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	Rubidium - Symmetricom
		Rubidium is a soft, silvery-white metallic element of the alkali metals group.
		Rubidium ignites spontaneously in air and reacts violently with water, setting fire to the liberated hydrogen.
		Rubidium is used as a getter in vacuum tubes and as a photocell component.
	www.symmttm.com /rubidium.html (292 words)

	Rubidium - Wikipedia, the free encyclopedia
		Rubidium is a chemical element in the periodic table that has the symbol Rb and atomic number 37.
		Rubidium is easily ionized, so it has been considered for use in ion engines for space vehicles (but caesium and xenon are more efficient for this purpose).
		Rubidium (L rubidus, deepest red) was discovered in 1861 by Robert Bunsen and Gustav Kirchhoff in the mineral lepidolite through the use of a spectroscope.
	en.wikipedia.org /wiki/Rubidium (831 words)

	Clocks and Watches - MSN Encarta
		In this clock, cesium-133 atoms in one hyperfine energy state are subjected to microwave radiation that is near the resonant frequency of the transition to another hyperfine energy state.
		Rubidium clocks are not as stable or as accurate as cesium-atom clocks, but they are more compact and less expensive.
		Devices almost as old as the shadow clock and sundial include the hourglass, in which the flow of sand is used to measure time intervals, and the water clock, or clepsydra, in which the flow of water indicates passage of time.
	encarta.msn.com /encyclopedia_761577936_2/Clocks_and_Watches.html (1140 words)

	Clocks Guaranteed To Run on Time for European Positioning Satellites
		The clocks available at the time were notoriously inaccurate at sea and the problem was solved only when John Harrison, a joiner from England, built a seaworthy clock that kept time to within about 1 second per day, equivalent to a positioning accuracy of about 500 m.
		The clocks that will fly on the satellites are the first of their type to be developed and built in Europe.
		The rubidium clock should be ready for qualification by the end of 2001, by which time an engineering model of the hydrogen maser should be available.
	www.space.com /missionlaunches/missions/esa_galileo_clocks_010320.html (855 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal (Site not responding. Last check: )
		Rubidium has also been considered for use in a thermoelectric generator using the magnetohydrodynamic principle, where rubidium ions are formed by heat at high temperature and passed through a magnetic field.
		Rubidium (L rubidus, deepest red) was discovered in 1861 by Robert Bunsen and Gustav Kirchhoff in the mineral lepidolite through the use of a spectroscope.
		Rubidium crystals are a key component of the subdermal transponders injected into Capt. James T. Kirk and Cmdr. Spock before they beam down to the surface of Ekos in the Star Trek episode "Patterns of Force".
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=rubidium (897 words)

	Rubidium (Site not responding. Last check: )
		Rubidium is highly reactive with properties to other elements in group 1 like spontaneously in air.
		Rubidium is the second most electropositive of the alkaline elements and can a liquid at room temperature.
		Rubidium can be easily ionized and because this has been considered for use in ion engines for space vehicles (but caesium and xenon are more efficient for this purpose).
	www.freeglossary.com /Rubidium (655 words)

	Rubidium Information Center - rubidium supplement
		Rubidium can be easily ionized, and because of this has been considered for use in ion engines model rubidium project for space vehicles (but caesium and xenon are more efficient for this isotope rubidium purpose).
		Its desirable rubidium oscillator where is rubidium found features for this application include the ready availability of inexpensive diode laser model rubidium light at the relevant wavelength rubidium periodic table and the moderate temperatures required to obtain substantial vapor pressures.
		Rubidium rubidium clock (L rubidus, deepest red) was discovered in 1861 by Robert atom of rubidium Bunsen and Gustav Kirchhoff in the mineral lepidolite model element rubidium project rubidium vapor pumping through the use of a spectroscope.
	www.scipeeps.com /Sci-Chemistry_Topics_Pr_-_R/Rubidium.html (858 words)

