NAME

ixpeevtrecon -- Reconstruct events of IXPE event files

USAGE

ixpeevtrecon infile outfile [parameter = < value >]

DESCRIPTION

'ixpeevtrecon' reconstructs the events of IXPE event files starting from raw data in FITS format. The first step of the track reconstruction is a fixed-threshold zero suppression, where pixels whose pedestal-subtracted signal is below (or equal to the) threshold are masked and ignored in all the following steps. After the zero suppression, a clustering stage is executed, with the aim of separating the physical photoelectron track from the residual noise pixels. The clustering stage is based on the DBSCAN algorithm and allows to identify the main track. The event reconstruction then includes a first moment analysis around the barycenter to identify the principal axis of the two-dimensional charge distribution. The results of this 1st pass of the moment analysis are written in the columns 'DETPHI1', 'BARX' and 'BARY'. As most of the energy is deposited in the Bragg peak at the end of the photoelectron path, the longitudinal charge profile can be used to discriminate the track head from its tail and estimate the photon absorption point. Finally, a second moment analysis is run, deweighting the pixels close to the end of the track, to get a more accurate estimate of the photoelectron emission direction. The columns calculated by this 2nd step of the moment analysis are 'DETPHI2', 'ABSX' and 'ABSY'.

The reconstruction algorithm provides estimates of the event energy, photon absorption point, photoelectron direction emission, as well as a series of topological variables characterizing both the region of interest and the physical track, e.g., the size, the longitudinal and lateral extension and the charge asymmetry.

For more details on the standard analysis of track images see Bellazzini et al. (2003), SPIE, Vol. 4843, p. 383-393.

PARAMETERS

infile [file name]
Name of the input FITS Event File.

outfile [file name]
Name of the output FITS Event File.

(pixeqfile=CALDB) [filename]
Name of the input pixel equalization calibration file or NONE. If set to CALDB (default), use the file in the Calibration Database.

(xpolpedestalfile=NONE) [filename]
Name of the XPOL pedestals calibration file or NONE. If set to CALDB, use the file in the Calibration Database.

(xpolnoisefile=NONE) [filename]
Name of the XPOL noise calibration file or NONE. If set to CALDB, use the file in the Calibration Database.

(CoherentNoiseOffset=CALDB) [filename]
Name of the input coherent column offset calibration file. If set to CALDB (default), use the file in the Calibration Database.

(TriggerMiniclusterOffset=CALDB) [filename]
Name of the input trigger minicluster offset calibration file. If set to CALDB (default), use the file in the Calibration Database.

(minTrackHits=6) [integer]
Minimun number of events to process for each input file.

(minDensityPoints=4) [integer]
Minimun number of neighbour pixels over threshold.

(threshold=20) [integer]
Zero-suppression threshold for the clustering stage.

(moma1Threshold=36.) [real]
Threshold for the first pass moments analysis.

(moma2Threshold=36.) [real]
Threshold for the second pass moments analysis.

(dmin=1.5) [real]
Internal radius of the horseshoe search region.

(dmax=3.5) [real]
External radius of the horseshoe search region

(weightScale=0.05) [real]
Scale distance, in mm, for the exponential weights used during the second step of reconstruction.

(writeTracks=no) [boolean]
Write the track in the output event file? (yes/no).

(ignoreErrorFlag=no) [boolean]
Ignore ERR_SUM column flag? (yes/no).

(firstEvent=0) [integer]
Number of initial events to be skipped.

(logFile=recon.log) [file name]
Name of event reconstruction log file.

(logTermLvl=1) [integer]
Log Terminal level (0=dbg, 1=info, 2=wrn, 3=error, 4=critical).

(logFileLvl=1) [integer]
Log File level (0=dbg, 1=info, 2=wrn, 3=error, 4=critical).

(clobber=no) [boolean]
If set to yes, overwrite the output file.

EXAMPLES

  1. Reconstruct the events for the input event file 'ixpe00000000_det1_evt1_v01.fits'. The results are written in the output event file 'ixpe00000000_det1_evt1_v01_out.fits'. 

     > ixpeevtrecon infile=ixpe00000000_det1_evt1_v01.fits outfile=ixpe00000000_det1_evt1_v01_out.fits

BUGS

SEE ALSO

LAST MODIFIED

February 2022