  Most formation scenarios of globular clusters assume a molecular cloud as the
progenitor of the stellar system. However, it is still unclear, how this cloud
is transformed into a star cluster, i.e. how the destructive processes related
to gas removal or low star formation efficiency can be avoided. Here a scheme
of supernova (SN) induced cluster formation is studied. According to this
scenario an expanding SN shell accumulates the mass of the cloud. This is
accompanied by fragmentation resulting in star formation in the shell. Provided
the stellar shell expands sufficiently slow, its self-gravity stops the
expansion and the shell recollapses, by this forming a stellar system.
  I present N-body simulations of collapsing shells which move in a galactic
potential on circular and elliptic orbits. It is shown that typical shells
(10^5 Msun, 30 pc) evolve to twin clusters over a large range of galactocentric
distances. Outside this range single stellar systems are formed, whereas at
small galactocentric distances the shells are tidally disrupted. In that case
many small fragments formed during the collapse survive as single bound
entities. About 1/3 of the twin cluster systems formed on circular orbits merge
within 400 Myr. On elliptic orbits the merger rate reduces to less than 4%.
Thus, there could be a significant number of twin clusters even in our Galaxy,
which, however, might be undetected as twins due to a large phase shift on
their common orbit.
