Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Migdall Responds



Alan L. Migdall


I thank Duane Jaecks for pointing out earlier origins of the first of the correlated photon metrology applications described in my article - absolute detector quantum efficiency. The work in these early references is helpful in putting the technique in a better historical context, although they do not use the high directionality of phase matching which greatly aids the application of the method.It is particularly interesting to follow the leads presented by Jaecks to even earlier times to a mention by N. Feather and J. V. Dunworth* of the possibility of observing coincidences visually in a scintillator initiated by two alpha particles emitted from the same nucleus.(* - Proc. of the Royal Soc. of London A 168 566-585 (1938))
Physics Today


absolute quantum efficiency, alpha particle, coincidence, correlated photons, measurement, phase matching


Migdall, A. (1999), Migdall Responds, Physics Today, [online], (Accessed April 20, 2024)
Created May 1, 1999, Updated February 19, 2017