examples/RICH/README.md

0001 Proximity Focusing RICH
0002 =======================
0003
0004 Example RICH demonstrating `Geant4OpticalTracker` Sensitive Detector plugin usage.
0005
0006 This detector design has been pulled from [ePIC](https://github.com/eic/epic), and was originally developed in
0007 [ATHENA](https://eicweb.phy.anl.gov/EIC/detectors/athena), for the Electron-Ion Collider.
0008
0009 ![PFRICH](doc/geometry.png)
0010
0011 For testing, it is recommended to follow `../README.md` and use `ctest`. See below for guidance for
0012 running this example standalone.
0013
0014 To use `ctest`, run:
0015 ```bash
0016 cd ..  # `pwd` should now be `DD4hep/examples`
0017 mkdir build
0018 cd build
0019 cmake -DDD4HEP_EXAMPLES="RICH" .. && make && make install
0020 ctest --output-on-failure   # or use `--verbose` to see all output
0021 ```
0022
0023 ## Local Development
0024 If you want to run this example standalone, without needing to run `ctest`,
0025 make a standalone build. The following assumes that your current working
0026 directory is `DD4hep/examples/RICH`.
0027
0028 Build with `cmake`, for example:
0029 ```bash
0030 cmake -B build -S . -D CMAKE_INSTALL_PREFIX=install
0031 cmake --build build -- install
0032 ```
0033
0034 Run a test simulation:
0035 ```bash
0036 install/bin/run_test_RICH.sh \
0037   python install/examples/RICH/scripts/richsim.py
0038 ```
0039 - See default settings in `scripts/richsim.py`
0040 - Override these settings, or add additional settings by appending `ddsim` options
0041
0042 Draw the hits, to show Cherenkov photon rings:
0043 ```bash
0044 root sim.root
0045 ```
0046 ```cpp
0047 // In ROOT interpreter:
0048 EVENT->Draw("PFRICHHits.position.Y():PFRICHHits.position.X()"); // hit positions
0049 EVENT->Draw("@PFRICHHits.size()");                              // raw number of hits per event
0050 ```
0051
0052 Test for the expected number of hits:
0053 ```bash
0054 root -b -q -l scripts/test_number_of_hits.C
0055 ```