1. The MAGIC Telescope MAGIC
International School of Cosmic Ray Astrophysics
Erice, July 2004
MAGIC
- talks in this session -
Overview - F.Goebel
Selected physics topics
Pulsars - R. de los Reyes
AGNs - R. Firpo
Microquasars - N. Sidro
GRBs - S. Mizobuchi
First Analysis
Analysis method - D. Mazin
First results - E. Aliu
Florian Goebel
Max-Planck-Institut für Physik (Werner-Heisenberg-Institut)
München
for the
MAGIC collaboration
Parlero’ telescopio MAGIC come esempio di “ground based experiment” per la gamma-astronomia.
Da quando fu osservata la prima sorgente nel 1989 (wipple) i Ttelescopi cherenkov hanno raffinato tecnologie e metodologie. Ora gli IACT sono un maturo strumento di misura e osservazione per l’astronomia gamma delle alte energie
Siamo giunti alla realizzazione di telescopi cherenkov di seconda generazione. Magic tra questi sara’ quello con la piu’ bassa soglia in energia
Esistono altri progetti di esperimento “ground based” non imaging cherenkov telescopes come solar array (celeste) o rivelatori di particelle in alta quota (ARGO) ma, almenno finora, non hanno dimostrato di avere un ottimale strategia di reiezione del fondo.
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

2. Outline - MAGIC overview
The MAGIC Telescope
The aim for low energy threshold (the physics case)
The key elements of the MAGIC telescope
Outlook
Nella prima parte del talk illustrero la tecnica IACT riassumendo le pricipali peculiuarità
Di seguito’ parlero del telescopio MAGIC, della collaborazione e dello stato di avanzamento della realizzazione dello strumento
Passero’ dunque ad illustrare gli obiettivi sceintifici di MAGIC
Infine le conclusioni
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

3. The MAGIC Collaboration
Major Atmospheric Gamma-Ray Imaging Cherenkov Telescope
Barcelona IFAE, Barcelona UAB, Crimean Observatory, U.C. Davis, U. Lodz, UCM Madrid, INR Moscow, MPI München, INFN/ U. Padua, INFN/ U. Siena, HU. Berlin, Tuorla Observatory, Yerevan Phys. Institute, INFN/ U. Udine, U. Würzburg, ETH Zürich
International collaboration of
~ 100 physicists
16 institutes
11 countries
Il mio talk vertirà sul telescopio magic come esempio di “ground based sxperiment” di seconda generazione
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

4. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
The MAGIC telescope
Largest Imaging Air Cherenkov Telescope (17 m mirror dish)
Located on Canary Island La Palma 2200 m asl)
Lowest energy threshold ever obtained with a Cherenkov telescope
Aim: detect –ray sources in the unexplored energy range: 30 (10)-> 300 GeV
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

5. Imaging Air Cherenkov Telescopes
Gamma
ray
Cherenkov light Image of particle shower in telescope camera
~ 10 km
Particle
shower
~ 1o
Cherenkov light
~ 120 m
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

6. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
Standard Analysis
gamma shower
Shower reconstruction
and background rejection
based on image shape
analysis
Hillas parameters:
Length, width, distance,
alpha
raw image
cleaned image
hadron shower (background)
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

7. First source observations
Mkn 421 (AGN)
February 2004
(in flaring state)
Source position
Alpha distribution
1200 excess events
800 background events
preliminary
100 minutes observation
=> Significance: 23 sigma
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

8. The unexplored spectrum gap
Satellites give nice crowded picture of –ray energies up to 10 GeV.
Effective area < 1 m2
Ground-based experiments show very few sources with energies > ~300 GeV.
Effective area > 104 m2
Something must happen in the gap, and it’s interesting enough to have an instrument to measure in it.
Also to confirm some of the EGRET catalogue sources at higher energies.
And also to cross check the energy calibration and measurements between satellites and ground based experiments.
Close gap with MAGIC
expect discovery of many
new sources
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

9. The MAGIC Physics Program
Cosmological g-Ray Horizon
AGNs
Pulsars
Origin of Cosmic Rays
Tests of Quantum Gravity effects
SNRs
Cold Dark Matter
GRBs
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

10. Absorption of extragalactic  - rays
-rays travelling cosmological distances interact with the Extragalactic Background Light (EBL)
For IACTs energies (10 GeV-10 TeV), the interaction takes place with infrared ’s (0.01 eV-3 eV, 100 m-0.5 m).
MAGIC
EBL
Attenuated flux is function of g-energy and source distance (redshift z).
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

11. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
Gamma Ray Horizon
The EBL absorption limits the maximum observable distance of g-ray sources.
Gamma Ray Horizon
A lower energy thresholds allows a deeper look into the universe
MAGIC phase I
MAGIC phase II
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

12. Measurement of the IR background
IR background light is result of history of the universe (Star formation, Radiation of stars, Absorption and reemission by ISM)
Mkn 501 (z=0.034)
By measuring AGN spectra up to z=1, MAGIC can help determining the IR background
Absorption leads to cutoff in AGN spectrum
Need several sources similar z) to disentangle source intrinsic effects.
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

13. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
Pulsars
7 -ray pulsars seen by EGRET (E < 10 GeV)
Only upper limits from present IACTs for pulsed emission (spectral cut-off)
Where do g-rays come from? Outer gap or polar cap?
30 – 100 GeV decisive energy range
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

14. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
Gamma Ray Bursts
Origin and acceleration mechanism not yet fully understood.
Do GRBs have E > 10 GeV counterparts?
GRBs are short (10 – 100 sec)
=> Need fast repositioning after GRB alert
If GRB origin very far
=> High energy -rays will be absorbed by EBL
=> Need low energy threshold
MAGIC can observe 1-2 GRB/year
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

15. Search for Dark Matter Particles
Neutralino (lightest SUSY particle) is attractive Cold Dark Matter candidate
g-flux from c annihilations:
CDM density:
g-ray flux ~ r2 => search for CDM clumps
observe: galactic center (high diffuse g background), dwarf spheroidal and nearby galaxies, globular clusters
g-line Eg = mc
g-line Eg = mc- mZ2/4 mc
g continuum
Particle physics:
g-continuum dominates
g-lines suppressed
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

16. Key Elements of the MAGIC Telescope
17 m diameter reflecting surface (240 m2 )
Light weight
Carbon fiber
Structure
for fast
repositioning
Active mirror control
Diamond milled aluminum mirrors
3.5o FOV camera 577 high QE PMTs
Analog signal transport via optical fibers
2-level trigger system & 300 MHz FADC system
IPE CE
NET
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

17. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
The Reflector
overall reflector:
parabolic (f/1), isochronous,
maintain time structure of Cherenkov light flashes (~2 nsec)
better bkg light rejection
~950 spherical mirror elements
49.5 x 49.5 cm2
All-aluminum, quartz coated, diamond milled, internal heating
>85% reflectivity ( nm)
4 mirrors mounted on 1 panel
mirror spot (after pre-alignment): d90%~1cm (pixelinner d=3cm)
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

18. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
The Frame
carbon fiber structure
lightweight dish & mirrors: 20 tons telescope: 65 tons
Stiff
allows fast slewing time (180º in both axes in 22s)
Fast follow-up of a Gamma Ray Burst
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice

19. The Active Mirror Control
PC controlled motors allow remote refocusing of all mirror panels anytime
Correct for small deformations of telescope structure
Panel orientation measured with laser beam
Achievable Point Spread Function: R80 ~ 15mm  0.05°  0.9 mrad
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

20. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
The Camera
Matrix of 577 PMTs
Field of View: 3.50
Inner part: pixel
Outer part: 0.20 pixel
Plate of Winston cones
 Active camera area 98%
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

21. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
High QE PMTs
Pixels:
6 stage PMTs
ET 9116A (1”)
ET 9117A (1,5”)
Quantum Efficiency increased up to 30 % with diffuse scattering coating
extended UV sensitivity by with wavelength shifter coating
239 m2 -> 284 m2 !!!
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

22. F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
The Signal Processing
Analog signals transmitted over 162 m long optical fiber:
Signal still short
Cable weight, noise immune.
Max trig rate ~ 1 kHz data rate => 20 MB/s => 800 GB/night
2 level trigger
Fast (5 nsec) next neighbor logic
Slower (150 nsec) topological pattern recognition
Stretch pulse to 6 nsec
Split to high & low gain (dynamic range > 1000)
Digitize with 300 MSamples/s 8 bit FlashADCs (testing 2GS/s)
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice
M. Mariotti Padova

23. Future of MAGIC observatory
MAGIC I
Second MAGIC type telescope under construction (more observation time, background rejection & better event reconstruction in coincidence mode)
Plans for 34 m telescope for gamma astronomy down to E = 5 GeV
ECO1000
F. Goebel, MPI München, 2-13 July 2004, ISCRA, Erice