William Happer

Princeton University

Primary Section: 13, Physics
Membership Type:
Member (elected 1996)

Research Interests

Spins have always had a special fascination for me. In my laboratory we have systematically studied how angular momentum can be transferred into nuclear, atomic, and molecular spin systems by optical pumping with lasers, and how that angular momentum can be exchanged with other spins and with the environment. Of special interest are spherical atoms like those of the alkali metals or the noble gases. Once the electron or nuclear spins of these atoms have been polarized, they are quite resistant to angular momentum losses in collisions. The interactions leading to those losses are subtle but are greatly enhanced by the large electric fields near the nuclei of heavy noble atoms like cesium or xenon. In the course of these studies, my research group and I have learned how to use optical pumping with lasers to make liters He-3 and Xe-129 gas with nuclear polarizations approaching 100 percent. Recently, we have been using these hyperpolarized gases to make magnetic resonance images of human and animal lungs. We believe that such images will have widespread clinical utility. Since Xe-129 is very soluble and retains its nuclear polarization in tissue and blood for tens of seconds, it may well be possible to use hyperpolarized Xe-129 to make useful images of other body organs, as well.

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