double records?

Double records?

We had seen 'double hits' all along. What is the precise origin? Here are some plots that Anuj made that show the problem: multiple hit plots

Throw a single track into the endcaps:

cfmgmc.input: 5. 5.0 11.0 3.75 0.0 1 0.0 0.0 0.0 0.0

Here is where it lands:

green track goes out at 11°, hitting 4 endcaps
same event, with only the last endcap silicon shown. Each of the 4 hits shown is actually a 'double', one pair for each of the endcaps.

Here is this single track:


 evt trk layer= 10 01 09 X,Y,Zglobal  4.0402  0.2666 +20.8385 
 evt trk layer= 10 01 09 X,Y,Zglobal  4.0456  0.2670 +20.8660 

 evt trk layer= 10 01 10 X,Y,Zglobal  4.8244  0.3194 +24.8840 
 evt trk layer= 10 01 10 X,Y,Zglobal  4.8298  0.3198 +24.9115 

 evt trk layer= 10 01 11 X,Y,Zglobal  6.0324  0.4004 +31.1170 
 evt trk layer= 10 01 11 X,Y,Zglobal  6.0378  0.4007 +31.1445 

 evt trk layer= 10 01 12 X,Y,Zglobal  7.1103  0.4726 +36.6814 
 evt trk layer= 10 01 12 X,Y,Zglobal  7.1157  0.4730 +36.7089 


      Xlocin/out=  0.0012  0.0006  Yi/o= -0.0124  0.0126  Zi/o= -0.2799 -0.2848
      Xlocin/out=  0.0006 -0.0002  Yi/o= -0.0149  0.0151  Zi/o= -2.8848 -2.8906

      Xlocin/out=  0.0026  0.0020  Yi/o= -0.0124  0.0126  Zi/o=  0.5675  0.5626
      Xlocin/out=  0.0020  0.0013  Yi/o= -0.0149  0.0151  Zi/o= -2.0374 -2.0431

      Xlocin/out=  0.0042  0.0037  Yi/o= -0.0124  0.0126  Zi/o=  0.5730  0.5681
      Xlocin/out=  0.0037  0.0030  Yi/o= -0.0149  0.0151  Zi/o= -0.7319 -0.7378
 
      Xlocin/out=  0.0058  0.0052  Yi/o= -0.0124  0.0126  Zi/o=  0.4378  0.4329
      Xlocin/out=  0.0052  0.0045  Yi/o= -0.0149  0.0151  Zi/o=  0.4329  0.4270

Note that for each 'hit' there are 2 records. For the first in a pair, YLOCIN-YLOCOUT = 250 um, for the second record 300 um. (in the 2nd block of numbers). Where does the 250 um come from???

Also, between the 2 records, the ZGLOBALs differ by ~275 um.

In SVX_DIGI.f, 2 hits per layer are seen:

  SVX_DIGI: Neutrals are stored
 
digi isub,cudet,nhits=   1  SI01  0
digi isub,cudet,nhits=   2  SI02  0
digi isub,cudet,nhits=   3  SI03  0
digi isub,cudet,nhits=   4  SI04  0
digi isub,cudet,nhits=   5  SI05  0
digi isub,cudet,nhits=   6  SI06  0
digi isub,cudet,nhits=   7  SI07  0
digi isub,cudet,nhits=   8  SI08  0
digi isub,cudet,nhits=   9  SI09  2
digi isub,cudet,nhits=  10  SI10  2
digi isub,cudet,nhits=  11  SI11  2
digi isub,cudet,nhits=  12  SI12  2
GEANT >

While with a track into the barrel:
cfmgmc.input = 5. 5.0 90.0 3.75 0.0 1 0.0 0.0 0.0 0.0
there is 1 hit/layer, so the problem occurs before SVX_DIGI.

==> look in SVX_GUSTEP:

4 hits in the barrel. Close inspection shows the hits are in the middle of the (red) silicon.

