Operation Totem at Maralinga was held in September 1956, with the Operation Buffalo series. Operation Totem Operation Totem was a pair of British atmospheric nuclear tests which took place at Emu Field in South Australia on 15 October 1953. They followed the Operation Hurricane test of the first British atomic bomb, which had taken place at the Montebello Islands a year previously. The main purpose of the trial was to determine the acceptable limit on the amount of plutonium-240 which could be present in a bomb. In addition to the two main tests, there was a series of five subcritical tests. These
Atomic clock of using atomic transitions to measure time was suggested by Lord Kelvin in 1879. Magnetic resonance, developed in the 1930s by Isidor Rabi, became the practical method for doing this. In 1945, Rabi first publicly suggested that atomic beam magnetic resonance might be used as the basis of a clock. The first atomic clock was an ammonia absorption line device at 23870.1 MHz built in 1949 at the U.S. National Bureau of Standards (NBS, now NIST). It was less accurate than existing quartz clocks, but served to demonstrate the concept. The first accurate atomic clock, a caesium standard based on