Fig. 1. Schematic illustration of ⁶²Cu isotope production. Quasicollimated e⁻ beams are produced from the interaction of the intense laser beam with the gas jet, and energetic bremsstrahlung photons are then generated efficiently from the Ta target irradiated by the laser-plasma-accelerated e⁻ beams. ⁶²Cu isotope production is realized in the following stage by irradiating a centimeter-scale Cu target with high-energy bremsstrahlung photons, inducing possible photonuclear reactions. A 2-mm-thick Ta plate is placed 2 cm downstream of the gas jet.

Fig. 2. Spatial profiles of the electron density at (a) t = 15T₀, (b) 20T₀, (c) 40T₀, and (d) 60T₀. A plasma density of n_e= 0.5n_c was used in the simulations.

Fig. 3. (a) Energy spectra of accelerated e⁻ beams as functions of the density of the NCD plasma. (b) Transverse profile of e⁻ beam recorded on the front surface of the Ta convertor. The plasma density is set to 0.5n_c, and the transport distance of the e⁻ beam from the accelerator exit to the front surface of the Ta converter is 2 cm.

Fig. 4. Electric charge of high-energy electrons as a function of the plasma density.

Fig. 5. Bremsstrahlung spectra for different plasma densities, together with the cross section on ^63,65Cu(γ, n) reactions.³⁰ The radius and thickness of the Ta convertors are set to 2 cm and 2 mm, respectively.

Fig. 6. Total production rate of ^62,64Cu isotopes as a function of the thickness of the activation target for different convertors. The plasma density is set to 0.5n_c.

Fig. 7. Projected distributions of product nuclei ^62,64Cu in the xy and xz planes.

Fig. 8. Production and detection yields of ^62,64Cu isotopes as functions of the thickness of the activation target.

Fig. 9. Induced activities of ^62,64Cu isotopes for a wide range of plasma density. The activity during the cooling time is also shown as indicated. The radius and thickness of the activation target used in the simulations are both 20 mm.

Fig. 10. Simulated and measured activities of a few PET isotopes as a function of laser irradiance. The laser specifications for the RAL measurements are given in Ref. 21. For comparison, all data are given for a laser repetition rate of 10 Hz.