sPHENIX discussion of software

[pinkenburg <pinkenburg AT bnl.gov>]

minutes:
Elitons study of step size dependency:
While the integrated energy loss is not too sensitive to the maximum step size in G4 the light output corrected by Birks law drops quite a bit for smaller step sizes. Lots of discussions about possible reasons for this.
Likely culprit larger fluctuations in dEdx which is the input for Birks law. The spacal is a very complex device and it's not clear what step sizes G4 would actually use. We probably should look into this. The step size study should be done with a simpler setup - e.g. one large block of scintillator - to establish a base line of what to expect. We also need to find out what is "correct", the maximum step size clearly has an influence but is the light output for smaller step sizes right? Maybe we can implement Olegs device and compare with his test beam data (and/or have Alexander Kiselev give us a little intro what buttons needed to push to reproduce it).

Just after the fact: I found a presentation from 2010 which deals with this issue:
http://irtg.physi.uni-heidelberg.de/activities/schools/fall_school_2010/A.Tadday.Application.of.Birks.low.of.nonlinearity.in.GEANT.pdf
The study seems to be done in a range where the G4 implementation of Birks law breaks down (caveat G4 from 2010 is not what we have now).

Chris Inner Hcal Update:
it never ends - trying to implement the calculation of the crossing angle from the number of crossings revealed another problem in the geometry. For extreme tilt angles (>40deg)  about 1cm of scintillator is missing at the inner radius.  Needs to be fixed. It exhibits strong phi dependencies when changing the tilt angle by only 2 degrees from the nominal value. Probably this doesn't matter if used as inner hcal but as tail catcher for e/pi separation the non uniformities may be a problem (sounds like something for next week to look int).

On 7/20/2015 4:42 PM, Huang, Jin wrote:

Dear All,

 

This is reminder of our weekly sPHENIX simulation meeting Tue July 21 1-3PM. For residents at BNL, we will meet in the 2-160 conference room as usual. Dave will host the discussion from BNL.

 

We will start the discussion with Eliton’s study of step-size dependency for the calorimeter simulations. More topics are welcomed too.

 

The agenda page is at https://indico.bnl.gov/conferenceDisplay.py?confId=1183     , for which the modification password is 1008

 

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Jin

 

 

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Jin HUANG

 

Brookhaven National Laboratory

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Christopher H. Pinkenburg	;    pinkenburg AT bnl.gov
				;    http://www.phenix.bnl.gov/~pinkenbu

Brookhaven National Laboratory	;    phone: (631) 344-5692
Physics Department Bldg 510 C	;    fax:   (631) 344-3253
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