17 november 2003euso meeting: r. mirzoyan the magic telescope project razmick mirzoyan...

17 November 2003 EUSO meeting: R. Mirzoyan

The MAGIC Telescope Project

Razmick Mirzoyan

Max-Planck-Institute for PhysicsMunich, Germany

EUSO meeting


MAGIC-I: inaugurated recently, on October 10

Location: Canary island La Palma


We hope to take the 1st gamma ray data from the Crab Nebulain the coming 2 months


Dense fog (or a cloud) helps to visualize the Active MirrorControl laser pointer beams

Photo by R. Wagner


Outline

• The MAGIC Collaboration– Aiming for low

threshold – Physics goals

• The Telescope– Design overview– MAGIC Key elements

for low threshold – Status of

commissioning of the telescope elements

• Plans & Conclusions


The MAGIC project

• First presentation in 95 at the

ICRC, Rome, (Bradbury et al)

• Approval of funding only late 2000

• Start of construction in 2001

• Now commissioning

• Inauguration October 10th


Barcelona IFAE, Barcelona UAB, Crimean Observatory, U.C. Davis, U. Lodz, UCM Madrid, INR Moscow, MPI Munich, INFN/ U. Padua, INFN/ U. Siena U. Siegen, Tuorla Observatory, Yerevan Phys. Institute, INFN/U. Udine , U. Wuerzburg, ETH Zurich

The MAGIC CollaborationMMajor ajor AAtmospheric tmospheric GGamma-Ray amma-Ray IImaging maging CCherenkov herenkov

TelescopeTelescope

MAGIC is an international collaboration MAGIC is an international collaboration operatingoperating a a 17 m Cherenkov Telescope17 m Cherenkov Telescope for observation offor observation of HE cosmic HE cosmic –rays.–rays.

Main aim: to detect Main aim: to detect –ray sources–ray sources in the in the unexplored energy range: unexplored energy range: 30 30 (10)-> (10)-> 250 250 GeVGeV

MAGIC MAGIC isis a a challe challennging desiging desiggn n to to decrease thedecrease the energy thresholdenergy threshold,, by by 1)1) increasing the increasing the mirror sizemirror size 2) 2) using using improvedimproved optics, light sensors and optics, light sensors and electronicselectronics 3) 3) using advanced using advanced triggertrigger

� MAGIC shall provide the lowest MAGIC shall provide the lowest thresholdthreshold ever obtained with a ever obtained with a Cherenkov telescope !!!Cherenkov telescope !!!


The MAGIC PHYSICS Goals

AGNsAGNs

SNRsSNRsCold Dark Cold Dark

MatterMatter

PulsarsPulsarsGRBsGRBs

Tests on Tests on Quantum Quantum Gravity Gravity effectseffects

Cosmological Cosmological ray horizonray horizon

Origin of Cosmic Rays


Key elements of the MAGIC telescope

• 577 pixels enhanced QE, ~4° deg FOV camera + advanced calibration system

• 3-level advanced trigger system

• Analog optical signal transport

via 162m long fibres

• Light weight carbon fibre frame

• 17 m diameter reflecting surface (240 m2 )

• Active mirror control


Any that crosses cosmological distances through the universe interacts with the EBL

Absorption of extragalactic - rays

eeEBLHE

E 1 cos 2 mec2 2

Attenuated flux function of -energy and redshift z.

For the energy range of IACTs (10 GeV-10 TeV), the interaction takes place with the infrared (0.01 eV-3 eV, 100 m-0.4 m). Star formation,

Radiation of stars, Absorption and reemission by ISM

MAGICBy measuring the cutoffs in the spectra of AGNs, MAGIC can help in determining the IR background

EBL


This produces a reduction factor e- in the ray flux. The GRH is defined as the “z” for the observed energy “E” that fulfils:

E,z d z cdt

d z 0

z

dxx

20

2

dn , z 2xE 1 z 2 2m 2c 4

Ex 1 z 2

1, zE

Optical Depth The probability of being absorbed for HE gamma crossing the universe is the integration of the cross-section over the incident angle and along the path from its origin to the observation.

