1. Daniel Mazin and Nadia Tonello Max-Planck-Institut für Physik München
Analysis chain for
MAGIC Telescope data
Daniel Mazin and Nadia Tonello
Max-Planck-Institut für Physik München
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

2. Technique Imaging Air Cherenkov Telescope Cherenkov light
Image of particle shower in telescope camera:
Atmosphere
Particle
shower
~ 10 km
~ 1o
Cherenkov light
~ 120 m
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

3. Calibration Calibration runs: same number of photons in all PMs
MAGIC Camera
Calibration
Calibration runs:
same number of photons in all PMs
Calibration methods:
Ffactor method (relative calibration)
Muons (absolute calibration)
Blind-pixel method …to be installed
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

4. Charge extraction 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
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

5. Calibration Relative pixel to pixel calibration Calibration runs:
MAGIC Camera
Calibration
Calibration runs:
Output of PMs not uniform
After calibration:
All PMs show the same photon density
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

6. Calibration Nphel = (Q2/ s2Q) F2 Q Mean charge for pixel
absolute calibration in number of photoelectrons
Calibration
Mean number of photoelectrons
Nphel = (Q2/ s2Q) F2
where F2= (measured)
Q Mean charge for pixel
from a calibration run
s2Q variance from the charge
distributions of the pixel
F2 correction for intrinsic noise
of the photomultiplier
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

7. Image cleaning Calibrated charge Arrival time Signal/Noise
Shower image
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

8. Hillas Parameters muon shower gamma shower hadron shower (background)
LENGTH, WIDTH, DISTANCE,
SIZE, ALPHA, …
Shower reconstruction and background rejection
based on image shape analysis
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

9. -hadron separation PRELIMINARY MC-
-hadron separation by using cuts in:
LENGTH, WIDTH,
DISTANCE, etc
MC-
Black: data
MC-hadrons
Since all these parameters are not independent, we use
Dynamical cuts
WIDTH
PRELIMINARY
MC-
Black: data
MC-hadrons
Remark: cuts are optimized using ON and OFF data.
MC data are not used for optimization due to ongoing tuning of MC
LENGTH
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

10. -hadron separation SuperCuts hadrons WIDTH gammas SIZE
Current analysis
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

11. -hadron separation Mean Scaled Hillas
For each SIZE bin Mean value of LENGTH is calculated
(red curve). Black curves – optimized cuts on LENGTH.
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

12. Alpha plot D.Mazin, N.Tonello ISCRA 14th Course
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

13. Preliminary results by using anode currents:
Source Position
For determination of the source dependant parameters:
SOURCE POSITION is needed
First step: pointing and tracking precision
Star guider (online correction, being commissioned)
Use anode currents to determine star positions (offline) H
Mrk 421
Crab Nebula
3C279
Triangulation
Second step: determine source position (known coordinates)
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
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

14. False Source Method If the source position unknown:
For each position in FoV the source dependant parameters are calculated
The same for the OFF data
For all positions in FoV the alpha plot is produced and Nexcess / significance are calculated
~5min of Mrk421 data
~5min of Mrk421 data
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

15. OUTLOOK Other analysis techniques: Further analysis steps:
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)
Further analysis steps:
Lightcurve (gamma-flux as a function of time)
Energy spectrum
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004

16. OUTLOOK NEXT TALK: presented by Ester Aliu MAGIC first results
D.Mazin, N.Tonello
MPI for Physics, Munich
ISCRA 14th Course
Erice, 2nd-13th July 2004