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The purpose of this page is to detail the Atom trapping and Cooling experiments being conducted at Manchester.
The new apparatus which has been developed is aimed at providing a high density source of atoms for several different experiments in cold atoms.
In the first of these experiments, new types of collision processes are to be studied, including electron collisions from cold atoms, BEC's and from slow atomic beams. The Cold Atom Facility which has been developed in Manchester is a bright source of cold atoms, and is shown in Figure 1.
Atoms emitted from the source can be laser collimated in the second stage of the experiment, which consists of a 6-way 200mm 316LN cross attached to the source chamber.
Laser collimation can be accomplished either using an optical molasses, through a 2D MOT or by exploiting the transverse momentum transferred to the atomic beam as it traverses this region using angled mirrors. Atoms from the collimated source that enter the Zeeman slower (figure 5) are longitudinally cooled and compressed in phase space using a blue detuned laser which passes along the axis of the Zeeman slower.
The design of the apparatus in Manchester allows atoms to be cooled, trapped and accumulated very rapidly from the source, which operates continuously.
It has been demonstrated that the trap density reaches saturation (where no more atoms can be trapped due to radiation trapping and other restrictions) within 1 second. The MOT1 chamber has been designed with numerous CF-70 ports to allow additional experiments to be connected to the chamber. Since the ratio of accumulation time to trapping time is 400:1, the apparatus will be able to continuously load different cold atom experiments from the main source while maintaining the maximum trapping density which can be achieved in each of these experiments. One of the goals in the design of this apparatus was to produce a well-collimated beam of atoms from the atomic beam source prior to laser collimation (see figure 1). There are several different types of atomic beam oven that can be used in these types of experiments, ranging from a simple crucible that directs atoms through a hypodermic needle (and hence produces a beam that is quite divergent) through capillary array sources (which are unsuitable for metal vapour targets as needed here), on through passively collimated sources as is used in Manchester for super-elastic scattering experiments from calcium and finally on to the most sophisticated (and most complex) sources which use a recirculating arrangement for collimation and recycling of the material under study. Recirculating oven sources have several advantages over other sources (if they are suitable).
Firstly, since the source only produces atoms which enter the atomic beam, there is very little waste of material.
As an example, the potassium source used in these cold atom experiments in Manchester has been operating for over 2 years without the need to refill the crucible. Secondly, the use of a condensation chamber surrounding the emitting nozzle means that vapour from the oven is re-condensed onto the inner walls of this chamber, to be fed back to the crucible. Figure 2 shows the recirculating oven that has been designed and commissioned in Manchester. The condensation chamber is held at a temperature ~340K so that the potassium on the walls is in a liquid form. Potassium vapour that is directed through the output aperture of the condensation chamber becomes the atomic beam which is used in the experiments.
Close control of the recirculating oven temperature is achieved by using several constant current supplies which feed the tungsten heaters as shown in figure 2.
Although not yet tested with Rb, it is fully expected that this atomic beam oven can be used with equal success using Rubidium (melting temperature 312K) as the chosen source. Rubidium will be used for the production of Bose Einstein Condensates (BEC's) and for other experiments in the near future. Details of this recirculating beam source are currently being written as a paper for submission to an appropriate journal. Following laser collimation using an optical molasses (figure 1), the atomic beam enters the Zeeman slower. The effective way to slow atoms down using lasers is to adopt the process of laser cooling where the spontaneous emission process is used as a mechanism to provide a dissipative force.
An atom initially travelling with momentum pA = MAv is subjected to laser radiation directed in the opposite direction, where MA is the mass of the atom and v is the velocity of the atom. Since linear momentum must be conserved, absorption of a photon from the field means that the atom must slow down. Firstly it is possible for a second photon from the laser field to stimulate the atom to decay back to the ground state. Secondly, the atom may relax back to the ground state spontaneously (spontaneous emission process). IF the photon is emitted in the same direction as the incident photon, then the momentum of the atom will return back to it's initial value prior to the interaction pA = MAv, and so the atom velocity does not change. By repeating this process many thousands of times, the atoms will slow down until they are stopped. The process of compression of the velocity distribution occurs since atoms with different velocities will only come into resonance with the laser beam at certain times during the cycling process. The method adopted here changes the internal states of the atoms by application of a magnetic field, which perturbs the atomic transitions which are coupled together by the laser radiation field. Figure 4 shows the type of magnetic field that is required to ensure the atoms can be effectively slowed and cooled. Figure 5 and figure 1 shows Zeeman slower that has been designed for the experiments in Manchester.
