Resonance photoproduction of pionic atoms at the proposed Gamma Factory

We present a possibility of direct resonance production of pionic atoms (Coulomb bound states of a negative pion and a nucleus) with a rate of up to $\approx {10}^{10}$ per second using the gamma-ray beams from the Gamma Factory.

Figure 1

Resonant cross section ${\sigma }_0$ for producing $ns$ pionic states with final nuclei with $9\le Z\le 92$.

Figure 2

Width ratio ${\mathrm{\Gamma }}_{\gamma }/{\mathrm{\Gamma }}_{\mathrm{tot}}$ (multiplied by ${10}^3$) of $ns$ pionic states with final nuclei with $9\le Z\le 92$.

Figure 3

Partial width ${\mathrm{\Gamma }}_{\gamma }$ of the $1s$ pionic state with final nuclei with $9\le Z\le 92$.

Figure 4

Fitting of $1s$ width data from Refs. [8, 36] shown as red dots on the graph. When width data for different isotopes with the same atomic number $Z$ are given, the average value of the widths is used for the fitting. Data for ${}^{40}\mathrm{Ca}$ and ${}^{90}\mathrm{Zr}$ are from Ref. [33]. $1s$ width for ${}^4\mathrm{He}$ is from Ref. [34]. The yellow curve and blue curve represent Eqs. (18) and (19), respectively.