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kalee20 · 26th Dec 2007, 6:16 pm

I'm a bit puzzled here! If you build a caesium beam frequency standard, why does it need a calibration certificate? The whole idea of SI units is that they are defined so that they can be re-created anywhere. And the second is defined in terms of the frequency emitted from an excited caesium atom.

So, a frequency standard derived from a caesium beam, is by definition correct.

26th Dec 2007, 6:16 pm	#18
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,081	Re: Frequency Standards I'm a bit puzzled here! If you build a caesium beam frequency standard, why does it need a calibration certificate? The whole idea of SI units is that they are defined so that they can be re-created anywhere. And the second is defined in terms of the frequency emitted from an excited caesium atom. So, a frequency standard derived from a caesium beam, is by definition correct.