Fig. 1. Partial nuclear chart around Zn and nuclear reactions with neutrons on a natural Zn target. Cu, Cu and Cu are produced by (n, p) reactions with high-energy neutrons on Zn, Zn and Zn, respectively. Cu, Cu and Cu are produced by (n, 2n) reactions on Zn, Zn and Zn, respectively. Cu and Cu are generated by (n, pn) reactions from Zn and Zn, respectively. High-energy neutrons could produce Ni by the Zn(n, )Ni reaction. Neutron capture also occurs.

Fig. 2. Experimental setup for the laser shot to generate neutrons. The laser is focused on the CD foil target. The Be neutron converter is placed 4 mm downstream of the CD foil. Behind the Be target, the Zn target was set in the hole at the center of the front surface.

Fig. 3. Fast neutron spectrum obtained from the TOF measurement. The neutron energies reached 17 MeV.

Fig. 4. -ray spectra measured for 120 h, 8.1 h, 5.1 h and 8 min. (a)–(c) The -ray spectra integrated for 120 h. The background signal measured for 99 h was normalized to the target measurement of 120 h. (d) The -ray spectrum measured for 8.1 h, where peaks corresponding to Zn^m are observed. (e) The -ray spectrum for 5.1 h, where peaks for Ni are observed. (f) The -ray spectrum for 8 min, which shows the Cu^m peak at 526 keV.

Fig. 5. Cross sections used in the simulation calculation, which are taken from the JENDL-4.0 nuclear data library.

Fig. 6. Geometry of the calculation of the yield of Cu using a laser for an optimized target system. (a) Cross-sectional view of the Be and Zn target. (b) 3D image of the target.

Table 1. Produced nuclides and their half-lives, -ray energies, emission probabilities of the -rays, nuclear reactions, numbers and activities.

Table 2. Experimental activities, calculated activities and their ratio of the obtained activities in the present experiment. The calculated activities were obtained using the PHITS simulation code with the measured neutron energy spectrum.