BESII Track and Vertex lists

This is a new documentation on BESII vertex and track lists because of both the upgrading of detector hardware and the improvements on reconstruction software. It is based on BES vertex and track list.

Common Block Description

There are three primary common blocks which are relevant to the event description: For the exact contents of these commons please refer to the source files with filetypes .INC in corresponding directories of BESLIB. Only those parts relevant to this document are included. The quantities of interest here are:
Variable Contents
TOTTKS Total number of entries (<= 80) in the TRKSUB array: TRKSUB(1:16, 1:TOTTKS)
NVTX Number of vertices (<=15) in the event: VRTSUB(1:8, 1:NVTX)
VRTSUB Pointers to ITRK where vertex lists are located (a zero value indicates non-existent subtype)
TRKSUB Pointers to ITRK where track lists are located. (a zero value indicates non-existent subtype)
NXTSUB Points to the last word filled in the TRK buffer. (i.e. next free location is TRK(NXTSUB+1))
TRK Large multi-purpose array which stores the vertex and track lists, amoung other things. 
The first 32 words of ITRK store the sizes of arrays and lists, in the following order: 
  • Initial value of NXTSUB on each new event: 1 word 
  • Number of words in /EVLST/ preceding VRTSUB: 1 word 
  • Dimension of VRTSUB: 2 words 
  • Lengths of vertex subtype lists: 8 words 
  • Dimension of TRKSUB: 2 words 
  • Lengths of track subtype lists: 16 words 
  • Spares: 2 words 
Notes:
The subtype 1 entry of a vertex or track entry must be filled in order for that entity to be logged out. I.e. unattached subtypes will be weeded out by EVLOG during data logging.
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VERTEX LISTS

For each vertex V in an event (1<=V<=15), the subtype lists contain the following information. The contents of the vertex list for Vertex=V, Subtype=N and item=J is given by
TRK(VRTSUB(N,V) + J).
No vertex information filled in reconstruction up to now. 

Subtype 1: Vertex Identification Block

This is the vertex ID block which must be present for any vertex entry into TRKLST. 
  J     NAME           CONTENTS
  -     ----     -----------------------------------------------
  1     NWDS     number of words in this record
  2     NCHRG    number of charged prongs in this vertex
  3     NNEU     number of neutral prongs in this vertex
                 (total tracks in this vertex is N = NPRNG+NEU)
  4     IVTYPE   Normally 1.  Set to 2 if TOF disagrees with
                 the ID made by VEEFND for sec tracks.
  5     IVID     ID of most probable decay
                     -1 = can't tell  0 = not made
                      1 = K zero,     2 = anti-lamda,
                      3 = lamda,      4 = gamma (conv at pipe)
                      5 = pi zero,    6 = eta
                    100 = D vertex (charged or neutral)
                 (if ambiguous, tens digit gives other choice)
  6     IBACK    index of backward (parent) vertex
  7     INTRK    track number of incoming track
  8     NFORE    number of forward vertex linkages
9-13    IFORE    indices of foreward linking vertices
13+1    ITK      track numbers for this vertex (outward tks.)
  .      .             "
  .      .             "
13+NPRNG .             "
  .      .             "
13+NPRNG+NEU           "
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Subtype 2: Simple Vertex Fit

This block is filled by routine VXKWIK for the primary vertex. It represents a crude vertex determination which may be of use in rejecting events with a 'bad' vertex (e.g. "wall" events .) where the "good" vertex fit may fail. The cuts used to select tracks for this fit are much looser than for subtype 4 below. 
 J     NAME              CONTENTS
 -     ----              --------

 1     NWDS     number of words in this record
 2     VFIT     method: 0=simple averages, large fid vol
                         1=fit for min dist, large fid vol
                         2=simple averages, small fid vol
                         3=fit for min dist, small fid vol
 3     QTOT     total charge of the prongs
 4     RXY      Perp distance from origin (0,0) to vertex .
 5     X        x (m) of vertex
 6     Y        y (m) of vertex
 7     Z        z (m) of vertex
 8     DX       error in x (m)
 9     DY       error in y (m)
10     DZ       error in z (m)
11     CHI2     total chi sq for vertex fit (-1.0 if failed)
12     NDOF     degrees of freedom
13     NTRK     The number of tracks used in crude fit.
13+1   TRK      List of the charged tracks used in this
  +2     "      vertex fit.
  .      "         .
  .                .
13+NTRKS

Subtype 3: Beam Position

Not used for the current version.

Subtype 4: Vertex Constrained Fit

The vertex constrained track fit produces a vertex position and a new set of track parameters for the fitted tracks . The track parameters from track subtype 3 below are used as input. The new constrained track fit results are written to Track subtype 8 below. For the primary vertex (=1) the beam constraint selects tracks with Rxy < 0.015m and |z| < 0.15m within the interaction rergion.

Note: This subtype is filled for Vee's as well as the primary vertex. 