	C&EN: IT'S ELEMENTAL: THE PERIODIC TABLE - RUBIDIUM
		Rubidium is a silvery white metal that, unlike MandM candies that "melt in your mouth, not in your hand," will start to melt in your hand (38.9 ºC) and explode in your mouth.
		Rubidium bursts into flame in air to form a set of oxides and reacts vigorously with water to form RbOH, one of the strongest known bases.
		As for applications, rubidium is used in a few electronic devices, as a frequency reference in atomic clocks, and to estimate the age of rocks.
	pubs.acs.org /cen/80th/print/rubidium.html (894 words)

	Rubidium Oscillator - Symmetricom
		Rubidium oscillator atomic clocks are the simplest and most compact of all.
		Rubidium oscillators use a glass cell of rubidium gas that changes its absorption of light at the optical rubidium frequency when the surrounding microwave frequency is just right.
		Based on many years of refinement, the 8040 rubidium physics package is a design that offers high reliability supported by tens of thousands of fielded units.
	symmttm.com /rubidium-oscillator.html (239 words)

	antique clock restoration
		The first public clock in New York City was built in 1716 for the City Hall at Nassau and Wall streets, and a clock was installed in Independence Hall in Philadelphia, Pennsylvania, by 1753.
		My experience with antique clocks began with a five year apprenticeship and has continued with work on pieces by respected makers, thus gaining vaulable familiarity with various styles and mechanisms for work than can include major rebuilding or delicate but sympathetic restoration A selection of carefully chosen stock is always available to view by appointment.
		Although English clocks form the major part of the selection, French decorative pieces with high quality cases and movements are also bought and sold as are the occasional sun dial or interesting scientific instrument.
	www.antiques-clocks.co.uk /antique-clock-restoration.htm (1218 words)

	Rubidium Oscillator - Symmetricom
		Rubidium oscillators offer low per month aging rates, excellent long-term stability performance, configuration flexibility, small size, low weight and cost effectiveness.
		Rubidium oscillator atomic clocks are the simplest and most compact of all.
		Rubidium oscillators use a glass cell of rubidium gas that changes its absorption of light at the optical rubidium frequency when the surrounding microwave frequency is just right.
	www.symmttm.com /rubidium-oscillator.html (239 words)

	GPS: The Role of Atomic C... - Practical Applications
		The rubidium clocks are considerably less expensive and smaller than cesium clocks, but they are not quite as accurate.
		By 1967, research in atomic clocks had proved so fruitful that the second was redefined in terms of the oscillations of a cesium atom.
		Over the years, all three clocks--the cesium-beam clock, the hydrogen-maser clock, and the rubidium clock--have seen service in space, either in satellites or in ground control systems.
	www.beyonddiscovery.org /content/view.page.asp?I=467 (622 words)

	Atomic Clocks
		The two most widely used atomic clocks in recent years have been the cesium beam atomic clock and the rubidium clock.
		Such clocks have provided the accuracy necessary to test general relativity and to track variations in the frequencies of pulsars.
		The frequency of this atomic clock is in the microwave region of the electromagnetic spectrum and is a convenient one for locking a microwave oscillator.
	hyperphysics.phy-astr.gsu.edu /hbase/acloc.html (296 words)

	Accubeat
		An atomic clock is a very high precision clock where the “pendulum” of the clock is the atom itself.
		A Rubidium Clock is an Atomic Clock which uses Rubidium atoms and an “optical pumping” technique to measure the atomic EM frequency.
		AccuBeat’s Rubidium Frequency Standards use a unique Frequency Lock Loop (FLL) to implement the disciplining of the crystal oscillator to the atomic resonance frequency (See Figure 2).
	www.accubeat.com /Rb_tech.asp (346 words)

	Physikalisch-Technische Bundesanstalt (PTB)
		Atomic clocks make use of transitions between such energy levels whose natural lifetime is long and whose energy is not significantly affected by electric or magnetic fields or other pertubations.
		Rubidium clocks can be manufactured with compact dimensions and at a low price.
		This limits the achievable long-term frequency stability and prevents the use of uncalibrated Rb clocks for the realisation of the unit of time; it is thus called a secondary frequency standard.
	www.ptb.de /en/org/4/44/441/info2_e.htm (1110 words)

