# ND Simulation How To

## TLDR;
**prerequest**
- `/sdf/group/neutrino/images/larcv2_ub20.04-cuda11.1-cudnn8-pytorch1.9.0-larndsim.sif`
- login to a GPU node (only required for det-sim stage w/ `larnd-sim`)

source /sdf/group/neutrino/kvtsang/nd-sim/mc-prod/setup.sh
gen-edepsim-g4mac mpvmpr_cfg.yaml g4.mac
edepsim-nd g4.mac 10 edepsim-output
detsim-nd -i edepsim-output.h5

## Generate GEANT4 macro

gen-edepsim-g4mac mpvmpr_cfg.yaml g4.mac

This script generates a macro file (reusable unless changes in the particle bomb config).

# ======
# g4.mac
# ======

/edep/hitSagitta drift 1.0 mm
/edep/hitLength drift 1.0 mm
/edep/update

/generator/kinematics/bomb/config /sdf/group/neutrino/kvtsang/nd-sim/mc-prod/etc/module0/mpvmpr_cfg.yaml
/generator/kinematics/bomb/verbose 0
/generator/kinematics/set bomb

/generator/count/fixed/number 1
/generator/count/set fixed
/generator/add

It takes particle boob config file `mpvmpr_cfg.yaml` as input.
You can provide your own config file.
The script looks for file in your working directory first. If not found, it will search from the default directory.

# ===============
# mpvmpr_cfg.yaml
# ===============

SEED: -1
GeneratorMPV:
  NumEvent: [1,2]
  NumParticle: [3,3]
  XRange: [-300,300]
  YRange: [-600,600]
  ZRange: [-300,300]
  TRange: [0,10]
  AddParent: True
  Particles:
    -
      PDG:      [11,13]
      NumRange: [1,1]
      KERange:  [0,1] 
      UseMom:   False
      Weight:   1
    -
      PDG:      [211,-211]
      NumRange: [0,2]
      KERange:  [0,1]
      UseMom:   False
      Weight:   1

    -
      PDG:      [22,111]
      NumRange: [0,2]
      KERange:  [0,1]
      UseMom:   False
      Weight:   1

    -
      PDG:      [2112]
      NumRange: [0,2]
      KERange:  [0,1]
      UseMom:   False
      Weight:   1

GeneratorMPR:
  NumEvent: [1,1]
  NumParticle: [1,5]
  XRange: [-300,300]
  YRange: [-600,600]
  ZRange: [-300,300]
  TRange: [0,10]
  Particles:
    -
      PDG:  [13]
      NumRange: [0,5]
      KERange:  [0,1]
      UseMom:   False
      Weight:   8
    -
      PDG:      [11]
      NumRange: [0,5]
      KERange:  [0,1]
      UseMom:   False
      Weight:   1

    -
      PDG:      [2112]
      NumRange: [0,5]
      KERange:  [0,1]
      UseMom:   False
      Weight:   1

## GEANT4 Simulation aka `edep-sim`

edepsim-nd g4.mac 10 edepsim-output

The script is a shortcut for `edep-sim` command.
It executes the GEANT4 edep-sim and output a root file (e.g. `edepsim-output.root`)
If `edep-sim` exit cleanly, it also convert the root file to hdf (e.g. `edepsim-output.h5`)

It is equivalent to `edep-sim -o output.root -g some_geo.gdml g4.mac`.

## Detector Simulation aka `larnd-sim`

detsim-nd -i edepsim-output.h5

The script does larpix readout simulation using **GPU**.
For more options, see `detsim-nd -h`

## Advanced Usage

It's possible to use different geometry, pixel layout, ..... etc.
To be documented. (Let me know if you want to try something different)