diff -u -r1.3 -r1.4
--- ParticleHelixProducer.java	10 Oct 2012 19:57:34 -0000	1.3
+++ ParticleHelixProducer.java	13 Oct 2012 02:58:02 -0000	1.4
@@ -45,6 +45,7 @@

 public class ParticleHelixProducer extends Driver {
     
     private boolean debug = false;

+    private boolean saveSingleTrack = false;

     private int _totalTracks = 0;
     TrackUtils trackUtils = new TrackUtils();
     TrackerHitUtils trackerhitutils = new TrackerHitUtils();

@@ -71,6 +72,10 @@

         this.debug = debug;
     }
 

+    public void setSaveSingleTrack(boolean single) {
+        this.saveSingleTrack = single;
+    }
+

     public void setTrackOutputCollectionName(String trackOutputCollectionName) {
         this.trackOutputCollectionName = trackOutputCollectionName;
     }

@@ -132,6 +137,7 @@

             double bfield = Math.abs(_bfield.z()); //remove sign from B-field, assumed to be along z-direction
             if(debug) System.out.println(this.getClass().getSimpleName() + ": bfield " + bfield );
             for(MCParticle part : fsParticles) {

+                if(Math.random()>0.5) continue;

                 if(ParticleTypeClassifier.isElectron(part.getPDGID()) || ParticleTypeClassifier.isPositron(part.getPDGID())) {
                     
                     

@@ -139,6 +145,16 @@

                     Hep3Vector org = part.getOrigin();
                     double q = -1*part.getCharge(); //since I flipped the B-field I need to flip the charge
 

+                    
+                    if(p.magnitude()<0.3 ) {
+                        if(debug) System.out.println(this.getClass().getSimpleName() + ": this MC particle had too small momentum p=" + p.toString());
+                        continue;
+                    }
+                    if(Math.abs( Math.atan(p.y()/p.z()) ) < 0.01) {
+                        if(debug) System.out.println(this.getClass().getSimpleName() + ": this MC particle had too small thetay =" + Math.abs( Math.atan(p.y()/p.z()) ));
+                        continue;
+                    }
+                    

                     //propagate to start of field region if needed
                     double dz = 0-org.z();
                     if(dz>0) {

@@ -159,10 +175,6 @@

                     org = VecOp.mult(detToTrk, org);
                     if(debug) System.out.println(this.getClass().getSimpleName() + ": MC particle p=" + p.toString() +" org=" + org.toString() +" q = " + q + " (rotated)");
                     

-                    if(p.magnitude()<0.3) {
-                        if(debug) System.out.println(this.getClass().getSimpleName() + ": this MC particle had too small momentum p=" + p.toString());
-                        continue;
-                    }

                     if(debug) {
                         double pt = Math.sqrt(p.x()*p.x() + p.y()*p.y());
                         double Rman = q*pt/(Constants.fieldConversion*bfield); 

@@ -195,6 +207,9 @@

                     h_slope.fill(htf.slope());
                     h_z0.fill(htf.z0());
                     

+                    
+                    if(saveSingleTrack && tracks.size()==1) break;
+                    

                 }
             }
         }