Allow generating particles over an annulus between two radii

Control/CalypsoExample/Generation/python/faser_parser.py

@@ -40,7 +40,7 @@ def faser_pgparser():
                         help="Specify PDG ID of particle (note plus/minus different) or list (e.g.: --pid -13 13)")
     parser.add_argument("--mass", default=105.66, type=float,
                         help="Specify particle mass (in MeV)")
-    parser.add_argument("--radius", default=100., type=float,
+    parser.add_argument("--radius", default=100., type=float, nargs="*",
                         help="Specify radius (in mm)")
     parser.add_argument("--angle", default=0.005, type=float_or_none,
                         help="Specify angular width (in Rad)")
@@ -55,7 +55,7 @@ def faser_pgparser():
 
     parser.add_argument("--sampler", default="log",
                         help="Specify energy sampling (log, lin, const, hist, hist2D)")
-    parser.add_argument("--hist_name", default="log",
+    parser.add_argument("--hist_name", default="",
                         help="Specify energy sampling name for hist sampler file.root:hist")
     
     parser.add_argument("--minE", default=10., type=float,