Sciencemadness Discussion Board

Cs and atomic clock

allbatros - 8-11-2006 at 13:11

Do you know that the isotope Cs-137 used for atomick clock (the freuqency of Cs-137)?

What u think about Cs or other elements which used for atomic clock :)

12AX7 - 8-11-2006 at 13:57

137 is rather radioactive.

Cs (and to a lesser extent, Rb) are capable of making very accurate clocks yes.

Tim

Jdurg - 8-11-2006 at 14:46

Quote:
Originally posted by allbatros
Do you know that the isotope Cs-137 used for atomick clock (the freuqency of Cs-137)?

What u think about Cs or other elements which used for atomic clock :)

Just so you know, your statement there is well..... wrong. ;) The isotope of cesium used in atomic clocks is Cs-133 which is quite stable and not radioactive. The definition of the second is based upon a certain number of cycles of light absorbed by a Cs-133 atom and not Cs-137.

Twospoons - 8-11-2006 at 16:51

Typical accuracy is in the region of 1 part in 10^14 for Cs clocks.
Best quartz oscillator I could produce while working at Rakon was accurate to 2 in 10^11 (over -30C to +70C). Rubidium clocks are around 1 in 10^13 IIRC.

allbatros - 9-11-2006 at 05:46

In first half of this year, I think it was in Physical Review, scientist built the more precise atomic clock of the only one atom Hg. His accuaracy is 1 s delay in 400 * 10<sup>6</sub>.

And yes u right, Cs-133 :)

My mistake :D :P

_1v4_ - 9-12-2006 at 05:45

Ofc I knew :) Cs-133 is used because of his frequency (9,192,631,770Hz).
The time unit, second, is defined as "the duration of 9,192,631,770 cycles of microwave light absorbed or emitted by the hyperfine transition of cesium-133 atoms in their ground state undisturbed by external fields".
It is used 'cause its verry accurate (one second in 1,400,000 years, if I recall it correctly?).