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LSTClovBuilder

Overview#

The data acquired at the ILL are stored in the LST format. These raw data are:

  • Not time-aligned
  • Not time-sorted
  • Not calibrated

The goal of the LSTClovBuilder is to pre-process these data before calibration. Specifically, the program:

  1. Reads the LST data
  2. Sorts and aligns the events in time
  3. Groups them into Clover events within defined time windows
  4. Writes the result to disk in binary format, compressed using LZ4 (if available on the system)

Configuration File: LSTClovBuilder.conf#

Parameters:

LUT_FILE                Path to the Look-Up Table (LUT)
RawDataDir              Path to the input directory containing raw LST files
OutputDir               Path to the directory for output binary files
Nloops                  Number of processing loops (for debugging); 0 means process the whole file
DTClover                Time window (in ns) to group Ge detectors from the same Clover
DTAC(min,max)           Time window (in ns) to search for BGO detectors (before and after the Ge event)
TimeAlignmentWindow     Time window (in ns) for time alignment plots
TimeBinning             Time precision of the clock (in ns)
IdRef                   Id taken as reference for the time difference calculations
PlotM                   Clover multiplicities to be plotted (e.g., 1,2,3,4)

Here is an example of LSTClovBuilder.conf file:

###################
### Input Files ###
###################

LUT_FILE       ./InputPars/LUTFiles/LUT_234.txt
RawDataDir     /net/serdon/illdata/234/fipps/internalUse/rawdata/
OutputDir       ./LSTSort

##################
### Parameters ###
##################

# number of loops (4096 evts) to process (0 means all)
NLoops 0

# Time used to build a clover event (AC and Ge dets needs to be in this time window)
DTClover 280

# Time window to consider an AC as a Clover rejection (must be within the DTClover window)
DTAC -250 150

# Time window taken to plot the TS diff related to Id0
TimeAlignmentWindow 5000

idref 32

TimeBinning 4

# Clover multiplicity plots (1,2,3,4)
PlotM 1,2

Clover Event Definition#

A Clover event refers to:

  • IFIN Clovers: 4 Germanium (Ge) detectors + 1 BGO
  • FIPPS Clovers: 4 Ge detectors + 3 BGO (Back, Front, Side)

When reading LST raw data, as soon as a Ge detector event is found, the program looks within DTClover ns to find other Ge detectors from the same Clover. It also searches for BGO events within the interval [DTAC_min, DTAC_max] relative to the Ge event.

Ancillary Detectors#

Ancillary detectors (such as the fission TAG) are automatically extracted and written in the output.

Usage#

To display usage information, run:

LSTClovBuilder

Time Alignment and Offset Correction#

Before saving, the program checks time alignment. If a channel has a time shift greater than 20 ns, a warning is issued.

To calculate and correct time offsets, use the CalcTimeOffset program:

CalcTimeOffset FileName [Options]
  • FileName is a ROOT file produced by LSTClovBuilder.
  • By default, the program analyzes raw timing and suggests offset values for the LUT file.
  • Use the -align option to inspect already aligned data.