  J     NAME              CONTENTS
  -     ----              --------
  1     NWDS       Number of words in record
  2     VFIT       Fit type
                   (0 = simple  ; 1 = good )
  3     QTOT       Total charge of the prongs
  4     RXY        Perpendicular distance (x-y) from vertex to
                   nominal beam location (XYZIR(1-2) in /RUNPRM/ )
  5     X          X (m) of vertex
  6     Y          Y (m) of vertex
  7     Z          Z (m) of vertex
  8     DX         Error in X (m)
  9     DY         Error in Y (m)
 10     DZ         Error in Z (m)
 11     CHI2       Total ChiSq for vertex fit
                   (set to -1. if fit failed)
 12     NDOF       Degrees of freedom (REAL)
 13     CHI2V      ChiSq contribution from X,Y,Z
13+1    CHIOFF     ChiSq contributions from
  .         .               individual tracks
  .         .                "
  .         .                "
13+NCHRG+NNEU                "
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Subtype 6: N-Prong Vertex List

The 2-prong vertex list is the only one with meaning. 
J     NAME              CONTENTS
-     ----              --------
1     NWDS       Number of words in this record
2     ACOLL      Acollinearity angle (radians)
3     ACOPL      Acoplanarity angle   (radians)
                 (ACOLL,ACOPL =  0. ,if back to back)
4     LCOLL      True if acollinear and xyz's match
5     LCOPL      True if acoplaner and xyz's match
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Subtype 7: Secondary Vertex Items

 J     NAME              CONTENTS
 -     ----              --------
 1     NWDS       number of words in this record
 2     MFSEC      Method of finding secondary vertex
                     1=veefnd,  2=pizero,  3=kink
 3     MASSO      Mass calculated from tracks at origin
 4     MASSV      Mass calculated at sec vertex point
 5     COS12      Cos of angle between vee tracks
 6     COSRP      Cos of angle between neutral decayer and
                  direction of secondary momentum vector
 7     P          Total momentum of secondary tracks
 8     PX           "   x-mentum  "    "         "
 9     PY           "   y   "     "    "         "
10     PZ           "   z   "     "    "         "
11     ZDIFF      Z difference at XY point of secondary.
12     E          Total energy of secondaries
13     CHI2       Chi square of fit (=-1.0 if fit failed)
14     NDOF       Degrees of freedom
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Subtype 8: Tagged D Vertex

  J     NAME              CONTENTS
  -     ----              --------
  1     NWDS       Number of words in this record
  2     NDTRKS     Number of decay products in the D tag
  3     ITAG       Code for the D decay mode

                         ITAG   decay mode
                         ----   ----- ----

                           1     K-  pi+
                           2     K-  pi+ pi+
                           3     K-  pi+ pi+ pi-
                           4     K0  pi+
                           5     K0  pi+ pi-
                           6     K0  pi+ pi+ pi-
                           7     K-  pi+ pi0
                           8     K-  pi+ pi+ pi0
                           9     K0  pi0
                          10     K0  pi+ pi0
                          11     K+  K-
                          12     K+  K-  pi+
                          13     K+  K-  pi+ pi-
                          14     pi+ pi-
                          15     pi+ pi+ pi-
                          16     K+  K0
                          17     K+  K0  pi-
                          18     pi+ pi0

  4     ICHRG      Charge of the D
  5     MASS       D final state invariant mass
  6     BCMASS     Beam-constrained mass of the D
  7     PX         Px of the D
  8     PY         Py of the D
  9     PZ         Pz of the D
 10     P          Total momentum of the D
 11     E          Total energy of the D
 12+13  ITKMAP     A double word bit map indicating track
                   numbers used in the TAG. Track # 1
                   corresponds to the LSB (20) of the first
                   word.

13+1    IDTRK      Packed word for each of the decay
  .                products of the D. Format is:
  .
  .                 BYTE4    BYTE3    BYTE2    BYTE1
  .               +-----------------------------------+
  .               |        |        |        |        |
  .               | DKTRK1 | DKTRK2 | TRK#   | TRKID  |
  .               |        |        |        |        |
  .               +-----------------------------------+
  .
  .                where...
  .
  .                TRKID =  particle type for the decay
  .                         product
  .
  .                         1 = chg pi
  .                         2 = chg K
  .                         4 = pi0
  .                         8 = K0
  .
  .                TRK#  =  BES track number assigned
  .                         to this particle. (virtual
  .                         track in the case of pi0 or K0)
  .
  .            DKTRK1(2) =  BES track numbers of the
  .                         the gammas from a pi0 or
  .                         the pions from a K0.
13+NDTRKS                   (only filled when TRKID=4,8)
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TRACK LISTS

For each track=T (either charged or neutral, 1<=T<80), the subtype lists contain the following information. The contents of the Track List for Track =T , Subtype = N and item = J is given by
TRK(TRKSUB(N,T) + J).

