update breakdown cut to include a cut on the number of calibrated PMT hits

This commit updates the breakdown cut to flag any event in which less than 70%
of the PMT hits have a good TAC value.

2 files changed, 26 insertions, 6 deletions

diff --git a/src/dc.c b/src/dc.c
index 6d538b4..e8a3183 100644
--- a/src/dc.c
+++ b/src/dc.c
@@ -623,25 +623,42 @@ int is_breakdown(event *ev)
     int i;
     double tac[20][512];
     int nhit[20] = {0};
+    int nhit_cal[20] = {0};
+    int nhit_cal_sum;
     double median_tac[20];
     size_t index[20];
 
     /* Breakdown event must have an nhit greater than 1000. */
     if (ev->nhit < 1000) return 0;
 
+    nhit_cal_sum = 0;
     for (i = 0; i < MAX_PMTS; i++) {
         if (!ev->pmt_hits[i].hit || pmts[i].pmt_type != PMT_NORMAL) continue;
 
-        tac[i/512][nhit[i/512]++] = ev->pmt_hits[i].tac;
+        nhit[i/512] += 1;
+
+        /* Sometimes during a breakdown, a lot of the channels have TAC values
+         * that are outside of the normal window. I'm not sure exactly what
+         * causes this, but we don't want to include these when calculating the
+         * median. */
+        if (ev->pmt_hits[i].tac < 400) continue;
+
+        tac[i/512][nhit_cal[i/512]++] = ev->pmt_hits[i].tac;
+
+        nhit_cal_sum += 1;
     }
 
+    /* Tag any event in which less than 70% of the PMT hit times are calibrated
+     * correctly. */
+    if (nhit_cal_sum < ev->nhit*BREAKDOWN_CAL_FRAC) return 1;
+
     for (i = 0; i < 19; i++) {
-        if (nhit[i] <= MIN_NHIT_CRATE) {
+        if (nhit_cal[i] <= MIN_NHIT_CRATE) {
             median_tac[i] = 0.0;
             continue;
         }
-        gsl_sort(&tac[i][0],1,nhit[i]);
-        median_tac[i] = gsl_stats_median_from_sorted_data(&tac[i][0],1,nhit[i]);
+        gsl_sort(&tac[i][0],1,nhit_cal[i]);
+        median_tac[i] = gsl_stats_median_from_sorted_data(&tac[i][0],1,nhit_cal[i]);
     }
 
     fargsort(median_tac,19,index);
diff --git a/src/dc.h b/src/dc.h
index e999235..248a6e0 100644
--- a/src/dc.h
+++ b/src/dc.h
@@ -38,9 +38,12 @@
 /* Minimum number of hits required for a crate to be considered the source of a
  * breakdown. */
 #define MIN_NHIT_BREAKDOWN 256
-/* Minimum number of hits for a crate to calculate the median TAC in the
- * breakdown cut. */
+/* Minimum number of calibrated hits for a crate to calculate the median TAC in
+ * the breakdown cut. */
 #define MIN_NHIT_CRATE 20
+/* Fraction of PMT hits which must have a good TAC value in order to pass the
+ * cut. */
+#define BREAKDOWN_CAL_FRAC 0.7
 
 /* Length of the sliding window used in the ITC cut (ns). */
 #define ITC_TIME_WINDOW 93.0