Fig. 7: Gamma spectrum.

Results of the gamma spectroscopy of the activated samples: a and c at 5^∘ (blue and orange spectra), b and d 15^∘ (red spectra) for the laser-target setup scenarios. The black spectrum in each panel represents the detector back ground spectrum. Blue and orange colors are used for different sequences of activation plates in the stack. The unequal count rate of the back ground between the panels (a), (c) and (b), (d) is caused by the differently HPGe detector stations with its own back ground shielding. Results are shown after subtraction of the detector background. An important indicator for signal differences between 5^∘ and 15^∘ is the pulse height of the annihilation line at 511 keV, because the most activated isotopes are β⁺-emitter.