Models for low-temperature helium dimers and trimers

We have shown that a simple model based on pairwise deltafunction potentials can, with an appropriate choice of parameters, represent the general behavior of ultra-low temperature helium dimers and trimers, including all possible isotopomers. The species 4 He 2 , 4 He 3 , and 4 He 2 3 He are stable, with binding energies of approximately 1.3, 100, and 10 mK, respectively. An Efimov state for 4 He 2 3 He is also predicted, bound by 2.4 mK. The remaining dimers and trimers, 4 He  3 He, 3 He 2 , 4 He  3 He 2 , and 3 He 3 , are evidently unstable. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34398/1/1807_ftp.pd

Targeting CD22 Reprograms B-Cells and Reverses Autoimmune Diabetes

OBJECTIVES—To investigate a B-cell–depleting strategy to reverse diabetes in naïve NOD mice

Matter-Wave Diffraction from a Periodic Array of Half Planes

We report on reflection and diffraction of beams of He and D2 from square-wave gratings of a 400-??m period and strip widths ranging from 10 to 200 ??m at grazing-incidence conditions. In each case we observe fully resolved matter-wave diffraction patterns including the specular reflection and diffracted beams up to the second diffraction order. With decreasing strip width, the observed diffraction efficiencies exhibit a transformation from the known regime of quantum reflection from the grating strips to the regime of edge diffraction from a half-plane array. The latter is described by a single-parameter model developed previously to describe phenomena as diverse as quantum billiards, scattering of radio waves in urban areas, and reflection of matter waves from microstructures. Our data provide experimental confirmation of the widespread model. Moreover, our results demonstrate that neither classical reflection nor quantum reflection are essential for reflective diffraction of matter waves from a structured solid, but it can result exclusively from half-plane edge diffraction

Applications of commercial optical gratings as mirrors for matter waves

Mirrors for atoms and molecules could open new frontiers in matter-wave optics with neutral particles. However, the realization of such components has required sophisticated electromagnetic fields, nano-fabrication, or particle cooling because of inherently short de Broglie wavelengths of atoms and molecules and their strong interaction with a surface. We demonstrate that blazed gratings designed for light waves can work as mirrors for atoms and molecules of thermal energy with up to 47% reflectivity when used under grazing incident conditions. The matter-waves of He atoms are reflected from blazed gratings of different periods (20, 3.33, and 0.417 ??m) that are commercially available. The specular reflection probability is well described by the multiple edge- diffraction reflection (MEDR) model. When a wave scatters off an array of half-planes at grazing incidence, it undergoes multiple diffractions by the half-plane edges. Within the MEDR model the reflection probability increases with decreasing incidence angle and grating period. This allows us to observe reflection of fragile He clusters (He2 and He3) with the 417-nm-period grating, which implies that the grating mirror based on the MEDR mechanism can also work for other exotic particles, such as antihydrogen atoms. It will be possible to prepare an almost perfect mirror (close to 100% reflectivity) for a neutral particle by tailoring the edges of a grating and shortening its period. Our experiment and analysis show that commercial optical blazed gratings can serve as a mirror in matter-wave optics, which paves the way toward developing various matter-wave-optical instruments