[G12] gsim feedback study

[Dennis Weygand]

On Jul 23, 2010, at 8:34 AM, Craig Bookwalter wrote:

>  g12ers,
>     This is an update on the 
> taking-real-CLAS-data-and-feeding-it-through-GSIM study. I've fixed my 
> previous error with the vertex for events going into GSIM--they now go 
> into GSIM with the PART sector 0 vertex for each track set to the MVRT 
> vertex from the real data. I also correct by hand the ttag and tpho of 
> the input TAGR bank to the event vertex. I do not smear with GPP. These 
> changes combine to give only about a 10% return. Before the vertex fix I 
> was getting 4500/8100 events or so reconstructed, now I am getting about 
> 5300/8100. I looked at 50 events with bosdump and CED and found 20 out 
> of these 50 were not identified as p pi+ pi- events. From these 20, the 
> following problems were identified:
> 
> * 9 events where an incorrect number of hit-based tracks were found. 
> This happens for various reasons--multiple scattering in the target 
> (most cases), or a lack of in-time DC hits (happened a few times), or a 
> lack of DC hits at all (happened a few times). Also, R1 hits seem to be 
> almost always marked as out-of-time by ced.


An 'incorrect' number? Too small or too large?



> * 5 events where a track struck the TOF with a reasonable time, but an 
> adjacent paddle was hit at a much later time, and the SCRC bank 
> reconstructs it into a "cluster" with some weighted average between 
> those two times. The average pulls the once-reasonable time of the 
> primary TOF hit up, resulting in pi's being cast adrift in the mass 
> region between pions and kaons (PID == 0) or shifted all the way to 
> being called K's. Protons get shifted into the deuteron region.



How can GSIM ever ever ever get a paddle struck at 'a much later time'? Everything must be in-time, no? What exactly does 'much later' mean?



> * 4 events with missing time-based tracks, usually because there is no 
> good TOF hit to associate with the track (ie the paddle didn't fire).


What caused the TOF to be missed? Remember, these are 'real' events!!!


> * 2 events where the TOF times were just too large to give the correct 
> PID--perhaps the track hits a dead paddle and produces a secondary that 
> fires the adjacent paddle.


How did this happen??? The TOF time must be consistent with the pid!


> 
> Draw what conclusions ye will. I think it would be foolish to pursue 
> this 95% number without more information on the study that got this 
> number, ie what ffread cards were being passed to GSIM, whether or not 
> GPP was used and if so how, etc.


What is the 95% number you are alluding to?

> 
> I welcome any comments.
> 
> --cb

Good work Craig, but right now it appears we are raising more questions than we are answering.  
Is there efficacy in putting accepted simulated events back into GSIM?

Dennis



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--
Dennis Weygand
weygand at jlab.org
(757) 269-5926