User name Sulkosky
Log entry time 07:49:18 on March 5,2006
Entry number 165277
Followups:
keyword=Barbara Polarization Time DependenceFigure 1 shows the spin up curves for Barbara for both Up and Down
Sweeps. Red points were taken at 220 degrees C, and the blue points
were taken at 235 degrees C. The curves are fits to only the red
points. If I include the blue points, the saturation polarization
is over 90 mV at 235 degrees C.
Note: if the spin up was done solely at 235 degs. C, then the time
constant should be faster by a factor of two based on past experience
with hybrid cells. Since our time constant is longer than we
expected, we are more sensitive to beam depolarization. AFP losses
were not corrected for from NMR and EPR. Unless otherwise noted, the
polarization should continue to be tracked.
Fit Parameters
Up Pmax = 81.23 mV
Up Time constant = 13.0 hours
Down Pmax = 79.78 mV
Down Time constant = 12.8 hours
Figure 2 shows the oven temperture and Big Bite currents over
a similar time period that the NMR measurements were taken.
FIGURE 1
FIGURE 2
