Operators: seely vziskin kohlm
Beam tuning continued. It became clear that by moving the septum the bqms could be dropped lower by a factor of 3.
After the tuning was done, we measure the atomic fraction in the target to be 53 %. This is not the best number. However, the icing was done during the beam tuning and after the cell was iced the beam continued to be tuned for few more hours before we made the measurents.
After we measure this we decided to run pol H with MFT 2-3 transition. From the z distribution it is clear that there is still some scattering going on from the target cell and other components around it. Most of these events are single tracks. The right side is consitently worst. It was counting twice as many single tracks as the left side. I think that it is not crazy to think that we are scattering something off the ion polarimeter component that is only on the right, like a deflector, etc. The acceptance is higher for those single tracks to to the right. This is consistent with the fact that the "upstream shoulder" is more prenounced on the right. Right now I'm getting a significant contribution from the empty target (~10%) cell even after e-p,z and coplanarity cuts, however TB claims that he can lower it. However, the z-distribution of CUT events from empty target now looks uniform in z with no "bumps" or "wings". So it seems that we can get rid of the single t!
rack events from the ends of the sell rather effectively. However, there is a uniform "grass" all along the target that I'm not sure that we can get rid of. Of course, the beam "blows up" when the gas is in the cell and therefore the "grass" could be even "higher".
Took pol H runs 2144, 2145 and 2146-------> crunching.
The BQMs are only 10% greater for gas in the target than they we for empty cell.
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