PRad-II Event Viewer & Monitor

EVIO decoder, event viewer, and online monitor for the PRad-II experiment at Jefferson Lab. Decodes FADC250 waveforms (HyCal) and SSP/MPD data (GEM), with a web-based GUI for waveform inspection, clustering, gain monitoring, and physics replay. Also supports original PRad (ADC1881M) via DAQ configuration.

Building

Linux

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(nproc)

CMake >= 3.14, C++17. Dependencies (evio, et) are resolved from the Hall-B CODA installation by default; if not found, CMake falls back to fetching from GitHub. Other dependencies (nlohmann/json, websocketpp, asio) are always fetched automatically.

Optional flags:

• -DBUILD_ANALYSIS=ON — ROOT-based replay and analysis tools (requires ROOT 6.0+)
• -DBUILD_GUI=ON — Qt standalone viewer and remote client (requires Qt6 or Qt5 WebEngine)
• -DWITH_ET=OFF — disable ET (live monitoring); required on Windows
• -DEVIO_SOURCE=fetch — force fetching evio from GitHub (no CODA needed)

Windows (MSYS2)

# MSYS2 packages
pacman -S mingw-w64-x86_64-toolchain mingw-w64-x86_64-cmake mingw-w64-x86_64-ninja mingw-w64-x86_64-expat

# Build (PowerShell with MinGW in PATH)
$env:PATH = "C:\msys64\mingw64\bin;" + $env:PATH
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DWITH_ET=OFF
cmake --build build

Or build natively in WSL2.

Server

prad2_server is a unified HTTP server that supports both file-based viewing and online ET monitoring. It replaces the former prad2_viewer and prad2_monitor executables.

prad2_server [evio_file] [-p port] [-H] [-i] [-f filter.json] [-c config.json] [-d data_dir] [-D daq_config.json] [--et]

Opens a web GUI at http://localhost:5051 with tabs: Waveform Data, Clustering, Gain Monitoring (LMS), EPICS, Physics, GEM. See docs/API.md for the full HTTP/WebSocket API reference and interactive CLI commands (-i).

File mode (default)

prad2_server data.evio -H                                          # PRad-II
prad2_server prad.evio -D database/prad1/prad_daq_config.json -H   # PRad
prad2_server -d /data/stage6 -H                                    # file browser

Online mode

prad2_server --et                       # connect to ET system (config from database/config.json)
prad2_server data.evio --et -H          # start with file, "Go Online" button available in UI

ET connection settings are read from the "online" section of config.json.

Mode switching

The server maintains separate data accumulators for file and online modes -- switching modes does not discard data from the other mode. Use "Clear All" in the UI to reset the active mode's data.

• Loading a file switches to file mode
• The "Go Online" button in the web UI (or --et flag) switches to online mode
• The toggle button appears when both capabilities are available (compiled with WITH_ET)

Test with et_feeder:

et_start -f /tmp/test_et -s 100000 -n 500
./bin/prad2_server --et -D ../database/prad1/prad_daq_config.json -c ../database/prad1/prad_config.json
./bin/et_feeder prad.evio -f /tmp/test_et -i 50 -n 5000

Remote access (JLab ifarm)

To run the server on a JLab ifarm node and view in your local browser:

1. Start the server on ifarm (pick a port, e.g. 5678):

ssh username@ifarm2402
cd /path/to/prad2evviewer/build
./bin/prad2_server data.evio -H -p 5678

2. SSH tunnel from your local machine:

ssh -L 5678:ifarm2402:5678 -J username@scilogin.jlab.org username@ifarm2402

3. Open in your local browser:

http://localhost:5678

This also works for online monitoring -- start prad2_server --et -p 5678 on the ifarm node where the ET system is accessible.

Qt Standalone Viewer (optional)

Build with -DBUILD_GUI=ON (uses Qt6 WebEngine by default, falls back to Qt5 if Qt6 is not found).

prad2evviewer embeds the server and web frontend in a native Qt window. No separate server process needed -- updates to the web frontend or server API are automatically reflected.

prad2evviewer                           # empty, use File > Open
prad2evviewer data.evio -H              # open file with histograms
prad2evviewer -d /data/stage6           # enable file browser

Features: native file dialogs (File > Open), drag-and-drop .evio files, View > Go Online (if compiled with ET), status bar with loading progress.

prad2_client is a thin Qt WebEngine wrapper that connects to a remote prad2_server instance:

prad2_client                            # connect to localhost:5051
prad2_client -H clonpc19 -p 8080       # connect to remote server

Tools

See test/README.md (diagnostic: evio_dump, gem_dump, ped_calc, livetime, ts_dump) and analysis/README.md (ROOT replay and physics analysis).

Python utilities: scripts/README.md (HyCal scaler map, pedestal monitor, trigger mask editor, GEM visualization).

Installation

cmake -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/opt/prad2
cmake --build build -j$(nproc)
cmake --install build

Set up the environment (sets PATH, LD_LIBRARY_PATH, PRAD2_DATABASE_DIR, PRAD2_RESOURCE_DIR):

source /opt/prad2/bin/setup.sh    # bash/zsh
source /opt/prad2/bin/setup.csh   # csh/tcsh

Configuration

database/config.json -- main config for the server (waveform, clustering, LMS, EPICS, elog, online/ET, color ranges).

PRad support: use -D database/prad1/prad_daq_config.json with the server.

Project Structure

prad2dec/           libprad2dec — EVIO/ET reader, FADC250/SSP/ADC1881M decoders
prad2det/           libprad2det — HyCal/GEM clustering and reconstruction
src/                Server, Qt GUI, data source layer
resources/          Web frontend (HTML/CSS/JS)
database/           DAQ config, channel maps, calibration constants
test/               Diagnostic CLI tools
analysis/           ROOT-based replay and physics analysis (optional)
calibration/        HyCal calibration scan tools
scripts/            Python monitoring and visualization utilities
docs/               ROL references, API documentation

Contributors

Chao Peng -- Argonne National Laboratory
Yuan Li -- Shandong University
Mingyu Li -- Shandong University