performances of sipmt array readout for fast time-of-flight detectors 13th conference on innovative...

Performances of SiPMT array readout Performances of SiPMT array readout for Fast Time-of-Flight Detectorsfor Fast Time-of-Flight Detectors

13th Conference on Innovative Particle and Radiation Detectors

Siena – 7-10 October 2013

M. Bonesini1, R. Bertoni1, A. De Bari2, R. Nardo’2, M. Prata2, M. Rossella2

Presented by M. BonesiniINFN, Sezione di Milano Bicocca - Dipartimento di Fisica G. Occhialini1

INFN, Sezione di Pavia - Dipartimento di Fisica Nucleare e Teorica2

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Outline Introduction Scintillator based TOF detectors PMTs vs SiPMT arrays Test setup Results Conclusions

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PID methods• Particle identification

(PID) is crucial in most experiments (from /K identification in B physics to e/ separation at 10-2 level for p< 1GeV)

• At low momenta TOF methods are used (p 3-4 GeV/c)

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Particle ID with TOF

12

22

L

tcpm

TOF based on measure of t over a fixed length L

Mass resolution dominated by t (not measure of L, p)

Separation power in standard deviation

tt cp

mmLn

2

2

2

2

121, 2

)(

Beam particle separation in HARP beam Tof , for a 3 GeV

beam

K

p

d1

2

22

L

tcpm

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Examples of TOF detectors Based on scintillator counters:

simple to made, sensitive to B, read at both ends by PMTs, good resolutions -> 50-100 ps (depends mainly on L,Npe)

Based on PPC or spark chambers: some care in production, not sensitive

to B, very good resolutions -> 30-50 ps

Based on RPC’s: cheap (suitable for large areas), not sensitive to B, R&D in development, very good resolutions -> 50 ps

Rate

problems

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Basics of double-sided scintillator counters

222

222

12

22

1

12

22

10

tv

ttvx

tttt

lightlight

light

light

vtt

x

vltt

t

2

221

0

210

Precise TOF and Hit position

Pmt

Scintillator + lightguide

elec

pe

plPMTsc

t N2

22int

2

Tof resolution can be expressed as:Some points to look have

high resolution tof’s

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Problems for high resolution scintillator based TOF (t < 100 ps)

pl dominated by geometrical dimensions (L/Npe)

scint ps (mainly connected with produced number of ’s fast and scintillator characteristics, such as risetime)

PMT PMT TTS (typically 70-150 ps)

• Additional problems in harsh environments:

1. B field (-> fine mesh PMTs/shielding of conventional PMTs)

2. High particle rates (tuning of operation HV for PMTs)

SiPMT arrays vs PMTs

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• PMTs 1. Large active area > 0.5 – 1 inches2. Gain G depends on external magnetic fields B (needs

shielding, aside fine-mesh PMTs)3. Good TTS: typical values in the range 150-400 ps4. Fast PMTs are quite expensive: 1000-1500 E5. Needs HV: typically 1000-2000 V6. Low noise rate ~1KHZ

• SiPMT arrays1. Active area up to 1x1 cm2 typically2. Gain G insensitive to external magnetic fields, but depend

on temperature T (needs feedback)3. Good STPR response for single SiPMT ~140-300 ps4. Quite cheap 5. Needs low voltages: ~30 V for SenSL, Advansid , ~70 V for

Hamamatsu 6. High noise rate up to MHZ

Timing resolution of photo detectors

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From K. Arikasa NIM A422 (2000)

Resolution improves:

•By decreasing active area •As

From G. Colazzuol (LIGHT11 2011)

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Conventional fast TOF with PMT readout have found application in many

experiments

MICE at RAL (Hamamatsu R4998 PMTS)

1m

e+

Liq. Xe Scin tilla tionDetector

Drift Cham ber

Liq. Xe Scin tilla tionDetector

e+

Tim ing Counter

Stopping TargetThin S uperconducting Coil

M uon Beam

Drift Cham ber

MEG at PSI (Hamamatsu fine

mesh PMTs)

AMS-02 exp (Hamamatsu fine

mesh PMTs)

Tof detectors

Studies of SPTR (timing for single photoelectrons)

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• Timing studies are usually done for single SiPMT (not arrays) with single p.e.

• For scintillation counters needs to study multiphoton response

from V.Puill et al NIM A695 (2012) 354

A small remark

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• Timing studies are usually done with fast lasers (eg 30-50 ps FWHM ): good for single p.e. studies, but scintillator have typically 200-300 p.e. signals and scintillator risetime are in the 1-2 ns range …

• Needs laser signals that resemble more physical scintillation light

Experimental lab setup

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Laser driver

Sync out

Prism injection system

PMTL PMTR

Fast photodiode

Fast Amplifier

BSLaser head

VMEtR

t0

LightMM fiber

x/y/z flexure (fiber launch

system)

Scintillation counter

Test setup: home-made laser system

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1. Fast Avtech AVO pulser + Nichia violet laser diode ( ~408 nm)

2. Laser pulses width selectable between 120 ps and 3 ns length, with a ~200 ps risetime (simulate scintillator response)

3. Laser pulse height selectable to give scintillator response between a fraction of MIP and 10-50 MIPS

4. Laser repetition rate selectable between ~100 Hz and 1 MHz

5. The laser beam is splitted by a 50% beamsplitter to give a reference t0 on a fast photodiode (Thorlabs DET10A risetime ~1 ns) amplified via a CAEN A1423 wideband inverting fast amplifier (up to 51 dB, ~1.5 GHz bandwidth)

Some details

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Laser injection system:•Newport 20X microscope objective•x/y/z Thorlabs micrometric flexure system

