T5 detector analysis

This project reconstructs T5 detector hits from WCTE input ROOT files and writes a simplified per-event ROOT tree for downstream analysis.

Dependencies

The code is built against ROOT 6 (the Makefile uses root-config).

Typical setup:

• ROOT 6.x
• C++ compiler with C++17 support
• GNU Make

Build

From the project root:

make

This produces the executable analyze_T5.

Usage

The current executable accepts the following command-line options:

./analyze_T5 -r <run_number> -i <input_file.root> [-o <output_dir>] [-d]

Options:

• -r <run_number>: required run number used for the analysis metadata.
• -i <input_file.root>: input ROOT file to analyze. You can pass this option multiple times.
• -o <output_dir>: output directory prefix used to write one reconstructed file per input file.
• -d: enable debug mode (currently limits the event loop to the first 5000 entries).

Example:

./analyze_T5 -r 1361 -i /path/to/run_1361.root -o output/

The program recognizes the following input trees:

• ProcessedWaveforms
• WCTEReadoutWindows

If neither tree is found, the program stops with an error.

What the program does

For each input file, the analysis:

1. Opens the input ROOT file.
2. Detects the appropriate TTree.
3. Reconstructs T5 hits using the T5 SiPM timing information.
4. Writes a new ROOT file containing a simplified event tree.

Output tree structure

The output ROOT file contains one tree named T5_Events with the following branches:

Branch name	Type	Description
event_nr	Int_t	Event number from the input tree
T5_hit_bitmask	Int_t	A bitmask
T5_n_main_bunch_particles	Int_t	Number of reconstructed main-bunch hits written for this event
T5_main_hit_time	Double_t	Time of the primary reconstructed hit
T5_main_hit_charge	Double_t	Charge of the primary reconstructed hit
T5_main_hit_pos_x	Double_t	Reconstructed x position of the primary hit [mm]
T5_main_hit_pos_y	Double_t	Reconstructed y position of the primary hit [mm]
T5_main_hit_pos_x_error	Double_t	Uncertainty of the reconstructed x position of the primary hit [mm]
T5_main_hit_pos_y_error	Double_t	Uncertainty of the reconstructed y position of the primary hit [mm]
T5_all_hits_pos_x	vector<double>	x positions of all reconstructed hits in an event
T5_all_hits_pos_y	vector<double>	y positions of all reconstructed hits in an event
T5_all_hits_pos_x_error	vector<double>	x positions of all reconstructed hits in an event
T5_all_hits_pos_y_error	vector<double>	y positions of all reconstructed hits in an event
T5_all_hits_time	vector<double>	Times of all reconstructed hits in an event
T5_all_hits_charge	vector<double>	Charges of all reconstructed hits in an event (sum of individual SiPM charges)

T5 hit bitmask

The output file has a T5 hit bitmask variable, that describes the error states that occured in the event. It can have the following values:

• 0 -- The event is clean, has one main hit reconstructed in the T5 detector bounds (or is within uncertainty), there are no additional hits in the main bunch of particles
• 1 -- The event is empty -- there was no hit in the main bunch of particles
• 2 -- The event has multiple hits in the main time window -- a 'main' hit cannot be reliably chosen
• 4 -- The event had a single hit in the main time window, but it was not successfully reconstructed within T5 bounds -- could indicate an SiPM time measurement error, or just an invalid hit.

Notes

• The program currently writes one output file per input file, using the input file basename with _T5.root appended.
• The output directory path passed to -o is used as the base location for those generated files.
• The reconstruction logic is implemented mainly in return_TOF_position.cpp and uses the detector geometry constants defined in return_TOF_position.h.