Method and arrangement for fixing a piston, or a piston rod attachment, to a piston rod, one of the piston and the piston rod having a hole running in its axial direction, and the other of these having a portion designed for being received by the hole for connection of the piston and the piston rod. The utensil has a pair of pivoting spring-loaded arms each having a forward functional end and a rear attachment end. Each of the end members is comprised of a truss having an upper wire and a lower wire. The pull-up length of the silicon single crystal in which nitrogen is doped at a high concentration can be increased.