Subtype 1: Track Identification Block

The track ID block must appear for every track entry in TRKLST in order to be logged out. 
J    Name     Contents
-    ----     --------
1    NWDS     number of words in this record
2    ID       track identifier:
              0 = no identification made
              1 = gamma
              2 = electron
              3 = muon
              4 = pi
              5 = K
              6 = P
              7 = LAMDA,
              8 = ANTI-LAMDA
              10 = ETA
              <0 = external track (e.g. backscatter)
3    IDUSED   Bit mask indicating data used in particle
              identification. The bit positions are encoded
              as follows:
               mask         Data type
               ----         ---- ----

               x'01'        TOF
               x'02'        dE/dX
               x'04'        Muon tubes
               x'08'        Shower counter

4    ICHRG    charge  0, +1, -1  (9 if can't tell sign)
              For MDC track, it's the same as that in track Subtype 3
              For VC track, it's the same as that in track Subtype 13
5    ITYPE    A bit mask indicating the track type.
              the systems are encoded as follows:
              mask          System
              ----          ------

              x'01'         Drift Chamber
              x'02'         Barrel shower counter
              x'04'         DC  SC data fitted simulaneously
                               -
              x'08'         Virtual (reconstructed) track
              x'10'         Hardware track info
              x'20'         TOF info
              x'40'         Muon tubes
              x'80'         End cap shower counter
             x'100'         Vertex Chamber
6    MISS     Bit mask indicating information lacking due to
              geometry. The systems are encoded as follows:
              mask          System
              ----          ------

              x'01'         TOF
              x'02'         Drift Chamber
              x'04'         Shower chamber
              x'08'         Muon tubes
              (It WOULD be too much to expect they'd be
               the same as any of the above....)

7    IFROM    vertex # from which this track originates
8    IDCAY    vertex number that this track
              decays to (0 if none)
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Subtype 3: Main Drift Chamber (MDC) One-Track Fit

  J Type Name           CONTENTS
  - ---- ----           --------
  1  I   NWDS       number of words in this record
  2  I   ICHRG      charge of track, +1, -1
  3  R   PXY        at min. dist. of approach to beam origin
  4  R   PX          "
  5  R   PY          " (note that  PZ/P gives cos(THETA),
  6  R   PZ          "             PXY/P gives sin(THETA),
  7  R   P           "             PX/PXY gives cos(PHI),
  8  R   THETA       "             PY/PXY gives sin(PHI)
  9  R   PHI         "    so use ratios rather than sin/cos
 10  R   X           "    to save cpu time )
 11  R   Y           "
 12  R   Z           "
 13  R   R           "
 14  I   MFIT       Fit method:
                      0 = circle fit
                      2 = ARCS fit
 15  I   NHIT       Number of drift chamber hits in the fit
 16  I   NUSED      Not used
 17  R   CHI2       Chi square from single track fit
 18  I   NDOF       Degrees of freedom
 19  R   RMS        Rms error of fit (ideally 1.0)
19+1 R   ER         Error matrix for good fit, triangular form
  .        .        in coordinate: PHI,K=1/PXY,S=TAN(LAMBDA),
  .        .        KSI,ETA(does not contain scattering error)
  .        .        from pipe)
  .        .           .
19+15 R    .           .
 35  R   EXTRP      Distance from origin to first reconstructed
                    layer
 36  R   PATHL      Total length of scattered track in measurement
                    region
 37  I   IWPLAN     Bit map (bits 0-32) of DC layers used AFTER
                    fit
 38  I   IWPLA1     Bit map (bits 33-40) of DC layers used AFTER
                    fit
 39  I   IVCHIT     Bit map (bits 0-39) of DC layers used in fit
 40  I   IVCHI1     Identical to 37/38
40+1 I   IHIT(1)    Predicted cell hit in Radial Layer 1
40+2 I   IHIT(2)    Predicetd cell hit in Radial Layer 2
   .        .
   .        .       (one word for each of 40 radial wires)
   .        .
40+40 I  IHIT(40)   Predicted cell hit in last radial wire
(=80)
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Subtype 4: Time-Of-Flight Counter Items

  J     NAME              CONTENTS
  -     ----              --------
  1     NWDS       number of words in this record

 2:18              Barrel TOF Items

  2     AIT        azmuthal counter number from projected
                   track fit  ( 1.0LE AIT LE 49.0 )
  3     IT         counter number (1-48, 0 if no hit)
  4     TOF        time of flight (nsec)
  5     BETA       beta of track
  6     ZTDC       z (m) from TDC information
  7     PH         corrected pulse height
  8     QUAL       TOF quality (1.0=good trk; .LE.2.0=usable)
                      0.0 if ZT-ZTDC didnt match
                      2.0 if double hit in counter
                      3.0 if no hit in counter
                      4.0 all wts are zero;otherwise TQUAL=1.0
                      5.0 all wts are zero;otherw.TQUAL=0,2
                      6.0 if neutral track with good hit
                      7.0 if more than 2 hits per counter
                      8.0 missed one tdc (early cosmic)
                      9.0 if double hit in counter with bad
                           match with ZTDC (partner of track
                           with TQUAL=2.0) means effectively
                           a lower limit on TOF value
                     16.0 if neutral track with hit at one end
   9     WTPI       weight for PI
  10     WTK          "     "  K
  11     WTP          "     "  P
  12     WTEPI        "     "  e for e-pi hypothesis
  13     MASS2      square of mass (gev)2 from TOF and P
  14     PATH       flight path length (m)
  15     TOFERR     estimate of error on TOF (nsec)
  16     LINK       Link to track hitting same counter.
                    These links form a closed loop.
  17     LADJAB     Link to track on adjacent counter (above).
  18     LADJBE     Link to track on adjacent counter (below).

