On the limits of spin-exchange optical pumping of 3He
Thomas R. Gentile, T G. Walker, E Babcock, Qiang NMN Ye, Wangchun Chen
Using diode bar lasers spectrally narrowed with chirped volume holographic gratings (VHGs), we have obtained an improvement in the 3He polarization achievable by spin-exchange optical pumping (SEOP). As compared to our past results with lasers narrowed with diffraction gratings, we have observed between 5 % and 11 % fractional increase in the 3He polarization. These results were primarily observed in large cells but we also report higher polarization in small cells, in particular one flat-windowed cell in which prior extensive studies indicated that the alkali-metal polarization was within 3 % of unity. We conclude that the most likely explanation for the improvement in 3He polarization is increased alkali-metal polarization, which has impact on understanding the maximum 3He polarization achievable by SEOP. The maximum polarization we have observed is P_ He=0.85 in a neutron spin filter cell nearly 1 liter in volume.
, Walker, T.
, Babcock, E.
, , Q.
and Chen, W.
On the limits of spin-exchange optical pumping of 3He, Physical Review A, [online], https://doi.org/10.1063/1.4886583
(Accessed September 28, 2023)