P . - J . Nacher

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This work reports the use of single-shot spin echo sequences to achieve in vivo diffusion gas measurements and ultrafast imaging of human lungs, in vivo, with hyperpolarized (3)He at 0.1 T. The observed transverse relaxation time of (3)He lasted up to 10 s, which made it possible to use long Carr-Purcell-Meiboom-Gill echo trains. Preliminary NMR studies(More)
We demonstrate time reversal of nuclear spin dynamics in highly magnetized dilute liquid (3)He-(4)He mixtures through effective inversion of long-range dipolar interactions. These experiments, which involve using magic sandwich NMR pulse sequences to generate spin echoes, probe the spatiotemporal development of turbulent spin dynamics and promise to serve(More)
Metastability exchange optical pumping of helium-3 is performed in a strong magnetic field of 1.5 T. The achieved nuclear polarizations, between 80% at 1.33 mbar and 25% at 67 mbar, show a substantial improvement at high pressures with respect to standard low-field optical pumping. The specific mechanisms of metastability exchange optical pumping at high(More)
We describe an actively shielded cylindrical RF transmit coil producing a highly uniform internal field (±0.5%) over an extended volume and a strongly suppressed (÷20) external field. Direct field mapping and experimental checks using in-situ NMR and MRI of polarised (3)He at low temperature demonstrate performance consistent with numerical field(More)
Diffusion of hyperpolarised 3He in a silica aerogel sample with 98% porosity was measured by NMR, and systematically studied as a function of pressure P in the range 20 mbar -1 bar. Spin-echo amplitudes, recorded with pulsed gradients in the usual CMPG sequence, follow a monoexponential decay, and the decay rate varies quadratically with the gradient(More)
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