BigBite Optics et cetera #18

Compass measurement:

Who is Andrej Leban?

Here is the compass-measurement report that Andrej prepared: Andrej_TargetReport.pdf

Sanity checks for TgTh, TgPh and TgY:

Plots limits set to acceptance limits:

Plots without limits:

Target-Delta calibration:

First attempt:

In the beginning I tried to determine TgDelta by trying to reconstruct the missing mass (mass of the neutron) using quasi-elastic deuteron runs. In the minimization algorithm I had to be careful to properly weight contribution of the events from different parts of the acceptance. It turned out, that this method is not working properly.

Second attempt:

This time I tried to use a bit different approach, where I calculated BigBite momentum from missing mass and q-vector and directly fit this value. This method also did not work, because of the problems with the sqrt. Please see the following PDF for more details:

SecondMethod.pdf

Here are plots that show difference between calculated and reconstructed momentum at the beginning and at the end of the minimization process. We can see that there is an obvious offset at high momenta, which suggests that method does not find the correct minimum for the high momenta regime. I discovered that I still have an offset in TgPh variable that affects the calculation of the momentum.

Plots where I used only elastics (beginning/end):

Results of the minimization when using elastics and quasi-elastics:

Third attempt:

This time I tried to use H,D elastic runs to calibrate the TgDelta variable. Unfortunately these elastic runs do not cover the whole acceptance. Please see the the PDF below: ElasticCoverage.pdf

Last modified: 08/18/10