A multi-Petawatt high-energy laser PETAL coupled to the Ligne d'Intégration Laser (LIL) is under construction in the Aquitaine Region in France. This Petawatt laser will be dedicated to academic experiments in the fields of high energy density physics and ultra high intensity. Nd : glass laser chain coupled with the chirped pulse amplification (CPA technique allows delivery of high energy. Optical parametric CPA for pre-amplification and a new compression scheme will be implemented. PETAL is designed to deliver 3.6 kJ of energy in 500 fs on a target corresponding to 7.2 PW. The PETAL beam linked to the up to 60 kJ ns UV beams from the LIL will present new scientific research opportunities.

Ultrafast transient voltage pulses (rise time 12 ps, width 29 ps) have been observed at 50 K across a current-biased very thin YBa2Cu3O7−x epitaxial film (thickness 30 nm) when illuminated by short laser pulses. The accuracy of the present measures shows the system reaction during the first tens of picoseconds. Such very narrow photosignals can be described as related to nonequilibrium phenomena. The measured decay times corroborate the biexponential escape of the deposited energy described by other authors.

Type Ila diamonds present photoconductive properties as well in X-ray detection range, as in near UV, visible, IR light range, in spite of the large bandgap of the material. Experimental results in these four fields, time measurements in picosecond and subpicosecond ranges are presented. I -INTRODUCTIONDiamond photoconductive detectors have already been used to measure the burn time on laser fusion experiments [1] [2]. They can also be devoted to measure X-ray radiation emitted from laser induced plasmas [31 [41 . Due to the 5.5 eV band gap of diamond intrinsic conductivity, we can expect they will not be sensitive to scattered laser radiation. Unfortunately, natural diamond presents a lot of impurities and its conductivity is nonnegligible for photon energies below the intrinsic band gap. One of the aims of this paper is to present the diamond sensitivities to 1064 nm (co), 532 nm (2 o)) and 355 nm (3 co) laser radiation wavelengths and to compare them with the X-ray radiation sensitivity. Another is to show the fast temporal response of such detectors. -DETECTOR DESIGN -GeometryPhotoconductive devices have been fabricated from Ila natural diamond (Dricker International Netherlands). They consist of two different sizes small cylinders : 3 mm diameter by 2 mm height for the first one and 5 mm in diameter by 3 mm high for the second one. They have been set by LETI (CEA, Grenoble, France) at the end of a 50 0l KS 2 or KS 3 semi rigid coaxial cable.as shown on Figure 1. Top and bottom electrodes are made of Ti/Pt/Au coating. This geometry is not so convenient to measure X-ray radiation but these detectors were previously designed for neutron measurement [2].The electrodes are realized on the plane faces of the crystal . The upper electrode is connected to the outer conductor of the coaxial cable and the bottom electrode to its inner conductor. To allow the input of the laser light or the X-ray radiation, a 1mm wide slit is made in the cable outerdacket, along the diamond crystal thickness. The detector bandwidth depends on the carrier life times and its capacity, LETI calculations [5] predict capacity values of 0.2 pf and 0.36 pf (figure 2) for KS2 and KS3 cable geometries.The corresponding risetime values x are respectively 22 ps and 40 ps (with Mat.

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