Characterizing laser-based MeV radiographic capability at NIF-ARC.*

X-ray radiography of high-areal density objects is desirable for many applications. During high-energy laser-solid interactions (\textgreater 1 x 10$^{\mathrm{18}}$ W/cm$^{\mathrm{2}})$, a population of hot-electrons are accelerated to mega-electron volt energies. Injecting this population into a high-Z, high-density converter creates a similarly high-energy x-ray beam via bremsstrahlung. These x-rays have been shown to have a small source size (100s $\mu $m), high dose (several Rad) and high temperature (\textgreater 1 MeV)[1]. We've performed experiments on NIF-ARC to benchmark the photon spectra. Diagnosing the x-ray spectrum in this regime is difficult due to low interaction cross sections. We have used a suite of complimentary diagnostics, such as photo-nuclear activation and absorption spectrometers, to reconstruct the spectrum. These experiments at NIF ARC have shown that the temperature of these x-rays is on the order of several MeV.