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    User name J. Singh

    Log entry time 06:25:44 on July24,2004

    Entry number 129515

    keyword=Rob's studies + switching back to HAPPEX detector

    @ 0455:
    We got the LH2 Q^2 data at the beam positions listed in the previous entry (129506). Rob wants to take the same data with beam centered at nominal zero. Therefore, we turned off the VDCs (0456), increased the beam current to 1 µA (0502), asked MCC to tweak the beam position (0507), reduced the beam current to 0.2 µA (0508), and finally turned on the VDCs back on (0511).

    We took LH2 data with beam positions at nominally:
    BPM4A (-0.03,-0.02) mm
    BPM4B (-0.02,-0.01) mm

    @ 0524:
    Now we are preparing to do background studies with the 20 cm Al dummy target. This target simulates the Al windows of the LH2 target. We took some data at 0.2 µA and then we increased the current to 1 µA (0536).

    @ 0548: Switching back to HAPPEX detector!
    (1) Turned off VDCs (0549)
    (2) Turned off all S2 HV in both arms (0555)
    (3) No other "standard" detector HV are on.
    (4) Rob switches the cable (unplugged) in the middle room.
    (5) HAPPEX detector HV are reset to previous values, halog 129478.
    (6) Checked spot. Looks good.

    @0605
    Rob and I double check that the HV settings are correct. We ask for the beam current to be increased to 35.5 µA. In addition the BPMs are back in "Forced Gain" on iocse8 and iocse10. The gain values are what they were before (halog 129182) with the "RF High" setting. About 10 min of data is taken on the 20cm dummy Al target with the HAPPEX detector.

    @0616: Switching back to Production!
    We turn beam modulation (dithering) back on and start moving the target back to LH2. The target is back in the LH2 position at 0622 and we request 36 µA. Production running resumes @ 0625.