19:35               Endcap TOF Items

  19    AIT        azmuthal counter number from projected
                   track fit
  20    IT         counter number (49-96, 0 if no hit)
  21    TOF        time of flight (nsec)
  22    BETA       beta of track
  23    ZTDC       z (m) from TDC information
  24    PH         corrected pulse height
  25    QUAL       TOF quality (1.0=good trk; .LE.2.0=usable)
                      0.0 if ZT-ZTDC didnt match
                      2.0 if double hit in counter
                      3.0 if no hit in counter
                      4.0 all wts are zero;otherwise TQUAL=1.0
                      5.0 all wts are zero;otherw.TQUAL=0,2
                      6.0 if neutral track with good hit
                      7.0 if more than 2 hits per counter
                      8.0 missed one tdc (early cosmic)
                      9.0 if double hit in counter with bad
                           match with ZTDC (partner of track
                           with TQUAL=2.0) means effectively
                           a lower limit on TOF value
                     16.0 if neutral track with hit at one end
  26     WTPI       weight for PI
  27     WTK          "     "  K
  28     WTP          "     "  P
  29     WTEPI        "     "  e for e-pi hypothesis
  30     MASS2      square of mass (gev)2 from TOF and P
  31     PATH       flight path length (m)
  32     TOFERR     estimate of error on TOF (nsec)
  33     LINK       Link to track hitting same counter.
                    These links form a closed loop.
  34     LADJAB     Link to track on adjacent counter (above).
  35     LADJBE     Link to track on adjacent counter (below).
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Subtype 5: Shower Counter Track

NOTE: All of these SUBTYPE 5 offsets (SCNWDS, SCNHIT, etc) are integerized and their values are kept in TRK5PT.INC. An "F" indicates this item has been filled in. 
 J     NAME   IorR       CONTENTS
 -     ----   ----       --------

 1 F   NWDS     I   number of words in this record
 2 F   NHIT     I   number of shower counter cell hits
 3 F   NPHIT    I   number of shower counter paired hits
 4 F   X1       R   shower coordinates at first layer hit
 5     DX1      R   shower coordinates error at first layer hit
 6 F   Y1       R               ..
 7     DY1      R               ..
 8 F   Z1       R               ..
 9     DZ1      R               ..
10 F   THETA    R   shower counter theta angle
11     DTHETA   R   shower counter theta angle error
12 F   PHI      R   shower counter phi angle
13     DPHI     R   shower counter phi angle error
14 F   E        R   total energy observed in SC (GEV)
15     DE       R   total energy error in SC (GEV)
16 F   CHI1     R   quality of SC fit, CHI2 TYPE 1
17 F   CHI2     R   quality of SC fit, CHI2 TYPE 2
18 F   STAT     R   cluster status/link
19 F   FLAG     I   shower counter fit flag
20 F   MOD      I   module number for this track
                      (1 - barrel, 2 - E endcap, 3 - W endcap)
21 F   CHIID    R   CHI SQ of identification
22 F   ID       I     1 = photon (SC particle identification)
                           1 = electron
                           2 = mu or min. ionizing
                           3 = hadron or fake photon
                           4 = e-h ambiguity or photon fake
                               ambiguity
                          -1 = didn't make cuts for photon
                               fake ambiguity
23     WTPH     R   weight for PHOTON
24     WTE      R   weight for ELECTRON
25     WTMU     R   weight for MU or MIN. IONIZING
26     WTHA     R   weight for HADRON
27 F   COSX     R   -|      direction cosines
28 F   COSY     R    |==>        from
29 F   COSZ     R   -|         track fit
30 F   ERAW     R   total raw energy (sum of PHs  0.01)
31 F   NBLK     I   number of layer blocks to follow

32 F NBLK+LAYL  I   first layer number
33 F NBLK+HITL  I   number of hit cells in this layer
34 F NBLK+EL    R   energy deposited in this layer (GeV)
35 F NBLK+PHIL  R  average PHI/X  for  this  layer
36 F NBLK+DPHL  R  PHI/X  RMS for  this layer
37 F NBLK+ZL    R  average  Z/Y (M)   for  this layer
38 F NBLK+DZL   R  Z/Y RMS for this layer

      NB: A "" in these last four quantities indicates the
          different interpetation for barrel vs endcaps

 .
 .     in similar fashion for next layer block
 .
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Subtype 6: Muon Chamber Items

This list is filled only for charged tracks with momenta greater than 600MeV/c and for incoming cosmics. 
 J     NAME              CONTENTS
 -     ----              --------

 1     NWDS     number of words in this block
                ( = 6 + 14MULEVP )
 2     ID       muon identifier:  0 = not a mu
                                  1 = mu
                                  2 = can't tell
 3     STAT     Status bits on:
                1-3     if hit within SIGVCT s.d. in V and
                        within SIGZCT s.d. in Z
                4-6     if hit had ambiguous Z-pairing
                7-9     if g.e.2 tubes hit
                10-12   if no Z due to overflows
                13-15   if no Z due to 2 trks in same mod
                16-18   if no Z due to Z calib problems
                19-21   if no Z due to no ganged hit
                22-24   if no Z info for track
 4     LEVR     number of layers "required" for a muon
                i.e. the number of layers in which
                a muon would have to scatter by more
                than 3 s.d. in position or momentum
                to avoid being detected
 5     LEVE     number of layers "expected" for a muon
                i.e. the number of layers in which
                a mu is expected but could miss being
                detected by any amount of scattering
                MULEVE > or = MULEVR
 6     LEVP     number of layers "possible" for a muon
                i.e. the number of layers a muon could
                reach by scattering L.E. than 3 s.d.
                MULEVP > or = MULEVE

