ADC/TDC information of Target fibers (and edge fibers) in UMC

			       Takeshi K. Komatsubara (KEK)
			       latest update: 2002-Nov-11(Mon)

 *This txt is based on my reply to Shaomin's question on the edge fibers.


 o In geomtg1.F (GEOMetry routine for TG), 
   the stopping target itself is treated as a single region 
   (a cylinder of scintillator).

   The actual assignment of energy to individual fibers left 
   to a simple binning procedure in ausgtg1.F (AUSGAB routine for TG).

 o In ausgtg1.F,
   the energy/timing in each transportation step is stored 
   into the variables dimensioned (col,row,main/edge)=(24,25,2), 
   where there are 23 rows of NSQTT(row) columns in the main fibers and 
   25 rows (including one below and one above the main fibers) of edge fibers.
   The column and raw of the step is determined 
   from the XY coordinates of the step. 

 So the energy and timing of edge fibers are properly set into the variables
 (though I am not sure how the edge-fiber XY positions are 
  reproduced in UMC). 


 Then

 o The Beamfile, obtained from the Kmu21 real-data analysis
   for generating the K+ stopping position in UMC: 
   
   See Peter's comment in ustart.F:
 
C 29-Jul-98 PDM: There is a spike at the outer edge of the main fiber
C      array in the radial beam stop position for K+, most likely an
C      artifact of SWATH not knowing about the edge fibers.  Empirically
C      smear this outward using a smearing shape from Jesse.  Controlled
C      by /conpar/BMSPIK.  


  "BMSPIKE" is set to 5.2 in alldat.F. 

  In ustart.F, 

C   If requested (the default), smear radial beam spike outward, a la Jesse.
C   The parameter BMSPIK<0.5 for no smearing and, if >0.5, equals the radius 
C   beyond which the smearing is applied.
C
          IF((BMSPIK.GT.0.5) .AND. (RTG.GT.BMSPIK))THEN
             RTGN = BMSPIK + 
     $              (3.0-SQRT(9.0-5.0*RANMAR(IDUM)))*(RTGTST-BMSPIK)
             XKS_REAL = XKS_REAL * RTGN/RTG
             YKS_REAL = YKS_REAL * RTGN/RTG
             XTG = XKS_REAL
             YTG = YKS_REAL
             RTG = RTGN
          ENDIF
  

 This algorithm means, 
  if RTG==sqrt(tgx^2+tgy^2) is greater than BMSPIKE[5.2cm]
  a "smearing" of the stopping radias is made , 
  with a formula and using a randum number, 
  between BMSPIKE[5.2cm] and RTGTST(== WTAR[5.98cm]). 


 The algorithm has been used in the UMC for E787 1996 analysis; 
 if the target radius of real data was reproduced well by UMC 
 in your E787-98 analysis, 
 the edge fibers in E949 should also be reproduced with this scheme. 
 
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