sentences:  Rockwell International's Science Center had previously announced the "Solid-State Photomultiplier" (SSPM), a wide-band (0.4-28 µm) detector.In the late 1980s a collaboration - initially consisting of Rockwell and UCLA - began developing scintillating-fiber particle trackers for use on the Superconducting Super Collider, based on an dedicated variant of the SSPM that came to be known as the Visible Light Photon Counter.The operating principles are similar to APDs but based on impurity band conduction - the devices are made from arsenic-doped silicon and have an impurity band 50 meV below the conduction band, resulting in a gain of 40 000 to 80 000 at a bias voltage of a few volts (e.g.