	Time: Keeping Time
		They showed that "rubidium atoms don't collide as often," Gibble explained, "and their collisions don't have as great an effect." This work has led other groups around the world to build similar clocks based on rubidium.
		Rubidium clocks now under construction at the U. Naval Observatory will soon be the basis for Earth's Global Positioning System.
		In the future, Gibble added, rubidium-based clocks could be capable of an accuracy that is difficult to imagine: within five seconds over the entire life of the universe.
	www.rps.psu.edu /time/keeping.html (1316 words)

	Rubidium - Reference.com/Encyclopedia/Rubidium (Site not responding. Last check: )
		Rubidium has the most pleasant-sounding name of all the elements, The drawback to this claim to fame is that rubidium isn't found in large quantities in
		Rubidium is an alkali metal in group 1 of the Periodic Table.
		Rubidium is a silvery white, very active metal as are the other alkali metals.
	supersearching.com /?q=rubidium (379 words)

	FE-5600M (Site not responding. Last check: )
		A rubidium clock is intended to be used where timing is critical but the host device may need to perform autonomously.
		As a result of this legacy, FEI was able to adapt its technology to produce rubidium clocks for use in cellular telephone base stations.
		The rubidium clock can be thought of as a "flywheel." If the cellular base station loses contact with the GPS, which can happen in heavy storms or antenna malfunctions, the rubidium clock provides the internal synchronization until such time that communication with GPS can be restored.
	www.freqelec.com /rubidiumstory.htm (734 words)

	Atomic Clocks and the 1999 Solar Eclipse
		An accumulated time difference of two cesium clocks of 468 ns and 65 µs for two rubidium clocks located in the same laboratory was observed.
		General relativity predicts that gravity does have an influence on clock rates, but it is not expected that clocks located at the same place in the frame should change their relative pace unless gravity has an influence on the value of the fine structure constant [7].
		In figure 1 the relative time differences of the clocks are shown for a 800 second interval with the eclipse in the center.
	www.mpq.mpg.de /~haensch/eclipse/full.html (1563 words)

	Matchbox-sized Atomic Clock
		The ultra-miniature Rubidium atomic clock is the next-generation, super-accurate clock no bigger than a matchbox and loses only one second every 10,000 years.
		The Kernco laser-based Ultra-miniature Rubidium Atomic Clock that is entirely optical in nature, a key breakthrough for miniaturizing atomic clocks.
		The difference between this new clock and other atomic clocks are the size, the weight, the power consumption, the transportability, and the price.
	www.physlink.com /News/090303MatchboxAtomicClock.cfm (416 words)

	Fundamental Physics of Space - Technical Details
		This clock will be used to perform a series of experiments to test Einstein's Theory of Relativity, and as well will advance the state of clock science into a new frontier.
		Future clocks based on the technology developed for RACE might be used to coordinate all of the world's clocks, as well as for and telecommunications, and navigation-both on Earth and in space.
		If we can compare the clocks at different parts of the satellites' orbit, we can test whether the speed of microwaves (which is the same as the speed of light, since both are forms of electromagnetic waves) is the same for all parts of the orbit, regardless of their orientation or velocity.
	funphysics.jpl.nasa.gov /technical/lcap/race.html (405 words)

	Sound & Vision: It's about time...
		This clock performance is usually measured in errors per millions (ppm), and a decent player may have errors in the 500 ppm range.
		The GS-25U employs a highly accurate, internal crystal oscillator known as a "master clock." This "clock" further reduces system noise and digital jitter, lowering the level between a DA convertor section or component and a digital transport to less than 1/100th of non-synchronized devices.
		The rubidium oscillator within the G-0s allows an ultra-precise master clock signal to be generated, and it also can centrally manage a group of digital devices.
	blogs.chron.com /soundvision/archives/2006/04/its_about_time.html (1116 words)

