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    User name X. Zheng

    Log entry time 03:15:35 on July26,2001

    Entry number 67648

    keyword=Target - EPR 45.2% and one laser test

    EPR measurement and one laser test

    target position: 12C/BeO, beam ON
    durint data taking of false asymmetry test run # 2271/21271~#2272/21272

    if you have only one 30 seconds, please read "Conclusion" directly...

    -----------------------------------
    what has been done

    1:49 am, EPR with 3 longitudinal lasers;
    photodiode signal DC -38mV, D2 31uV;
    RF 15.0V, Mod 0.8Vpp;
    comments: good flips, down flip is slow but okay
    Polarization (average of down & up, 0th fit) = 45.2%
    (average of down & up, 1st fit) = 45.2%

    1:53 am, turn off laser #5 and #7
    photodiode signal DC -13mV, D2 20uV;

    2:02 am, EPR (3 sweeps) with laser #6;
    Polarization (average of down & up 0th fit) = 44.8%, 44.7%, 44.9%
    (all with ~ 3% abs. error)
    RF 15.0V, Mod 1.5 Vpp;
    comments: adjusted abs./rel. gains a few times but none of these sweeps is acceptable;

    2:13~2:15 am, turn on lasers #5 and #7, set abs/rel gains back to original setting for 3 lasers;

    2:25 am: EPR with 3 lasers;
    RF 15.0V, Mod 0.8 Vpp;
    comments: spectrum confirms that the gains are the same as original setting, good flips;
    Polarization (average of down & up, 0th fit) = 43.7%
    (average of down & up, 1st fit) = 43.6%

    -------------------------------------------------
    Conclusion:

    Here is a list of cell vs. EPR configuration vs. photodiode signal

    Cell Name......... one laser ...... three lasers....... photodiode DC ........
    Gore.................. good ............. acceptable ................210 mV ............
    Tilghman.......... not acceptable....... good..................47 mV...............
    Shapiro.............. not tested....... not tested ................210 mV ............
    Duke ................. not tested...............good ................. 48 mV .............
    Virginia One ..... not tested........not tested................. not tested ........

    There is a strong indication that whether one laser configuration is acceptable
    or not depends on the photodiode signal DC amplitude. So I expect that one
    laser configuration works for Shapiro @ transverse (which will save time during g2)
    but not for Duke. For Virginia One no conclusion can be made yet.

    -------------------------------------------------
    boring fit data:

    AFP7_26_1_49am
    1st order:
    down: freq. shift = -50.09 KHz +/- 1.32 KHz, P = -45.74%+/- 1.20%
    up: freq. shift = 49.01 KHz +/- 1.34 KHz, P = 44.76%+/- 1.22%
    0th order:
    down: freq. shift = -49.76 KHz +/- 1.34 KHz, P = -45.45%+/- 1.23%
    up: freq. shift = 49.23 KHz +/- 1.36 KHz, P = 44.95%+/- 1.25%


    AFP7_26_2_01am
    0th order:
    down: freq. shift = -48.77 KHz +/- 2.72 KHz, P = -45.21%+/- 2.52%
    up: freq. shift = 47.81 KHz +/- 2.53 KHz, P = 44.31%+/- 2.35%
    up: freq. shift = 0.88 KHz +/- 3.40 KHz, P = 0.82%+/- 3.15%
    down: freq. shift = -48.64 KHz +/- 5.64 KHz, P = -45.09%+/- 5.22%
    up: freq. shift = 47.86 KHz +/- 6.13 KHz, P = 44.37%+/- 5.68%
    up: freq. shift = 0.85 KHz +/- 4.40 KHz, P = 0.79%+/- 4.08%
    down: freq. shift = -47.98 KHz +/- 2.92 KHz, P = -44.47%+/- 2.71%
    up: freq. shift = 48.95 KHz +/- 2.61 KHz, P = 45.37%+/- 2.42%

    AFP7_26_2_26am
    1st order:
    down: freq. shift = -48.13 KHz +/- 0.96 KHz, P = -43.95%+/- 0.88%
    up: freq. shift = 47.43 KHz +/- 0.87 KHz, P = 43.31%+/- 0.80%
    0th order:
    down: freq. shift = -48.18 KHz +/- 0.95 KHz, P = -44.00%+/- 0.87%
    up: freq. shift = 47.50 KHz +/- 0.86 KHz, P = 43.38%+/- 0.79%