The Fiber Cluster Common Block

typedef struct FIBER_CLUSTER_COM {
  int   numfibers, ixy;
  int   clusterid;
  int   weight;
  int   npix,tadc;
  int   npe;
  float pos, z;
  int   fhit[MAX_DAUGHTER_FIBERS];
  float fhitw[MAX_DAUGHTER_FIBERS];
} FIBER_CLUSTER_COM;

       common/fgfibc/fgfibc_nfib, fgfibc_ixy,
     &               fgfibc_cid, fgfibc_wgt,
     &               fgfibc_npix,fgfibc_tadc, 
     &               fgfibc_npe,
     &               fgfibc_pos, fgfibc_z,
     &               fgfibc_fhit, fgfibc_fhitw

The Fiber Cluster common block describes a cluster of hit fibers. Each fiber cluster represents a single particle hit for a fiber plane. numfibers is the number of fibers in the cluster. clusterid is a unique identifier for the cluster and is assigned to be the same as the fiber id of one of its member fibers. (It is implicitly assumed that no two fiber clusters will share a single fiber.) weight is the strength of the hit, in arbitrary units. This may be total ADC or number of pixels or some other indicator. npix and tadc are optionally filled variables which contain the total number of pixels and ADC counts associated with the constituent fibers. npe is an estimate of the number of photoelectrons in the hit. ¹The position of the cluster is stored in pos and z. pos is the distance perpendicular to the beam axis (transverse coordinate); z is the position along the beam axis (longitudinal coordinate). Whether or not pos is an X or a Y coordinate can be determined from the variable ixy. The daughter list fhit contains a list of all fibers which are part of the fiber cluster, weighted by fhitw.