[Clas_offline] more fun with GSIM

[Craig Bookwalter]

Hi offliners,
    I am in the middle of a study where I take real events from 
reconstructed g12 data and feed those four-vectors back through GSIM, 
with the hypothesis that since these tracks have already been detected 
by CLAS in real life, after passing through GSIM and reconstruction I 
should recover close to 100% of them. Currently I am having a problem 
with GSIM not generating DC hits for some tracks which pass through the 
DC volumes. When I look at these events in gsim_int, I see that GSIM 
propogates them along strange trajectories--strange because I have 
decays and multiple scattering turned off. I have a PART file with a few 
events exhibiting this problem located here:

/work/clas/clasg12/craigb/tmp/gsim_feedback/clas_offline/dc_no_hits.part

Only the first seven events in this file are examples of what I am 
having trouble with; I had to add more events to the end to get some BOS 
buffer to flush and actually write the events to file.

Also, I created this file to try and get a concentrated sample of my 
troublesome events, but now when I run my gsim script on this file, some 
of them have successfully-generated hits, even though I have the RNDM 
card set. I am guessing this is because RNDM just sets the random seed, 
which means changing an event's position within a file changes your 
position within the random number sequence. If there's a more 
intelligent/convenient way to share this information with everyone, 
please let me know.

So in short, I would appreciate it if you all might take a look at this 
with me and offer any suggestions as to why GSIM would just not produce 
DC hits for what looks like 1% of tracks. Also, if I use the "NOSEC 
'ALL'" card this no-DC-hits behavior is enhanced by a factor of 2 or so. 
Thanks in advance.

--cb


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 Craig Bookwalter			FSU Office:  (850) 644 3808
 Department of Physics			JLab Office: (757) 269 5465
 Florida State University		craigb at hadron.physics.fsu.edu
 Tallahasse, FL 32306			craigb at jlab.org		


"One toke? You poor fool. Just wait till you see those (expletive) bats."
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