Gamma Ray Horizon (GRH)

i.e. a reduction 1/e of the flux of the extragalactic source.

Optical Depth & GRH

MAGIC phase I

MAGIC phase II


MAGIC Expected sources

MAGIC is just starting to operate, therefore it is still a mystery how many extragalactic sources we would detect. One can use the EGRET catalogue

to pick the probable source candidates.

By using 50 hours of observation time for each of these candidates,

because of high sensitivity we expect to be able to measure the GRH at different redshifts with MAGIC.


Pulsars

Where do -rays come from? Outer gap or polar cap?

Many of the ~170 EGRET unidentified sources may be pulsars.

77 -ray pulsars seen by -ray pulsars seen by EGRET. Only upper EGRET. Only upper limits from present limits from present IACTs (spectral cut-off)IACTs (spectral cut-off)

4-fold nn-logic


Gamma Ray Bursts

• Mechanism not yet fully resolved.

• MAGIC can take advantage of:

– Huge collection area

– Fast repositioning.

• Low energy threshold

Under the assumption that it is possible to extrapolate the GRB energy spectrum in the GeV region, MAGIC can observe 2-3 GRB/year

MAGIC is designed to observe MAGIC is designed to observe the prompt emission of a the prompt emission of a GRB! GRB!


Other Physics targets for MAGIC

Search for Search for neutralinoneutralino annihilation gamma-rays annihilation gamma-rays

((galactic centergalactic center, neighboring galaxies, globular clusters), neighboring galaxies, globular clusters)

Tests of possible Tests of possible Lorentz invarianceLorentz invariance violation: violation:

search for delay of HE gamma rays in rapidly search for delay of HE gamma rays in rapidly

varying phenomena at large distances (AGN varying phenomena at large distances (AGN

flares, GRBs)flares, GRBs)


c

L

E

Et

QG

Given the huge sensitivity, MAGIC Given the huge sensitivity, MAGIC can observe fast transient can observe fast transient

phenomena like phenomena like GRB and/or flare GRB and/or flare of AGNof AGN..

GeVEGeV QG1916 10104

Test of invariance of speed of light

• Quantum Gravity models predict energy dispersion of c.

• Non trivial dispersion relation where EQG appears! (1016-1019)

• Photon delay depending on energy over distance

10 s delay

Lorenz Invariance Violation

S.D. Biller et al. PhRev Let 83, 2108 (1999)

EQG > 61016 GeV


The frame• The 17m diameter f/1 telescope

frame is a lightweight carbon fiber structure (tube and knot system)

• The foundation started in September 2001 and the telescope frame was completed in Dec. 2001. The assembly of the frame took ~2 months

•


The reflector

• Tessellated surface:– ~950 mirror elements – 49.5 x 49.5 cm2 (~240 m2)– All-aluminium, quartz coated,

diamond milled, internal heating– >85% reflectivity in 300-650nm

• The overall reflector shape is parabolic (f/1), isochronous, to maintain the time structure of Cherenkov light flashes in the camera plane

– Better light of night sky rejection (less pile-up)


Optical alignmentOptical alignment

4 mirrors spots after the pre-alignment close to the virtual center of the MAGIC camera

Final spot of a panel after The precise alignment of the mirrors


The Active Mirror Control

• The panels can be oriented during the telescope operation through an Active Mirror Control system (AMC) to correct for possible deformation of the telescope structure


The alignment of the mirrors

• The alignment of the first 103 mirrors in the telescope structure has been done by using a 20 W light source at a distance of 920m

• The camera plane was moved 29 cm backward to focus the lamp light

103 spots before and after the alignment

~1 pixel


The camera

• Two sections:– Inner part: 0.100 PMTs

– Outer part: 0.200 PMTs

Plate of Winston conesPlate of Winston cones Active camera area Active camera area 95 % 95 %

includes 577 PMTsincludes 577 PMTs


The camera

Pixels:Pixels: The photocatode QE is The photocatode QE is

enhanced up to enhanced up to 30 %30 % and and extended to UV by a extended to UV by a special coating of PM special coating of PM surface with milky surface with milky wavelength shifterwavelength shifter

• Each PM is connected to Each PM is connected to an ultrafast low-noise an ultrafast low-noise transimpedance preamp.transimpedance preamp.

