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User name zhangyi
Log entry time 11:45:34 on November 2,2008
Entry number 246221
keyword=NMR Calibration for Longitudinal Polarization
Around 12 o'clock I finish a NMR calibration. The procedure is:
step 1: turn off laser, leave the target in optics position.
step 2: while the holding field is vertical, make sure the RF is longiturdinal, I do a NMR measurement, the data number is 103018, I get the polarization is 62.46%.
step 3: lower the target to pick-up coil position, do a NMR without changing anything else (data No. 103814). I get a polarization as 62.82% (they are should be same.)
step 4: rotate the field to longitudinal+, change RF to vertical(cell is in pick-up coil position), do a NMR. I got signal as high as 77.626mV in pumping chamber transverse PU coil(data No.104739).
step 5: rotat the field back to vertical+, change RF to longitudinal(cell is in pick-up coil position, then do a NMR. I got a polarization as 51.00%(data No 105458).
conclusion: We roughly consume 2 rotations have the same depolariztion effect. So the polarization in step 4 should be 56.82%. Then we get the relationship between longitudinal polarization and signal in pumping chamber:
height of signal * 0.732 = polarization in %