Hits in gustep are:


definitions: 

      character*4 inrNMSH(15) /'POSX','POSY','POSZ' ! Global positions
     &     ,'DELE','TOFL'                           ! Energy loss & TOF
     &     ,'P_ID','MOMX', 'MOMY', 'MOMZ'           ! Particle ID & Entry mom.
     &     ,'XILC','YILC','ZILC','XOLC','YOLC','ZOLC'/ ! Local entry & exit


HITS =  2.46755195  0.161757946  9.28673785E-07  0.  8.25037538E-11  5.
  4.98917532  0.327292949  1.95178054E-05 -0.164742678 -0.00989967771
 -2.83599925  0.  0.  0.
 HITS =  2.47755647  0.162414253  9.67811616E-07  6.81812089E-05  8.2838264E-11
  5.  4.98917532  0.327292949  1.95178054E-05 -0.164742678 -0.00989967771
 -2.83599925 -0.163291827  0.0100998143 -2.83599925
   
 HITS =  5.02725458  0.329846114  0.000320149731  0.  1.68089251E-10  5.
  4.98908567  0.327621222  0.000626938068  0.312071502 -0.00990129728
 -2.83567977 -0.163291827  0.0100998143 -2.83599925
 HITS =  5.03740549  0.330512702  0.000321425323  6.28063135E-05  1.6842866E-10
  5.  4.98908567  0.327621222  0.000626938068  0.312071502 -0.00990129728
 -2.83567977  0.3158077  0.0100982524 -2.83567715
   
 HITS =  9.89082623  0.649888158  0.00133930054  0.  3.30707683E-10  5.
  4.98897839  0.328297138  0.00104718388 -0.658644199 -0.0249003395
  0.00134017051  0.3158077  0.0100982524 -2.83567715
 HITS =  9.91582203  0.651533008  0.00134454714  0.000705222599  3.31543432E-10
  5.  4.98897839  0.328297138  0.00104718388 -0.658644199 -0.0249003395
  0.00134017051 -0.655493379  0.0251002107  0.0013506636
   
 HITS =  13.862236  0.911275506  0.00148035667  0.  4.63495881E-10  5.
  4.98826981  0.328315258  0.000166083628 -0.921377003 -0.0248992331
 -3.22761869 -0.655493379  0.0251002107  0.0013506636
 HITS =  13.8872223  0.912920058  0.00148118858  0.0002158141  4.64331351E-10
  5.  4.98826981  0.328315258  0.000166083628 -0.921377003 -0.0248992331
 -3.22761869 -0.918509066  0.0251001902 -3.22761703

endcaps:

next; draw sien 68.2 180 0 -355 10 10 10
dxyz
dhits

In the closeup you can see that the first hit lies in front of the silicon, and the second is in the middle of the silicon, where it is supposed to be. This corresponds to what we saw above with the double records.



 HITS =  4.03904438  0.266151309  20.8255386  0.  7.078233E-10  5.  0.951721966
  0.0630393475  4.90758896  0.000845264934 -0.0124021135 -0.278635323  0.  0.
  0.
 HITS =  4.04146862  0.266311884  20.8380394  0.000105706466  7.08248238E-10
  5.  0.951721966  0.0630393475  4.90758896  0.000845264934 -0.0124021135
 -0.278635323  0.000236216161  0.0125972833 -0.283477485
   
 HITS =  4.04389334  0.266472489  20.8505421  0.  7.08673176E-10  5.
  0.953059971  0.0637630746  4.90721226  0.000236514272 -0.0149023011
 -2.88347745  0.000236216161  0.0125972833 -0.283477485
 HITS =  4.04680681  0.266667426  20.8655434  0.000121396995  7.09183046E-10
  5.  0.953059971  0.0637630746  4.90721226  0.000236514272 -0.0149023011
 -2.88347745 -0.00049050618  0.0150988223 -2.8892796
   
 HITS =  4.82493782  0.318786979  24.8703461  0.  8.4530849E-10  5.
  0.953431368  0.063861616  4.90701485  0.00191937701 -0.0124020688
  0.570633352 -0.00049050618  0.0150988223 -2.8892796
 HITS =  4.82736683  0.31894967  24.8828468  9.63643761E-05  8.45733372E-10  5.
  0.953431368  0.063861616  4.90701485  0.00191937701 -0.0124020688
  0.570633352  0.00131392071  0.0125989532  0.565800071
   
