diff --git a/bind/G4Calo.py b/bind/G4Calo.py
index eca3820..18c6b8e 100644
--- a/bind/G4Calo.py
+++ b/bind/G4Calo.py
@@ -22,11 +22,13 @@ class __G4System(_G4System):
         particleSpec: str,
         minEnergy_GeV: float,
         maxEnergy_GeV: float = -1.0,
+        filename: str = "",
     ):
 
         if maxEnergy_GeV < 0:
             maxEnergy_GeV = minEnergy_GeV
 
+        save_file = len(filename) > 0
         # filename without file ending(!)
         filename = "_" + str(time.perf_counter_ns()) + ".root"
         _G4System.run_batch(self, nEvents, particleSpec, minEnergy_GeV, maxEnergy_GeV, filename=filename)
@@ -49,13 +51,13 @@ class __G4System(_G4System):
             df = index_out_of_bounds_workaround(ttree["Hits;1"])
 
         # save to pickle and delete root file
-        df.to_pickle(filename.replace(".root", ".pkl"))
+        if save_file:
+            df.to_pickle(filename.replace(".root", ".pkl"))
         os.system("rm "+filename)
         
         return df
 
 
-
     def displayEvent(self, logE = False, renderer=None):
         # for loop over all layers
         to_plot = []