H * 0) can be created through the use of second or higher Born approximations. Because of the extreme smallness of the scattering length as compared to the de Broglie wavelength of the neutron, it is reasonable to expect that the cross section for emitting any transverse wave should be much smaller than the corresponding cross section for a longitudinal wave. Thus, the existing measurements of total cross sections 2 > 4 already give an indication that these excitations are longitudinal waves. However, because of our limited knowledge concerning the unusual behavior of He H, it is desirable to have a direct experimental determination of the helicity of these excitations as discussed above. If experimentally one finds that both the long-wavelength (k

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A new ultra-fast imaging technique that does not place extreme demands on the speed of the gradient system is described. When used with comparable MRI systems, the rotating ultra-fast imaging sequence (RUFIS) can acquire images 4 to 5 times faster than gradient-moment nulled EPI and more than twice as fast as DUFIS, OUFIS, or BURST techniques. Because the technique uses free induction decays instead of echoes, it can be made particularly insensitive to effects of motion, flow, and diffusion. Preliminary images of turbulent flow are presented to demonstrate this insensitivity. However, with appropriate encoding, flow effects may be imaged.