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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
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))
0123456789
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
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 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
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%
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