1 files changed, 6 insertions, 1 deletions
diff --git a/g4gen.py b/g4gen.py
index 409570f..718df6e 100644
--- a/g4gen.py
+++ b/g4gen.py
@@ -18,7 +18,7 @@ except:
     import G4chroma
 
 class G4Generator(object):
-    def __init__(self, material):
+    def __init__(self, material, seed=None):
         '''Create generator to produce photons inside the specified material.
 
            material: chroma.geometry.Material object with density, 
@@ -26,7 +26,12 @@ class G4Generator(object):
 
                      composition dictionary should be 
                         { element_symbol : fraction_by_weight, ... }.
+           seed: Random number generator seed for HepRandom. If None,
+                 generator is not seeded.
         '''
+        if seed is not None:
+            HepRandom.setTheSeed(seed)
+
         g4py.NISTmaterials.Construct()
         g4py.ezgeom.Construct()
         self.physics_list = G4chroma.ChromaPhysicsList()