Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Bulletin of the American Physical Society

Ultra-cold methods of atomic hydrogen electron spin separation

V. G. Luppov, William A. Kaufman, Alan D. Krisch

Published Apr 1, 1995• 0 citations
OpenAlex

Abstract

Two ultra-cold methods of atomic hydrogen electron spin separation for polarized jet targets and sources will be described and compared. Both of them use a helium-film coated cell at 300 mK located in a high magnetic field. The first one, microwave driven extraction, uses a 212 GHz microwave system and 7.5 T magnetic field with a high uniformity ({Delta}B/B{approx} 10{sup {minus}5}). The second method employs the gradient of a high magnetic field for the state separation and beam formation. Experimental results from the two methods will be presented.

Related papers

The ultra-cold polarized hydrogen jet project

R. S. Raymond, Donald G. Crabb, T. Roser +2 more

Research is described on a jet of polarized atomic hydrogen.Atoms in the two lower hyperfine states are trapped at 0.4 k in a 5 T magnetic field.Microwaves at 140 GHz then drive transitions to the upper hyperfine states and these atoms are expelled from the field to form the beam.Atoms have been trapped, transitions driven, and atoms detected outside the trapping field, but preliminary measurements are not fully understood.Studies are continuing.Work is continuing to test the applicability of cryogenic atomic physics techniques to the production of dense polarized atomic hydrogen beams.At high magnetic fields (5 T) and low temperatures (0.5 k), the magnetic energy of a hydrogen atom, approximately #, • B, is considerably higher than the thermal energy, kT.When cold atoms approach a high magnetic field, atoms in the two upper hyperfme states see a potential hill and are repulsed.Atoms in the two lower hyperfine states see a potential well, are attracted in, thermalize by hitting cold walls and are trapped.These trapped atoms are then irradiated with microwaves of the proper frequency (approximately 140 GHz for a 5 T field) to drive transition to one of the upper hyperflne states.These flipped atoms, now on a potential hill, are accelerated out of the field to form the beam.

AIP conference proceedings•Jan 1, 1989•0 citations

Polarized atomic hydrogen beam studies in the Michigan ultra-cold jet

R. S. Raymond

Studies of an ultra-cold jet of polarized hydrogen atoms are described. This atomic beam is formed by the acceleration of cold (0.3 K) atoms emerging from a region of high magnetic field (12 T). The maximum measured density was about 1012 atoms cm−3. The beam’s full width half maximum size was less than 4 mm.

AIP conference proceedings•Jan 1, 2000•0 citations

Focusing a beam of ultracold spin-polarized hydrogen atoms with a helium-film-coated quasiparabolic mirror

V. G. Luppov, William A. Kaufman, K. M. Hill +2 more

We formed the first ``atomic-optics'' beam of electron-spin-polarized hydrogen atoms using a quasiparabolic polished copper mirror coated with a hydrogen-atom-reflecting film of superfluid $^{4}\mathrm{He}$. The mirror was located in the gradient of an 8-T solenoidal magnetic field and mounted on an ultracold cell at 350 mK. After the focusing by the mirror surface, the beam was again focused with a sextupole magnet. The mirror, which was especially designed for operation in the magnetic field gradient of our solenoid, increased the focused beam intensity by a factor of about 7.5.

Physical Review Letters•Oct 11, 1993•12 citations

ESR on spin-polarized atomic hydrogen at temperatures below 0.5 K

B. W. Statt

Spin-polarized atomic hydrogen (H↓) gas at low temperatures (<0.5 K) has been studied using Electron Spin Resonance (ESR) techniques which allow direct measurements of the densities of H atoms in each of the two lower hyperfine states (a and b). It has been demonstrated that ESR can be made to yield accurate and detailed information about the decay of H↓ densities in time. Crucial to the analysis of the data is the ability to confine the sample of H↓, gas inside the liquid ⁴He coated microwave cavity where the magnetic field and temperature are well known. Measurements of K[sub aa] and K[sub ab], the two surface recombination rate constants, and their ratio γ=K[sub aa]/K[sub ab] have been made and from these results the binding energy of H on liquid ⁴He has been extracted. Also reported are the results of the first detailed study of the one-body surface relaxation rate which we find is due to microscopic magnetic impurities in the cell walls. Theoretical calculations of the two-body dipole-dipole relaxation rate of H↓ in the gas and on the surface are also presented.

