Improved alternating gradient transport and focusing of neutral molecules

Kalnins, J.G.; Lambertson, G.; Gould, Harvey

doi:10.1063/1.1485778

Cited by 20 publications

(35 citation statements)

References 14 publications

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“…Third, different from the electrostatic potential, the gradient of the electric field magnitude in free space is not equal to zero [7]. The second and third point introduce aggravating non-linearities in electric lenses [8,9]. Last but not least, the force experienced by polar molecules in inhomogeneous fields is typically some eight to ten orders of magnitude weaker than the forces that can be exerted on ions.…”

Section: Introductionmentioning

confidence: 99%

A Forty-Segment Molecular Synchrotron

Zieger

Eyles

Meerakker

et al. 2013

Zeitschrift Für Physikalische Chemie

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We present a synchrotron for polar molecules consisting of 40 straight hexapoles arranged in a circle with a 50 cm diameter. The mechanical design and alignment procedure as well as the trigger scheme used to switch the voltages applied to the hexapoles is described in detail. The stability of the synchrotron is demonstrated by measurements in which multiple packets are stored for over 13 seconds, during which they have completed over 1000 round trips and traveled a distance of over one mile. Furthermore, we demonstrate the simultaneous trapping of 26 packets; 13 revolving clock-wise and 13 counter clock-wise in the ring that are injected into the ring by two Stark decelerator beamlines. We discuss the opportunities for using the synchrotron as low-energy collider.

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Section: Introductionmentioning

confidence: 99%

A Forty-Segment Molecular Synchrotron

Zieger

Eyles

Meerakker

et al. 2013

Zeitschrift Für Physikalische Chemie

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“…Decelerators in which dedicated and spatially separated elements are used for transverse focusing and longitudinal deceleration have been considered before [13,36]. In chargedparticle accelerators, such separation is common practice, and the detrimental effects of elements that affect simultaneously the longitudinal and transverse particle motions are well known [37].…”

Section: Zeeman Decelerator Concept and Designmentioning

confidence: 99%

Multistage Zeeman decelerator for molecular-scattering studies

Cremers¹,

Chefdeville²,

Janssen³

et al. 2017

Phys. Rev. A

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We present a concept for a multistage Zeeman decelerator that is optimized particularly for applications in molecular beam scattering experiments. The decelerator consists of a series of alternating hexapoles and solenoids, that effectively decouple the transverse focusing and longitudinal deceleration properties of the decelerator. It can be operated in a deceleration and acceleration mode, as well as in a hybrid mode that makes it possible to guide a particle beam through the decelerator at constant speed. The deceleration features phase stability, with a relatively large six-dimensional phase-space acceptance. The separated focusing and deceleration elements result in an unequal partitioning of this acceptance between the longitudinal and transverse directions. This is ideal in scattering experiments, which typically benefit from a large longitudinal acceptance combined with narrow transverse distributions. We demonstrate the successful experimental implementation of this concept using a Zeeman decelerator consisting of an array of 25 hexapoles and 24 solenoids. The performance of the decelerator in acceleration, deceleration, and guiding modes is characterized using beams of metastable helium ( 3 S) atoms. Up to 60% of the kinetic energy was removed for He atoms that have an initial velocity of 520 m/s. The hexapoles consist of permanent magnets, whereas the solenoids are produced from a single hollow copper capillary through which cooling liquid is passed. The solenoid design allows for excellent thermal properties and enables the use of readily available and cheap electronics components to pulse high currents through the solenoids. The Zeeman decelerator demonstrated here is mechanically easy to build, can be operated with cost-effective electronics, and can run at repetition rates up to 10 Hz.

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“…The higher order pure multipole fields give nonlinear forces that are also defocusing in both directions. However, if a combination of a dipole and a sextupole potential is used, the resulting forces will focus the beam in one direction and defocus in the other [2,5].…”

Section: Transverse-focusing Lens Fieldsmentioning

confidence: 99%

“…In previous publications describing the use of static inhomogeneous electric fields to focus (strong-fieldseeking) neutral atoms and molecules, end effects were neglected [2][3][4][5]. This was justified because the lens length was long enough, the transverse electric field gradient large enough, and the electric dipole field small enough that the lens focusing/defocusing forces were large compared to the end-field effects.…”

Section: Introductionmentioning

confidence: 99%

Electrostatic end-field defocusing of neutral atoms and its compensation

Kalnins

2011

Phys. Rev. ST Accel. Beams

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Neutral atoms entering an electric field experience a defocusing force in the dipole field direction, which is proportional to the field gradient. If an experiment, such as the search for a permanent electron electric dipole moment (eEDM), requires a very strong electric field (13:5 MV=m), then this end-field defocusing results in beam blowup and much reduced phase-space acceptance. In this paper we discuss how these defocusing fields arise from the longitudinal changes in the electric dipole field and their dependence on the electrode shape and spacing between lenses. We find that the end-field defocusing comes from strong impulse forces, whose defocusing power was calculated for simple electrodes with rounded ends. To compensate for this end-field defocusing, a triplet of transverse-focusing lenses was added to the pure dipole field plates in the generic eEDM cesium fountain experiment used to study the neutral beam optics. Envelope equations, which calculated the beam sizes of the atom bunch for the linear forces, are used to obtain a set of lens parameters that give a well focused beam in the fountain. Atom trajectory equations allow us to calculate the phase-space acceptance of the lens system with the nonlinear force terms included.

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Improved alternating gradient transport and focusing of neutral molecules

Cited by 20 publications

References 14 publications

A Forty-Segment Molecular Synchrotron

A Forty-Segment Molecular Synchrotron

Multistage Zeeman decelerator for molecular-scattering studies

Electrostatic end-field defocusing of neutral atoms and its compensation

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