Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 1: Posters Monday (Cluster, Atoms in Fields)
A 1.28: Poster
Montag, 2. April 2001, 12:30–15:00, AT3
Hyperpolarization of 3He by spin-exchange with light alkalis — •Peter I. Borel, Lise V. Søgaard, Winnie Svendsen, and Nils Andersen — Niels Bohr Institute, Ørsted Laboratory, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
Hyperpolarized 3He, with nuclear polarization on the order of tens of percent, may be produced by spin-exchange with optically pumped alkali atoms. The polarized gas, which can have lifetimes of hundreds of hours, has found applications within a variety of fields such as lung imaging by MRI, targets for nuclear experiments, neutron spin filters. Traditionally, rubidium has been used as spin-exchange partner. However, the spin-exchange process has previously been shown to be more efficient when using potassium, and the spin-exchange efficiency is expected to be even higher when sodium is used.
We are currently measuring the key spin-exchange and spin-destruction rates that determine the efficiency for polarizing 3He using potassium or sodium, and we will present preliminary results. We measure the total spin-destruction rate by so-called relaxation in the dark experiments in sealed glass cells. The alkali polarization is monitored by use of a photo-elastic modulator and the 3He polarization by NMR. In the near future we plan to determine the 3He polarization in situ by measuring the polarization-induced shift in the alkali EPR frequency.