Magnetic trapping of spin-polarized atomic hydrogen

Hess, Harald F.; Kochanski, Greg; Doyle, John M.; Masuhara, N.; Kleppner, Daniel; Greytak, Thomas J.

doi:10.1103/physrevlett.59.672

Cited by 215 publications

(104 citation statements)

References 13 publications

(13 reference statements)

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“…Nevertheless, magnetically trapped hydrogen atoms in state H d have been produced at temperatures of 40 to 100 mK and densities up to 3 × 10 14 cm −3 by purely cryogenic methods [47,48] and then evaporatively cooled to produce a BEC of 10 9 atoms at a temperature of around 50 μK and densities between 10 14 and 5 × 10 15 cm −3 [49]. In addition, Zeeman deceleration and magnetic trapping of hydrogen have recently been demonstrated [50][51][52][53], although at higher temperatures and lower number densities.…”

Section: A Atomic Hyperfine and Zeeman Levelsmentioning

confidence: 99%

Sympathetic cooling of fluorine atoms with ultracold atomic hydrogen

González-Martínez

Hutson²

2013

Phys. Rev. A

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We consider the prospect of using ultracold hydrogen atoms for sympathetic cooling of fluorine atoms to microkelvin temperatures. We carry out quantum-mechanical calculations on collisions between cold F and H atoms in magnetically trappable states and show that the ratio of elastic to inelastic cross sections remains high across a wide range of temperatures and magnetic fields. For F atoms initially in the spin-stretched state ( 2 P 3/2 , f = m f = +2), sympathetic cooling appears likely to succeed from starting temperatures around 1 K or even higher. This occurs because inelastic collisions are suppressed by p-wave and d-wave barriers that are 600 mK and 3.2 K high, respectively. In combination with recent results on H + NH and H + OH collisions [M. L. González-Martínez and J. M. Hutson, Phys. Rev. Lett. 111, 203004 (2013)], this establishes ultracold H atoms as a very promising and versatile coolant for atoms and molecules that cannot be laser-cooled.

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Section: A Atomic Hyperfine and Zeeman Levelsmentioning

confidence: 99%

Sympathetic cooling of fluorine atoms with ultracold atomic hydrogen

González-Martínez

Hutson²

2013

Phys. Rev. A

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“…Spin-changing collisions between trapped atoms [ 22 ] are negligible because of the low antihydrogen density. The main background gases in our cryogenic vacuum are expected to be He and H 2 .…”

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Confinement of antihydrogen for 1,000 seconds

et al. 2011

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Reported trapping times of magnetically confined (matter) atoms range from <1 s in the first, room temperature, traps [ 18 ] to 10 to 30 minutes in cryogenic devices [ 19,20,21,22 ]. However, antimatter atoms can annihilate on background gases. Also, the loading of our trap (i.e., anti-atom production via merging of cold plasmas) is different from that of ordinary atom traps, and the loading dynamics could adversely affect the trapping and orbit dynamics. Mechanisms exist for temporary magnetic trapping of particles (e.g., in quasi-stable trapping orbits [ 23 ], or in excited internal states [ 24 ]); such particles could be short-lived with a trapping time of a few 100 ms. Thus, it is not a priori obvious what trapping time should be expected for antihydrogen. 5In this article, we report the first systematic investigations of the characteristics of trapped antihydrogen. These studies were made possible by significant advances in our trapping techniques subsequent to Ref. [ 17 ]. These developments, including incorporation of evaporative antiproton cooling[ 25 ] into our trapping operation, and optimisation of autoresonant mixing [ 26 ], resulted in up to a factor of five increase in the number of trapped atoms per attempt. A total sample of 309 trapped antihydrogen annihilation events was studied, a large increase from the previously published 38 events.Here we report trapping of antihydrogen for 1000 s, extending earlier results [ 17 ] by nearly four orders of magnitude. Further, we have exploited the temporal and spatial resolution of our detector system to perform a detailed analysis of the antihydrogen release process, from which we infer information on the trapped antihydrogen kinetic energy distribution.The ALPHA antihydrogen trap [ 27,28 ] is comprised of the superposition of a Penning trap for antihydrogen production and a magnetic field configuration that has a three-dimensional minimum in magnitude (Fig. 1). For ground-state antihydrogen, our trap well-depth is 0.54 K (in temperature units).The large discrepancy in the energy scales between the magnetic trap depth (~50 eV), and the characteristic energy scale of the trapped plasmas (a few eV) presents a formidable challenge to trapping neutral anti-atoms. antiprotons at ~100K, with radius 0.4 mm and density 7x10 7 cm -3 is prepared for mixing with positrons.Independently, the positron plasma, accumulated in a Surko-type buffer gas accumulator [ 33 ,34 ], is transferred to the mixing region, and is also radially compressed. The magnetic trap is then energized, 6 and the positron plasma is cooled further via evaporation, resulting in a plasma with a radius of 0.8 mm and containing 1x10 6 positrons at a density of 5x10 7 cm -3 and a temperature of ~40 K. The silicon vertex detector, surrounding the mixing trap in three layers (Fig. 1 a) ]. Knowledge of annihilation positions also provides sensitivity to the antihydrogen energy distribution, as we will show.In Table 1 and Fig. 2, we present the results for a series of measurements, wherein the confinemen...

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“…So sind lo9 Natrium-Atome [31], und mehr als lo'* Wasserstoff-Atome in magnetischen Fallen eingeschlossen worden [32].…”

Section: Ionen In Der Falleunclassified