diff --git a/bind/example.py b/bind/example.py
index 5d76507..99be684 100644
--- a/bind/example.py
+++ b/bind/example.py
@@ -8,4 +8,4 @@ cw.addLayer(10,"G4_Si",False)
 
 sb = SystemBuilder()
 sb.init(cw)
-sb.run_batch(100, "e-", 1000, 5000)
+sb.run_batch(100, "gamma", 1000, 5000)