Oi= 6+(i-1)14   Offset pointer for layer=i

Oi + 1 OCTANT     octant number for layer=i  (0-7)
Oi + 2 DELSTR     number of s. d. from ranging
                  out due to strag
Oi + 3 XPROJ      projected x in layer=i
Oi + 4 YPROJ          "     y  "   "   "
Oi + 5 ZPROJ          "     z  "   "   "
Oi + 6 DVNORM     normalized residual in v-plane
Oi + 7 PPROJ      projected momentum
Oi + 8 XMUL       expected sigma in position
Oi + 9 SIGSTR        "       "    " STRAGGLING
Oi +10 XHIT       x co-ordinate of closest muon hit
Oi +11 YHIT       y    "       "     "     "    "
Oi +12 ZHIT       Z    "       "     "     "    "
Oi +13 DELPOS     number of s. d. between projected
                  track and closest hit
Oi +14 GRMST      equivalent grams of iron traversed
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Subtype 7: dE/dX Information

This subtype of data has not been checked. 
   J  type   Name              Contents
   -  ----   ----              --------

   1   I     NWDS       number words this record
   2   I     NDEDX      no. of good dE/dX hits (ex. overflows)
   3   I     NTOT       no. of good dE/dX hits (inc. overflows)

   4   I     TRBL       flag indicating any problems in dE/dX
                        analysis:
                          TROUBL meaning
                             0   no info (NTOT=0)
                             1   AOK
                             2   more overflows than truncated
                                 points. PHMP represents a
                                 minimum value. ID attempts to
                                 take this situation into
                                 account properly.

   5         RES1       Reserved for future use
   6         RES2       Reserved for future use

   7   I     ID         Particle type from dE/dX fit
                            ID   meaning
Note: "definitness"          0   inconclusive (error or tail)
in the ID of a particle      1   definite e
is based on roughly a 95%    2      "     mu
decision (skew cuts). e.g.   3   e/mu
a track within 95% prob.     4   definite pi
for a pion and outside of    5   e/pi
95% prob. for all other      6   mu/pi
particles is called a        7   e/mu/pi
definite pion.               8   definite K
One may notice ID is         9   e/K
simply a 5-bit integer      10   mu/K
with a bit turned on        11   e/mu/K
for each particle           12   pi/K
hypothesis satisfied:       13   e/pi/K
                            14   mu/pi/K
   Mask  particle           15   e/mu/pi/K
   ----  --------
  x'01'    e                16   definite p
  x'02'    mu               17   e/p
  x'04'    pi               18   mu/p
  x'08'    K                19   e/mu/p
  x'10'    p                20   pi/p
                            21   e/pi/p
                            22   mu/pi/p
                            23   e/mu/pi/p
                            24   K/p
                            25   e/K/p
                            26   mu/K/p
                            27   e/mu/K/p
                            28   pi/K/p
                            29   e/pi/K/p
                            30   mu/pi/K/p
                            31   inconclusive
                                 (big sigma or
                                  high momentum)

   8   R     PHMP       most probable pulse height from
                        truncated mean
   9   R     DPHMP      fractional uncertainty (sigma) on
                        measured pulse height
  10   R     PHMIP      average pulse height for minimum ionized particle
                        = 0.651×Run_Std_PH(IRUN)
  11   R     PHRC1      run correction for pulse heights
                        = PHMP×1286.6/Run_Std_PH(IRUN)

  12         PHRC2               "                          |
  13         PHRC3               "                          | Not filled at all
  14         PHRC4               "                          |

                        Note:Following items 15:19 are
                        signed values !

  15   R     XSE        # of sigma from e
  16   R     XSMU          "    "   "   mu
  17   R     XSPI          "    "   "   pi
  18   R     XSK           "    "   "   K
  19   R     XSP           "    "   "   p
19+1   I     XTAG(J)     status of hit in wire layer J      |
   .                     (j=1 to 40)                        |
19+j                                                        |
   .                     XTAG  meaning                      |
   .                       1   good hit                     |
   .                       2   overflow                     |
   .                       3   no mtac hit                  | Not filled at all
                           4   predict > 1 track in cell    |
   .                       5   multiple mtac hits           |
   .                       6   mtac but no dedx             |
   .                       7   bad wire                     |
   .                       8   corrected ph is < 0.         |
   .                       9   outside good time window     |
19+40                                                       |

59+1   R     PH(J)      Corrected pulse height for signal
   .                    from wire layer J.
59+j 
   .
   .
59+40

