DFDCGeometry.cc

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// $Id$
//
//    File: DFDCGeometry.h
// Created: Wed Nov 29 13:35 EST 2006
// Creator: davidl (on Darwin swire-b241.jlab.org 8.7.0 powerpc)
//

#include "DFDCGeometry.h"

#if 0  // Old method for FDC geometry with hard coded positions!!!

// Static globals used by all instances of DCDCTrackHit_factory
static pthread_mutex_t wire_mutex = PTHREAD_MUTEX_INITIALIZER;
static bool wire_table_initialized = false;
static DFDCWire fdcwire[FDC_NUM_LAYERS][WIRES_PER_PLANE];

//-----------------
// DFDCGeometry   (Constructor)
//-----------------
DFDCGeometry::DFDCGeometry(void)
{
   // We use the mutex and wire_table_initialized flag to
   // make sure the table is initialized only once.
   pthread_mutex_lock(&wire_mutex);
   if(wire_table_initialized){
      pthread_mutex_unlock(&wire_mutex);
      return;
   }

   float degrees00  = 0.0;
   float degrees60  = 60.0*M_PI/180.0;
   for(int layer=1; layer<=FDC_NUM_LAYERS; layer++){
      
      float angle=0.0;
      float z_anode=188.5+85.0; 
      switch(layer){
         case  1: z_anode+= -76.0-4.5-3.0;   angle=  degrees00; break;
         case  2: z_anode+= -76.0-4.5-0.0;   angle= +degrees60; break;
         case  3: z_anode+= -76.0-4.5+3.0;   angle= -degrees60; break;
         case  4: z_anode+= -76.0+4.5-3.0;   angle=  degrees00; break;
         case  5: z_anode+= -76.0+4.5-0.0;   angle= +degrees60; break;
         case  6: z_anode+= -76.0+4.5+3.0;   angle= -degrees60; break;

         case  7: z_anode+= -25.33-4.5-3.0;  angle=  degrees00; break;
         case  8: z_anode+= -25.33-4.5-0.0;  angle= +degrees60; break;
         case  9: z_anode+= -25.33-4.5+3.0;  angle= -degrees60; break;
         case 10: z_anode+= -25.33+4.5-3.0;  angle=  degrees00; break;
         case 11: z_anode+= -25.33+4.5-0.0;  angle= +degrees60; break;
         case 12: z_anode+= -25.33+4.5+3.0;  angle= -degrees60; break;

         case 13: z_anode+= +25.33-4.5-3.0;  angle=  degrees00; break;
         case 14: z_anode+= +25.33-4.5-0.0;  angle= +degrees60; break;
         case 15: z_anode+= +25.33-4.5+3.0;  angle= -degrees60; break;
         case 16: z_anode+= +25.33+4.5-3.0;  angle=  degrees00; break;
         case 17: z_anode+= +25.33+4.5-0.0;  angle= +degrees60; break;
         case 18: z_anode+= +25.33+4.5+3.0;  angle= -degrees60; break;

         case 19: z_anode+= +76.0-4.5-3.0;   angle=  degrees00; break;
         case 20: z_anode+= +76.0-4.5-0.0;   angle= +degrees60; break;
         case 21: z_anode+= +76.0-4.5+3.0;   angle= -degrees60; break;
         case 22: z_anode+= +76.0+4.5-3.0;   angle=  degrees00; break;
         case 23: z_anode+= +76.0+4.5-0.0;   angle= +degrees60; break;
         case 24: z_anode+= +76.0+4.5+3.0;   angle= -degrees60; break;
      }
      
      // Somewhere between HDDS and here I'm missing a sign. I'm not
      // sure where it is, but empirically, it must be here for things
      // to be consistent.
      angle=-angle;

      for(int wire=1; wire<=WIRES_PER_PLANE; wire++){

         DFDCWire *w = &fdcwire[layer-1][wire-1];
         w->layer = layer;
         w->wire = wire;
         w->angle = angle;
         
         // find coordinates of center of wire in rotated system
         float u = U_OF_WIRE_ZERO + WIRE_SPACING*(float)(wire-1);
         
         // Rotate coordinates into lab system and set the wire's origin
         // Note that the FDC measures "angle" such that angle=0
         // corresponds to the anode wire in the vertical direction
         // (i.e. at phi=90 degrees).
         float x = u*sin(angle + M_PI/2.0);
         float y = u*cos(angle + M_PI/2.0);
         w->origin.SetXYZ(x,y,z_anode);
         
         // Length of wire is set by active radius
         w->L = 2.0*sqrt(pow(FDC_ACTIVE_RADIUS,2.0) - u*u);
         
         // Set directions of wire's coordinate system with "udir"
         // along wire.
         w->udir.SetXYZ(sin(angle),cos(angle),0.0);
         
         // "s" points in direction from beamline to midpoint of
         // wire. This happens to be the same direction as "origin"
         w->sdir = w->origin;
         w->sdir.SetMag(1.0);
         
         w->tdir = w->udir.Cross(w->sdir);
         w->tdir.SetMag(1.0); // This isn't really needed
      }
   }

   // Flag table as initialized and release the lock so other threads
   // can continue.
   wire_table_initialized=true;
   pthread_mutex_unlock(&wire_mutex);
}

//-----------------
// DFDCGeometry   (Constructor)
//-----------------
const DFDCWire* DFDCGeometry::GetDFDCWire(int layer, int wire)
{
   if(layer<1)return NULL;
   if(layer>FDC_NUM_LAYERS)return NULL;
   if(wire<1)return NULL;
   if(wire>WIRES_PER_PLANE)return NULL;

   return &fdcwire[layer-1][wire-1];
}
#endif