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    User name Jin Huang

    Log entry time 00:04:36 on February 25, 2009

    Entry number 263195

    This entry is a followup to: 262945

    Followups:

    keyword=Correction Coil On to Reduce Massing

    Target polarization stablize at ~55% with 20min/spin flip, lower than our expectation.

    Therefore, this afternoon flip interval was increased to 40min. However, the higher polarization of each spin flip pair increased, while the lower one (cooresponding to high energy state -> lower state) stay at same level. Therefore, it's now more likely that there is a massing effect limiting the polarization.

    So, as an attempt to increase the massing threshold, mall correction coil is turned on to 1A. As a result extra field gradiant should be introduced so the massing threshold should be higher.

    The NMR polarization calibration constant could be shifted a little due to the extra gradiant. However, if the massing effect is reduced, the overall signal hight (proportional to online pol.) should increase.

    A copy of this log entry has been emailed to: jpchen, yqiang