Track and Vertex lists

This document describes the BES vertex and track lists. It is derived from a note by Wang Taijie. The following sections are included:

Common Block Description

There are three primary common blocks which are relevant to the event description ;

     RAWDAT - Which holds the raw event data (ADC values etc.) Certain
     track subtypes point back to the relevant rawdata portion of this
     block.

     EVLST - Which contains event description information and pointers
     to the track and vertex information in TRKLST.  In particular the
     TRKSUB and VRTSUB arrays are used to  index  the  the  track  and
     vertex entries .  The counters TOTTKS and NVTX give the number of
     track  and  vertex  entries  pointed  to  by  TRKSUB  and  VRTSUB
     respectively.



     TRKLST - Which contains the track and vertex  information  blocks
     (subtypes) in one large array.

          For the exact contents of these commons please refer to  the
     source  files  with filetypes .INC in BES$LIBPAMS:[BESCDE].  Only
     those parts  relevant  to  this  document  are  included  .   The
     quantities of interest here are;
        TOTTKS : total number of entries in the TRKSUB array.
                 This is the largest value of the 2-nd index
                 of the TRKSUB array for the event.
        NVTX   : number of vertices (15 max) in the event
                 This is the largest value of the 2-nd index
                 of the VRTSUB array for the event.
        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 valued pointer indicates non-existent subtype)
                 The value in TRKSUB points to the TOP of the
                 record of interest so that ITRK(TRKSUB(n,trk)+1)
                 is the first word of subtype=n for track=trk.
                 (Also true for VRTSUB )
        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 26 words of ITRK store the sizes of
                 arrays and lists, in the following order ;
                 Initial value of NXTSUB on each new event,
                 Number of words in  /EVLST/ preceding vrtsub,
                 Dimension of VRTSUB (2 items),
                 Lengths of vertex subtype lists (8 items),
                 Dimension of TRKSUB (2 items),
                 Lengths of track subtype lists (12 items).

     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.
          The order of the VRTSUB and TRKSUB indices is subtype first,
     track or vertex number second.
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VERTEX LISTS

For each vertex V in an event (1.le.V.le.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

  Item =TRK(VRTSUB(N,V) + J) . 

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     NPRNG    number of charged prongs in this vertex
             3     NEU      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 = cant 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     IVFIT    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     IQTOT    total charge of the prongs
             4     RVXY     Perp distance from origin (0,0) to vertex .
             5     XV       x (m) of vertex
             6     YV       y (m) of vertex
             7     ZV       z (m) of vertex
             8     XER      error in x (m)
             9     YER      error in y (m)
            10     ZER      error in z (m)
            11     CH2TOT   total chi sq for vertex fit (-1.0 if failed)
            12     DFTOT    degrees of freedom
            13     NTRKS    The number of tracks used in crude fit.
            13+1   TRKNUM   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 < .015 and |z| < 0.15 (meters) 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     IVCFIT     Fit type
                              (0 = simple  ; 1 = good )
             3     IVCQT      Total charge of the prongs
             4     RVXY       Perpendicular distance (x-y) from vertex to
                              nominal beam location (XYZIR(1-2) in /RUNPRM/ )
             5     VCXV       X (m) of vertex
             6     VCYV       Y (m) of vertex
             7     VCZV       Z (m) of vertex
             8     VCXER      Error in X (m)
             9     VCYER      Error in Y (m)
            10     VCZER      Error in Z (m)
            11     VCCH2T     Total ChiSq for vertex fit
                              (set to -1. if fit failed)
            12     VCDFT      Degrees of freedom (REAL)
            13     VCCH2V     ChiSq contribution from X,Y,Z
           13+1    VCH2NP     ChiSq contributions from
             .         .               individual tracks
             .         .                "
             .         .                "
           13+NPRNG+NEU                 "
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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 this record
             2     MFSEC      Method of finding secondary vertex
                                 1=veefnd,  2=pizero,  3=kink
             3     SMASSO     Mass calculated from tracks at origin
             4     SMASSV     Mass calculated at sec vertex point
             5     SCOS12     Cos of angle between vee tracks
             6     SCOSOP     Cos of angle between neutral decayer and
                              direction of secondary momentum vector
             7     SPTOT      Total momentum of secondary tracks
             8     SPTOTX       "   x-mentum  "    "         "
             9     SPTOTY       "   y   "     "    "         "
            10     SPTOTZ       "   z   "     "    "         "
            11     SZDIFF     Z difference at XY point of secondary.
            12     SENRGY     Total energy of secondaries
            13     SCH2       Chi square of fit (=-1.0 if fit failed)
            14     SDF        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     ICHRGD     Charge of the D
             5     DMASS      D final state invariant mass
             6     BCMASS     Beam-constrained mass of the D
             7     PXD        Px of the D
             8     PYD        Py of the D
             9     PZD        Pz of the D
            10     PD         Total momentum of the D
            11     ED         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.le.T.le.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

 Item  = 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
                            &le 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 cant tell sign)
              5    ITKTYP   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
              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    IVFROM   vertex # from which this track originates
              8    IVDCAY   vertex number that this track
                            decays to (0 if none)
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Subtype 3 : One-Track Fit

