Beamed neutron emission driven by laser accelerated light ions

摘要

Highly anisotropic, beam-like neutron emission with peak flux of the order of109 n/sr was obtained from light nuclei reactions in a pitcher-catcher scenario, by employing MeV ions driven by sub-petawatt laser. The spatial prole of the neutron beam, fully captured for the first time by employing a CR39 nuclear track detector, shows a FWHM divergence angle of ∼70°, with a peak flux nearly an order of magnitude higher than the isotropic component elsewhere. The observed beamed flux of neutrons is highly favourable for a wide range of applications, and indeed for further transport and moderation to thermal energies.  A systematic study employing various combinations of pitcher-catcher materials indicates the dominant reactions being d(p,n+p)1H and d(d,n)3He. Albeit in sufficient cross-section data are available for modelling, the observed anisotropy in the neutrons' spatial and spectral profiles are most likely related to the directionality and high energy of the projectile ions.