•Jan 1, 2010•1 citation

H↓ atomic beam source: A feasibility study

T. O. Nünikoski, S. Penttilä, J.M. Rieubland +1 more

The possible application of the stable atomic hydrogen (H↓) in intense polarized atom or ion beam sources is discussed. The proposed scheme is based on flipping the electron spin of stored atoms by microwaves; this results in the magnetic acceleration and focusing of the flipped atoms. The main advantages of such beams are: accumulation and pulsing with time structure convenient for injection into synchrotrons via Linac injectors; high density due to the slow velocity and high initial density; and monochromaticity which allows atomic beam transport with focusing elements having no large chromatic errors. The possible problems and limitations in such an extraction scheme are: depolarization and slow spin diffusion due to spin exchange collisions in the dense gas phase, and loss of density due to recombination of the flipped atoms on the walls, before reaching the extraction aperture and accelerating field gradient.The results of the first tests of our apparatus are presented. The apparatus, based on a powerful dilution refrigerator, is described briefly.

AIP conference proceedings•Jan 1, 1984•0 citations

Cold source of atomic hydrogen for loading large magnetic traps

Aleksei Semakin, Janne Ahokas, Otto Hanski +8 more

We present a design and performance tests of an intense source of cold hydrogen atoms for loading large magnetic traps. Our source is based on a cryogenic dissociator of molecular hydrogen at 0.6 K followed by a series of thermal accommodators at 0.5, 0.2 and 0.13 K with inner surfaces covered by a superfluid helium film. All components are thermally anchored to corresponding stages of a dilution refrigerator. The source provides a continuous flux of 7$\cdot$$10^{13}$ H atoms/s in a temperature range of 130-200 mK. We have successfully used the source for loading a large Ioffe-Pritchard magnetic trap recently built in our laboratory [arXiv:2108.09123 or Rev. Sci. Instr. 93 (2), 023201 (2022)]. Calorimetric measurements of the atomic recombination heat allow reliable determination of the atomic flux and H gas density in the trap. We have tested the performance of the source and loading of H atoms into the trap at various configurations of the trapping field, reducing the magnetic barrier height to 75% and 50% of the nominal value of 0.8 T (0.54 K) as well as at the open configuration of the trap at its lower end, when the atoms are in contact with the trapping cell walls covered by a superfluid helium film. In the latter case, raising the trapping cell temperature to 200-250 mK, the low-field seeking atoms at densities exceeding 10$^{11}$ cm$^{-3}$ can be stored for the time over 1000 s, sufficiently long for experiments on precision spectroscopy of cold H gas.

