As with any detector system, this needed both a medium which, was sensitive to the passage of particles and a method of amplifying the signal to produce a macroscopic effect (usually electronic). He found information on photomultipliers in a Radio Corporation of America catalogue and combined them with zinc sulphide scintillator to produce immediately a working detector. This was the first simple form of the modern scintillation counter.
Curran reported this invention to E O Lawrence, his boss, who ruled that instrumentation development took place in Chicago and not Berkeley, therefore, Curran must stop. The work was declared to be an official secret.
The secret status prevented Curran from discussing or working openly on this invention. The technique was gradually revealed by others and the work was declassified subsequently on Curran's request.