How to create a GPS source

Hi dear
I would like to define a GPS source with following requirements

  1. Electron beam with energy spectrum given by Gaussian with mean energy of 5.90 MeV and sigma 0.051 MeV.
  2. Spot taken to be Gaussian with sigma in X of 0.6645 mm and sigma in Y of 0.7274 mm;
  3. beam divergence given by Gaussian with sigma of 1 mrad, mean 0.

I tried

/gps/source/intensity 1
/gps/particle electron
# shape
/gps/pos/type Plane
/gps/pos/shape Circle 
/gps/pos/centre 0. 0. -5 mm
/gps/pos/radius 0.5 mm
/gps/pos/sigma_x 0.6645 mm
/gps/pos/sigma_y 0.7274 mm
# energy distribution 
/gps/ene/type Gauss
/gps/ene/mono 5.90 MeV
/gps/ene/sigma 0.051 MeV

Can anyone help me to define a source with the third requirement?
Thank you in advance.