Replacing muons by protons: polarized beam NMR

Numerous applications of mu SR use the muon as a light substitute for the proton, One key reason why mu SR is used in many cases rather than NMR on 'real' protons is the huge difference in sensitivity. Conventional NMR uses the tiny nuclear polarization which is due to the Boltzmann distribution and typically of the order of 10(-5), About five orders of magnitude in sensitivity can thus be gained if protons (or other nuclei) from highly polarized beams are used. Such beams have already been used for decades in nuclear physics research. The high polarization achieved renders the free induction decay signal of a few mu As of protons detectable. We demonstrated this with polarized protons implanted into D2O, liquid Br-2, and crystalline Si. (C) 2000 Elsevier Science B.V. All rights reserved.