Pixel Instrument For Precision Neutrino Observations

Introduction

This is the GEANT4 simulation code for Pinpoint, a pixel-based neutrino detector concept for the FASER Run 4 upgrade.

This code is based off the FPFSim GEANT4 simulation written by Matteo Vicenzi and Wenjie Wu.

Getting started

This code can be compiled on lxplus or any Alma Linux9 machine with cvmfs access. To install this code do:

git clone https://github.com/PinpointDetector/Pinpoint_G4.git
cd Pinpoint_G4
source Pinpoint/setup.sh
mkdir build && cd build
cmake ../Pinpoint
make -j 8

In case your machine is not suitable, you can compile and run the code in a Docker container. An el9 Docker container which mimics the lxplus environment is available from DockerHub.

A repository containing a script to easily run the container and mount cvmfs is available from github.com/benw22022/el9-cvmfs-docker

To get started do:

git clone https://github.com/benw22022/el9-cvmfs-docker.git
cd el9-cvmfs-docker/
./run_container /path/to/Pinpoint_G4

Macro commands

There are a number of user defined macro commands which can be used to control the simulation.

Geometry Commands

Command	Description	Default
/det/setTungstenThickness	Tungsten sheet thickness in mm	5 mm
/det/setSiliconThickness	Silicon layer thickness in $\mu$m	50 um
/det/setBoxThickness	Silicon box (filled with air) thickness in mm	5 mm
/det/setNLayers	Number of tungsten/pixel layer	100
/det/setPixelHeight	Set the height of an individual pixel in $\mu$m	22.8 um
/det/setPixelWidth	Set the width of an individual pixel in $\mu$m	20.8 um
/det/setDetectorWidth	Set the width of the detector in cm	26.6
/det/setDetectorHeight	Set height of the detector in cm	19.6
/det/setGDMLFile	Set the output file for the gdml file	pinpoint.gdml

Output file commands

Command	Description
/out/fileName	option for AnalysisManagerMessenger, set name of the file saving all analysis variables
/out/saveTrack	if true save all tracks, false by default, requires \tracking\storeTrajectory 1
/out/saveTruthHits	if true save truth hit x, y, z position, false by default

Next steps

• Geometry (Dhruv)
  • Add scintillator layers
  • Check deposited energy (smear with Landau distribution)
  • Add messenger to enable/disable from macro files
• Neutrino Interactions (Tobi)
  • Set z-position of vertex to random position within one layer
  • Check charm decays (Tobi)
• Output (Ben)
  • Add parent track id, or write out tau decay products
  • Check file size including true position of all particles
• Add HTCondor submission script