Neutron production by fast protons from ultraintense laser-plasma interactions

Abstract

Tens of MeV proton beams have been generated by interactions of the VULCAN petawatt laser with foil targets and used to induce nuclear reactions in zinc and boron samples. The numbers of C11, Ga66, Ga67, Ga68, Cu61, Zn62, Zn63, and Zn69m nuclei have been measured and used to determine the proton energy spectrum. It is known that (p,n) reactions provide an important method for producing neutron sources and in the present experiment up to ∼109neutronssr−1 have been generated via B11(p,n)C11 reactions. Using experimentally determined proton energy spectra, the production of neutrons via (p,n) reactions in various targets has been simulated, to quantify neutron pulse intensities and energy spectra. It has been shown that as high as 4×109neutronssr−1 per laser pulse can be generated via Li7(p,n)B7 reactions using the present VULCAN petawatt laser-pulse conditions.