The use of silicon photodiodes for x-ray diagnostics in the PALS plasma experiments

Silicon photodiodes of different types were tested for the possibility of measurement of high-intensity x-ray pulses from the plasmas produced by the 1 kJ PALS laser system in Prague. The x-ray energy range of the operation of the detectors was 1–20 keV. The tests were done with the use of different targets at the laser energy up to 740 J in the case of fundamental frequency (1ω, 1315 nm) and up to 230 J in the case of the 3rd harmonics (3ω). The detectors that were assigned for the measurement of the harder part of the spectrum (5–20 keV) can operate without overloading at all laser energies used, but the detectors for soft radiation can be easily overloaded above 200 J (at the fundamental frequency). Some problems with noise compatibility were encountered, as well. The possible improvements of detection systems for the future experiments are proposed. The detectors investigated in the experiment can be applied for finding the optimal condition for producing the hottest plasmas and for a precise calibration of the target positioning system.