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Topic: Doppler temperature

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Laser cooling

	Doppler cooling limit - Wikipedia, the free encyclopedia
		Doppler temperature is the minimum temperature achievable with Doppler cooling, one of the methods of laser cooling.
		At the temperature when this effect exactly balances out the cooling effect of the laser, no further cooling is possible.
		The term Doppler arises from the fact that the Doppler effect, which provides a velocity dependence of the absorption rate and thus the light force, is an essential ingredient of the Doppler cooling mechanism.
	en.wikipedia.org /wiki/Doppler_temperature (226 words)

	Doppler effect - Wikipedia, the free encyclopedia
		The Doppler effect, named after Christian Andreas Doppler, is the apparent change in frequency and wavelength of a wave that is perceived by an observer moving relative to the source of the waves.
		Another use of the Doppler effect which is found mostly in astronomy, is the estimation of the temperature of a gas which is emitting a spectral line.
		This line shape is called a Doppler profile and the width of the line is proportional to the square root of the temperature of the gas, allowing the Doppler-broadened line to be used to measure the temperature of the emitting gas.
	en.wikipedia.org /wiki/Doppler_effect (1578 words)

	Encyclopedia :: encyclopedia : Temperature (Site not responding. Last check: 2007-10-30)
		Temperature is the physical property of a system which underlies the common notions of "hot" and "cold"; the material with the higher temperature is said to be hotter.
		Temperature is a measure of the average kinetic energy of the particles in a sample of matter.
		Temperature is an intensive property of a system, meaning that it does not depend on the system size or the amount of material in the system.
	www.hallencyclopedia.com /Temperature (2401 words)

	Laser cooling - Wikipedia, the free encyclopedia
		Since the temperature of an ensemble of atoms is a measure of the random internal kinetic energy, this is equivalent to cooling the atoms.
		Lower temperatures, down to the recoil temperature, may be obtained by sub-Doppler cooling.
		Counterpropagating sets of laser beams in all three Cartesian dimensions may be used to cool all the three degrees of freedom of the atom.
	en.wikipedia.org /wiki/Laser_cooling (1074 words)

	SCERP Project Number: AQ95_4
		The doppler frequency shifts observed in the radar signal returns scattered by the atmospheric turbulent eddies in each pointing direction are proportional to the radial velocity of the winds.
		Temperature profiles are measured using a combination of a vertically transmitted variable frequency acoustic wave and vertically transmitted radar pulses.
		Data from lidars, sodars, towers, balloon borne instruments, doppler radars and laser doppler velocimeters located at various sites in the valley were used in the study.
	www.scerp.org /projects/aq95_4.html (2577 words)

	Doppler Open Channel Flow Meter UK
		Some doppler flowmeters are deployed on the channel-bed whilst others measure the velocity of the surface water.
		For in-channel doppler flowmeters this is normally achieved by utilising a hydrostatic sensor (pressure) although ultrasonic level devices can be used.
		The doppler flowmeter sensor is installed in partially full and surcharged pipes, rectangular, trapezoid and egg-shaped channels..
	www.rshydro.co.uk /doppler-ultrasonic-flowmeter.shtml (455 words)

	Doppler Imaging: Results
		Our Doppler images from four spectral lines show a cool polar spot and various high-latitude spot features with a temperature contrast of 500-1600 K relative to the effective (photospheric) temperature.
		Fig.2: Doppler image of HII 314 from a 20-Å piece of spectrum including the Li I 6707 Å and the Ca I 6717 Å lines.
		The temperature scale is indicated and is the same for all projections.
	www.aip.de /groups/activity/DI/results.html (1317 words)

	USATODAY.com (Site not responding. Last check: 2007-10-30)
		Doppler refers to the principle the Austrian scientist Christian Doppler discovered in 1842.
		Doppler worked out his ideas using sound waves, long before radio, much less radar, was invented.
		The computer that's a part of a Doppler radar uses the frequency changes to show directions and speeds of the winds blowing around the raindrops, insects and other objects that reflected the radio waves.
	www.usatoday.com /weather/wdoppler.htm (331 words)

