Each justice of the district court retired therefrom by age limitation who has served on such court shall upon retirement become a referee. Such referees shall be empowered and may be assigned to act as such in the district courts, and their powers and the procedures for hearings before them shall be determined by statute or rule of court. Such referees shall be allowed their expenses and a per diem compensation determined by the supreme court upon recommendation by the judicial branch administrative council, established pursuant to supreme court rule.