GRAS Reverse Monte Carlo with monoenergetic electrons

Dear experts,

I’m trying to setup a reverse monte carlo with GRAS for a given geometry. My choice for the RMC is due to the geometry dimensions, where the target is a CCD and much smaller than the full geometry.

What I’m trying to do now is setting up the simulations with monoenergetic electrons. Is that possible in RMC? I ask because from the user guide, the RMC accepts exponential or power-law spectrums, or a user specified spectrum. I tried setting up with the latter option, with the following form:

/gps/ene/type Arb
/gps/hist/type arb
/gps/ene/min    3.000E+00 MeV
/gps/ene/max    3.000E+00 MeV 
/gps/hist/point    3.00   1.00E+09
/gras/analysis/adjoint/addUserDefinedPrimSpectrum e- 1.00E+09 1/cm2 Arb

When I run the simulation, I seem not to get any results, and there are no converges whatsoever.

In addition, I add the normalization factor of 1.00E+09 so I get a transmission efficiency for a given primary energy.

Is that the way to go? I’d really appreciate any inputs.

Thanks in advance.