Microstructure-Assisted Laser-Driven Photonuclear Pulsed Neutron Source

A scheme for a high-yield photonuclear pulsed neutron source is proposed by use of a relativistic femtosecond laser interacting with a microstructure target combined with a high-$Z$ converter. By using three-dimensional particle-in-cell and Monte Carlo simulations, we find that bright $\ensuremath{\gamma}$ rays are emitted by bremsstrahlung radiation when energetic dense electron bunches pulled out from the microstructure target pass through the converter. A large number of neutrons are thus induced via photonuclear reactions. With a laser of intensity of approximately $3.4\ifmmode\times\else\texttimes\fi{}{10}^{21}\phantom{\rule{0.2em}{0ex}}{\mathrm{W/cm}}^{2}$ and energy of approximately $6.2$ J, a neutron pulse of yield as high as $1.9\ifmmode\times\else\texttimes\fi{}{10}^{8}\phantom{\rule{0.1em}{0ex}}{\mathrm{J}}^{\ensuremath{-}1}$ and duration of approximately $45$ ps can be obtained. This scheme could be realized in laboratories with current multipetawatt laser facilities.