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    User name markowitz

    Log entry time 08:14:58 on February 7,2000

    Entry number 33006

    keyword=shift summary

    Started shift taking 3He(e,e) elastic data.

    12:10 Called Mark Stevens in for access to change spectrometer angles. Theta_e=78.151. Also set Pe=0.731.
    01:40 beam back. Going to 100 mikes, setting 19 kinematics. 3He(e,e'p) QE at pm=0 . started run 1961

    02:00 beam is still stable and we have not done more than check rates and spectra yet.

    run 1962 we started with 45 mikes. Data are good.

    02:30 MCC called. They do not know why we are having trouble going to higher currents but the bigger raster size may be part of it. Speculation followed aboiut maybe in the energy change, the raster currents were NOT changed, and the (too) big raster is tripping off the ion chambers.

    02:40 MCC called back to say that even with a smaller raster, things are not improved and we are still current limited at the moment.

    The beam spot looks odd in the center (e.g., we run "spot" and get a dark patch in teh center of the target). The raster pattern should not produce such a dark spot, so it is either an artifact of the paw / spot analysis and plotting, or there is something odd in the raster hardware. mcc is not aware of anything that could cause this. At the moment we continue to take data.

    04:00 mcc has a few ideas on trying to get the current up (cycling magnets, reloading files, etc). We turn over the beam to mcc for a few minutes. We have about 500 2-body 3He(e,ep)X events in the first 20K we analyzed of run 1962. There are 800K, or 20k of 2-body events. [We want 40k.]

    04:15 mcc calls back. They find no difference on the ion chambers. We are going to the 10 cm dummy target (low current running).

    04:25 start 10 cm dummy run, 1963. Beam unstable, stop and start 1964
    04:30 change to 4 cm dummy run 1965

    04:40 move to 12C target. Here, 50 mikes is ok as that is the administrative limit for carbon (jlab doesn't want us to generate any diamond foils). run 1966

    05:30 change back to 3He(e,e'p) for more running at 50 mikes. run 1967 started. Looking at spot, the dark point at the center of the target is not there anymore. Taking another 800k of triggers. [500 qe in the first 20k --> need 1.6M events total and we already had .8M]

    07:00 changed electron mometnum to 0.433 and angle to 81.9. DAQ had roc14 troubles at this moment as well.

    07:30 mcc called. They are going to briefly remove the otr foil to see if it has any effect on the ion chamber. MCC says with the otr gone the rate drops to 0!! They also claim they are not hitting the frame of the otr. So this is interesting.
    Our choice is to either run with 50 mikes and otr in or 100 mikes and otr out. we chose 50 mikes at the moment. Started run 1969 at 7:41