real part of the crystal third-order non-linearity tensor. Because this process is highly non-linear with the input intensity and varies as the cubic power of the intensity of the wave, XPW generation may be used to discriminate low intensity level parts of a sub-picosecond pulse (that is: prepulse, pulse background, time-dependant wings) from the pulse peak. When used between crossed-polarizers, XPW generation allows the system to reject the low-intensity parts of the pulse and therefore improves the temporal contrast of the intense laser pulse. We present the experimental XPW pulse filtering using a nonlinear crystal (BaF₂) in 2 different peta-watt front end lasers: a Ti:Sapphire amplifier at 800 nm and an optical parametric chirped pulse amplification system at 1057 nm. The contrast reaches 10^-10 for milli-joule input pulse. Efficiency is demonstrated at 800 nm and 1 μm. The method is reliable enough to solve the contrast issue for peta-watt class lasers

[en] One of the main bottlenecks for future peta-watt class ultra-short lasers is the temporal contrast of the pulses. In classical femtosecond laser chains, a nanosecond pedestal of amplified spontaneous emission and some parasitic pulses are generated at the same time as the femtosecond pulse. We present a new third-order non-linear solid-state cleaner for temporal femtosecond pulses. This filter is based on cross-polarized wave generation in non-linear crystals. The contrast reaches 10^-10 for milli-joule input pulse. The method is reliable enough to solve the contrast issue for peta-watt class lasers

[en] The use of a sequence of two ultra short light pulses enabled us to produce ions, neutrals and nanoparticles from a Ti metallic target and successively irradiate them. Efficient formation of nanoparticles was observed as well as their subsequent fragmentation into neutral atoms. The size distribution of the nanoparticles obeys a log-normal law, characterized by a statistical median diameter size of 70 nm. Measurements of their spectral emission provides information regarding their temperature

[en] Ultrashort terahertz pulses with energies in the μJ range can be generated with laser wakefield accelerators (LWFA), which are novel, compact accelerators that produce ultrashort electron bunches with energies up to 1 GeV and energy spreads of a few-percent. Laser pulses interacting with a plasma create accelerated electrons which upon exiting the plasma emit terahertz pulses via transition radiation. Because these electron bunches are ultrashort (<50 fs), they can radiate coherently (coherent transition radiation--CTR) in a wide bandwidth (∼1-10 THz) yielding high intensity terahertz pulses. In addition to providing a non-invasive bunch-length diagnostic and thus feedback for the LWFA, these high peak power THz pulses are suitable for high field (MV/cm) pump-probe experiments. Here we present energy-based measurements using a Golay cell and an electro-optic technique which were used to characterize these THz pulses.