Do not count zero energy pulse heights

src/tallies/tally_scoring.cpp

@@ -2752,6 +2752,10 @@ void score_pulse_height_tally(Particle& p, const vector<int>& tallies)
       // Temporarily change energy of particle to pulse-height value
       p.E_last() = p.pht_storage()[index];
 
+      // Skip pulses with zero energy
+      if (p.E_last() == 0.0)
+        continue;
+
       // Initialize an iterator over valid filter bin combinations. If
       // there are no valid combinations, use a continue statement to ensure
       // we skip the assume_separate break below.

tests/regression_tests/pulse_height/results_true.dat

@@ -1,6 +1,6 @@
 tally 1:
-4.140000E+00
-3.443000E+00
+3.000000E-02
+3.000000E-04
 1.000000E-02
 1.000000E-04
 1.000000E-02

tests/unit_tests/test_pulse_height.py

@@ -0,0 +1,24 @@
+import openmc
+
+
+def test_zero_energy_pulse_heights(run_in_tmpdir):
+    surf = openmc.Sphere(r=10.0, boundary_type='vacuum')
+    cell = openmc.Cell(region=-surf)
+    model = openmc.Model()
+    model.geometry = openmc.Geometry([cell])
+    model.settings.run_mode = 'fixed source'
+    model.settings.source = openmc.IndependentSource(
+        space=openmc.stats.Point(),
+        energy=openmc.stats.Discrete([5.0e6], [1.0]),
+        particle='photon',
+    )
+    model.settings.particles = 100
+    model.settings.batches = 1
+    model.settings.electron_treatment = 'led'
+
+    tally = openmc.Tally()
+    tally.scores = ['pulse-height']
+    model.tallies = openmc.Tallies([tally])
+    model.run(apply_tally_results=True)
+
+    assert (tally.mean == 0.0).all(), "Zero energy pulses should not be counted"