PhotoPhoto--detectors for detectors for GammaGamma--Astronomy (IACT)Astronomy (IACT)

MehrMehr LichtLicht!!

M. M. TeshimaTeshima

MaxMax--PlanckPlanck--Institute Institute ffüürr PhysikPhysik, , MMüünchennchen

MAGIC TelescopeMAGIC Telescope

MAGIC-II is under construction and will becompleted at the end of this year

Improve sensitivity by a factor of threeEffectively lower the threshold energy

New technologiesto lower the threshold energy

17m diameter world largest cherenkov tel.0.1°High resolution cameraHemispherical PMT with enhanced QEAnalogue signal fiber transmission

Current MAGIC-I Performance

Fast rotation for GRB < 40secsTrigger threshold ~50GeVSensitivity ~2.0% of Crab (50hrs)Angular resolution ~0.1 degreesEnergy Resolution 20-30%

85m

Option:Mix of telescope types

~10 central Huge telescopes

~100 Medium + Small Telescopes

CTACTA

PMTsPMTs

MAGICMAGIC--I Camera 3.5I Camera 3.5°°576pixels576pixels

394x 0.1394x 0.1ºº PMTs(1PMTs(1””), 180x 0.2 ), 180x 0.2 ºº PMTs(1.5PMTs(1.5””))

MAGICMAGIC--II Camera and pixelII Camera and pixel

PMT HV Amplifier VCSEL

HamamatsuR10408Mod SBA-PMT

~35% Q.E.

After pulse rate of large PMT After pulse rate of large PMT by Damien by Damien DornicDornic (IPN, (IPN, OrsayOrsay))

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7 7,5 8 8,5 9 9,5 10 10,5

Sensibilité de Photocathode CB (µA/lmF)

Prob

abili

té (%

)Courtesy of Damien Dornic (IPN, Orsay)

Afterpulse rate as a function of the photocathode sensitivity. The

measurements were made for 3 XP1803 (5 inches), 4 XP1806 (8”) and 2 XP1804 (10”).

High after pulse rate will makethe low trigger threshold difficult!!

Must be examined for other tubes!! Correlation between QE and after pulse rate

MAGICMAGIC--II New SBA II New SBA PMTsPMTs from from HamamatsuHamamatsu

Low after pulse rate<0.2% after pulse rate >5p.e.

Very fast ResponseFWHM =1.1 nsecRise T = 0.7 nsec

N.S.B.~100MHz After pulses ~100kHz

High Q.E. High Q.E. PMTsPMTs materials from companiesmaterials from companies

HamamatsuHamamatsu UBA MAPMTUBA MAPMT

HPDHPD

HPD R9792UHPD R9792U--40 18mm GaAsP HPD 40 18mm GaAsP HPD by MPI & by MPI & HamamatsuHamamatsu

GaAsP photocathode

R9792U-40分光感度特性(44本）

0

10

20

30

40

50

60

70

200 250 300 350 400 450 500 550 600 650 700 750 800Wavelength [nm]

QE

[%]

+ High Photoelectron collection eff.

GaAsP HPD Gains, Dynamic range and GaAsP HPD Gains, Dynamic range and time responsetime response

Electron Bombardment Gain

APD Gain and Dark current

Dynamic range, 1pe ~5000 p.e.

Time response FWHM ~2.7nsec

Comparison of after pulse rates Comparison of after pulse rates between PMT and HPDbetween PMT and HPD

At least, HPDs has different

1) High vacuum2) Ion feedback protectionhelp to reduce the after pulse rate

GaAsP HPD life timeGaAsP HPD life timeTotal charge; 3.5 Total charge; 3.5 mCmC in Photocathode in Photocathode (ca. 100 C in APD output @(ca. 100 C in APD output @ gain 30000]gain 30000]))

Lifetime (20% degradation)

(～10 times larger intensity than NSB)

GaAsP HPD First Test with Wavelength GaAsP HPD First Test with Wavelength Shifter (WLS)Shifter (WLS)

2.172.172.072.072.002.001.991.99With WLSWith WLS2.142.142.002.001.921.921.901.90No WLSNo WLS6060°°4545°°2525°°00°°ZAZA

Equivalent to increase the mirror diameter from 17m to 24m!!

