CESR Focusing Magnets

The electron and positron beams are focused at the interaction point by a series of magnets just outside and inside the CLEO II detector. Focusing the beams down to a small cross section increases the particle density at the interaction point, increasing the chances that a collision and annihilation will occur. The picture above shows the face of the CLEO II detector partially disassembled, with the endcaps partially rolled out of the detector. The blue objects in the left-hand side of the picture are solendoidal quadropole focusing magnets that are the first stage of the interaction point beam focusing. After the beams passes through the solenoidal quads, they are further focused by rare-earth magnets that surround the beam pipe part of the way inside the CLEO II detector.

The red cylinder in front of the quads is one of the Crystal Calorimeter Endcaps. The tubes ringing the opening are light pipes for the time of flight system.