Acquisition system:•VME based (CAEN V2718 interface) •VME CAEN TDC V1290A (25 ps res)•VME CAEN QADC V792 •VME CAEN V895 L.E. discriminator (typ discr values -50 -100 mV)• home-written acquisition software

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Tuning of laser setup

• Tune laser settings to reproduce testbeam results (twith a single counter equipped with R4998 PMTs and MIP response

• Study single counter response substituting PMTS readout with SiPMT arrays readout

• Advantage as respect to cosmics is the possibility to collect a high statistics in a short time, with different exp conditions (amplifier tuning, …)

From R. Bertoni et al., NIM A615 (2010) 14

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BC 404 scintillation counter (60 cm long, 6 cm wide) equipped with Hamamatsu R4998 PMTs (as in MICE expt)

PMT signals with laser

PMT signals with cosmics

Readout chain for SiPMT arrays

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• SiPMT array custom mount

• 16 macrocells signals are summed up in the basette and then amplified

Schematic of one ``basette’’

Custom amplifier

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Amplifier: •Custom made (INFN Pv) •1 or 2 channels•Gain up to 100X (30X with pole zero suppression)•Input dynamic range: 0-70 mV•Bandwith : 600 MHz

This may limit timing response, tests will be redone soon with a 50x PLS 774 amplifier (bandwith ~1.50 GHZ)

Amplifier performances

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100X amplifier Amplifier linearity

Vout

Vin

SiPMT arrays under test

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Available SiPMT arrays use 3x3 mm2 or 4x4 mm2

macro-cells arranged in 4x4 (or more) arrays.

•SENSL ArraySL-4-30035-CER arrays with 3x3 mm2

macrocells, Vop ~29.5 V•Hamamatsu S11828-3344 , S12642 arrays with 3x3 mm2 macrocells, Vop~72.5 V•Advansid FBK/IRST ASD-SiPM3S-4x4T (RGB) arrays with 3x3 mm2 macrocells, Vbkw ~28.5 V •Advansid FBK/IRST ASD-SiPM4S-4x4T (RGB) arrays with 4x4 mm2 macrocells, Vbkw ~29.2 V

•We plan to extend study to new NUV types, better matched to scintillator light emission

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Results with conventional PMTs (as benchmark)

Very low laser light intensity (1 MIP or less)

Standard laser light intensity

(2-3 MIP)

Vop = V0+V

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SenSL ArraySL-4-30035-CER arrays

• Risetime of SenSL arrays much bigger than one of Hamamatsu or FBK/IRST

• Preliminary results quite bad , we need further studies with new blue extended arrays from SenSL to get conclusions

SiPMT I-V characterization (our measure)

Results with FBK/IRST arrays

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SiPMT I-V characteristics

(manufacture specs)

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Results with FBK/IRST SiPMT arrays

Standard light intensity

t~60 ps at best, but RGB array !!

Typical difference TDC (converted in ps) : t=TDC/2

Vop

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Results with Hamamatsu S11828-3344 Arrays

SiPMT I-V characterisation(our characterisation)

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Results with Hamamatsu S11828 Arrays

Standard light intensity

We foresee soon tests with Hamamatsu S12642 arrays, TSV package , where better results may be expected

Foreseen improvements

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•Higher bandwith amplifiers (bandwidth > 1 GHz)•Extension of measurements to NUV extended SiPMT arrays (better matched to scintillator emission max ~400 nm)•Use of better signal cables (eg RG213 instead of RG58)•See effect of CF discriminators vs LE discriminators (even if we expect no big change: laser light signal/cosmics signal at counter center + equalized response of photodetectors)•Test of fully equipped detectors at BTF

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Conclusions

SiPMT arrays may be a good repacement for fast PMTs in scintillator time-of-flight system

Preliminary conclusions show a “comparable” timing resolution with fast PMTs

Clearly results must be validated by testbeam (one at BTF is foreseen)

Some optimization may be needed: use of fast (> 1 GHz) amplifiers, NUV SiPMT arrays (instead of RGB ones) to better match scintillator emission

Acknowledgements: many thanks Mr. F. Chignoli, G. Stringhini and O. Barnaba for skilful help and work in the setup installation and laboratory measurements and Dr. Bombonati of Hamamatsu Italia

Backup slides

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Estimation of Npe

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• If QADC P.H. distribution is fully described by photoelectron statistics : Npe=(<R>/R)2 where peak value R and sigma R are obtained with a gaussian fit.

• From published data (R. Bertoni et al NIM …) we expect 200-300 pe per MIP; from QADC fit we obtain that our standard light intensity is equivalent to 2-3 MIP

Timing resolution as function of discriminator threshold

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Fine Mesh Photomultiplier Tubes

• Secondary electrons accelerated parallel to the B-field.• Gain with no field: 5 x 10 5 – 10 7

• With B=1.0 Tesla: 2 x 104 - 2.5 x 10 5

• Prompt risetime and good TTS• Manufactured by Hamamatsu Photonics

Measures at INFN LASA laboratory to study behaviour in B field (up to 1.2 T ) as respect to gain, rate capability,timing

R5505 R7761 R5924

Tube diameter 1” 1.5” 2 “

No. Of stages 15 19 19

Q.E.at peak .23 .23 .22

Gain (B=0 T) typ

5.0 x 10 5

1.0 x 10 7 1.0 x 10 7

Gain (B=1 T) typ

1.8 x 10 4 1.5 x 10 5 2.0 x 10 5

Risetime (ns) 1.5 2.1 2.5

TTS (ns) 0.35 0.35 0.44