Ciro Santilli
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Atomic clock
...
Physics
System of units
List of systems of units
International System of Units
Time
Clock
OurBigBook.com
words: 247
articles: 1
Video 3
. How an atomic clock works, and its use in the global positioning system (GPS) by
EngineerGuy
(2012)
Source
. Shows how conceptually an atomic clock is based on a
feedback loop
of two
hyperfine structure
states of
caesium
atoms (non-
radioactive
caesium-133
as clarified by the
Wikipedia
page). Like a
quartz clock
, it also relies on the
piezoelectricity
of quartz, but unlike the
quartz clock
, the
quartz
is not shaped like a
tuning fork
, and has a much larger resonating frequency of about 7
MHz
. The feedback is completed by producing
photons
that
resonate
at the right frequency to excite the
caesium
.
Video 4
. Inside the
HP
5061A Cesium Clock by
CuriousMarc
(2020)
Source
.
A similar model was used in the
Hafele-Keating experiment
to test
special relativity
on two planes flying in opposite directions. Miniaturization was key.
Contains a disposable tube with 6g of
Caesium
. You boil it, so when it runs out, you change the tube, 40k USD. Their tube is made by
Agilent Technologies
, so a replacement since that opened in 1999, and the original machine is from the 60s.
Detection is done with an
electron multiplier
.
youtu.be/eOti3kKWX-c?t=1166
They compare it with their 100 dollar
GPS
disciplined oscillator, since
GPS
satellites
have
atomic clocks
in them.
Video 5
. Quick presentation of the
atomic clock
at the
National Physical Laboratory
(2010)
Source
. Their super accurate setup first does
laser cooling
on the
caesium
atoms.
Table of contents
247
1
Caesium standard (1967, 3.26 cm)
Atomic clock
58
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Clock
Time
International System of Units
List of systems of units
System of units
Physics
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