analysis chain for magic telescope data daniel mazin and nadia tonello max-planck-institut für...
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Analysis chain for MAGIC Telescope
data
Daniel Mazin and Nadia Tonello Max-Planck-Institut für Physik München
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
Tech
niq
ue
~ 10 km
~ 1o
Ch
eren
kov
ligh
t
~ 120 m
Particleshower
AtmosphereCherenkov light Image of particle shower in telescope camera:
Imaging AirCherenkov Telescope
Calib
rati
on
MAGIC Camera
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
Calibration runs: same number of photons in all PMs
Calibration methods: Ffactor method (relative calibration)Muons (absolute calibration)Blind-pixel method …to be installed
Charg
e
extr
act
ion
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
Extract signal from ADC data:
• signal digitized every 3.3 ns
• pedestal subtraction
• sum N-ADC slices
• N=large: collect charge in tails
• N=small: reduce
NightSkyBackground contribution
• typical value: N=4
Pulse shape after pedestal subtraction
Calib
rati
on
MAGIC Camera
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
Calibration runs: Output of PMs not uniform
After calibration: All PMs show the same photon density
Relative pixel to pixel calibration
Q Mean charge for pixel
from a calibration run 2
Q variance from the charge
distributions of the pixel
F2 correction for intrinsic noise
of the photomultiplierCalib
rati
on
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
Mean number of photoelectrons
Nphel = (Q2/ 2Q) F2
where F2= 1.335 (measured)
absolute calibration in number of photoelectrons
Image c
leanin
g
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
Calibrated charge Arrival time
Signal/Noise Shower image
Hill
as
Para
mete
rs
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
gamma shower hadron shower (background)
muon shower
Shower reconstruction and background rejection based on image shape analysis
Hillas parameters:LENGTH, WIDTH, DISTANCE,SIZE, ALPHA, …
-h
ad
ron
sep
ara
tion
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
MC-Black: dataMC-hadrons
MC-Black: dataMC-hadrons
PRELIMINARY
-hadron separation by using cuts in:
• LENGTH, WIDTH,
DISTANCE, etc
Since all these parameters are not independent, we use
Dynamical cuts
LENGTH
WIDTH
Remark: cuts are optimized using ON and OFF data.
MC data are not used for optimization due to ongoing tuning of MC
-h
ad
ron
sep
ara
tion
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
SuperCutshadrons
gammas
SIZE
WID
TH
Current analysis
-h
ad
ron
sep
ara
tion
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
Mean Scaled HillasFor each SIZE bin Mean value of LENGTH is calculated
(red curve). Black curves – optimized cuts on LENGTH.
Alp
ha p
lot
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
Sourc
e P
osi
tion
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
First step: pointing and tracking precision• Star guider (online correction, being commissioned)• Use anode currents to determine star positions (offline)
For determination of the source dependant parameters:SOURCE POSITION is needed
Preliminary results by using anode currents:
• Position with a statistical error ~0.01
• possible to detect stars until 8th magnitude in the inner pixels
• updating every 10 sec
Second step: determine source position (known coordinates)
Triangulation Crab Nebula
Mrk 421H1426+428
3C279
Fals
e S
ou
rce M
eth
od
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
If the source position unknown:
1. For each position in FoV the source dependant parameters are calculated
2. The same for the OFF data
3. For all positions in FoV the alpha plot is produced and Nexcess / significance are calculated
~5min of Mrk421 data
~5min of Mrk421 data
OU
TLO
OK
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
Other analysis techniques:
• Further optimization of gamma-hadron separation using Hillas parameters:
• Random Forest (is used)
• Neural Net (ready to be used)
• Fit the complete camera event information:
• Model Analysis (being development)
• Lightcurve (gamma-flux as a function of time)
• Energy spectrum
Further analysis steps:
OU
TLO
OK
D.Mazin, N.TonelloMPI for Physics, Munich
ISCRA 14th Course Erice, 2nd-13th July 2004
NEXT TALK:
MAGIC first results
presented by Ester Aliu