3,500m of rectangular section aluminium wire is used to provide the field, wound onto the flight tube as 5 individual coils. These coils are operated by 5 x 20A constant current supplies whose current can be tailored so as to produce the required field profile along the flight tube. Four additional coils are located at the exit of the Zeeman slower which disrupt the field so as to release atoms into the MOT chamber.
The Zeeman slower dissipates ~5,000W when operated at full current, and cooling of the slower is implemented by the external copper coils and by an internal water jacket next to the flight tube. Six laser beams of appropriate polarization are directed at the centre of the coils (the trapping region) which act as an OPTICAL MOLASSES to the atoms which enter this region, as shown in Figure 7.
The laser interaction acts as the velocity dependent frictional force that slows the atoms down, in the same way as inside the Zeeman Slower. Since the molasses component is velocity dependent, as the atoms slow down they will gradually stop moving (within these approximations).
The magnetic field from the anti-Helmholtz coils in combination with the laser beams ensures that the force acting on the atoms also has a restoring component that drives the atoms back to the centre of the trapping region (this force depends on the distance from the centre of the trap). Since the restoring component is distance dependent, atoms subjected to this component will perform simple Harmonic motion (within these approximations). This does not happen, as the atoms may still absorb and emit photons from the laser field, leading to a minimum velocity that is given by the recoil momentum of the atoms undergoing these absorption and emission processes (the quantum limit).
For potassium atoms in the experiment in Manchester, the temperature of the atoms in the trap has been measured to be ~250 micro-Kelvin. The success of the apparatus in producing a bright rapidly accumulating source of cold atoms means that new experiments now become possible. The first experiments to be attempted will scatter low energy electrons from the cold atoms either produced from the Zeeman slower, or as inside the MOT. For these experiments, a pulsed electron gun has been constructed and installed in the MOT chamber to produce a low energy electron beam of up to 10 microamps current at energies from 2eV to 100eV. Electrons from this source are directed at the trapped or slow atoms, so that they are ionized by the electron collision as shown in figure 11.
In this case, momentum of incident electron beam is known, as is momentum of cooled or trapped atoms. By measuring the recoiling ions, it is then possible to measure differential cross sections for ionization of these cold targets over the complete scattering geometry as shown in Figure 12. The graph shows the momentum which is transferred from the electron to the ionized potassium target as a function of the momentum of the neutral target, where both outgoing electrons are scattered symmetrically wrt the incident beam direction.
By detecting one electron in coincidence with the ion momentum, it is possible to completely determine the cross section for all scattering geometries.

This technique is also used in COLTRIMS experiments which exploit supersonically prepared target atoms, however by using cold atoms the sensitivity of the technique is enhanced many times.
Further, since the momentum of the initial target can be controlled by the Zeeman slower, it is possible to take sensitive measurements at different angles so as to ensure accuracy in the data. Other experiments being considered include super-elastic scattering of electrons from trapped atoms, study of interaction of electrons with BEC's, and interaction of fermions with ultra-cold ensembles. Watch this space for new results and developments in these collision experiments, including details of the AC-MOT!
The Cold Atom Facility developed in Manchester has potential to deliver a high density of cold atoms to different experiments so as to allow multiple experiments to be performed from the one source.
This page describes the atom trapping and cooling experiments currently being conducted in Manchester. Dieser Artikel wird A?ber das Programm zum weltweiten Versand verschickt und mit einer internationalen Sendungsnummer versehen.
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Laser brukes ogsa i forbindelse med oyeoperasjoner og innen skjonnhetspleie for a forbedre collagenet i huden, for a fjerne rynker og kviser, samt behandle areknuter og uonsket harvekst. ForebyggNa som hosten har fatt et godt grep om gradestokken, oker ogsa faren for forkjolelser og influensa.
