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| Code Block |
|---|
def peakIsSelected() :
"""Apply peak selection criteria to each peak from file
"""
amax, atot, npix, x, y, r, phi = sp.amax, sp.atot, sp.npix, sp.x, sp.y, sp.r, sp.phi
if amax<150 : return False
if atot<2500 : return False
if npix<30 : return False
if r<434 : return False
if r>444 : return False
if phi<150 and phi>-150 : return False
return True |
Few sets of parameters listed in table were tested in order to justify selection parameters.
| Parameter | Sel.1 (rpeak5) | Sel.2 (rpeak7) | Sel.3 (rpeak3) |
|---|---|---|---|
in module NDArrDropletFinder:Arc | |||
threshold_low | 10 | 10 | 10 |
threshold_high | 100 | 100 | 150 |
peak_radius | 5 | 7 | 3 |
| in method peaks_filter(...) | |||
atot_thr | 2000 | 2000 | 2000 |
npix_thr | 20 | 30 | 20 |
npeaks_min | 1 | 1 | 1 |
npeaks_max | 10 | 20 | 10 |
Save selected peaks in file | |||
Process peaks from file | |||
amax | 150 | 150 | 150 |
atot | 2500 | 2500 | 2500 |
npix | 3020 | 40 | 20 |
rmin | 434 | 434 | 434 |
| rmax | 444 | 444 | 444 |
phi | <-150 & >150 | <-150 & >150 | <-150 & >150 |
Sel.1 (rpeak=5):
Sel.2 (rpeak=7):
Sel.3 (rpeak=3):
Plots for selection parameters
Distribution for selection parameters are shown below. The 1st group of plots is accumulated for all peaks saved in the file with list of peaks:
- phi - azimuths angle [degree] of the peak, evaluated as
atan2(y,x) - Amax - maximal pixel intensity [ADU]
- Atot - total peak intensity [ADU] for all pixels at the distance in x and y less or equal than
peak_radius(peak region) - Npix - number of pixels in the peak region with intensity above
threshold_low - r - peak radius, evaluated as sqrt(x*x + y*y)
- Npeaks - number of peaks in the arc region after peak-finder after
Two other plots were accumulated after method peakIsSelected() is applied
- Npeaks selected - number of peaks in the event
- Distance - between two peaks [pixels] in the event which has two selected peaks only
Sel.1 (rpeak=5):
These distributions were obtained for "reasonable-by-eye" selection criteria. Now the question is how optimal the selection parameters are?
Sel.2 (rpeak=7):
These plots look noisy, because it was allowed to save up to 20 peaks in the event.
Sel.3 (rpeak=3):
Tight parameters in this case reduce a number of signal events in the Distance distribution.
Optimal parameters
- peak_radius = 3, 5, 7 - or peak region sixe 7x7, 11x11, 15x15, respectively does not show significant influence on figure of merit (FOM) distance distribution. Keep 5 as golden-medium.
- amax and atot show significant increase in number of peaks for <150 and <2500, respectively. These selection criteria do not decrease a signal peak in FOM. To be safe we may still pre-select peaks with amax<100 and atot<2000 and then apply tight selection later.
npix -it is safe to require >20 or >30.
- r - chosen range 434 ≤ r ≤ 444 looks optimal
- npeaks_max is less than 6 after selection. It looks safe to constrain npeaks_max = 10. Used 20 adds too much noise.
So far original Selection 1 looks optimal.
References
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