In comparison with the current PMTsWith milky coating

γγ Shower Events Shower Events ( by MC simulation)( by MC simulation)

HPD with 10ns gate

(2 Gsamples/s FADC)

PMTwith 20ns gate

(300Msamples/s FADC)

17m telescope becomes equivalent with 24m telescope

Upgrade of MAGICUpgrade of MAGIC--II Camera II Camera with HPDwith HPD

First phase6 clusters 42HPDs

Second phase61 clusters 427HPDs ±1.3 degrees

SIPM/SPM/MPPC/GSIPM/SPM/MPPC/G--APDAPD

SiPM for TESLA SiPM for TESLA by by DolgosheinDolgoshein et al. et al. MEPhIMEPhI

Single photoelectron measurementSingle photoelectron measurementGain ~10Gain ~1066

UbiasUbias = 30~60= 30~60P = 50P = 50μμW/mm2W/mm2NpixelNpixel ~ 1000~ 1000Insensitive to Magnetic fieldInsensitive to Magnetic field

SiPM for TESLA SiPM for TESLA by by DolgosheinDolgoshein et al. et al. MEPhIMEPhI

SiPMSiPM, SPM, MPPC, G, SPM, MPPC, G--APD,,,APD,,,

Several problems in SiPMSeveral problems in SiPMLow filling factor (low aperture)Low filling factor (low aperture)

PDE = Transmittance x Fill factor x PDE = Transmittance x Fill factor x Q.E.xQ.E.x Geiger Geiger effeff..2525--50 50 μμm m 100 100 μμmm

Crosstalk between microCrosstalk between micro--pixelspixelsLow amplification in Geiger gain Low amplification in Geiger gain may result in low PDEmay result in low PDETrench between pixels, double Trench between pixels, double pp--nn structurestructure

Dark currentDark currentLow temperature operation(0Low temperature operation(0℃℃ ~ ~ --1515℃℃))

High temperature dependence 3~10%/degHigh temperature dependence 3~10%/degTemperature stabilization is necessaryTemperature stabilization is necessary

Small size (1mmx1mm)Small size (1mmx1mm)1mm x 1mm (2003) 1mm x 1mm (2003) 3mm x 3mm (2004) 3mm x 3mm (2004)

5mm x 5mm (2005) 5mm x 5mm (2005) 8mm x 8mm (2007)8mm x 8mm (2007)Blue sensitivity is relatively lowBlue sensitivity is relatively low

AntiAnti--reflection coatreflection coatReverse the structure ( Reverse the structure ( pp--onon--nn structure)structure)

Optical Crosstalk suppressionOptical Crosstalk suppression

Sketch from Cova et al. NIST 2003Workshop on single photon detectors

Reduction of cross talk between Reduction of cross talk between micro pixelsmicro pixels

Usual SiPMs, E.N.F. = 1.6 New type of SiPM developed by MPI and MEPhI E.N.F. = 0.97±0.05

5mmx 5mm size1mmx1mm size

PhotodetectionPhotodetection efficiencyefficiency

Hamamatsu SiPM100μ

pitch, p-on-n structure35% (300nm) ~ 65% (400nm)20% overestimated28% (300nm) ~ 52% (400nm)

MPI+MEPhI SiPM100μ

pitch, n-on-p structure33-38%(400-600nm)

50% at 550nm at high OV.

MPIMPI--HLL Back illuminated Drift SiPMHLL Back illuminated Drift SiPMStructure of Micro-Pixel

MPI-HLL Facility

Expected Q.E.Internal Q.E. in Silicon

Internal Register type Internal Register type SiPMSiPM (GAPD) (GAPD) aim PDE~ 61%aim PDE~ 61%

Filling factor 75%150μm pitch 20μm isolation gap

Transmittance 90%Geiger Efficiency 90%

Total PDE ~61%

Packaging of Packaging of SiPMSiPM

Possible structure of SubPossible structure of Sub--module and module and the camerathe camera

Sub-moduleTop view

Side view

Top view

DAQ board

Cooling plate 0 ~ -15 degrees

ConclusionConclusion

High Q.E. High Q.E. PMTsPMTs are certainly good candidates for the next generation are certainly good candidates for the next generation IACT at presentIACT at present

HamamatsuHamamatsu R10408R10408--SBA will be used in MAGICSBA will be used in MAGIC--IIIIBe careful to after pulsing rate for some type of Be careful to after pulsing rate for some type of PMTsPMTs!!!!

GaAsPGaAsP HPD also can be the candidateHPD also can be the candidateWill be demonstrated on MAGICWill be demonstrated on MAGIC--II / MAGICII / MAGIC--IIHigh Q.E. x High High Q.E. x High p.ep.e. collection efficiency x very low after pulsing rate. collection efficiency x very low after pulsing ratebut several times expensive than but several times expensive than PMTsPMTs

SiPMSiPM/SPM/MPPC/G/SPM/MPPC/G--APD can be the good option in near future(2~3 APD can be the good option in near future(2~3 years)years)

6060--70% P.D.E. will be achieved soon (7070% P.D.E. will be achieved soon (70--80% could be the hard limit)80% could be the hard limit)Several UVSeveral UV--sensitive sensitive SiPMSiPM will be available soonwill be available soonModerate cooling / Temperature stabilization are very importantModerate cooling / Temperature stabilization are very importantSeveral types of Several types of SiPMSiPM Array will be available soonArray will be available soonDemonstration is highly recommended / requiredDemonstration is highly recommended / required