Negative Electron Affinity Materials in Photomultipliers

Since their introduction as laboratory devices about five years ago, negative electron affinity (NEA) electron emitters have found many applications for low-light-level detection. Over forty types of photomultiplier tubes with NEA materials are now available for detection of light from the ultraviolet to the near infrared. These devices provide useful photosensitivity to 1.1 micrometers. The detectors which are currently available will be reviewed, and the prospects for the near future will be discussed. A general summary of the contribution of NEA materials to low-light-level detection will be included.