             J Type Name           CONTENTS
             - ---- ----           --------
             1  I   NWDS       number of words this record
             2  I   ICHRGE     charge of track, +1, -1
             3  R   PXYM       at min. dist. of approach to beam origin
             4  R   PXM         "
             5  R   PYM         " (note that  PZ/P gives cos(THETA),
             6  R   PZM         "             PXY/P gives sin(THETA),
             7  R   P           "             PX/PXY gives cos(PHI),
             8  R   THETA       "             PY/PXY gives sin(PHI)
             9  R   PHIM        "    so use ratios rather than sin/cos
            10  R   XM          "    to save cpu time )
            11  R   YM          "
            12  R   ZM          "
            13  R   RM          "
            14  I   MFIT       Fit method:
                                 0 = circle fit
                                 2 = ARCS fit
            15  I   NDCH       Number of drift chamber hits in the fit
            16  I   IHIT       Not used
            17  R   CH2        Chi square from single track fit
            18  I   DF         Degrees of freedom
            19  R   RMS        Rms error of fit (ideally 1.0)
           19+1 R   ERR        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   AD1        Distance from origin to first reconstructed
                               layer
            36  R   AD2        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      :
           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     TOFPH      corrected pulse height
             8     TQUAL      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     AMASS2     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     LINADJ,1   Link to track on adjacent counter (above).
             18     LINADJ,1   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    TOFPH      corrected pulse height
             25    TQUAL      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     AMASS2     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     LINADJ,1   Link to track on adjacent counter (above).
             35     LINADJ,1   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   SCNWDS   I   number of words this record
             2 F   SCNHIT   I   number of shower counter cell hits
             3 F   SCPHIT   I   number of shower counter paired hits
             4 F   SCXSH    R   shower coords at first layer hit
             5     SCDXSH   R   shower coords error at first layer hit
             6 F   SCYSH    R               ..
             7     SCDYSH   R               ..
             8 F   SCZSH    R               ..
             9     SCDZSH   R               ..
            10 F   SCTHT    R   shower counter theta angle
            11     SCDTHT   R   shower counter theta angle error
            12 F   SCPHI    R   shower counter phi angle
            13     SCDPHI   R   shower counter phi angle error
            14 F   SCENG    R   total energy observed in SC (GEV)
                                -- No calibration done, same as SCERAW
                                   for the current version
            15     SCDENG   R   total energy error in SC (GEV)
            16 F   SCCHI1   R   quality of SC fit, CHI2 TYPE 1
            17 F   SCCHI2   R   quality of SC fit, CHI2 TYPE 2
            18 F   SCSTAT   R   cluster status/link
            19 F   SCFLAG   I   shower counter fit flag
            20 F   SCMOD    I   module number for this track
                                  (1 - barrel, 2 - E endcap, 3 - W endcap)
            21 F   SCCHID   R   CHI SQ of identification
            22 F   SCSHID   R     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     SCWTPH   R   weight for PHOTON
            24     SCWTEL   R   weight for ELECTRON
            25     SCWTMU   R   weight for MU or MIN. IONIZING
            26     SCWTHA   R   weight for HADRON
            27 F   SCCOSX   R   -|      direction cosines
            28 F   SCCOSY   R    |==>        from
            29 F   SCCOSZ   R   -|         track fit
            30 F   SCERAW   R   total raw energy (sum of PHs  0.01)

            31 F   SCNBLK   I   number of layer blocks to follow
            32 F SCNBLK+SCLAYL  I   first layer number
            33 F SCNBLK+SCHITL  I   number of hit cells in this layer
            34 F SCNBLK+SCENGL  R   energy deposited in this layer (GeV)
            35 F SCNBLK+SCPHIL  R  average PHI/X  for  this  layer
            36 F SCNBLK+SCDPHL  R  PHI/X  RMS for  this layer
            37 F SCNBLK+SCZL    R  average  Z/Y (M)   for  this layer
            38 F SCNBLK+SCDZL   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 600 MeV/c and for incoming cosmics.

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

             1     NWRDS    number of words in this block
                            ( = 6 + 14MULEVP )
             2     MUID     muon identifier:  0 = not a mu
                                              1 = mu
                                              2 = cant tell
             3     MUSTAT   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     MULEVR   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     MULEVE   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     MULEVP   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 NSECT      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 level=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 AGRMST     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                    Reserved for future use
              6                    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     PHMPER     fractional uncertainty (sigma) on
                                   measured pulse height
             10                    reserved for future use
             11                        "
             12                        "
             13                        "
             14                        "

                                   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+j   I     XTAG(J)    status of hit in wire layer
              .                    J of layer 2 (J=1-12)
              .
              .                     XTAG  meaning
              .                       1   good hit
              .                       2   overflow
              .                       3   no mtac hit
                                      4   predict > 1 track in cell
              .                       5   multiple mtac hits
              .                       6   mtac but no dedx
              .                       7   bad wire
              .                       8   corrected ph is &le 0.
              .                       9   outside good time window
           19+12
           31+1         PH(J)      corrected pulse height for signal
              .                    from wire layer J. filled when
              .                    XTAG(J) &le 3.
              .
              .
           31+12

