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tracker. calorimeter. Application of novel Silicon-based photo-detectors to calorimetry and medical physics. MPPC. Nicola D’Ascenzo, Erika Garutti , Martin G ö ttlich University of Hamburg – DESY Hans-Christian Schultz-Coulon, Alexander Tadday University of Heidelberg.

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Application of novel Silicon-based photo-detectors to calorimetry and medical physics

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Application of novel silicon based photo detectors to calorimetry and medical physics l.jpg

tracker

calorimeter

Application of novel Silicon-based photo-detectors to calorimetry and medical physics

MPPC

Nicola D’Ascenzo, Erika Garutti, Martin Göttlich

University of Hamburg – DESY

Hans-Christian Schultz-Coulon, Alexander Tadday

University of Heidelberg


The multi pixels photon counter from hamamatsu l.jpg

1x1 mm2 active area

3x3 mm2 active area

The Multi Pixels Photon Counter(from Hamamatsu)

The MPPC is a multi-pixel avalanche photo-diode operated in Geiger mode

calorimetry

application

Blue sensitive device:

ideal for direct r/o of plastic scint. and crystals

PET application

Erika Garutti - IEEE


Mppc characterization l.jpg

MPPC characterization

intrinsic recovery time

of MPPC ~ 4 ns

measured at university ofShinshu (see talk S. Uozumi, N41-4)

response curve to a 50ns long light signal

dynamic range artificially extended for

long signals due to fast recovery time

MPPC 1600pix has ~ 6000 effective pix. for

50ns long signal

Erika Garutti - IEEE


Application in hep calorimeters l.jpg

Application in HEP calorimeters

Task: readout of active layers of highly-segmented and granular calorimeter

Single calorimeter cell readout with SiPM

3x3 cm2 x 0.5 cm thick

see talk by F. Sefkow, N13-5

CALICE test beam

CERN 2007

DATA

prototype

active layer

100x100 cm2

  • Requirements to photo-detector:

  • insensitive to B-field (~ 5T)

  • couple to organic scintillator (green/blue)

  • low noise (dark rate + cross talk above thresh.) ~ 10-4

  • detection eff. for Minimum Ionizing Particles* >95%

  •  light yield for MIP ~10 pixels

  • dynamic range ~ 100-500 MIP

~8000 SiPM

operated

Erika Garutti - IEEE

* one MIP in 0.5 cm scintillator ~ 10000 g ( · WLS eff ~ 200 g on SiPM)


Readout of plastic scintillators with mppc l.jpg

Present status

SiPM 1056 pixels

(MEPHI/Pulsar, RU)

green sensitive

Scintillator tile (Uniplast, Vladimir RU) + Green wavelength shifter fiber (Kurakay)

Readout of plastic scintillators with MPPC

study driven by calorimetry applications for a ILC detector

MIP

response to

Ru106 source

3 cm

MPPC 1600 px

operation point

w WLS fiber

light yield [pixels/MIP]

R&D: direct r/o of scintillator tiles 3x3x0.5cm3

direct r/o

Vbias - Vbreakdown [V]

MPPC directly coupled

 LY sufficient for calorimeter application

but higher LY would allow thinner tiles (lower cost)

Erika Garutti - IEEE


Slide6 l.jpg

Readout of plastic scintillators with MPPC

MIP collection efficiency

noise spectrum

w WLS fiber

threshold at 1.5 pix

dark rate < 3 kHz

direct r/o

  • ILC requirement

  • dark rate < 300 Hz

  • MIP eff ~ 95%

    low but acceptable

MIP detection efficiency > 97%

for all r/o combinations

comparable with present status

400 px

Cut at3KHz

MIP spectrum

 larger dynamic

range than at present

1600 px

Erika Garutti - IEEE


Slide7 l.jpg

Application in PET detectors

reduction of background

Task: identify back-to-back scattered 511 keV photons from e+e- annihilation

suppress background and determine true line of response

Background events

remove combinatorial bg by ToF meas.

