Flat Neutrino Event Spectra Generation

To generate a flat neutrino event spectra, the method employed here is to warp the incoming neutrino flux to have a 1/E distribution. Since the cross section in higher energy is dominated by the deep inelastic scattering process, roughly linear in E, the neutrino spectrum can be made flat this way.

Warp the flux to 1/E

Use the modified ROOT script "warp_gsimple.C" attached in this page to warp a given flux file.

$ genie -b -q 'warp_gsimple.C+("gsimple_out_nd.root","/nova/data/flux/gsimple/nova_v07/nd/mn/fhc/gsimple_NOvA-ND_mn000z200i_rp11_bs1.1_pnut_lowth_f11f093bbirds_000q_00001.root")'

, where the first argument is the output file name and the second is the flux file you want to use for warping.

Prepare the FHiCL files and run GENIE simulation

Modify the GENIEGen.fcl to include a section for your warped flux file.

# Near detector warped
genie_simpleflux_nd_inverseenergy:                  @local::standard_genie
#genie_simpleflux_nd_inverseenergy.EventsPerSpill:   0
genie_simpleflux_nd_inverseenergy.EventsPerSpill:   1
#genie_simpleflux_nd_inverseenergy.POTPerSpill:      2.5e13 #Originally 5e13
genie_simpleflux_nd_inverseenergy.POTPerSpill:      0
genie_simpleflux_nd_inverseenergy.FluxType:         "simple_flux" 
genie_simpleflux_nd_inverseenergy.BeamName:         "numi" 
genie_simpleflux_nd_inverseenergy.DetectorLocation: "NOvA-ND" 
genie_simpleflux_nd_inverseenergy.FluxSearchPaths:  "<your flux file path>" 

Note how the EventsPerSpill and the POTPerSpill are configured here since POT accounting is meaningless in the warped flux.

Now generate the job FHiCL file with the make_sim_fcl script:

$ make_sim_fcl -n 10000 -det nd -gen genie -fs nonswap -hp fhc -f foo.fcl

For more information on make_sim_fcl, type "make_sim_fcl --help" in the terminal.

Then tell the foo.fcl thus generated to use the inverse energy settings in GENIEGen.fcl:

generator: @local::genie_simpleflux_nd_inverseenergy

To run GENIE, simply type:

$ nova -c foo.fcl -o <output_file_name>

Make CAF files out of the GENIE output

One can make CAF files from the sim files only if the slicer information is added to the data product. To add the slicer information, run

$ nova -c slicer4djob.fcl <GENIE_output_file>

Now one can make CAF:

$ nova -c cafmakerjob.fcl <slicer_output>