	Article in IWGGCR--24: Determination of the temperature coefficients and the kinetic parameters for the HTTR safety ...
		Doppler coefficient was evaluated under the conditions of all control rods withdrawn and the uniform change of fuel temperature.
		The moderator temperature coefficient was evaluated under the conditions of all control rods withdrawn and the uniform change of moderator temperature.
		We surveyed the effects of the Xe existence, the control rods existence, the fuel temperature and the region in which the temperature was changed on the moderator temperature coefficients.
	www.iaea.org /programmes/inis/aws/htgr/abstracts/abst_iwggcr24_4.html (408 words)

	SCERP Project Number: AQ93_3
		For a given scenario the upper air temperature and wind profiles must be known or have expected values and be supplied as inputs to the computer models.
		The lower altitude temperature and wind profile data are being compared with the UTEP measurements.
		Data from lidars, sodars, towers, doppler radars and laser doppler velocimeters at various locations in the valley were used in the study.
	www.scerp.org /projects/AQ93_3.html (1193 words)

	Further evidence of a two-level mesopause and its variations from UARS high-resolution Doppler imager temperature data
		During December solstice (1992), the mesopause is at the high level of 100 km in the Northern Hemisphere with a temperature of 190 K, and around 40°S, the mesopause changes to a low level of 88 km with a cool temperature (150 K) of 40 K less than the high-level mesopause.
		The high-level mesopause with temperatures of 180–190 K and the low-level mesopause with temperatures of 140–150 K are observed.
		The lowest mesopause temperatures at northern high latitudes are observed between May and August, which is consistent with the period of polar mesosphere summer echo observed by using VHF radar at these latitudes.
	www.agu.org /pubs/crossref/2002/2000JD000118.shtml (408 words)

	Press Release: The 1997 Nobel Prize in Physics
		When the temperature is one-millionth of a degree from this point (termed 1 µK, microkelvin) free hydrogen atoms, for example, move at speeds of less than 1 km/hr (= 25 cm/s).
		It was found that the temperature was about 240 µK. This corresponds to a sodium atom speed of about 30 cm/s, and agreed very well with a theoretically calculated temperature - the Doppler limit - then considered the lowest temperature that could be reached with Doppler cooling.
		He developed several new methods of measuring the temperature, including one in which the atoms are allowed to fall under the influence of gravity, the curve of their fall being determined with the help of a measuring laser.
	nobelprize.org /physics/laureates/1997/press.html (2340 words)

	Spectroscopy
		Christian Doppler (1803-1853), and it is therefore known as the Doppler Effect.
		The Doppler Effect applies to light as well, although because the speed of light is almost nine hundred thousand times greater than that of sound, the frequency shift is harder to notice.
		The Doppler Effect shifts this peak towards the red or the blue end of the spectrum, "sliding" the frequency graph one way or the other.
	snews.bnl.gov /popsci/spectroscope.html (2965 words)

	The Doppler Effect for Sound
		You hear the high pitch of the siren of the approaching ambulance, and notice that its pitch drops suddenly as the ambulance passes you.
		An approaching source moves closer during period of the sound wave so the effective wavelength is shortened, giving a higher pitch since the velocity of the wave is unchanged.
		Note: The frequency will default to A4 (440 Hz) and the temperature will default to 20 C if those values are not entered.
	hyperphysics.phy-astr.gsu.edu /hbase/sound/dopp.html (212 words)

	The VE2EMM Montreal III Doppler DF unit
		The Doppler II uses a 2-stage op-amp based peaking filter: Unless very temperature-stable components are used, this filter may be prone to drift, causing phase/direction errors at different temperatures.
		The Doppler III uses a 2-stage integrated switched-capacitor filter that is intrinsically stable in terms of temperature.
		Note that the potential temperature drift problem of the Doppler II is minimized by using good-quality stable capacitors in the peaking filter: I'd found that allowing the unit to warm up for 5 minutes or so before calibrating minimized this problem.
	www.ussc.com /~turner/emm3.html (3726 words)