99+1   I     PHRAW(J)   Raw pulse height for signal from wire layer J.
   .                    Bit  0-12('0000 1FFF'X): Raw pulse height
99+j                    Bit 13-19('000F E000'X): Cell number
   .                    Bit 20-30('7FF0 0000'X): Drift distance in 10 microns
   .                    Bit 31   ('8000 0000'X): Side flag
99+40
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Subtype 8: Vertex Constrained Track Fit

Beam constraint is added for primarly vertex (=IVTX) as indicated in vertex subtype 4 discussion above. 
 J     NAME              CONTENTS
 -     ----              --------
 1     NWDS       number words this record
 2     ICHRG      charge of track  +1, -1, 0
 3     PXY        PXY at location of vertex
 4     PX         PX   "    "     "     "
 5     PY         PY   "    "     "     "
 6     PZ         PZ   "    "     "     "
 7     P          P    "    "     "     "
 8     THETA      THET "(see note in subtype 3 for this)
 9     PHI        PHI  "  "   "   "    "   "   "   "
10     X          X    "    "     "     "
11     Y          Y    "    "     "     "
12     Z          Z    "    "     "     "
13     RXY        R in XY plane
                  (not filled for secondary vertices )
14     MFIT       Fit method: 0 = circle fit
                              1 = good one track fit
15     NDCH       Number of dc hits in the fit
16     spare      Reserved - added to make this format the same
                  as Subtype 3 above.
17     CHI2       Chi square from single track fit
18     NDOF       Degrees of freedom
19     RMS        RMS error of fit
19+1   ERR        Error matrix (in phi, 1/pxy, s)
 .                ( diagonal element = 999. and
 .                  off-diagonal = 0. for fits with
19+6                VFIT .le.1 .                    )
26     DPX        Error PX
27     DPY        Error PY
28     DPZ        Error PZ
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Subtype 9: Main Drift Chamber (MDC) Pointers

Contains pointers to the rawdata for hits involved in helical fitting of the corresponding MDC track in Subtype 3 above. 
  J     NAME              CONTENTS
  -     ----              --------
  1     NWDS       Number of words in this record (NWDS=3+NDCP)
  2     NDCP       Number of DC pointers to follow
2+1     IDCH       bits 20-31: residual in 10 micron units
  .        .            18-19: Use bit
  .        .                   =1 means weight in helical fit greater than 0
  .        .            16-17: wire side assigned
  .        .                   1=+, 2=-, 3 don't care
  .        .             0-15: pointer to IRAW
  .        .            e.g. for M'th dc hit in track ITK, let
                        IP=IBITS(ITRK(TRKSUB(9,ITK)+2+M),0,16)
2+NDCP                  then IRAW(IP) contains the DC TAG/TDC word
NWDS               Spare
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Subtype 10: Shower Counter (SC) Pointers

J     NAME              CONTENTS
-     ----              --------

1    NWDS       Number words this record
                 = # of SC hits  2 + 1
2    HITRAW     Raw data of the first hit
3    HITFLG     Status flag of the first hit
4    HITRAW
5    HITFLG
:
:

                Meaning of HITRAW

                    31       15       0: bit
                     _________________
                    | PNT2   | PNT1   |
                    |________|________|

                BARREL:
                  PNT1 = pointer to east end of wire
                  PNT2 = pointer to west end of wire

                ENDCAP:
                  PNT1 = pointer to top    end of wire
                  PNT2 = pointer to bottom end of wire

                For meanings of HITFLG, refer to HITLST.INC
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Subtype 11: Projected/Decay Coordinates Of MDC Tracks

Contains entries for projected or decay coordinates. All entries set to 999. for unreachable coordinates. 
  Following format for PROJECTIONS (IVDCAY=0)
  --------- ------ --- ----------- ----------

  J     NAME              CONTENTS
  -     ----              --------

  1     NWDS       number words this record
  2     XBT        coordinates at barrel TOF radius
  3     YBT          "     "     "      "
  4     ZBT          "     "     "      "
  5     THETABT    direction of track at XT,YT,ZT
  6     PHIBT        "     "     "      "
  7     PBT        P at XT,YT,ZT
  8     XSC        coordinates at barrel SC entrance
  9     YSC          "     "  "    "
 10     ZSC          "     "  "    "
 11     THETASC    direction of track at XSC,YSC,ZSC
 12     PHISC        "     "  "    "
 13     PSC        P at XSC,YSC,ZSC
 14     XET        coordinates at end cap TOF plane
 15     YET          "     "  "   "    "
 16     ZET          "     "  "   "    "
 17     THETAET    direction of track at XET,YET,ZET
 18     PHIET        "     "  "   "    "
 19     PEC        P at XET,YET,ZET
 20     XEC        coordinates at end cap SC entrance
 21     YEC          "     "  "   "    "
 22     ZEC          "     "  "   "    "
 23     THETAEC    direction of track at XEC,YEC,ZEC
 24     PHIEC        "     "  "   "    "
 25     PEC        P at XEC,YEC,ZEC
 26     XC         coordinates at coil radius
 27     YC           "     "   "     "
 28     ZC           "     "   "     "
 29     THETAC     direction of track at XC,YC,ZC
 30     PHIC         "     "   "     "
 31     PC         P at XC,YC,ZC
 32     BTPATH     path length from XM,YM to XBT,YBT
 33     ETPATH     path length from XM,YM to XET,YET
 34     XDC        coordinates at DC inner cylinder entrance
 35     YDC          "     "  "   "    "
 36     ZDC          "     "  "   "    "
 37     THETADC    direction of track at XDC,YDC,ZDC
 38     PHIDC        "     "  "   "    "
 39     PDC        P at XDC,YDC,ZDC