arXiv:2412.13981•Dec 18, 2024•0 citations
Two ultra-cold methods of atomic hydrogen electron spin separation for polarized jet targets and sources will be described and compared. Both of them use a helium-film coated cell at 300 mK located in a high magnetic field. The first one, microwave driven extraction, uses a 212 GHz microwave system and 7.5 T magnetic field with a high uniformity ({Delta}B/B{approx} 10{sup {minus}5}). The second method employs the gradient of a high magnetic field for the state separation and beam formation. Experimental results from the two methods will be presented.
Research is described on a jet of polarized atomic hydrogen.Atoms in the two lower hyperfine states are trapped at 0.4 k in a 5 T magnetic field.Microwaves at 140 GHz then drive transitions to the upper hyperfine states and these atoms are expelled from the field to form the beam.Atoms have been trapped, transitions driven, and atoms detected outside the trapping field, but preliminary measurements are not fully understood.Studies are continuing.Work is continuing to test the applicability of cryogenic atomic physics techniques to the production of dense polarized atomic hydrogen beams.At high magnetic fields (5 T) and low temperatures (0.5 k), the magnetic energy of a hydrogen atom, approximately #, • B, is considerably higher than the thermal energy, kT.When cold atoms approach a high magnetic field, atoms in the two upper hyperfme states see a potential hill and are repulsed.Atoms in the two lower hyperfine states see a potential well, are attracted in, thermalize by hitting cold walls and are trapped.These trapped atoms are then irradiated with microwaves of the proper frequency (approximately 140 GHz for a 5 T field) to drive transition to one of the upper hyperflne states.These flipped atoms, now on a potential hill, are accelerated out of the field to form the beam.
We formed the first ``atomic-optics'' beam of electron-spin-polarized hydrogen atoms using a quasiparabolic polished copper mirror coated with a hydrogen-atom-reflecting film of superfluid 4He^{4}\mathrm{He}4He. The mirror was located in the gradient of an 8-T solenoidal magnetic field and mounted on an ultracold cell at 350 mK. After the focusing by the mirror surface, the beam was again focused with a sextupole magnet. The mirror, which was especially designed for operation in the magnetic field gradient of our solenoid, increased the focused beam intensity by a factor of about 7.5.
Spin-polarized atomic hydrogen (H↓) gas at low temperatures (<0.5 K) has been studied using Electron Spin Resonance (ESR) techniques which allow direct measurements of the densities of H atoms in each of the two lower hyperfine states (a and b). It has been demonstrated that ESR can be made to yield accurate and detailed information about the decay of H↓ densities in time. Crucial to the analysis of the data is the ability to confine the sample of H↓, gas inside the liquid ⁴He coated microwave cavity where the magnetic field and temperature are well known. Measurements of K[sub aa] and K[sub ab], the two surface recombination rate constants, and their ratio γ=K[sub aa]/K[sub ab] have been made and from these results the binding energy of H on liquid ⁴He has been extracted. Also reported are the results of the first detailed study of the one-body surface relaxation rate which we find is due to microscopic magnetic impurities in the cell walls. Theoretical calculations of the two-body dipole-dipole relaxation rate of H↓ in the gas and on the surface are also presented.
The possible application of the stable atomic hydrogen (H↓) in intense polarized atom or ion beam sources is discussed. The proposed scheme is based on flipping the electron spin of stored atoms by microwaves; this results in the magnetic acceleration and focusing of the flipped atoms. The main advantages of such beams are: accumulation and pulsing with time structure convenient for injection into synchrotrons via Linac injectors; high density due to the slow velocity and high initial density; and monochromaticity which allows atomic beam transport with focusing elements having no large chromatic errors. The possible problems and limitations in such an extraction scheme are: depolarization and slow spin diffusion due to spin exchange collisions in the dense gas phase, and loss of density due to recombination of the flipped atoms on the walls, before reaching the extraction aperture and accelerating field gradient.The results of the first tests of our apparatus are presented. The apparatus, based on a powerful dilution refrigerator, is described briefly.
We present a design and performance tests of an intense source of cold hydrogen atoms for loading large magnetic traps. Our source is based on a cryogenic dissociator of molecular hydrogen at 0.6 K followed by a series of thermal accommodators at 0.5, 0.2 and 0.13 K with inner surfaces covered by a superfluid helium film. All components are thermally anchored to corresponding stages of a dilution refrigerator. The source provides a continuous flux of 7⋅\cdot⋅101310^{13}1013 H atoms/s in a temperature range of 130-200 mK. We have successfully used the source for loading a large Ioffe-Pritchard magnetic trap recently built in our laboratory [arXiv:2108.09123 or Rev. Sci. Instr. 93 (2), 023201 (2022)]. Calorimetric measurements of the atomic recombination heat allow reliable determination of the atomic flux and H gas density in the trap. We have tested the performance of the source and loading of H atoms into the trap at various configurations of the trapping field, reducing the magnetic barrier height to 75% and 50% of the nominal value of 0.8 T (0.54 K) as well as at the open configuration of the trap at its lower end, when the atoms are in contact with the trapping cell walls covered by a superfluid helium film. In the latter case, raising the trapping cell temperature to 200-250 mK, the low-field seeking atoms at densities exceeding 1011^{11}11 cm−3^{-3}−3 can be stored for the time over 1000 s, sufficiently long for experiments on precision spectroscopy of cold H gas.