BigBite Optics #3

I have started working again on the BigBite optics calibration. For my second iteration I still have to find matrix elements for TgPh and TgTh variables (while I was at JLab I only managed to determine matrix elements for TgY and TgDelta). This week I have started with the calibration of the BB.tr.tg_ph variable. When I finish this first iteration I was thinking of using these results and try to calculate some raw asymmetries. I would like to see how much will the results change with respect to my first attempt to calculate them.

TgPh Calibration:

For the TgPh calibration I decided to use following Hydrogen-reference cell runs:

1.) #2814: H2, E0 = 2.425GeV, thBB = 82deg
2.) #1518: H2, E0 = 1.245GeV, thBB = 74deg
3.) #3488: H2, E0 = 2.425GeV, tgBB = 75deg
4.) #3586: H2, E0 = 3.606GeV, tgBB = 75deg

Problems with run #2814:

When I was trying to calibrate angle TgPh with this run, I found large discrepancy between directly measured angle (with BB) and reconstructed angle from HRS-L via q-vector. In the end I realized, that there are no good elastic coincidence events for this kinematics and that events that I thought are Hydrogen elastic events were actually events from the windows of the target cell.

Before ReactZ cut:
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With cut on the inner portion of the target cell:
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Matrix element "[FpPh|TgPh]"

At this point I have used runs #1518 and #3488 to calibrate this matrix element. At the moment I have considered only this matrix element and neglected TgPh dependence on FpX, FpY and FpTh. I have determined this matrix element by making narrow cuts on the reconstructed PhTg angle and then for each setting determined the mean value of the gaussian distribution on the focal plane of the BB. Here are my current results:

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Last modified: 03/03/10