Zelda, there is a way to deter children and teenagers from congregating in the vicinity of your apartment.
A Welsh firm developed a device called the Mosquito. It emits a high-pitched sound only audible to the young. (Our ears just wouldn't hear it at all.) You place the device where gangs of youths gather, and they get irritated and move on.
http://www.compoundsecurity.co.uk/de...t_news_26.html
Actually, they normally just capture the sound as a mobile phone ringtone, which their teachers can't hear.
Here's a link to an mp3. I can't hear it.
http://www.npr.org/templates/story/s...toryId=5434687