Can I know who up/down votes my answers/comments? If yes, how to check it? If no, could you make it possible?
Even the community moderators can't see that. But it is registered in the database, and the CMs (community managers, SE employee) can. They register even the ips of the votes.
There are multiple watching/alarming mechanisms, used mainly against various misuses (like voting fraud using sock-puppets or so).