1004 atof bar hits noise rejection (#1007)

* feat: adding cut on bar time sum for events for which the start time is defined

* feat: changing cut to fixed 40ns around bar time sum mean

Author: N-Plx

reconstruction/alert/src/main/java/org/jlab/rec/atof/hit/ATOFHit.java

@@ -26,7 +26,9 @@ public class ATOFHit {
     private String type;
     private boolean isInACluster;
     private int associatedClusterIndex;
+    private double meanTimeAligned;
     int idTDC;
+    
 
     public int getSector() {
         return sector;
@@ -79,6 +81,14 @@ public void setTot(int tot) {
     public double getTime() {
         return time;
     }
+    
+    public double getStartTime() {
+        return this.startTime;
+    }
+    
+    public double getMeanTimeAligned(){
+        return this.meanTimeAligned;
+    }
 
     public void setTime(double time) {
         this.time = time;
@@ -198,12 +208,12 @@ public final int convertTdcToTime() {
         //Time offsets
         double[] timeOffsets = CalibrationConstantsLoader.ATOF_TIME_OFFSETS.get(key);
         double[] timeOffsetsRef = CalibrationConstantsLoader.ATOF_TIME_OFFSETS.get(referenceModuleKey);
-        
+        this.meanTimeAligned = timeOffsetsRef[0];
         //The names below correspond to the CCDB entries
         //They will most probably evolve
         //For now let's say t0 is used to store the bar-to-bar and wedge-to-wedge alignments
         double t0 = timeOffsets[0];
-        double tChannelToChannelPhiAlignment = (t0 - timeOffsetsRef[0]);
+        double tChannelToChannelPhiAlignment = (t0 - this.meanTimeAligned);
         if(this.type=="bar up" || this.type=="bar down") //bar alignment is done with the sum of the two times
             tChannelToChannelPhiAlignment=tChannelToChannelPhiAlignment/2.;
 

reconstruction/alert/src/main/java/org/jlab/rec/atof/hit/BarHit.java

@@ -21,6 +21,27 @@ public class BarHit extends ATOFHit {
     public ATOFHit getHitUp() {
         return hitUp;
     }
+    
+    /**
+     * Computes bar time sum and check if it is around 
+     * the value the hits were aligned to. For now,
+     * 40ns cut. When calibrations are final, it should
+     * be refined to reflect the resolution.
+     * 
+     */
+    public boolean isInTime() {
+        double timeShift = 0;
+        //For FT electron for which the startTime is set at -1000
+        //We need to shift where the cut is applied
+        if(this.hitUp.getStartTime()<0) timeShift = 2180;
+        if(Math.abs(
+                this.hitUp.getTime()+this.hitDown.getTime()
+                        -timeShift
+                        -this.hitUp.getMeanTimeAligned())
+                <40)
+            return true;
+        return false;
+    }
 
     public void setHitUp(ATOFHit hit_up) {
         this.hitUp = hit_up;

reconstruction/alert/src/main/java/org/jlab/rec/atof/hit/HitFinder.java

@@ -5,6 +5,7 @@
 import org.jlab.geom.base.Detector;
 import org.jlab.io.base.DataBank;
 import org.jlab.io.base.DataEvent;
+import org.jlab.rec.alert.constants.CalibrationConstantsLoader;
 
 /**
  * The {@code HitFinder} class finds hits in the atof.
@@ -124,12 +125,9 @@ public void findHits(DataEvent event, Detector atof, float startTime) {
                 //Matching the hits: if same module and different order, they make up a bar hit
                 if (this_hit_up.matchBar(this_hit_down)) {
                     //Bar hits are matched to ahdc tracks and listed
-                    if (countMatches > 0) {
-                        //If the up hit was already involved in a match, do not make an additionnal match
-                        //Chosing to ignore double matches for now because it happened for <1% of events in cosmic runs
-                        continue;
-                    }
                     BarHit this_bar_hit = new BarHit(this_hit_down, this_hit_up);
+                    //Only add bar hits for which the time sum is in time
+                    if(!this_bar_hit.isInTime()) continue;
                     this.barHits.add(this_bar_hit);
                     countMatches++;
                 }