OK: HERES THE SOLUTION TO NOT HEARING YOUR ALARM GO OFF ON YOUR IPAD IN IOS 6:
Had the same problem with an alarm I set. All I got was a notification on my screen that read "Alarm". Not very helpful when you're asleep. Here's what I discovered. You actually have to toggle the volume up when you're setting the alarm. The volume of the alarm is not based on the main volume, but adheres to the specific volume value you set when you're setting the alarm. Here are the steps.
Go to the Alarm tab on the on Clock App.
Hit the + button to set a new alarm.
Set the time you want to wake up.
Then select the ringtone sound. (It's normally Marimba by defaut)
So hit the > button next to the ring tone next ot Marimba and select another ringtone.
It will play an example of that ringtone.
At that moment you want to hit the physical + volume button on the ipad and you'll hear the volume of the alarm go up.
Keep raising the volume to the level you think will wake you up.
Save the alarm.
Now when your alarm goes off in the morning you'll actually wake up.
I know. It's totally unitiutive. Apple needs to fix it.