Forskare har nu kommit pa en teknik dar man genom att skjuta laser genom en bilkupe kan upptacka om nagon i bilen ar berusad. Ett forskarteam pa Warszawas militara tekniska universitet har utvecklat en laser som kan upptacka rattfyllerister pa distans. I Sverige gar gransen for rattfylleri som kant vid 0,2 promille och utrustningen kan tyckas vara otillracklig, men forskarna pastar att med en riktig manniska som ar berusad kan systemet sannolikt registrera annu lagre nivaer. Systemet ar i nulaget i ett tidigt skede i utvecklingen och oppna fonster eller klimatanlaggning kan stora ut det. Enligt forskarna som tagit fram systemet ar nasta steg att undersoka scenarion som kan paverka dess precision samt gora det mer kompakt.
Du maste aktivera javascript for att ska fungera korrekt och for att kunna lyssna pa ljud. Det var nar piloterna precis hade lyft planet fran Jonkopings flygplats och befann sig lite drygt 150 meter upp i luften som piloterna upptackte en gron laserstrale som lyste in genom cockpiten, alltsa langst fram i flygplanet dar piloterna sitter. Det har ar forsta gangen Jonkopings flygplats drabbas av nagot liknande, men det har hant upprepade ganger pa andra flygplatser i Sverige. Martin Lindgren, pa Stralskyddsmyndigheten, hur farligt ar det att fa gron laser in i cockpiten pa ett plan pa 150-175 meters hojd? The apparatus produces a bright, cold atom source which competes with the best in the world for speed of accumulation of cold atoms into a Magneto-Optical Trap (MOT), and for the lifetime of atoms that are subsequently cooled and trapped. These experiments will exploit the momentum transferred in the collision process to ascertain new information about the target interactions, and to study collisions with cold and ultra-cold targets for the first time.
The apparatus consists of a recirculating oven source, which produces a quasi-collimated beam of atoms into the laser collimation stage. The cold atom facility that has been developed at Manchester, showing the various components of the apparatus and the laser beams which are used to cool and trap the atoms emitted from the source. Large windows are attached to the cross to allow the collimating laser beams to enter this region.
In the present setup, optical molasses has been used to increase the collimation of the atomic beam prior to the Zeeman slower. The aim of this design is to facilitate rapid trapping of the cold atoms, then transfer of these cold atoms to different experiments that are connected to the MOT1 chamber via these ports. In this way, experiments which have low cross sections (such as collisions experiments with electrons, neutrals or ions) will be possible in the near future. By ensuring this criteria is met, the vacuum chambers are far less polluted by unwanted atoms that are emitted from the source.
This means that the source can be operated for very long periods of time without the need to refill the crucible. The physical size of the condensation crucible and the output aperture then defines the collimation of the atomic beam that exits and therefore becomes the emerging atomic beam.
The crucible is loaded with potassium (melting temperature ~337K) and the temperature of different components of the source are closely controlled. Surface tension ensures that the liquid potassium runs down the walls of the condensation chamber and is gravity fed back to the crucible (which operates at a temperature of ~650K).
The temperature of the condensation chamber is accurately controlled by passing a heated high temperature silicon oil through a sealed chamber within the walls of the chamber as shown.
Since atoms emerging from the oven have a wide range of different velocities (as dictated by the Maxwell Boltzmann distribution), it is necessary to slow these atoms down so that they can be captured by the MOT. The laser frequency (wavelength) is set to be resonant with the atomic transition so that there is a high probability of absorption of a photon from the laser field by the atom, which is then promoted to an excited state. In this case (stimulated emission process) the photon from the atom emerges in the same direction as the photon in the laser field. In this case, the atom has no 'memory' of how it was excited, and so does not know the direction of the incident photon. By ensuring that either the laser frequency or the atomic transition frequency is time (or space) dependent, compression can occur.
One method that is used is to 'chirp' the slowing laser beam (figure 1) so that as the atoms slow down they remain in resonance with the laser beam. As the atoms slow down, the magnetic field is then adjusted so that the atoms remain in resonance with the laser beam (or they will Doppler shift out of resonance).