  Following format is used to specify DECAY points (IVDCAY ne 0)
  --------- ------ -- ---- -- ------- ----- ------ ------- -- --

  2     IDCHR      charge 0, +1, -1   (9 if sign unknown)
  3     PXYDY      at xdcy,ydcy,zdcy
  4     PXDY        "  "
  5     PYDY        "  "
  6     PZDY        "  "
  7     PDY         "  "
  8     THETADY     "  "
  9     PHIDY       "  "
 10     XDY        coordinates of decaying track near decay vertex
 11     YDY           "    "    "       "    "     "     "
 12     ZDY           "    "    "       "    "     "     "
 13     DYLEN      3-D path length of decaying particle
                    (from parent vtx to decay vtx)
13+ 1   ERRDY      error matrix at decay point on track
 .        .          "
13+15     .          "
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Subtype 12: Reconstructed (virtual) Track

Contains track parameters for "reconstructed" tracks such as K0's, Lambda's . 
 J     NAME              CONTENTS
 -     ----              --------
 1     NWDS       number of words in this record
 2     ICHRG      charge of track, 0, +1, -1
 3     PXY        at secondary vertex (starting point coordinates)
 4     PX          "
 5     PY          "   (note that  PZ/P gives cos(THETA),
 6     PZ          "               PXY/P gives sin(THETA),
 7     P           "               PX/PXY gives cos(PHI),
 8     THETA       "               PY/PXY gives sin(PHI)
 ..or  TANLAM (for new tracking code)
 9     PHI         "    so use ratios rather than sin/cos
10     X           "    to save cpu time).
11     Y           "
12     Z           " <=ZDY-(XY path from IR > cot(THETA))
13     RXY         " (in XY plane)
14     MFIT       fit method
                    1=VEEFND,  2=PIZERO
15     MASS       mass of particle
16     ITYPE      type of fit
17     CHI2       chisq of fit
18     NDOF       degrees of freedom for fit
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Subtype 13: Vertex Chamber (VC) One-Track Fit

Track list subtype 13 is designed for BES vertex chamber one-track fit, with VC track matched to DC track, the hierachy is almost identical to that of subtype 3, except for the redundant VC part. 
   J Type Name           CONTENTS
   - ---- ----           --------
   1  I   NWDS       number of words in this record
   2  I   ICHRG      charge of track, +1, -1
   3  R   PXY        at min. dist. of approach to beam origin
   4  R   PX          "
   5  R   PY          " (note that  PZ/P gives cos(THETA),
   6  R   PZ          "             PXY/P gives sin(THETA),
   7  R   P           "             PX/PXY gives cos(PHI),
   8  R   THETA       "             PY/PXY gives sin(PHI)
   9  R   PHI         "    so use ratios rather than sin/cos
  10  R   X           "    to save cpu time )
  11  R   Y           "
  12  R   Z           "
  13  R   R           "
  14  I   MFIT       Fit method:
                       0 = circle fit
                       2 = ARCS fit
  15  I   NHIT       Number of vertex chamber hits in the fit
  16  I   NUSED      Not used
  17  R   CHI2       Chi square from single track fit
  18  I   NDOF       Degrees of freedom
  19  R   RMS        Rms error of fit (ideally 1.0)
 19+1 R   ER         Error matrix for good fit, triangular form
   .        .        in coordinate: PHI,K=1/PXY,S=TAN(LAMBDA),
   .        .        KSI,ETA(does not contain scattering error)
   .        .        from pipe)
   .        .           .
 19+15 R    .           .
  35  R   EXTRP      Distance from origin to first reconstructed
                     layer
  36  R   PATHL      Total length of scattered track in measurement
                     region
  37  I   IWPLAN     Bit map used AFTER fit
                     bits 0-31 for DC layers 
  38  I   IWPLA1     Bit map used AFTER fit
                     bits 0-7 for DC layers, bits 8-19 for VC layers
  39  I   IVCHIT     Bit map (bits 0-51) of DC+VC layers used in fit
  40  I   IVCHI1
 40+1 I   IHIT(13)   Predicted DC cell hit in Radial Layer 1
 40+2 I   IHIT(14)   Predicetd DC cell hit in Radial Layer 2
    .        .
    .        .       (one word for each of 40 radial DC wires)
    .        .
40+40 I   IHIT(52)   Predicted DC cell hit in last radial wire
 80+1 I   IHIT(1)    Predicted VC cell hit in Layer 1
 80+2 I   IHIT(2)    Predicetd VC cell hit in Layer 2
    .        .
    .        .       (one word for each of 12 VC layers)
    .        .
80+12 I   IHIT(12)   Predicted VC cell hit in last VC layer
  93  I   MQVCDC     Quality of VC-DC track Match
  94  I   MQVCEC     Quality of VC-EC track Match
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Subtype 14: Vertex Chamber (VC) Pointers

