Circular dichroism of RbHe and RbN<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>molecules

Lancor, Brian; Babcock, Earl; Wyllie, Robert; Walker, Thad

doi:10.1103/physreva.82.043435

Cited by 24 publications

(27 citation statements)

References 23 publications

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“…We justify the use of this approach because it reliably reproduces the measured values of P ∞ as function of ν for a pure Rb cell reported in Ref. [32], when we set T d = 0.3 ps for Rb D2. Finally, the benefits of pure K & Na SEOP are also limited by off resonant absorption by the D2 lines, where (3σ…”

Section: The Alkali X-factorssupporting

confidence: 57%

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Development of high-performance alkali-hybrid polarizedHe3targets for electron scattering

et al. 2015

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We present the development of high-performance polarized 3 He targets for use in electron scattering experiments that utilize the technique of alkali-hybrid spin-exchange optical pumping. We include data obtained during the characterization of 24 separate target cells, each of which was constructed while preparing for one of four experiments at Jefferson Laboratory in Newport News, Virginia. The results presented here document dramatic improvement in the performance of polarized 3 He targets, as well as the target properties and operating parameters that made those improvements possible. Included in our measurements were determinations of the so-called X-factors that quantify a temperature-dependent and as-yet poorly understood spin-relaxation mechanism that limits the maximum achievable 3 He polarization to well under 100%. The presence of this spinrelaxation mechanism was clearly evident in our data. We also present results from a simulation of the alkali-hydrid spin-exchange optical pumping process that was developed to provide guidance in the design of these targets. Good agreement with actual performance was obtained by including details such as off-resonant optical pumping. Now benchmarked against experimental data, the simulation is useful for the design of future targets. Included in our results is a measurement of the K-3 He spin-exchange rate coefficient k K se = (7.46 ± 0.62)×10 −20 cm 3 /s over the temperature range 503 K to 563 K.

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Section: The Alkali X-factorssupporting

confidence: 57%

“…where we've assumed pumping with perfectly monochromatic light with frequency ν. Measurements by Romalis et al [20] and more recently by Lancor et al [31][32][33] indicate that |T d | is of order 0.1 ps for alkali-3 He collisions. Using this value, we find that (3σ 3 .…”

Section: The Alkali X-factorsmentioning

confidence: 95%

Development of high-performance alkali-hybrid polarizedHe3targets for electron scattering

et al. 2015

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“…Under the high density conditions of SEOP, absorption of light during alkali-metal-He (or N 2 ) collisions does not obey the selection rules for isolated atoms (Lancor et al , 2010a,b). This is because the fine-structure states are mixed during collisions with He atoms, as illustrated in Fig.…”

Section: Spin-exchange Optical Pumpingmentioning

confidence: 99%

“…Figure 8 shows measurements of the circular dichroism P ∞ of maximally polarized Rb atoms in the presence of 3 He gas (Lancor et al , 2010a,b). While the dichroism peaks at very close to 1 right on resonance, at only 1 nm (475 GHz) detuning from the line center, the dichroism has already dropped to 0.9.…”

Section: Spin-exchange Optical Pumpingmentioning

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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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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Circular dichroism of RbHe and RbN2molecules

Cited by 24 publications

References 23 publications

Development of high-performance alkali-hybrid polarizedHe3targets for electron scattering

Development of high-performance alkali-hybrid polarizedHe3targets for electron scattering

Optically polarizedHe3

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

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