Effects of nitrogen quenching gas on spin-exchange optical pumping of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">He</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>

Lancor, Brian; Walker, Thad

doi:10.1103/physreva.82.043417

Cited by 15 publications

(14 citation statements)

References 23 publications

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“…The angular momentum is also lost by light absorption at a rate R K by the potassium atoms. The factors of 1/2 assume relaxation of the electronic angular momentum in the excited state, and that sufficient N 2 quenching gas is included in the cell so that the nuclear spin is conserved in the excited state [12]. In steady state, the polarization becomes…”

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confidence: 99%

Polarization limits in K-Rb spin-exchange mixtures

Lancor

Walker

2011

Phys. Rev. A

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confidence: 99%

Polarization limits in K-Rb spin-exchange mixtures

Lancor

Walker

2011

Phys. Rev. A

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“…Rapid quenching of the excited atoms by N 2 molecules plays an essential role in this process (Lancor and Walker, 2010). Since SEOP typically takes place in extremely optically thick cells, the reabsorption probability for photons emitted by the excited alkali atoms can be considered to be nearly unity.…”

Section: Spin-exchange Optical Pumpingmentioning

confidence: 99%

“…At lower densities, however, as the electrons are rapidly relaxed in the excited state, hyperfine coupling with the nuclei causes some nuclear spin-relaxation, reducing the optical pumping efficiency and requiring more photons per atom to reach full polarization (Lancor and Walker, 2010). …”

Section: Spin-exchange Optical Pumpingmentioning

confidence: 99%

“…The degree of the circular polarization (99% or better is usually attained with commercial wave plates) is not highly critical because the relatively high alkali-metal density strongly absorbs the undesired photon spin state (Bhaskar et al , 1979; Chann et al , 2002b). To suppress radiation trapping from radiative decay of the excited alkali-metal atoms, on the order of 0.1 amg of nitrogen gas is added to provide rapid collisional de-excitation (Lancor and Walker, 2010; Walker and Happer, 1997). …”

Section: Introductionmentioning

confidence: 99%

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Optically polarizedHe3

et al. 2017

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This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements.

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“…A number of new effects that will decrease the calculated alkalimetal polarization have recently been reported, including circular dichroism, 42 potassium absorption, 43 excited state relaxation, radiation trapping, and laser heating. 44 Work is in progress to develop a complete model that will include all these effects. It is likely that such an improved model will affect the comparison to measured results, but primarily for large cells optically pumped at relatively high spin-exchange rates rather than small cells or low rates.…”

Section: Ramifications For Seopmentioning

confidence: 99%

On the limits of spin-exchange optical pumping of 3He

Chen

Gentile

et al. 2014

Journal of Applied Physics

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We have obtained improvement in the 3 He polarization achievable by spin-exchange optical pumping (SEOP). These results were primarily obtained in large neutron spin filter cells using diode bar lasers spectrally narrowed with chirped volume holographic gratings. As compared to our past results with lasers narrowed with diffraction gratings, we have observed between 5% and 11% fractional increase in the 3 He polarization P He . We also report a comparable improvement in P He for two small cells, for which we would not have expected an increase from improved laser performance. In particular, prior extensive studies had indicated that the alkali-metal polarization was within 3% of unity in one of these cells. These results have impact on understanding the maximum P He achievable by SEOP, whether the origin of the improvement is from increased alkali-metal polarization or decreased temperature-dependent relaxation. We conclude that the most likely explanation for the improvement in P He is increased alkali-metal polarization. We have observed P He of between 0.80 and 0.85 in several large cells, which marks a new precedent for the polarization achievable by SEOP. V C 2014 AIP Publishing LLC. [http://dx.

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Effects of nitrogen quenching gas on spin-exchange optical pumping ofHe3

Cited by 15 publications

References 23 publications

Polarization limits in K-Rb spin-exchange mixtures

Polarization limits in K-Rb spin-exchange mixtures

Optically polarizedHe3

On the limits of spin-exchange optical pumping of 3He

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