Preliminary estimate of performances using a 2-

telescope system

Preliminary estimate of performances using a 2-

telescope system

CTA meetingCTA meeting

E. CarmonaE. Carmona

on behalf of the MAGIC on behalf of the MAGIC collaborationcollaboration

Berlin, 5 May 2006Berlin, 5 May 2006

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Objective Objective • Estimate performances of a next generation Estimate performances of a next generation

CTA, optimized for low energy CTA, optimized for low energy ray showers ray showers

• Assuming current technology, but with:Assuming current technology, but with: Large light collection area (Ø 23 m)Large light collection area (Ø 23 m) High QE detectors (Si PMs)High QE detectors (Si PMs)

• Simulate a 2 telescope system. Later, scale the Simulate a 2 telescope system. Later, scale the results by the number of pairsresults by the number of pairs

• Done by using MAGIC-II Monte-Carlo data and Done by using MAGIC-II Monte-Carlo data and analysis toolsanalysis tools DATA:DATA: same same reflector filesreflector files used for MAGIC II studies used for MAGIC II studies

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MAGIC IIMAGIC II• Second Second ØØ17 m telescope 17 m telescope

close to MAGIC I (~85 m)close to MAGIC I (~85 m)

• MC study showed a factor MC study showed a factor ~2 improvement in ~2 improvement in sensitivity when going sensitivity when going from 1 to 2 telescopefrom 1 to 2 telescope

MAGIC-IMAGIC-I MAGIC-IIMAGIC-II

• Distance between telescopes Distance between telescopes not criticalnot critical

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Parameters of the simulationParameters of the simulation• Simulation parameters:Simulation parameters:

ØØmirrormirror = 23 m (estimated from 17 m) = 23 m (estimated from 17 m) f/D = 1 f/D = 1 (FIXED)(FIXED) Improved Reflectivity: 85% - 95% Improved Reflectivity: 85% - 95% Camera FoV up to 4.7º Camera FoV up to 4.7º Camera with different number of pixels Camera with different number of pixels Camera pixels: SiPM, 50% QE, 10% gain fluctuationsCamera pixels: SiPM, 50% QE, 10% gain fluctuations 3NN trigger3NN trigger FADC 2 Gs/sFADC 2 Gs/s Distance between telescopes: 90 m Distance between telescopes: 90 m (FIXED)(FIXED) Events analysed only in stereo modeEvents analysed only in stereo mode

• Aperture (AAperture (Amirrormirror×Ref×QE) ×Ref×QE) ~168 m~168 m22 – MAGIC I ~26 m – MAGIC I ~26 m22

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Simulation and analysis chainSimulation and analysis chain• and proton showers produced with Corsika and proton showers produced with Corsika

(v. 6.019)(v. 6.019)• Photons on ground reflected with Photons on ground reflected with ReflectorReflector

(atmospheric absorption) program: (atmospheric absorption) program: Reflector Reflector filesfiles

• Camera simulation:Camera simulation: New pixel response (SiPM)New pixel response (SiPM) Different number of pixelsDifferent number of pixels

• CalibrationCalibration• Hillas parameters from camera output Hillas parameters from camera output • / hadron separation using / hadron separation using Random ForestRandom Forest

MAGICII

CTA

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MC eventsMC events From 10 GeV to 10 TeVFrom 10 GeV to 10 TeV

— 22×10×1066 gammas, 20 files gammas, 20 files

From 100 GeV to 10 TeVFrom 100 GeV to 10 TeV— ~1.4~1.4×10×1077 protons, 1411 files protons, 1411 files

Low energy proton production, Low energy proton production, 50 GeV – 100 GeV 50 GeV – 100 GeV

— ~3.5×10~3.5×1077 protons, 3450 files protons, 3450 files

Very low energy proton production, Very low energy proton production, 30 GeV – 50 GeV30 GeV – 50 GeV

— ~1×10~1×1077 protons, 1014 files protons, 1014 files

•Gammas

•Protons

• Estimate of other backgrounds added later: 50% proton rate increased (accounts for other hadrons) Rough estimate of e flux (extrapolated from results)

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Camera simulationCamera simulation• Hexagonal camera and pixelsHexagonal camera and pixels• f/D = 1f/D = 1• Example:Example:

3571 pixels, 3571 pixels, 0.067º0.067º 4.65º FoV4.65º FoV 3.30º Trigger3.30º Trigger

• Different cameras have been simulated:Different cameras have been simulated: 3571 Pixels, 0.067º (4.65º FoV, 3.3º trigger)3571 Pixels, 0.067º (4.65º FoV, 3.3º trigger) 3571 Pixels, optimistic optics3571 Pixels, optimistic optics 1657 pixels, 0.067º (3.3º FoV, 3.3º trigger)1657 pixels, 0.067º (3.3º FoV, 3.3º trigger) 1519 Pixels, 0.10º (4.54º FoV, 3.2º trigger)1519 Pixels, 0.10º (4.54º FoV, 3.2º trigger) 721 Pixels, 0.10º (3.2º FoV, 3.2º trigger)721 Pixels, 0.10º (3.2º FoV, 3.2º trigger)

