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Due to the extreme experimental conditions encountered, the Laser Mégajoule facility (LMJ) needs to develop and characterize new organic scintillators with unseen features: a fast decay time, in the order of one nanosecond with almost no afterglow, and an emission wavelength in the red region, typically more than 600 nm. Thus, various compositions have been evaluated, prepared and tested. The materials are composed of a matrix (either liquid or plastic) embedding two fluorophores and a light quencher. Time-Correlated Single Photon Counting was used to assess the main criteria of the materials, which is their photoluminescence decay. In the liquid state, ultra-fast materials were successfully prepared. One liquid scintillator formulation showed the following characteristics: an emission wavelength > 600 nm, a mean decay time of 0.84 ns with a FWHM pulse width of 1.92 ns. In the plastic state the preparation was less straightforward. A plastic scintillator with emission wavelength > 600 nm, a decay time < 7 ns with a FWHM of 8.60 ns was obtained. We have verified that the best plastic sample does not present any afterglow. A light yield around 200 ph/MeV has been estimated from relative radioluminescence measurements, this value being around 4 times lower than the BC-422Q 2%, quenched plastic scintillator. [ABSTRACT FROM AUTHOR]

Abstract: The French Commissariat à l’Energie Atomique (CEA) began the construction of the Laser Megajoule (LMJ), a 240 beams laser facility, at the CEA Laboratory CESTA near Bordeaux. The LMJ will be a cornerstone of the CEA “Programme Simulation”, similar to LLNL “NIF” facility. The LMJ is designed to deliver 2MJ of 0.35μm light to targets for high energy density physics experiments and to ultimately obtain ignition and propagating burn with DT targets in the laboratory. The scientific conception and system design was completed in 1999 and was followed by the Demonstration of an Engineering Prototype which was achieved in early 2003 with operation of one beam of the Ligne d’Intégration Laser (LIL) at CESTA, with 9.5kJ of UV light (0.35μm) in less than 9ns from a single laser beam. The construction phase of the LMJ facility was initiated in March 2003 with the start of work on the building and the target chamber. This paper will present a summary of 2004 LIL results and a description of LMJ, which is expected to demonstrate first light performance through 240 beams by 2009. [Copyright &y& Elsevier]

The Laser Megajoule (LMJ) is a facility dedicated to inertial confinement fusion experiments. Building construction phase should start in the first half of year 2003. Use of a deuterium–tritium mixture in the experiments and high neutron yield generation induces hazards such as contamination of equipments inside the target chamber and activation of materials. Calculations have been undertaken to estimate dose rates levels in the facility. Optimization is under development on ALARA principle basis to reduce activation and workers exposure. Decontamination is an other important safety issue for LMJ; different processes are available and have to be considered (lasers, foams …). Radioactive wastes will be generated and their disposal has to be taken into account. [Copyright &y& Elsevier]

Abstract: The first experiments on the National Ignition Facility (NIF) in the US started and will be followed by the Laser MégaJoule (LMJ) in France. Such facilities will provide unique tools for inertial confinement fusion (ICF) physics & for basic science. A petawatt short pulse laser (ps) is being added to the ns pulse beams of the LMJ. This is PETAL (PETawatt Aquitaine Laser), under construction on the LMJ site near Bordeaux (France). The Petal+ project is aiming at the design and construction of diagnostics dedicated to experiments with PETAL and LMJ laser beams. Within Petal+, three types of diagnostics are under study: a proton spectrometer, an electron spectrometer and a large-band X-ray spectrometer. The first goal of these diagnostics will be to characterize the secondary radiation and particle sources produced with PETAL. They will also be used for experiments using both ns and ps beams. In the present paper emphasis is put on the charged-particle diagnostics. [Copyright &y& Elsevier]