[Clas_offline] more fun with GSIM

[Craig Bookwalter]

No problem man, this is a hard problem to explain. g12 had the target 
centered at -90 cm, that's why the vertices are so far back. A better 
way to understand it is with the pictures I attached--"input.png" is an 
event that goes in, and "output.png" is what it looks like after going 
through GSIM and a1c. As you can see, one of the tracks just disappears, 
GSIM generates no hits for it.  Not sure how that happens.

Kijun Park wrote:
> Craig Bookwalter wrote:
>> I'm not clear on what you mean by trigger time--for MC the event 
>> start time is always 0 minus the photon propogation time to the event 
>> vertex, and it's useful to keep it that way for debugging stuff like 
>> this. Along with times from the ST and and TOF, that is the only time 
>> I need for reconstruction. I think, at least.
>>
>> Kijun Park wrote:
>>> Craig Bookwalter wrote:
>>>> 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
>>>>
>>>>
>>>>   
>>> Hi Craig.
>>> I saw you didn't use the -T in your gpp. waht is the "trigbit: 
>>> 0xffff" at HEAD bank in your  dc_no_hits.gpp ?
>>> How do you know trigger time ?
>>> Kijun
>>>
>>>
>>
>>
> Well, I  thought your problem is  out of scale of z-vertex (since I am 
> not g12 guy) from you first seven event in that file.
> If not, could you point out your trouble from your file. Sorry for 
> slow understanding.
> Kijun
>


-- 
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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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