BigBite Optics #13

My poster for MENU 2010

Here is my poster for the upcoming conference MENU 2010:posterMenu2010.pdf

TgTh calibration:

I have corrected the offset that we observed for the TgTh variable when looking at elastic runs.

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After:

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Results of the random analysis for TgTh:

Calibration of the target variables requires the determination of approx. 30 matrix elements. Initial parameters for the \chi^2 minimization are arbitrary. Due to the numerical complexity of the problem it is not certain that the solution is unique. The robustness of the method is tested by checking the convergence of the minimization for a large number of randomly chosen initial sets of parameters. Our method is robust over a wide range of initial parameters.

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Results of the random analysis for TgY:

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Strange plots from last week

On a last week phone meeting I was showing you strange BB.tr.x vs. BB.tr.th plots with sections where events were eaten away and I did not understand what caused this strange behavior. Today I think I found an answer. The problem was in a raw coincidence cut, that I used in my calibration. I wanted to have a really clean set of events for my calibration. Therefore I placed a very narrow cut on DL.t3 variable. However, this variable is a raw coincidence time and does not consider the Time-of-flight corrections. Therefore events from different paddles cause coincidence trigger at slightly different times. By placing a narrow cut on this variable I by mistake cut away events from a few paddles. Please see figures attached. This problem can be easily fixed by placing a broader cut on DL.t3 variable.

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Problem with DB for Rastered Beam:

I have run script that generates DB for the rastered beam. Unfortunately the results that I get with this script do not agree with the results that Ge Jin sent me. Also the results of my analysis differ significantly when using both versions of this file. Is he using different DB?

Ge's results:

-0.00552753 0.00609701 2.17332e-06 -1.24226e-06 0. 0.
-0.00885383 0.00750883 2.6609e-06 -1.59721e-06 0. 0.
-0.0103345 0.00814748 2.88651e-06 -1.76044e-06 0. 0.

Miha's results:

-0.00326402 0.00804666 1.44225e-06 -1.87195e-06 0. 0.
-0.00608248 0.0100156 1.76582e-06 -2.40683e-06 0. 0.
-0.0073282 0.0109104 1.91553e-06 -2.6528e-06 0. 0.

Last modified: 05/18/10