Assertion: fountain atomic clock | /r/HasProperty | operated by metrology laboratories
Facets:
value: in france
type: LOCATION
value: in the united kingdom
type: LOCATION
value: in germany
type: LOCATION
value: in the united states
type: LOCATION
value: in italy
type: LOCATION
Source sentences:
text: Researchers compared data from 1999 to 2014 for a total of 12 clocks—four hydrogen masers (microwave lasers) in the NIST time scale with eight of the most accurate cesium fountain atomic clocks operated by metrology laboratories in the United States, the United Kingdom, France, Germany and Italy.