	[No title]
		It should be borne in mind that formula (3.15) corresponding to the quasiclassical dynamics of the atom can be used when the temperature T exceeds the minimum possible temperature defined by recoil energy (1.5) (Castin and Dalibard, 1991).
		Because of their relatively high initial temperature, the atoms are located at vibrational levels with v>>0 (the case illustrated in Fig.
		Obviously the diffusion of atoms in the momentum space causes, in contrast to the VSCPT effect, the temperature of the entire atomic ensemble to rise.
	www.sciner.com /ALO/S3.doc (2128 words)

	HITUV: High temperature ultrasonic velocimetry (Site not responding. Last check: 2007-10-30)
		The objective of this project is to extent the applicability of the Ultrasonic Doppler technique to velocity measurements in high temperature liquid metal flows.
		To apply the Ultrasonic Doppler Velocimetry in high temperature metallic melts the thermal restriction of the ultrasonic transducers has to be overcome.
		To realise this concept, a couple of problems have to be solved, like acoustic coupling between ultrasonic transducer and wave guide, transmission of the ultrasound through the wave guide, wetting between the metallic melt and the wave guide, or allocation of reflecting particles in the melt.
	www.aramis-research.ch /d/7079.html (283 words)

	CMB Temperature Field
		It is precisely the spatial and temporal variation of these quantities, especially the monopole, which determines the pattern of anisotropies we observe today.
		A distant observer sees spatial variations in the local temperature or monopole, at a distance given by the lookback time, as a fine-scale angular anisotropy.
		Similarly, local dipoles appear as a Doppler shifted temperature which is viewed analogously.
	background.uchicago.edu /~whu/araa/node4.html (584 words)

	Integral Approach
		However, the Doppler effect has a directional dependence as well since it is only the line-of-sight velocity that produces the effect.
		Physically this corresponds to the fact that the velocity is irrotational and hence has no component in the direction orthogonal to the wavevector (see Plate 3).
		The observed peaks must be acoustic peaks in the effective temperature not ``Doppler peaks''.
	background.uchicago.edu /~whu/araa/node14.html (778 words)

	ISTP Event: Raw Data for January 6-11, 1997 (Site not responding. Last check: 2007-10-30)
		data indicate the wind and temperature response of the Earth's thermosphere at about 250 km altitude to the driving forces imposed upon it by the solar-terrestrial system.
		These plots show the distribution of neutral temperature across the visible sky for each "exposure" of the instrument.
		These are cartesian plots of the overall sky temperature inferred from all "zones" in the sky versus universal time.
	thing.pfrr.alaska.edu /conde/ISTPDATAHTM.htm (734 words)

	NUKEFACTS ... and fictions
		F caused by the Doppler coefficient, and the reactivity change from 0% to 40% voids caused by the void coefficient
		The moderator temperature coefficient (alpha-T) represents the change in _____________ resulting from a unit increase in __________________.
		Question 41: (revised) The reactivity change resulting from a 1 °F increase in fuel temperature is referred to as the ______________ temperature coefficient.
	www.pipeline.com /~rstater/nuke1m4a.html (2608 words)

	The Nine Planets Glossary
		fluid circulation driven by temperature gradients in the presence of gravity; the transfer of heat by this mechanism.
		increase in temperature caused when incoming solar radiation is passed but outgoing thermal radiation is blocked by the atmosphere (carbon dioxide and water vapor are the major factors).
		a star that has low surface temperature and a diameter that is large relative to the Sun.
	www.nineplanets.org /help.html (4937 words)

	Finding a gas plume’s temperature from its infrared spectrum
		We tested the spectroscopic temperature diagnostic using emission from two CO transitions at wavelengths of 4.2 and 14.5μm.
		The spectroscopic temperatures were in good agreement with thermocouple values; the RMS error, computed from all data sets, was 22K, on the order of 5% of the absolute temperature values.
		The greatest source of error was probably the variation in the plume's location and temperature caused by wind and turbulence within the plume.
	newsroom.spie.org /x2877.xml (885 words)