A set of 'disruption coils' are used at the exit of the slower to ensure atoms can escape into the MOT chamber.
Picture of the Zeeman slower shown with the cooling coils surrounding the current carrying coils. Inside this chamber is a twin set of coils setup to produce zero field at the centre of the coils (anti-Helmholtz configuration), as shown in figure 6. Movie of the atoms being trapped in the MOT from the Zeeman slower (first successful trapping with an accumulation time ~1sec, and aA  lifetime ~10 seconds).
Collisional ionization of atoms from the Zeeman slower or within the MOT trap, showing the setup of the experiment which detects the recoiling ions from the interaction.
The collision for ionization of cold atoms from Zeeman slower and those trapped in the MOT.

The incident energy is 30eV, and the curves show the effect of the ionization process on the final ion momenta (velocity and angle) as a function of the scattering angle. These experiments may be far ranging, depending on the apparatus that is connected to the source. Auf die in diesem Zusammenhang abgeschlossenen VertrA¤ge finden die nachfolgenden Bedingungen Anwendung.
Stellen wir mittels der eBay-Dienste einen Artikel im Auktions- oder Festpreisformat ein, so geben wir ein verbindliches Angebot zum Abschluss eines Vertrags A?ber diesen Artikel ab. Wir kA¶nnen Angebote im Auktionsformat zusA¤tzlich mit einer Sofort-Kaufen-Funktion versehen. Bei vorzeitiger Beendigung des Angebots durch uns kommt zwischen uns und dem HA¶chstbietenden ein Vertrag zustande, es sei denn wir waren dazu berechtigt, das Angebot zurA?ckzunehmen und die vorliegenden Gebote zu streichen.
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FA?r diese RA?ckzahlung verwenden wir dasselbe Zahlungsmittel, das Sie bei der ursprA?nglichen Transaktion eingesetzt haben, es sei denn, mit Ihnen wurde ausdrA?cklich etwas anderes vereinbart; in keinem Fall werden Ihnen wegen dieser RA?ckzahlung Entgelte berechnet.
Die Lieferzeit betrA¤gt soweit im konkreten Vertrag nichts anderes vereinbart 3-5 Werktage. Wenn Sie auf Gebot bestA¤tigen klicken und HA¶chstbietender sind, gehen Sie einen rechtsverbindlichen Vertrag mit dem VerkA¤ufer ein. Hun driver Randi Heggdal Naturterapi pa Amfisenteret i Verdal, og har en bredspektret utdanning innen naturmedisin.
Ofte er oregangene sare og rode, og de fleste har trommehinner som er trykt langt innover pa grunn av vakuum, sier Randi.
Mange av hennes klienter er mennesker som har v?rt ille plaget med oreinfeksjoner siden barnsben, og som kommer til henne i voksen alder for a fa hjelp. Forskning har blant annet bevist at laser har klar effekt mot smerter i ledd og seneapparat. Jeg ma gi klienten en helhetlig behandling, for problemet er ofte omfattende, forklarer Randi.Selv om hun lenge var fornoyd med orelysbehandlingen av klientene, er hun enda mer begeistret for laserterapien.
Det kan naturligvis stikke litt nar den nar de omme punktene, men ellers er det en mild behandlingsform. De ovrige luftveiene blir utsatt for stormangrep fra bakterier, og Randi mener den aller beste maten a unnga oreinfeksjoner pa, er simpelthen forebygging.
