BigBite Optics #5
Matrix elements "[TgPh|FpPh]" and "[TgTh|x]"
I am working on a code, that would calculate matrix elements for TgPh and
TgTh variables. At the moment I am using Root and Mathematica to estimate these
matrix elements. This is not a best choice, since mathematica is very slow and
consumes a lot of memory and processor power to calculate matrix elements. Beside
that it is very, very slow. However, I am using it, because I am able to quickly
write mathematical formulas which enables me to quickly develop a matrix-element-determination-procedure.
Once I will know, that my procedure works, I intend to rewrite all my code to C++.
Short description of the procedure:
In this procedure I have used 12C runs #3490 and #3491. Before going any further I performed a series of
cuts that gave me much cleaner set of data. I considered left-arm acceptance cuts and target cuts. I was also interested
only in coincidence events. In the end I also demanded that every particle track though the MWDC must be consistent with
the hit in the E-trigger-plane. After I performed these cuts I was able to start my matrix element determination procedure
from my current approximation of the sieve-hole reconstruction (using my first guesses for the matrix elements):
At this point I was already able to see the majority of the holes in the middle section of the collimator. I assumed that relative positions of the holes are already correct. This enabled me to separate events that correspond to each hole to different files.
As a result I ended with many files with focal plane variables, that contain only those events that travel through the specific hole in the collimator. Here are the results from that separation:
Since I know the correct position of sieve-holes from the sieve-schematics I was able to
set the matrix elements for both variables in a way, that all the events from a given file (that correspond to each
hole) go through the same hole. In this procedure I have chosen my matrix elements in a way, that same matrix elements are used
for all sets of data ie. for transport of the particles through all considered holes. As I results of this procedure,
I got following results:
My current results:
Comparing these plots with the first plot, we can see that the reconstructed hole-pattern is much better now. The
spacings between the holes in the y-direction is correct now and we are also able to see holes below and above the
double and triple holes:
To-Do
Next I intend to repeat this procedure, this time using these new results as my initial set of data. Since I
can see more sieve-holes now I will be able to generate more sets of data (One set corresponds to each sieve-hole)
and hopefully determine next better approximation for the matrix elements.
Last modified: 03/17/10
