[Xgt2] Status report for X>2 analysis

[Zhihong Ye]

Dear all,

I am writing this email  to report the current status of X>2 analysis, 
because we don't have meeting for a while.

Basically, since the beginning of December, I was preparing the Hall-A 
meeting, then I became a Run coordinator of G2P experiment till the 
holiday close. I spent the whole holidays to relocate in 
Charlottesville. After the holidays, I was able to pick up my mind and 
start to do some analysis. Although I have no results to show, there are 
some things I have done or been doing:

0, Took few days to settle down in my new office and set up a new Linux 
system in my desktop (:->). Most of softwares for analysis are working 
except XEM code. Experiment data and analysis codes are also copied to 
my desktop.

1, Run 5M Monti-Calo simulation events for each kinematics setting of 
C12 target.  I wrote a script to submit simulation jobs on batch farm. 
The code can split a 5M run (which will take few days using one CPU) 
into any number of small runs which can run simultaneously on different 
batch form CPU slots. So if the batch farm is not very busy, I am able 
to get enough Monti-Calo events for all targets and all settings within 
one or two days.

2, Extract Cross Section (XS) from C12 data. As you have seen, the SAMC 
code give good agreement between real data and simulation data for C12, 
so I think I can start to extract the C12 XS with reasonable tight 
acceptance cuts. We always can open up the cuts in the future when 
everything is well known.

     As Donal suggested, I will bin on dP(momentum) since he knows 
better features of XS .vs. P.  We can bin on other variable such as Xbj 
after corrections working well. I will also bin on Theta_Tg but not 
Scattering Angle since inclusive XS does not depend on Phi_tg (from 
Vahe's thesis, corrected me if I am wrong). Base on my understanding, 
the Bin-Center Correct is only applied to Theta_Tg (and Y_tg for long 
targets), so for one kinematics setting, the XS after correction will 
vary with dP-bin only.

3, C++ Version of XEM code exists now!

    One of the reasons I want to make the C++-Version is that  the code 
is written in and compiled with Fortran 77 and required old CERN lib. 
Most of Linux systems give up Fortran 77 and only provide Fortran90 or 
95, and compilers in 32-bit and 64-bit Linux work slightly different. I 
remembered when the first time I had the code from Patricia, I complied 
the same code in different Linux and had different cross section 
results! Since I don't use Jlab Linux anymore, I can not compile the XEM 
code in my Ubuntu system.

   The other reason is that this version of XEM code was modified to 
specifically study EMC effect, and mostly work on low Xbj corrections, 
which we don't care too much for our data. And this XEM code can only go 
up to xbj=2. There are many old subroutines not longer called by the 
main programs and some bugs was discovered during I modifying the code.

  Now the C++ version XEM code becomes a independent subroutine, which 
can be called by other programs by giving E0,Ep, Theta and Target, and 
return a value of BORN XS. I don't include Radiation Correction in the 
code since it is really complicate in the XEM code and the SAMC can 
handle this part. I do include the Coulomb Correction in the code 
because it looks simpler. However, I will still need more time to debug 
it since it is a complicate code. I am not sure when it will fully 
function but once it is ready, I will use it to study the Y_tg 
distributions of long targets.

4, Time on Analysis. Unfortunately, I will have a heavy load of classes 
and teaching duty in the next few months. Whole days of Mon and Tue, and 
half days of Wed and Thu are taken. I can only focus on the analysis on 
Friday and probably one of the weekend.  So the analysis will slow down 
but I will do as much as I can. I suggestion we have our analysis 
meeting for every four weeks and Friday is a good time for me.


-- 
Best Regards
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Zhihong Ye
  Physics Department, University of Virginia
  Office:  Physics Building 014
  Phone:   434-924-3357,434-515-2211
  Address: 382 McCormick RD, Charlottesville, VA 22904-4714