Neutron Source from (γ,<i>n</i>) Reactions at a Laser-Plasma Accelerator and Its Use for Electron Beam Characterization

Abstract

Development of compact laboratory-scale neutron sources is of importance both for fundamental physical research and practical applications (for example, neutron radiography and spectroscopy). One of the most promising approaches to the development of such a source is the implementation of laser-plasma accelerated electrons or ions, and the subsequent initiation of nuclear reactions (γ,n), (p,n) or (d,n) with the emission of neutrons. In the present work, a neutron source produced via photodisintegration reactions (γ,n) using an electron beam from a one TW laser-plasma accelerator has been created and characterized. Maximum observed neutron flux was ~105 neutrons/s · srad with a ~106 neutrons per J of laser radiation efficiency. With constant efficiency and 10 times increase in the laser pulse energy the neutron flux will be sufficient for certain applications. Numerical Monte-Carlo simulations of neutron generation by an electron beam with parameters corresponding to those measured experimentally were also carried out. It was demonstrated that the number of generated neutrons can be used to estimate the charge and average energy of accelerated electrons. The obtained values are in good agreement with the values measured by the standard beam diagnostic tools.