Use php to trigger another php script, then ignore

What I'm trying to work out how to do is this: I've got a php file let's call trigger.php that runs some php code that sets off another php file we'll call backgroundProcess.php to start processing.

Although trigger.php needs to ignore what happens to backgroundProcess.php, it just has to start it processing and it will stop while backgroundProcess.php keeps going.

edit1

I'm running this on Windows Wampserver 2.1 So this has to be a windows command.

edit2

Solved it with the following command, thanks to jakenoble's suggestions:

exec("C:\wamp\bin\php\phpVERSION_NUMBER\php.exe -f C:\wamp\www\path\to\backgroundProcess.php");