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    User name jinhuang

    Log entry time 16:29:14 on November 02, 2008

    Entry number 246271

    This entry is a followup to: 246268

    keyword=Before taking beam@4PM, he3 Pol. is estimated to be 38%.

    An NMR polarization measurament is performed @15:58:10 11/2/2008, before taking beam. Pol. is estimated to be 38%.

    Calculation detail:

    ----------------

    We had a vertical field, Long. RF, run 10:31:19 this morning: http://www.jlab.org/~bbsoftw/TargetReports/GenericLog/NMRField_02-11_10- 31-19.html The pumping chamber pickup coil reads 40mV. And base on EPR calibration last night(1.5%/mV), the pol at that time is 60%.

    ----------------

    Then at 10:49:19 this morning, target is lowered to Pickup Coil location. An NMR is performed at Long. Holding Field, Vert RF, and target chamber pickup coil: http://www.jlab.org/~bbsoftw/TargetReports/GenericLog/NMRField_02-11_10- 49-19.html The pickup coil reading are:

    UpStream =240mV

    DownStream =250mV

    So the calib constant for target chamber pickup coils are roughly: 0.12%/mV * (UpStream NMR+ DownStream NMR)

    ----------------

    At 15:58:10, the target is lowered to pickup location again, and a same NMR is performed: Long. Holding Field, Vert RF, and target chamber pickup coil: http://www.jlab.org/~bbsoftw/TargetReports/GenericLog/NMRField_02-11_15- 58-10.html The pickup coil reading are:

    UpStream =155mV

    DownStream =160mV

    Therefore the Pol at 4PM is ~38%