Dt = 500 ps 

remove Compton-scattered g

with good energy resolution

Erika Garutti - IEEE


Slide8 l.jpg

2 x scintillator crystals

LSO*: 1x1x15 mm3

3x3x15 mm3

LFS**: 3x3x15 mm3

emission: ~420 nm

decay time: ~40 ns

Teflon wrapping

2 x MPPC

1x1 mm2, 400 pixels

3x3 mm2, 3600 pixels

coupled with optical grease

Na22 source

Readout of scintillators crystals with MPPC

study driven by possible PET applications

  • due to high MPPT gain (7.5x105) no amplification needed  simple readout

  • energy integral on VME QDC (Lecroy 1182)

  • time resolution measurement: 4 GHz Oscilloscope, 50 ps resolution (Textronix TDS7404B)

* Lutetium OrthoSilicate from Heilger Crystals

** Lutetium Fine Silicate from Lebedev, Moskow

Erika Garutti - IEEE


Slide9 l.jpg

Readout of scintillators crystals with MPPC

Energy resolution

3x3 mm2 systems

1x1 mm2 system

LSO Crystal

MPPC 400

MPPC 3600

blue sensitivity

~ 8% for LSO negligible

  • LSO and LFS similar performance (within syst. uncertainty of ~ ± 2%)

  • Result comparable with typical value for LSO crystals + PMT is DE/E ~ 10 % @ 511 keV

Erika Garutti - IEEE

! after 4 months of test E resolution ~ 13±2%  degradation of MPPC package or crystal surface ?


Issue of mppc saturation l.jpg

Issue of MPPC saturation

3600 pix. MPPC coupled to 3x3x15 mm3 LSO crystal

QDC spectrum

scope signal

  • integral of 511 keV g signal ~ 2000 p.e.

  • ! but: signal width ~120 ns

  • peak amplitude ~ 400 p.e.

  • below saturation estimated at > 10000 pix. for 3600 pix. MPPC and 120 ns signal

  • but MPPC response non-linear everywhere (see talk N18-2, K.C. Burr)

Erika Garutti - IEEE


Slide11 l.jpg

Npe

1.

Readout of scintillators crystals with MPPC

Time resolution

  • Procedure for time resolution measurement:

  • 0. store two waveforms from scope if amplitude > noise level (~ 2mV or ~10 pixels)

  • apply energy cut to exclude Compton background

  • define a timing threshold to measure time difference between signals

2.

tcut

two waveforms from the photon peak

the voltage of the two MPPC is tuned

to give same response to 511 keV g

Erika Garutti - IEEE


Time resolution result l.jpg

# events

2 photon-peak amplitudes

Compton background

Background

time difference [ns]

Time resolution: result

fix threshold discr.

threshold [pixels]

  • Npe = ± 1 s of photon peak

  • ~10-15% of collected events used

  • for lowest threshold FWHM ~ 650 ps

    limited by scope noise

    *no Jitter analysis package used for this analysis

Photoelectric

Constant fraction discr.

Erika Garutti - IEEE


Conclusions l.jpg

Conclusions

  • MPPC 400 and 1600pix very good candidates for highly-granular calorimeter:

    - direct coupling to plastic scintillator

    - LYMIP ~ 7 (10) p.e. with direct coupling (WLS fiber mediated coupling)

    - satisfactory MIP detection efficiency with required noise cut

  • MPPC 3600 pixels excellent performance for PET application:

    - E resolution comparable to PMT

    - t resolution < 650 ps (noise limited)

  • next step: build 2 matrices of 6x6 MPPC

    with individual readout to test

    homogeneity, stability, reproducibility,

    calibration, multi-channel system

6x6 LFS crystals 3x3x15 cm3

6x6 MPPC 3600

we would like to thank Hamamatsu

for providing the MPPC samples for this study

Erika Garutti - IEEE


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