def configureBeam(x, y, z, szNm):
   """configureBeam(x,y,z, szNm)
   Create xtraParams entries to configure the beam for the simulation.
   Input:
   x, y, z - positions of the beam in meters
   szNm    - the beam diameter in nm (converted to m internally)"""
   return { "PosX" : x, "PosY" : y, "PosZ": z, "nmSize": szNm}