Re: brag and acceptances

From: Djamel Ouerdane (ouerdane@nbi.dk)
Date: Thu Jul 04 2002 - 11:23:37 EDT

  • Next message: Flemming Videbaek: "Re: brag and acceptances"

    Hi Flemming,
    
    What does that imply for all the simulations done so far ?
    I remember having seen this GSAHIT message billions of times in the FS 
    simulations. Are the cdat files created so far for the FS good enough ? 
    
    
    Djam
    
    
    On Thu, 4 Jul 2002, Flemming Videbaek wrote:
    
    > Djam observed and reported a problem in the acceptance calculation using brag for 30 deg. That hits in T2 looked strange.
    > I checked it this morning and observed that geant gave an error message when being run
    > 
    >  ***** GSAHIT OVERFLOW WHEN IUSET= T2   IUDET= T2PR HITS( 1)=-0.4113410E+03 ORIG=  0.4000000E+03 FACT=  0.1000000E+04
    >  ***** GSAHIT OVERFLOW WHEN IUSET= T2   IUDET= T2PR HITS( 4)=-0.4129992E+03 ORIG=  0.4000000E+03 FACT=  0.1000000E+04
    > 
    > This is the clue - the global xhits are more negative than the orgin for the hit in that variable. Since hits are stored (global) inside
    > geant as hitval= (x + origin)*fact as integer the wrong global value is stored.
    > 
    > See the cern geant web pages fro more on hits (and nearby pages)
    > http://wwwinfo.cern.ch/asdoc/geant_html3/node148.html
    > 
    > The origins for t2,tof2, c1 as well for t3,t4 t5 were changed and commited (FFS up to 30 deg BFS to~20deg - which it cannot do physically)
    > The version is now 1.1.14 and has been installed in opt/brahms/new.
    > 
    > Lesson to be learned
    > a) Though much of BRAG has been extensively tested there can still be problems
    > b) In case of problems check log-output for possible errors that might be a clue.
    > c) As was done- communicate problems 
    > 
    > 
    > 
    > Thanks to Pawel for posting tracking effeciencies for the FS. 
    > 
    > This bring up a point- I would think that part of the effeciencies say determined for T1 (and T1) is due to 
    > bad and non-instrumented pads. If this is the case I think it is   --incorrect -- in the geometric acceptance to
    > take into account dead and non instrumented pads as I believe it is done in the BrGeanToTpcTrackCandidate.
    > If so we should either change the geometric acceptance-calculation, or take the effect of of the 'experimental
    > tracking eff' which seems at best difficult.
    > 
    > Comments to this?
    > 
    > 
    > regards from a hot and steamy Long Island
    > 
    > Flemming
    > 
    > 
    > 
    > ------------------------------------------------------
    > Flemming Videbaek
    > Physics Department
    > Brookhaven National Laboratory
    > 
    > tlf: 631-344-4106
    > fax 631-344-1334
    > e-mail: videbaek@bnl.gov
    > 
    
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    Djamel Ouerdane ------------------------------------------o
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