We have discovered that 5 keV bursts of 5 × 107 positrons with an initial longitudinal spin polarization of (28.8 ± 0.7)%, when implanted into a thin Ni(100) crystal, are emitted with 20% efficiency at thermal energies from its surface with (30.9 ± 0.5)% polarization. We conclude that the positron spin polarization is preserved while interacting with the Ni, despite the 0.61 T average transverse magnetization of the Ni at room temperature. The resulting polarized beam has been focused to a 0.025-mm mean-diameter spot when accelerated to 5 keV and will be uniquely suited for experiments on a neutral spin aligned e+-e − plasma, spin- and angle-resolved positronium emission spectroscopy, and critical for producing a triplet positronium Bose-Einstein condensate.
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A simple, isotropic depolarized light source
Unpolarized light can be an important tool in optical experiments. Producing it, however, can prove to be a challenge. Natural sources of light that are commonly thought of as unpolarized are, in fact, either weakly polarized or not practical sources of light in a laboratory setting. Standard, commercially available light depolarizers produce unpolarized light only after the polarization state of the light across the diameter of the output beam has been averaged. Locally, such beams are highly polarized. In this work, we report a simple, low cost light depolarizer capable of producing light with a total polarization of less than 1% for a 15-mm diameter output beam. Based upon diffuse scattering, the light transmitted through the depolarizer discussed here produces only small polarizations locally, with the total polarization for a 1.25-mm diameter area being <6%. The effects of the depolarizer on the transmitted beam’s intensity are also reported.
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- Award ID(s):
- 2110358
- PAR ID:
- 10530306
- Publisher / Repository:
- AIP
- Date Published:
- Journal Name:
- Review of Scientific Instruments
- Volume:
- 94
- Issue:
- 10
- ISSN:
- 0034-6748
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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