	Press Release: The Nobel Prize in Physics 1997
		Phillips found in 1988 that a temperature as low as 40 µK could be attained.
		This value was six times lower than the theoretically calculated Doppler limit! It turned out that the Doppler limit had been calculated for a simplified model atom that had previously been considered sufficiently realistic.
		The reason why the recoil velocity an atom obtains from a single photon sets a limit to both Doppler cooling and Sisyphus cooling is that even the slowest atoms are continually being forced to absorb and emit photons.
	physics.nist.gov /News/Nobel/OtherSites/physics97.html (2269 words)

	Abstract: The purpose of this paper is to introduce Dr (Site not responding. Last check: 2007-10-30)
		Doppler cooling is a form of laser cooling, however, the cooling effects are limited due to spontaneous emission of electrons (i.e.
		Meystre’s studies in Quantum Optics apply the fundamentals of Physical optics by using what we now study as the wave portion of optics.
		By treating atoms at extremely low temperatures which leads to the Bose-Einstein condensation, the behavior of individual atoms eventually disappears and we are left with a group of atoms that act as one single entity.
	www.u.arizona.edu /~jdn/ResearchOfDr.Meystre.htm (1541 words)

	Encyclopedia of Laser Physics and Technology - laser cooling, Doppler cooling, light forces, ion trap (Site not responding. Last check: 2007-10-30)
		Laser cooling is usually not meant to be the cooling of lasers, but rather the use of dissipative light forces for reducing the random motion and thus the temperature of small particles, typically atoms or ions.
		A simple scheme for laser cooling is Doppler cooling, where light forces are exerted by absorption and subsequent spontaneous emission of photons, and the rate of these processes depends on the velocity of an atom or ion due to the Doppler shift.
		The method of Doppler cooling is limited in terms of the reachable temperature (→ Doppler limit).
	www.rp-photonics.com /laser_cooling.html (845 words)

	IAEA0854: SIGMA1-2002, Doppler Broadening ENDF Format Linear-Linear. Interpolated Point Cross Section
		The data is Doppler broadened, thinned, and output in the ENDF/B format.
		SIGMA-1 starts from the free-atom Doppler broadening equations and adds the assumptions of linear data within the table and constant data outside the range of the table.
		If the data is already at a temperature higher than the final temperature, Doppler broadening is not performed.
	www.nea.fr /abs/html/iaea0854.html (572 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		Energy Citations Database (ECD) Document #7155761 - Doppler temperature and the intensity of the 6300 A emission
		Doppler temperature and the intensity of the 6300 A emission
		The simultaneous dependence of the intensity of the 6300 A emission on its Doppler temperature and h`F/sub 2/ and f/sub 0/F/sub 2/ under geomagnetically quiet conditions is established.^The Doppler temperature of the 6300 A emission is compared with the temperature of the upper atmosphere according to CIRA-1972.
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=7155761 (157 words)

	Moor Instruments \| laser Doppler blood flow assessment
		Moor Instruments, established in 1987, is a world leader in the design, manufacture and distribution of laser Doppler systems, used for the measurement of blood flow in the microvasculature.
		The MIC2 was designed specifically for all laser Doppler users with low current doses, variable delivery periods and the ability to assess electrical skin resistance.
		The most advanced laser Doppler monitor: dedicated software options for assessment of tissue blood flow, skin perfusion pressure, pulse volume, limb and toe pressure.
	www.moor.co.uk (455 words)

	Encyclopedia of Laser Physics and Technology - Doppler limit, laser cooling
		Definition: a limit for the temperature which is achievable with certain laser cooling techniques
		The temperature achievable with Doppler cooling is given by the Doppler limit
		Typical values for the Doppler limit are of the order of hundreds of microkelvins.
	www.rp-photonics.com /doppler_limit.html (172 words)

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