maart 1912: radiumconferentie in Parijs

In March 1912, the committee met again in Paris to intercompare the Curie standard with three Vienna standards of RaCl2 prepared by Hönigschmid. The intercomparison was made by comparing the gamma-ray emission rates of the four samples. The Curie standard was stored at the Bureau International des Poids et Mesures (BIPM) in Sèvres in the Paris suburbs. Hönigschmid was then charged with preparing another set of standards for distribution to the metrology laboratories of several countries. The account of the U.S. national standard is best described in Noah Dorsey's own words:



The International Committee on Radium Standards also arranged for the preparation of standards for those governments that required them. These secondary standards are compared directly both with the International Standard in Paris and with the Vienna Standard.

http://physics.nist.gov/GenInt/Curie/1913.html