Contains pointers to the rawdata for each VC track in Subtype 13 above, pretty similar to subtype 9, but with the VC pointers appended to those of DC. 
TRK(J):J  Type   Name              CONTENTS
       -  ----   ----   ------------------------------------
       1    I    NWDS   Number of WorDS, = 3+NDCH+5*NVCH
       2    I    NDCH   Number of DC Hits
     2+1    I    IDCH
                        bits <20:31>=residual in 10 microns
                             <18-19>=unused
                             <16-17>=wire side
                                     1=+, 2=-, 3 don't care
                             <0:15>= pointer to IRAW
  2+NDCH    I    IDCH
2+NDCH+1    I    NVCH   Number of VC Hits
3+NDCH+1    R    RESD   RESiDual of hit 1 (in microns)
      +2    R    DFTF   Fit DriFT distance of hit 1
      +3    R    ZFIT   FIT Z position  for hit 1
      +4    I    INDW   INDex into IRAW for hit 1
      +5    I    TUBE   TUBE number of hit 1
                        <0 for stereo hits when only 2 stereo hits
                 ...
                 ...
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Subtype 15: Projected/Decay Coordinates Of VC Tracks

Contains entries for VC projected or decay coordinates. All entries set to 999.0 for unreachable coordinates. The structure is the same as that of subtype 11. 
TRK(J):J  Type   Name                  CONTENTS
       -  ----   ----      ------------------------------------
       1    I    NWDS      number words this record
       2    R    XBT       coordinates at barrel TOF radius
       3    R    YBT         "     "     "      "
       4    R    ZBT         "     "     "      "
       5    R    THETABT   direction of track at XT,YT,ZT
       6    R    PHIBT       "     "     "      "
       7    R    PBT       P at XT,YT,ZT
       8    R    XSC       coordinates at barrel SC entrance
       9    R    YSC         "     "  "    "
      10    R    ZSC         "     "  "    "
      11    R    THETASC   direction of track at XSC,YSC,ZSC
      12    R    PHISC       "     "  "    "
      13    R    PSC       P at XSC,YSC,ZSC
      14    R    XET       coordinates at end cap TOF plane
      15    R    YET         "     "  "   "    "
      16    R    ZET         "     "  "   "    "
      17    R    THETAET   direction of track at XET,YET,ZET
      18    R    PHIET       "     "  "   "    "
      19    R    PET       P at XET,YET,ZET
      20    R    XEC       coordinates at end cap SC entrance
      21    R    YEC         "     "  "   "    "
      22    R    ZEC         "     "  "   "    "
      23    R    THETAEC   direction of track at XEC,YEC,ZEC
      24    R    PHIEC       "     "  "   "    "
      25    R    PEC       P at XEC,YEC,ZEC
      26    R    XC        coordinates at coil radius
      27    R    YC          "     "   "     "
      28    R    ZC          "     "   "     "
      29    R    THETAC    direction of track at XZ,YC,ZC
      30    R    PHIC        "     "   "     "
      31    R    PC        P at XC,YC,ZC
      32    R    BTPATH    path length from XM,YM to XBT,YBT
      33    R    ETPATH    path length from XM,YM to XET,YET
      34    R    XDC       coordinates at DC inner cylinder entrance
      35    R    YDC         "     "  "   "    "
      36    R    ZDC         "     "  "   "    "
      37    R    THETADC   direction of track at XDC,YDC,ZDC
      38    R    PHIDC       "     "  "   "    "
      39    R    PDC       P at XDC,YDC,ZDC
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Subtype 16: MDC-VC track matching information

TRK(J):J  Type   Name                  CONTENTS
       -  ----   ----      ------------------------------------
       1    I    NWDS      number words this record
       2    I    NRPHIS    Total hitted wires of DC & VC in this track 
       3    I    NVCW      Total hitted wires of VC in this track
       4    I    ZBT       Hit MAP of VC
       5    R    ADVC1     position from first hitted layer to last hitted layer of VC
       6    R    ADVC2     position From initial point to last hitted layer of VC
       7    I    L1cel     hitted cell number in layer 1  of VC
       8    I    L2cel        "    "    "     "   "    2  of VC
       9    I    L3cel        "    "    "     "   "    3  of VC
      10    I    L4cel        "    "    "     "   "    4  of VC
      11    I    L5cel        "     "   "     "   "    5  of VC
      12    I    L6cel        "     "   "     "   "    6  of VC
      13    I    L7cel        "     "   "     "   "    7  of VC
      14    I    L8cel        "     "   "     "   "    8  of VC
      15    I    L9cel        "     "   "     "   "    9  of VC
      16    I    L10cel       "     "   "     "   "   10  of VC
      17    I    L11cel       "     "   "     "   "   11  of VC
      18    I    L12cel       "     "   "     "   "   12  of VC
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What's new?

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Any comments, please contact
Guangpei Chen
Zepu Mao
Jing Liu
Gang Rong
Peiqing Li
Jingfa Qiu
Yuehong Xie
Ye Yuan
Liangfeng Sun
Changchun Zhang

The original document comes from trklst.html
Last modified: Wed Feb 24 11:08:42 EAT 1999