Systemet fungerar sa att en laserstrale skjuts genom kupen pa en passerande bil och traffar en spegel som skickar stralen vidare till en detektor for att fanga upp spritangor. Men det kan daremot ge en indikering till polisen om vilka bilar som verkar misstankta och de kan da stannas for att lamna utandningsprov. Om systemet i framtiden kan komma att anvandas av polisen skulle arbetssattet teoretiskt sett bli mer effektivt da farre bilar behover stoppas for att komma at rattfyllerister. Nagon lyste med gron laser in i cockpiten dar piloterna sitter nar de precis hade kommit upp i luften. Initial collimation of the atomic beam is achieved in the recirculating oven source through the use of small apertures as is shown in figure 2. The Zeeman slower is shown without the cooling coils which surround the current carrying coils, and the liquid nitrogen trap has yet to be installed onto the source chamber. In this way, atoms accumulated in MOT1 can be transferred to several different experiments where they can be recaptured for further study, or experiments can be directly conducted on the trapped atoms in MOT1. Since no atoms are emitted apart from those in the atomic beam, contamination of the vacuum chamber is virtually eliminated. In this way, atoms are emitted from the nozzle into the condensation chamber, where they are re-condensed onto the walls of this chamber. In this way, the complex temperature conditions which are essential for correct operation of this source can be maintained. Further, it is important to also compress the velocity distribution of these atoms so that they have a much narrower distribution at the exit of the slowing tube. In this case, the momentum of the atom will return back to its original value pA, and there is NO slowing of the atom by the laser beam. Diese kann von einem KA¤ufer ausgeA?bt werden, solange noch kein Gebot auf den Artikel abgegeben oder ein Mindestpreis noch nicht erreicht wurde. Die Annahme erfolgt unter der aufschiebenden Bedingung, dass der KA¤ufer nach Ablauf der Angebotsdauer HA¶chstbietender ist. Nach einer berechtigten GebotsrA?cknahme kommt zwischen dem Nutzer, der nach Ablauf der Auktion aufgrund der GebotsrA?cknahme wieder HA¶chstbietender ist und uns kein Vertrag zustande. Die Preisvorschlag-Funktion ermA¶glicht es KA¤ufern und uns, den Preis fA?r einen Artikel auszuhandeln. A?ber jeden Status der Abwicklung (Zahlungseingang, Versand, etc.) wird der Kunde per E-Mail informiert. Heldigvis finnes det flere ulike former for behandling mot oreinfeksjon, og en effektiv metode er laserterapi.
Hvis oreinfeksjonen forblir ubehandlet, kan den medfore smerter, oresus og konstant trykk i oret og nedover halsen. Biopati, akupunktur, oteopati, ern?ring, tarmskylling og laserbehandling er bare noen av omradene hun jobber med.
Ifolge statistikken, er barn som far mest problemer med orene, og de far gjerne gjentatte infeksjoner. Lyset som oppstar av stralingen, beveger seg i en bestemt retning som en snorrett lysstripe.
Det vil sprake og smelle litt i oret etter at laseren har gjort sitt, men det betyr at det jobbes inne i oret. Med ett system for att simulera en berusad persons andedrakt kunde forskarna registrera blodalkoholkoncentration hogre an 0,1 procent, alltsa 1,0 promille. Ingen skadades av detta men handelsen har polisanmalts och flygplatschefen vid flygplatsen Hazze Sandstrom ser mycket allvarligt pa det hela. In the first experiments using this Facility, potassium atoms have been cooled and trapped.
Once the atoms enter MOT1, they experience frictional force due to the laser interaction and a restoring force due to the magnetic field, so that they rapidly cool to a temperature ~250 micro-Kelvin around the centre of the trap. Ein Gebot erlischt, wenn ein anderer KA¤ufer wA¤hrend der Angebotsdauer ein hA¶heres Gebot abgibt. Hos sma barn kan oreinfeksjon i verste fall fore til nedsatt horsel, sprak- og uttalevansker og l?revansker. Gjennom mange ar har hun behandlet oreproblemer, bade med oteopati (orelysbehandling) og laser.
Nar denne elektromagnetiske lysstripen moter menneskelig organisme, vil den sette i gang svingninger i cellene slik at disse stimuleres til regenerering. Legen wir beim Auktionsformat einen Mindestpreis fest, so steht das Angebot unter der aufschiebenden Bedingung, dass der Mindestpreis erreicht wird.
Zur Wahrung der Widerrufsfrist reicht es aus, dass Sie die Mitteilung A?ber die AusA?bung des Widerrufsrechts vor Ablauf der Widerrufsfrist absenden. Die Frist ist gewahrt, wenn Sie die Waren vor Ablauf der Frist von vierzehn Tagen absenden.
Laserens oppgave er a stimulere pa celleniva, slik at kroppen pavirkes til a regenere seg selv.

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