[DOC] [TLE] Second - Wikipedia [PAR] The second (symbol: s) (abbreviated s or sec) is the base unit of time in the 
International System of Units (SI). It is qualitatively defined as the second division 
of the hour by sixty, the first division by sixty being the minute. SI definition of 
second is "the duration of 9 192 631 770 periods of the radiation ... In 1997 CIPM 
added that the periods would be defined for a caesium atom at... [DOC] [TLE] Why is a second defined as 'the duration of 9,192,631,770 periods of ... [PAR] In 1895, the astronomer Simon Newcomb published his "Tables of the Sun," 
based on ... Time (physics)  Science  Physics. Why is a second defined as "the 
duration of 9,192,631,770 periods of the radiation corresponding to the transition 
between the two hyperfine levels of the ground state of the caesium 133 atom."? [DOC] [TLE] cesium atomic clocks - Time Service Department [PAR] The 1955 Cesium Atomic Clock at the National Physical Laboratory, UK. ... 
metallic element cesium, in particular its isotope of atomic weight 133 ("Cs-133"). 
... 9,192,631,770 hertz (Hz = cycles/second), provides the fundamental unit of 
time, .... In 1967, the 13th General Conference on Weights and Measures first 
defined the... [DOC] [TLE] Base unit definitions: Second [PAR] The unit of time, the second, was defined originally as the fraction 1/86 400 of the 
... the 13th CGPM (1967) decided to replace the definition of the second by the 
following ... The second is the duration of 9 192 631 770 periods of the radiation 
... between the two hyperfine levels of the ground state of the cesium 133 atom. [DOC] [TLE] How does one arrive at the exact number of cycles of radiation a ... [PAR] At its 13th official meeting in 1967, the committee adopted the following definition: "The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom." [DOC] [TLE] Atomic Clocks - HyperPhysics [PAR] 1 second = 9,192, 631,770 cycles of the standard Cs-133 transition ... In 1967 a 
standard second was adopted based on the frequency of a transition in the Cs-
133 ... The SI unit of time, the second, is now defined by this transition in cesium. [DOC] [TLE] time - Why is a second equal to the duration of exactly ... [PAR] It's a definition of a unit, which is an arbitrary choice. ... The currently accepted 
definition is as "9192631770 cycles of the radiation corresponding to ... than 
those one can build with cesium atoms and so it can be expected that the 
definition will .... so in 1967 the definition of a second was changed to be based 
on cesium 133. [DOC] [TLE] second | unit of time | Britannica.com [PAR] The second was formerly defined as 1/86,400 of the mean solar dayi.e., ... 
defined the second as 9,192,631,770 cycles of radiation associated with the ... 
hyperfine levels of the ground state of the cesium-133 atom (see atomic time). ... 
NIST-F1 cesium fountain atomic clock, the primary time and frequency standard 
for the. [DOC] [TLE] Atomic Clock [PAR] Astronomers use atomic clocks to measure the amazingly regular cycles of ... The 
cesium-atom clock is used to define the second, the basic unit of time of the ... 
Units. In this clock, cesium-133 atoms in one hyperfine energy state are 
subjected to ... The second is defined as the duration of 9,192,631,770 periods of 
radiation. [DOC] [TLE] How Does an Atomic Clock Work? - Live Science [PAR] Jun 21, 2010 ... Atomic clocks are a bit more accurate than counting, "one Mississippi, two 
Mississippi...". ... NIST-F1, the nation's primary time and frequency standard, ... 
Since 1967, the official definition of a second is 9,192,631,770 cycles of the 
radiation ... Inside a cesium atomic clock, cesium atoms are funneled down a... [DOC] [TLE] Atomic Clocks, Accuracy, and (Re)Defining the Second - worn&wound [PAR] Jun 14, 2016 ... Atomic clocks came about

Question: In 1967 this unit of time was defined as 9,192,631,770 cycles of radiation of a cesium-133 atom
Answer: the second