[hibernate-users] When does reattachment occur?

So, if I have the following scenario when using Ehcache. open session a load object a using criteria query close session a open session b load object a using criteria query (2nd level cache hit) close session b Can anybody tell me is explicit reattachment necessary or is the object attached to session b when it's loaded even when it comes out of ehcache and what put it in ehcache is the earlier session a.