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    User name A. Kolarkar

    Log entry time 02:34:53 on April20,2006

    Entry number 171318

    keyword=Target Studies for the day

    During the down on Wednesday, I did some target studies which are summarized below.

    1. Did two calibrations with Rubidium (Rb). (Well, actually did three, but during the first one, noticed that the RTDs were not updating, so had to reboot the IOC and thus, had no good data on the temperatures.) This will be a good cross-check against the Potassium (K) calibrations. The Rb EPR signal was noisier than the K at 245°C - as has always been the case - but very steady. Increasing the EPR RF amplitude cleaned up the signal. Did one in the morning and one at night after the laser controlled access.

    2. Did the "Wolfgang test" - i.e. studied the EPR signal as a function of the EPR-RF amplitude. This was done on K in the "hat" state at 245°C. Shall do a similar test in the "well" state when/if it (the well state) happens.

    3. During the final Rb EPR, while in the higher frequency state (spins flipped the first time for a "hat" EPR), I turned the NMR-RF function generator off. I see no difference in the frequency. This is the same result as was obtained with the K EPR earlier in the experiment. This test has not yet been done in the "well" state. Shall do it when I get the chance - along with the "Wolfgang test".

    Note that the NMR RF effect study can be done during a normal EPR calibration process - with a few tweaks - and the Wolfgang test does not require a spin flip, so not much polarization will be lost in doing both tests.

    4. Also managed to squeeze in a K-EPR around noon.

    5. The target (Windows) computer is showing it's true color - Blue (Screen of Death)! It happened thrice today, and has happened five times overall. So spent some time backing up most of the data. They now reside on the farms. Let's just hope the machine lasts for a few more days!

    Finally, the polarization at 2200 hours was about 41% with the beam still 5 hours away (at least?), so that should bring the polarization back in the vicinity of 50% (phew!). Note that the above studies were not the only reason for the polarization drop. Others include

    i) Turning the lasers off for about 30 minutes (total) when the wood shielding was removed from the target box.

    ii) The fibers and laser power tests done in the evening during the laser controlled access (~ 2 hrs).

    That's it for now!