Berlin 2012 – wissenschaftliches Programm

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ST: Fachverband Strahlen- und Medizinphysik

ST 4: Poster

ST 4.3: Poster

Dienstag, 27. März 2012, 10:10–11:30, Poster F

Preventing rubidium runaway in a compact continuous-flow SEOP hyperpolariser for xenon NMR — •Christopher Witte, Martin Kunth, Federica Rossella, and Leif Schröder — Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany

Hyperpolarised noble gases have many applications in medical physics such as magnetic resonance (MR) lung imaging and MR biosensor design. Noble gases can be hyperpolarised using processes such as spin exchange optical pumping (SEOP), increasing their detectable magnetisation by 3–4 orders of magnitude above thermal polarisation. In SEOP the easily generated angular momentum of laser light is used to polarise rubidium and through collisions this is then transferred to the noble gas. Recently available high power diode laser have the potential to efficiently pump rubidium even at high vapour pressures. Unfortunately in most compact SEOP polarisers the increased laser power can cause excessive heating of the pumping cell. This leads to a deleterious process known as rubidium runaway. We present a modified continuous-flow hyperpolariser for xenon MR studies specifically designed to overcome this problem. Utilising thermal management we can dissipate this excess heat and prevent rubidium runaway while maintaining a compact design. When increasing the laser power from 100 to 150 W with optimised temperatures we observed an increase in xenon spin polarisation by a factor of 4.