If there are two people in the hand. It goes to where you have to show your cards and the caller shows second but he doesn't choose to show cause he lost and throws them in the muck. Does the raiser have the right to see those cards he mucked if he asks the dealer ??
Depends on where you play. 20 years ago a caller had the right to see any called hand was pretty much the standard rule in any poker room. This rule is changing in many locations. You don't necessarily have a right to see a hand, and a floor person must be called to make a ruling rather or not you can see the hand.
You really need to ask what the rule is were you play.
The traditional rule is that if it is the apparent winner of the hand who asks to see the loser's hand, then the dealer may show the hand and it is live, that is, the player asks to see the hand at his own risk. If, say, a third or fourth player who called to the river asks to see the hand, then the dealer should pick up the hand, touch it to the muck to emphasize that it is a dead hand, and then show it.
Many casinos nowadays are putting further restrictions on the right to see a called hand. Some going much too far, in my opinion. I don't personally believe that a player has any right to muck a called hand with the expectation of privacy. If his opponents paid to see it, their right comes first.