	New clocks to keep time for Galileo satellite navigation system
		The clocks available at the time were notoriously inaccurate at sea and the problem was solved only when John Harrison, a joiner from England, built a seaworthy clock that kept time to within about 1 second per day, equivalent to a positioning accuracy of about 500 metres.
		These clocks are being designed to a standard that seventeenth century sailors would find impossible to comprehend.
		It is being built by the Observatoire de Neuchatel in co-operation with Officine Galileo of Italy, the former being responsible for the overall development and in particular for the so-called physics package, and the latter being in charge of the electronics.
	www.spacedaily.com /news/gps-euro-01c.html (960 words)

	ESA - Navigation - The future - Galileo - Galileo satellites
		It is an atomic clock which uses the ultra stable 1.4 GHz transition in a hydrogen atom to measure time to within 0.45 ns over 12 hours.
		If the problem with the failed maser clock is unique to that clock, the second maser clock will take over from the rubidium clock after a few days when it is fully operational.
		It passes the signal from the active master clock to the NSU and also ensures that the frequencies produced by the master clock and the active spare are in phase, so that the spare can take over instantly should the master clock fail.
	www.esa.int /esaNA/SEMF5OZCU8E_galileo_0.html (911 words)

	An Assessment of Precision Time and Time Interval Science and Technology
		Rubidium Gas Cell The rubidium gas cell standard is based on rubidium-87 atoms sealed in a gas cell with a buffer gas.
		However, rubidium atom collisions with buffer gas atoms cause a pressure- and temperature-dependent frequency shift; another effect, the so-called light shift, is dependent on both the light intensity and spectral distribution of the lamp used to state select the atoms.
		The time difference between the local clock pulse and the received pulse is recorded at both sites, and from those data and calibration of all the delays, many of which tend to cancel, the time difference between the local clocks at the two sites can be determined.
	www.nap.edu /openbook.php?record_id=10541&page=12 (5465 words)

	SciCom
		An atomic clock is a precision clock that depends for its operation on an electrical oscillator regulated by the natural vibration frequencies of an atomic system.
		Without atomic clocks, GPS navigation would be impossible, the Internet would not synchronize, and the position of the planets would not be known with enough accuracy for space probes and landers to be launched and monitored.
		This atomic clock maintains hydrogen atoms at the required energy level in a container with walls of a special material so that the atoms don't lose their higher energy state too quickly.
	web.mit.edu /scicom/www/atomicclock.html (528 words)

	Frequency Electronics Inc. (Site not responding. Last check: )
		A "cesium atomic clock" is a device that uses as a reference the exact frequency of the microwave spectral line emitted by atoms of the metallic element cesium, in particular the isotope of atomic weight 133 ("Cs-133").
		For the measurement of time atomic clock technology has advanced with improvements such as the replacement of the state-selection magnets with laser beams, which can select and detect the required transition with greater efficiency and less motion of, hence less noise from, the radiating atoms.
		By developing the Rubidium oscillator, our Rubidium clocks provide the internal synchronization that is required for a cellular base station to maintain contact, in the event of heavy storms or antenna malfunctions interrupting contact.
	www.freqelec.com /frequency_seo/overview.html (815 words)

	The USNO Cesium Fountain Clock Project
		One of the transitions in Cesium has an oscillation frequency of 9 192 631 770 Hz, which is used to define the second.
		standard atomic clock, the cesium atoms in a hot beam are interrogated twice by microwave radiation.
		As the clock runs over a period of time, we are able to average out any random noise that is present, so the performance improves until non-random (systematic) noise sources begin to dominate.
	tycho.usno.navy.mil /clockdev/cesium.html (542 words)

	Physics News Update Number 499 - Story RUBIDIUM FOUNTAIN CLOCK
		Atomic clocks keep time by counting the cycles of light in a microwave cavity tuned to correspond to the internal energy transition of atoms launched from a trap.
		The atoms never absorb light at precisely the same frequency, so clock accuracy can be enhanced by averaging over larger samples of atoms, or by watching the atoms for longer periods by chilling the atoms to make them more uniform.
		High precision is manifested in a narrow linewidth in the spectrum of microwaves absorbed by the atoms.
	www.aip.org /pnu/2000/split/pnu499-1.htm (182 words)

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