• 6-dynode HV system 6-dynode HV system zener stabilized with an zener stabilized with an active loadactive load

240 m2 -> 312 m2 !!!


The readoutCherenkov light pulses from air showers are typically ~ 2-5 ns long

• Pixel signals are modulating the VCSEL lasers @850 nm and thus transported over 162 m multimode optical fibres to the counting house:

– Very low dispersion

– Low weight, noise inmune.

• Sampling using 300 Msample/s FlashADCs:– /h discrimination through signal shape– LONS pick-up reduction– Event buffering, telescope system synchronization...


Trigger

Two level trigger system

The level 1 (L1) is a fast coincidence device (2-5 ns) with simple patterns (N-next-neighbour logic) on single trigger cells.Level 2 (L2) is slower (50-150 ns), and can perform a global sophisticated pattern recognition

Two level trigger system

The level 1 (L1) is a fast coincidence device (2-5 ns) with simple patterns (N-next-neighbour logic) on single trigger cells.Level 2 (L2) is slower (50-150 ns), and can perform a global sophisticated pattern recognition

DiscriminatorsL0

DiscriminatorsL0

Set the minimum number of photoelectrons per pixel to be used in the trigger

Level 2L2

Level 2L2

Perform an advanced pattern recognitionto use topological constraint: • pixel counting in a given region of the detector• mask hot spots like bright stars• rough image reconstruction, etc….

On-line event selectionTo FADC

Level 1L1

Level 1L1

Make a tight time coincidenceon simple pattern of compact images and enable L2

TWO FOLD KINDS (86) THREE FOLD KINDS (51)

FOUR FOLD KINDS (67) FIVE FOLD KINDS (106)


Trigger- 44 GeV- 44 GeVTrigger display

L2 pattern recognitionL2 pattern recognition

Off-lineOff-line

On-lineOn-line

On-line image analysis on the trigger event

Off-line analysis


The Data Acquisition System

• Needs:– 577 PMT x 1 Byte x 30 samples x 1 kHz

~ 20 MByte/s (x 11 hours )

~ 800 GB/night (longest nights in December)

• Cheap PC based solution:– Multiprocessor threaded system.– PCI FPGA based readout card & RAID0 disks system.

IPEIPEIPE

CENET

IPEIPEIPE

CENET


GRB alert from satellites: prompt follow-up

• The light weight structure and the low inertia of the structure allows a fast slewing time in such a way that the telescope will be able to perform an early follow-up of a Gamma Ray Burst

• With the motors running at 70% of full power, the telescope is able to turn 180º in both axes in less than 22s


Near Future Plans: MAGIC-I

• Winter 2003- spring 2004:

• System debugging &

• Start regular observations

• Step-by-step lowering of the threshold setting towards few 10’s of GeV


Near Future Plans: MAGIC-II Just now ordering the frame structure for the MAGIC-II telescope.The frame with understructure shall be ready in La Palma in May 2005, the 2nd Telescope to be completed near the end of 2005.

The 2nd telescope will essentially be the clone of the 1st telescope,only a few improvements will be implemented. This will save ustime and finances.


Conclusions

• So far all the new technical and technological novelties implemented in MAGIC behave as expected

• In the next few month we will make extensive tests of the apparatus with engineering and physics runs

• We are considering MAGIC as the first element of an international observatory to study the deep universe with high energy gamma rays. Construction of the 2nd telescope has already been started.

• Our proposal is to transform the MAGIC site, Roque de los Muchachos, in the “European Cherenkov Observatory” ECO

17 november 2003euso meeting: r. mirzoyan the magic telescope project razmick mirzoyan...

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