Maybe dentention camp? Similiar to what was going on in Cuba in Miami? How about good old-fashion jails?
Also, what we have is not equally cruel (as you suggest) to facilities that are commonly known as concentration camps (again, associated with Nazi Germany), even in the slightest. I'm not approaching this as feeling better about innocent people dying or trying to quiet the conscious as children suffer or whatever it is your last sentence dreams up, but more from having actually spent a day walking among and seeing what concentration camps and extermination camps are and more importantly why they existed.
The camps at the border are in reaction to an event, they aren't a proactive and supporting resource. I'd argue Guantanomo Bay is more of a "Nazi Concnetration Camp" or "concentration camp" to those who want to cloak themselves in plausible deniability about the emotional manipulation of the term, than what's going on at the border.