Anomalous spin echoes in highly polarised liquid helium mixtures

Abstract : NMR experiments are performed on laser polarised liquid helium mixtures in low field (2 mT) above 1 K. Concentrations range from 0.5% to 10% and nuclear polarisations up to 0.1. For large magnetisations, following a 90degrees-tau-180degrees RF pulse pair the spin echo signal detected at time 2tau is significantly smaller than expected from attenuation due to diffusion in the applied static field gradient. Unexpected echoes are also observed at times 3tau, 4tau, 5tau, etc. The first feature may be related to other effects of large dipolar fields in bulk samples (dynamic instabilities, altered transverse decay). Numerical simulations on lattices have been performed to quantitatively interpret all spin echo results. (C) 2003 Elsevier Science B.V. All rights reserved.
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Contributor : Geneviève Tastevin <>
Submitted on : Wednesday, February 13, 2019 - 9:36:59 PM
Last modification on : Monday, September 2, 2019 - 5:54:10 PM

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G. Tastevin, N. Piegay, F. Marion, Pierre-Jean Nacher. Anomalous spin echoes in highly polarised liquid helium mixtures. Physica B: Condensed Matter, Elsevier, 2003, 329-333, pp.187-188. ⟨hal-02018540⟩

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