X-ray Dose and Spectrum Measurement in Intense Laser-irradiated Solid Target

To study the radiological hazards from intense laser-solid target interactions, a series of laser-target experiments were carried out on the XG Ⅲ 300 TW laser systems. The laser intensity is 5×10¹⁸-4×10¹⁹ W/cm² and the laser energy is 60-153 J. The target is Ta cylinder with thickness of 1 mm and diameter of 1 mm. The X-ray dose, X-ray spectrum, and hot electron spectrum were measured respectively. The results show that the X-ray dose up to 16.8 mSv is measured at 50 cm close to the laser propagation direction (0°). The X-ray dose at 0° increases significantly with the laser intensity, while the X-ray dose at 90° is less correlated to the laser intensity. The measured X-ray spectrum can be approximately described as an exponential distribution with two X-ray temperatures ranged from 0.4 to 1.15 MeV at 0° and from 0.25 to 0.54 MeV at 90°. The measured hot electron temperature is consistent with the predicted electron temperature by Wilks law.