 HITS =  4.82979536  0.31911236  24.8953476  0.  8.46158255E-10  5.
  0.953777254  0.0642635599  4.90684366  0.00131422468 -0.0149008101
 -2.03420043  0.00131392071  0.0125989532  0.565800071
 HITS =  4.83271122  0.319308817  24.910347  0.000105853323  8.46668069E-10  5.
  0.953777254  0.0642635599  4.90684366  0.00131422468 -0.0149008101
 -2.03420043  0.000590001349  0.0150985196 -2.03999686
   
 HITS =  6.03613043  0.400868297  31.1019688  0.  1.05712783E-09  5.
  0.953687727  0.0646353513  4.90674829  0.00453414628 -0.0124011943
  0.579571784  0.000590001349  0.0150985196 -2.03999686
 HITS =  6.03855991  0.401032954  31.1144676  8.87874921E-05  1.05755271E-09
  5.  0.953687727  0.0646353513  4.90674829  0.00453414628 -0.0124011943
  0.579571784  0.00393254869  0.0125987828  0.574740827
   
 HITS =  6.0409894  0.401197612  31.1269684  0.  1.05797759E-09  5.  0.95309788
  0.0641320571  4.90677929  0.00393276429 -0.0149010085 -0.725259304
  0.00393254869  0.0125987828  0.574740827
 HITS =  6.04390335  0.401393652  31.1419678  0.000106265477  1.05848752E-09
  5.  0.95309788  0.0641320571  4.90677929  0.00393276429 -0.0149010085
 -0.725259304  0.00320800953  0.0150986351 -0.731060207
   
 HITS =  7.11621666  0.473477751  36.6654892  0.  1.24622956E-09  5.  0.9525792
  0.0640350133  4.90677261  0.00628017122 -0.0124016218  0.446778029
  0.00320800953  0.0150986351 -0.731060207
 HITS =  7.11864376  0.473640889  36.67799  9.01740932E-05  1.24665445E-09  5.
  0.9525792  0.0640350133  4.90677261  0.00628017122 -0.0124016218  0.446778029
  0.00567589095  0.0125980265  0.441941291
   
 HITS =  7.12107038  0.473804027  36.6904907  0.  1.24707933E-09  5.
  0.952412188  0.0634786636  4.90672064  0.00567593472 -0.0149019752
  0.441940963  0.00567589095  0.0125980265  0.441941291
 HITS =  7.12398243  0.4739981  36.7054901  9.10159506E-05  1.24758914E-09  5.
  0.952412188  0.0634786636  4.90672064  0.00567593472 -0.0149019752
  0.441940963  0.00494746957  0.0150978258  0.43613562
 
   Call to SVX_DIGI.... etc

An email to Charlie gave the following debug instructions:

change the STEE option in pisa.kumac to read
STEE 'KINE' 'HITS' 'DIGI' 'JXYZ'
Reduce the number active and passive volumes to a minimum, e.g.
GEOP 'CENT' 'PIPE' in pisa.kumac
and only have the SVX turned ON
Then in your pisa.input stream, before you give the ptrig command, you have the line DEBUG ON
Then you can look at the output log file to see what volume names are being traversed as a function of numerical distance. Something should pop out as strange at that the positions you noted below.

pisa < pisa_debug.input > pisa_debug.out

Sure enough, volumes SCHP turned up sensitive, where only volumes SISI should register hits. This was caused by the fact that in svx.f, where the detector gets put together, these readout chips, which are bump-bonded to the silicon detectors, were made of the same MATERIAL (sili_med_silicon) that the Si detectors were made of, and thus became sensitive. They are now made out of sili_med_passive, and the problem is gone.

CVS commit svx.f, phnxSili.par on 30 Aug 2005.

Last update 30 aug 05 - HvH

	green track goes out at 11°, hitting 4 endcaps
	same event, with only the last endcap silicon shown. Each of the 4 hits shown is actually a 'double', one pair for each of the endcaps.