diff --git a/python/examples/first_interactions.py b/python/examples/first_interactions.py
index d86d8d70dd7cbe21adad95ac6eed4d71b8dfa97a..25476eb80f7b5b1dbc1c453ce82c65579a9e3278 100644
--- a/python/examples/first_interactions.py
+++ b/python/examples/first_interactions.py
@@ -54,7 +54,6 @@ for ish, sh_id in enumerate(shower_ids):
     daughters = interactions[interactions["shower"] == sh_id]
 
     mother = projectiles[ish]
-    norm = np.sqrt(sum(np.array(mother.momentum) ** 2))  # total momentum
 
     print("Plotting shower", sh_id)
     print(mother)