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imagesimagesNO NOISENO NOISE

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imagesimages

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Energy thresholdEnergy threshold• High photon collection efficiency allows to go High photon collection efficiency allows to go

down in energydown in energy

Number of eventsafter computing Hillas parameters

No /h separation

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/h separation/h separation• Is done with Random ForestIs done with Random Forest• Mean scaled width and length are useful Mean scaled width and length are useful

parameters for separationparameters for separation

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/h separation/h separation• /h separation improves with size/h separation improves with size

3571 pixels50<size<150

3571 pixels150<size<300

3571 pixles300<size<600

3571 pixels600<size<1000

3571 pixels1000<size<2000

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Effective area for gammasEffective area for gammas3571 pixels, 4.7º3571 pixels, 4.7º 1519 pixels, 4.7º1519 pixels, 4.7º

1657 pixels, 3.3º1657 pixels, 3.3º 721 pixels, 3.3º721 pixels, 3.3º

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Angular ResolutionAngular Resolution (( containing 50% containing 50% in in 22 plot plot))3571 pixels, 4.7º3571 pixels, 4.7º 1519 pixels, 4.7º1519 pixels, 4.7º

1657 pixels, 3.3º1657 pixels, 3.3º 721 pixels, 3.3º721 pixels, 3.3º

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Flux sensitivityFlux sensitivity3571 pixels, 4.7º3571 pixels, 4.7º 1519 pixels, 4.7º1519 pixels, 4.7º

1657 pixels, 3.3º1657 pixels, 3.3º 721 pixels, 3.3º721 pixels, 3.3º

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Improved spread functionImproved spread function• Optimistic optical PSF Optimistic optical PSF

of photonsof photons

• Differences only Differences only important for low Eimportant for low E

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Electron estimateElectron estimate• Electron flux estimated from Electron flux estimated from showers from 10 showers from 10

to 100 GeV. Assuming:to 100 GeV. Assuming: Electron flux: Electron flux: 1.21.2×10×10-3-3 E E-1-1 (1 + (E/5 GeV) (1 + (E/5 GeV)2.32.3))-1-1 cm cm-2-2 sr sr-1-1 s s-1-1 GeV GeV-1-1

Hadronness of electronsHadronness of electronsequal to equal to ss

Flat distributionFlat distribution

in in 22

• Effect is small, Effect is small,

because of because of 22 cut cut

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CT array flux limitsCT array flux limits

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Conclusions Conclusions • 2-telescope with high light collection efficiency (mirror 2-telescope with high light collection efficiency (mirror

area and QE) has been studiedarea and QE) has been studied

• Simple analysis without any improvement can lower the Simple analysis without any improvement can lower the energy threshold of a CT to ~10 GeV (lower?)energy threshold of a CT to ~10 GeV (lower?)

• Pixel size has a small effect at low energiesPixel size has a small effect at low energies

• Smaller pixels allow an improvement in angular Smaller pixels allow an improvement in angular resolution and flux sensitivityresolution and flux sensitivity

• Improving psf of photons before camera (better optics) Improving psf of photons before camera (better optics) might be important to improve performance at low might be important to improve performance at low energiesenergies

• Electron flux not a problem, efficiently reduced with Electron flux not a problem, efficiently reduced with 2 2

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To be doneTo be done• Study energy resolutionStudy energy resolution

• Use time in the analysisUse time in the analysis

• Use 3 or more telescopes in coincidenceUse 3 or more telescopes in coincidence

• Change geometry of the arrayChange geometry of the array

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SiPMsSiPMs• Flat 50% QE betweenFlat 50% QE between

300 – 600 nm 300 – 600 nm

• Gain fluctuations of Gain fluctuations of 10% introduce in camera10% introduce in camera

• NSB factor for SiPMNSB factor for SiPM

2.4 (w.r.t. EMI 2.4 (w.r.t. EMI coated)coated)

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Proton imagesProton images

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Camera OutputCamera Output

• Full simulation of camera performed. Output is data in Full simulation of camera performed. Output is data in the RAW data format of MAGICthe RAW data format of MAGIC

• Size of the raw output files and simulation time is a Size of the raw output files and simulation time is a problem:problem: Gammas Gammas → → 21.8 Gb, ~25 hours for 1021.8 Gb, ~25 hours for 1055 showers showers Protons Protons →→ 540 Mb, ~1 hours for 10 540 Mb, ~1 hours for 1044 showers showers Protons low EProtons low E → → 96 Mb, ~20 minutes for 1096 Mb, ~20 minutes for 1044 showers showers Protons very low E → Protons very low E → 210 Mb, ~100 minutes for 10210 Mb, ~100 minutes for 1055 showers showers

• The whole simulation-analysis process has been The whole simulation-analysis process has been automatizedautomatized

• Only a small part of the data is finally storedOnly a small part of the data is finally stored

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/h separation/h separation