Studies of \Lambda \Lambda-double-hypernuclei and \Omega  -atoms by means of \gamma -ray spectroscopy with Ge detectors represent a unique tool to investigate YN and YY interaction and to measure the only directly observable quadrupole moment of a hadron. These challenging experiments will be performed by the PANDA collaboration (Proton ANtiproton at DArmstadt) at the High Energy Storage Ring (HESR) of the future GSI facility. For the \Lambda} \Lambda -double-hypernuclear \gamma -ray spectroscopy, a rate of several hundreds \gamma -ray events per day is expected.

PACS numbers: 21.80.+a, 25.43.+t, 29.30.Kv, 36.10.-k