The Summary of Experimental Results on the Observation of a Gamma Resonance of the Long-Lived Isomer AG-109m

Abstract

The data obtained in 11 experiments performed up to now with gamma sources made of silver metal doped by $^109$Cd show that there is no large broadening of $^109m$Ag M\"ossbauer gamma line with energy of 88.03 keV, that is the theoretically predicted gamma line broadening by $\sim 10^5$ times as compared with a natural width via the dipole-dipole interaction of nuclear magnetic moments is absent. The designed in ITEP instrument of quite new type - so called "gravitational gamma spectrometer" permitted to observe the form of $^109m$Ag gamma resonance which turned out to be $\sim 10^8$ times narrower than that of well known nuclide $^57$Fe. Some ideas are discussed as an attempt to explain this situation.