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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     IVCHRG     charge of track  +1, -1, 0
             3     VCPXY      PXY at location of vertex
             4     VCPX       PX   "    "     "     "
             5     VCPY       PY   "    "     "     "
             6     VCPZ       PZ   "    "     "     "
             7     VCP        P    "    "     "     "
             8     VCTHET     THET "(see note in subtype 3 for this)
             9     VCPHI      PHI  "  "   "   "    "   "   "   "
            10     VCX        X    "    "     "     "
            11     VCY        Y    "    "     "     "
            12     VCZ        Z    "    "     "     "
            13     VCR        R in XY plane
                              (not filled for secondary vertices )
            14     MVCFIT     Fit method: 0 = circle fit
                                          1 = good one track fit
            15     NVCDC      Number of dc hits in the fit
            16     spare      Reserved - added to make this format the same
                              as Subtype 3 above.
            17     VCH2       Chi square from single track fit
            18     VCDF       Degrees of freedom
            19     VCRMS      RMS error of fit
            19+1   VCERR      Error matrix (in phi, 1/pxy, s)
             .                ( diagonal element = 999. and
             .                  off-diagonal = 0. for fits with
            19+6                VFIT .le.1 .                    )
            26     VDPX       Error PX
            27     VDPY       Error PY
            28     VDPZ       Error PZ
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Subtype 9 : Drift Chamber (DC) Pointers

Contains pointers to the rawdata for each track in Subtype 3 above.

             J     NAME              CONTENTS
             -     ----              --------
             1     NWDS       number words this record (3+NDCH)
             2     NDCH       number of dc pointers to follow
             3     IDCH       bits 20-31: residual in 10 micron units
                                   18-19: unused
                                   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)
             .        .        then IRAW(IP) contains tag word/mtac valueT
             .        .
           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 Coords Of DC Tracks

Contains entries for projected or decay coordinates. All entries set to 999. for unreachable coords.

             Following format for PROJECTIONS (IVDCAY=0)
             --------- ------ --- ----------- ----------

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

             1     NWDS       number words this record
             2     XBT        coords at barrel TOF radius
             3     YBT          "     "     "      "
             4     ZBT          "     "     "      "
             5     THETBT     direction of track at XT,YT,ZT
             6     PHIBT        "     "     "      "
             7     PBT        P at XT,YT,ZT
             8     XSC        coords at barrel SC entrance
             9     YSC          "     "  "    "
            10     ZSC          "     "  "    "
            11     THETSC     direction of track at XSC,YSC,ZSC
            12     PHISC        "     "  "    "
            13     PSC        P at XSC,YSC,ZSC
            14     XET        coords at end cap TOF plane
            15     YET          "     "  "   "    "
            16     ZET          "     "  "   "    "
            17     THETET     direction of track at XET,YET,ZET
            18     PHIET        "     "  "   "    "
            19     PEC        P at XET,YET,ZET
            20     XEC        coords at end cap SC entrance
            21     YEC          "     "  "   "    "
            22     ZEC          "     "  "   "    "
            23     THETEC     direction of track at XEC,YEC,ZEC
            24     PHIEC        "     "  "   "    "
            25     PEC        P at XEC,YEC,ZEC
            26     XC         coords at coil radius
            27     YC           "     "   "     "
            28     ZC           "     "   "     "
            29     THETC      direction of track at XZ,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

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

             2     IDYCHR     charge 0, +1, -1   (9 if sign unknown)
             3     PXYDCY     at xdcy,ydcy,zdcy
             4     PXDCY       "  "
             5     PYDCY       "  "
             6     PZDCY       "  "
             7     PDCY        "  "
             8     THETDY      "  "
             9     PHIDCY      "  "
            10     XDCY       coords of decaying track near decay vertex
            11     YDCY          "    "    "       "    "     "     "
            12     ZDCY          "    "    "       "    "     "     "
            13     DCYLEN     3-D path length of decaying particle
                               (from parent vtx to decay vtx)
           13+ 1   ERRDCY     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 this record
             2     IRCHRG     charge of track, 0, +1, -1
             3     RPXY       at secondary vertex (starting point coords)
             4     RPX         "
             5     RPY         "   (note that  PZ/P gives cos(THETA),
             6     RPZ         "               PXY/P gives sin(THETA),
             7     RP          "               PX/PXY gives cos(PHI),
             8     RTHETA      "               PY/PXY gives sin(PHI)
             ..or  TANLAM (for new tracking code)
             9     RPHI        "    so use ratios rather than sin/cos
            10     RX          "    to save cpu time).
            11     RY          "
            12     RZ          " <=ZDCY-(XY path from IR>cot(RTHETA))
            13     RR          " (in XY plane)
            14     MRFIT      fit method
                                1=VEEFND,  2=PIZERO
            15     RMASS      mass of particle
            16     RTYPE      type of fit
            17     RCHISQ     chisq of fit
            18     RDF        degrees of freedom for fit

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