Product Code: ILSC2011_503

Analysis and Mitigation Of X-Ray Hazard Generated From High Intensity Laser-Target Interactions
Authors:
R. Qiu, SLAC National Accelerator Laboratory; - USA
J. C. Liu, SLAC National Accelerator Laboratory; Menlo Park
A. A. Prinz, SLAC National Accelerator Laboratory; Menlo Park
S. H. Rokni, SLAC National Accelerator Laboratory; Menlo Park USA
M. Woods, SLAC National Accelerator Laboratory; Menlo Park CA USA
Z. Xia, SLAC National Accelerator Laboratory; Menlo Park CA USA
Presented at ILSC 2011

Interaction of high intensity laser with matter may generate ionization radiation hazard. However, very limited studies have been made on the laser induced radiation protection issue.
In this work, literatures of the physics and characteristics of laser-induced X-ray hazard such as laser-to-electron conversion efficiency, electron angular distribution, electron energy spectrum, and electron temperature are reviewed and summarized. The parameters of laser systems considered at the Matter in Extreme Conditions Instrument of LCLS (peak 4 TW, 4x1018 W/cm2 for current phase and 100 TW, 1020 W/cm2 for potential upgrade) are used as examples in the analysis. The dose is estimated based on both the measurement results and analytical formula found in the literatures, which agree within a factor of 2. Detailed shielding calculation is performed for different shielding material such as concrete, lead, stainless steel and aluminum with FLUKA.
The impacts of the laser pre-pulse effects and the use of a gas target are not well known, but may increase the X-ray energy and dose significantly. They are also discussed based on the current understanding. A reasonably conservative approach with a combination of engineered and administrative controls is proposed to mitigate the laser induced radiation hazard.