ADIT Electron Tubes specializes in photomultipliers used in radiation detection and measurement devices with diameters ranging from 13 to 133 mm (0.5 to 5 in.). The ADIT product line of photomultiplier tubes (PMTs) is a descendant of products manufactured and developed by Space Research Corporation, Inc. (S.R.C.). S.R.C.’s assets were acquired by a private group that formed the ADIT Company. The name "ADIT" was chosen after one of the founders came across the word “adit” while looking for an alternative word for conduit, since he envisioned the company serving as “the conduit of PMTs to the market”. ADIT operated for several years in Fairfield, Connecticut, until it was acquired by Ludlum Measurements, Inc. in 1992. ADIT moved to its current location in Sweetwater, Texas in 1995.

After Ludlum Measurements acquired the UK-based photomultiplier manufacturer ET Enterprises, Ltd. (formerly Electron Tubes) in 2007, the ADIT name changed to ADIT Electron Tubes. The ET Enterprises acquisition also gave ADIT the benefit of the combined manufacturing and development capabilities of both facilities. ADIT Electron Tubes serves as the North American distributor of the Electron Tubes brand, and ET Enterprises serves as the distributor of the ADIT brand outside of North America.