Induced depletion of $^{108m}$Ag with 6 MeV bremsstrahlung

The nuclide $^{108}$Ag possesses an interesting combination of a long-lived isomer (T$_{1/2 }$= 418 years, I$^{\pi }$ = 6$^{+}$, E = 109 keV) and a short-lived ground state (T$_{1/2}$ = 2.37 minutes, I$^{\pi }$ = 1$^{+})$. The ground state decays primarily by $\beta ^{-}$ emission with Q$_{\beta -}$ = 1,649 keV. A search of the available nuclear data (e. g., ENSDF and Phys. Rev. C 52, 104 (1995)) suggests two possible transitions at energies below 500 keV from the isomer to higher-lying levels, whose subsequent decay can branch to the ground state. This process would lead to a partial depletion of any population trapped within the isomeric state, $^{108m}$Ag. Currently, the cross section for induced isomer depletion via these transitions cannot be accurately deduced due to unknown branching ratios, and level widths and spins. Other ``depletion'' levels requiring excitation $>$ 500 keV are also likely. An experimental test of $^{108m}$Ag depletion has been performed using 6 MeV bremsstrahlung at the US Army Research Laboratory, with isomeric targets and a computer-controlled repetitive measurement system. The design of the system and experimental results will be discussed.