[DOC] [TLE] Caesium: A brief history of timekeeping - BBC News - BBC.com [PAR] Oct 4, 2014 ... Caesium is the chemical element that has literally redefined time. ... That all 
began to change with the world's first railways, here in the UK. ... Quartz clocks 
exploit the fact that quartz crystals vibrate at a very high ... His first atomic clock 
created at NPL in 1955 was accurate to one second in 1.4 million years. [DOC] [TLE] Introducing the World's Most Precise Clock - IEEE Spectrum [PAR] Sep 30, 2014 ... At bottom is one of two modern optical-lattice clocks that have been built at the 
Paris ... A new generation of atomic clocks that use laser light instead of ... These 
surpassed the accuracy of cesium clocks by a full order of magnitude. ... other 
frequency sources, such as hydrogen masers and quartz clocks. [DOC] [TLE] 5 of the Most Precise Clocks Ever Made - Live Science [PAR] Mar 20, 2015 ... Here are some of the most accurate clocks ever built, from one that relies on 
chilled cesium atoms to an optical lattice atomic clock that loses a second only 
every ... Most timepieces people use to tell time are accurate to within 10 or 15 ... 
(The quartz in a watch oscillates at about 32,000 times per second,... [DOC] [TLE] How radio-controlled and atomic clocks work - Explain that Stuff [PAR] Mar 30, 2016 ... Now quartz watches synchronized with radio signals mean anyone can ... It's 
pretty obvious that an RCC is only going to be as accurate as the ... At one end of 
the clock, an oven (red) heats a lump of cesium metal so ... 1955: Essen and 
Parry build the first highly accurate cesium atomic clock, Cesium-1. [DOC] [TLE] How Does an Atomic Clock Work? - Boston Commons High Tech ... [PAR] Dec 22, 2015 ... [6] Now quartz watches synchronized with radio signals mean anyone can ... [5] 
This early atomic clock retains its accuracy within 1 sec for every 300 years and 
..... Today's standard-bearing atomic clocks work by using cesium, an element 
that ... level that surpasses any of the atomic clocks in current use. [DOC] [TLE] Agilent AN 1289 The Science of Timekeeping [PAR] of Colorado, Boulder, in 1955, and the M.S. and Ph.D. degrees from. Harvard .... 
centuries, clocks were insufficiently accurate to navigate with any certainty, and 
this all ... oscillator and quartz-crystal filters, which are essential elements for 
radio, radar ..... the cesium-133 atom, whose unperturbed frequency has been 
defined. [DOC] [TLE] Bulova Watches - History of Time - American Watches [PAR] Elements of a Clock ... Modern clocks use a balance wheel, pendulum, vibrating 
crystal, .... In 1721, George Graham improved the pendulum clock's accuracy to 1 
... the timekeeping performance of quartz clocks has been substantially 
surpassed ... As of January, 2002, NIST's latest primary cesium standard was 
capable of... [DOC] [TLE] time and frequency - National Institute of Standards and Technology [PAR] NBS-5; this frequency standard shows a tentative potential accuracy of 2 ... AT(
NBS) is one of seven inputs to the TAI scale maintained by the Bureau 
International ...... firmed with quartz clocks and atomic clocks [ 17,18, ..... least 12 
cesium standards conveniently available and com- ..... versity Press, London, 
England, 1955). [DOC] [TLE] OSA | Cs vapor microcells with Ne-He buffer gas mixture for high ... [PAR] Vapor cell atomic clocks use interactions of resonant light with alkali atomic vapor 
in ... of accuracy, making difficult the realization of buffer-gas filled vapor cells 
with .... to cool down the Cs-Ne cell temperature at 80C with a Peltier element 
but at ... a 10 MHz quartz-crystal oscillator frequency-multiplied to 4.596 GHz by a 
low... [DOC] [TLE] Ultracold atoms and precise time standards | Philosophical - Journals [PAR] Sep 19, 2011 ... At the time, the most stable frequency standards were quartz ... These effects 
limited both the accuracy of the measured transition ... In 1968, these caesium (
Cs) clocks became the primary standard when the second was redefined

Question: The accuracy of the Quartz clock was surpassed in 1955 by one using this element, Cs
Answer: Cesium