28 June 2007G. Pauletta: ALCPG 20071 Tests of IRST SiPMs G. Pauletta Univ. & I.N.F.N. Udine Outline...

28 June 2007 G. Pauletta: ALCPG 2007 1

Tests of IRST SiPMs

G. Pauletta Univ. & I.N.F.N. Udine

Outline

1. IRST SiPMs : baseline characteristics2. first application at FNAL test beam

3. subsequent evolution 4.New devices for T956


13

14

15

16

17

18

19

20

0 0.2 0.4 0.6 0.8 1 1.2 1.4

depth (um)

Do

pin

g c

on

c. (1

0^)

[1/c

m^

3]0E+00

1E+05

2E+05

3E+05

4E+05

5E+05

6E+05

7E+05

E fi

eld

(V/c

m)

Doping

Field

n+ p

Shallow-Junction SiPM

p+ subst.

epi

n+

*C. Piemonte “A new Silicon Photomultiplier structure for blue light detection” NIMA 568 (2006)

IRST technology

Distinguishing characteristics: 1) Very shallow junction 2) ARC optimized for short wavelenghts (~400nm) 3) polysilicon quenching resistors


Development started at the beginning of 2005

Baseline geometry

SiPM structure:- 25x25 cells- microcell size: 40x40mm2

Development has continued over last two years: several succeeding production runs to to develop geometries for different applications

Geometry of baseline model NOT optimized formaximum PDE

( fill factor ~20%) .

1mm

1mm

and to optmize operational characteristics


y = -40375x + 2E+06

y = 0.0765x + 28.833

28

28.5

29

29.5

30

30.5

31

-10 0 10 20 30

0.00E+00

5.00E+05

1.00E+06

1.50E+06

2.00E+06

2.50E+06

Vbd

Gain

G Ampl

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

3.5E+06

4.0E+06

28.5 29.5 30.5 31.5 32.5 33.5 34.5 35.5

-5°C

5°C

15°C

25°C

Gain & Dark countDC

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

0 1 2 3 4 5 6 7 8 9 10

-5°C

5°C

15°C

25°C

Performed in the climatic chamber. Devices from the third batchD

ark

coun

t

Gai

n

VB

D (

V) G

ain

Temp. (C)

Over-voltage (V) Bias voltage (V)

C. Piemonte: June 13th, 2007, Perugia


After-pulsing

-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

-1.0E-08 1.0E-08 3.0E-08 5.0E-08 7.0E-08Time (s)

Vo

ltag

e (

V)

y = 0.0067x2 - 0.4218x + 6.639

y = 0.0068x2 - 0.4259x + 6.705

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

31 32 33 34 35 36

Voltage (V)

Afte

rpu

lse

/pu

lse

Tint = 60ns

Tint = 100ns

Events with after-pulsemeasured on a single micropixel.

The amplitude of the after-pulse increases as the cell recovers to its opertional condition

After-pulse probability vs bias

It increases following a parabolic law:

01PPP ca

linear with Vbiaslinear with Vbias



Short integration time only single/double/….pulses are counted

0

200

400

600

800

1000

1200

1400

-8E-10 -6E-10 -4E-10 -2E-10 0E+00QDC

Co

un

ts

33.5V35.5V

double peak

Charge (a.u.)4 3 2 1 0

V = 4.5V 1.5V

Number of events with optical cross-talk increaseswith voltage

Cross-talk below 5%at 4V over-voltage.

Optical cross-talk



Photodetection efficiency

30

40

50

60

70

80

90

100

300 400 500 600 700 800Wavelength (nm)

QE

(%

)

0V

-2V

Simul

Simul ARC

0.00E+00

2.00E+00

4.00E+00

6.00E+00

8.00E+00

1.00E+01

1.20E+01

1.40E+01

1.60E+01

350 400 450 500 550 600 650 700 750 800

Wavelength (nm)

PD

E (

%)

36V

36.5V

37V

37.5V

38V

V=2V

2.5V

3.5V

3V

4V

QE vs Wavelengthlong : low PDE becauselow QE

short : low PDE becauseavalanche triggered byholes

Measured on a diode

Reduced bysmall epi thickness

Reduced by ARC

Area efficiency ~ 20%

PDE=QE*Pt*Ae

QE=quantum eff.Pt=avalanche prob.Ae=area eff.

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0

PD

E

350 400 450 500 550 600 650 700 750 800



Application at FNAL T956


Preliminary study of Scint. Strip viewed by IRST SiPM at the FNAL test beam

Beam (12 GeV protons)

Counter readout on both ends by SiPMs

T956 neutron counter arrays

Bias = -36V (V=2V)

Data with 120 Gev proton - beam

6

..

..

106.1

5.1

%99

..5.6

G

MHzN

epN

cd

ep


Future work

Beam (p,,e)

T956 neutron counter arrays:64 scint strips each(read out by wls fiber and MAPMTs)

Add one plane of scint strips read out by Wls fiber andSiPMs

Scintillator strips : 4cm x 1cm x (1 – 2 m), read out by wls fiber. Groove for fiber extruded with scintillator

Whole assembly mounted onmovable (x,y) support


* Establish functionality and base-line parameters

* Verify reproducibility of the first batch* First attempt to reduce optical cross-

talk

First batch

Second batch

September 2005

May 2006

Development started at the beginning of 2005.

* First attempt to reduce dark count rate Third batchOctober 2006

Fourth batchMay 2007 * optimize fill factor

* new geometries for different applications (including T956)

* continue the study on dark count reduction

Perspective

Trento/INFN funds development of SiPM devices, mainly for PET application

Second Batch tested at FNAL (T956). FACTOR collaboration (Ts/Ud/Me) apllies for INFN funding to develop: for calorimetry/muons

FACTOR funded


Static measurements-1

Ileak

VBD

Ibd

Itot

, since and

.

count dark and gain toprop. is

current dark

2VI

VDCVG

DCGI

DCG

III

dc

dc

leaktotdc

IRST 1mm2

second batch

Sensitive to principal characteristics

Rapid check functionality & uniformity

Baseline version

IRST devices generally very uniform


dynamic measurements-1Amplifier used for fast characterization of SiPMs:Agilent ABA-52563 3.5 GHz RFIC Amplifier(economic, compact, internally 50-Ω matched, gain ~ 20 dB)Dimensions 1.8 x 1.8 mm2

Orange trace: input from pulse generator, FWHM = 0.9 ns, tr = tf = 300 psRed trace: amplifier’s output


type “A”, D.C.(ΔV=2V) ≈ 1.5 MHztype “B”, D.C.(ΔV=2V) ≈ 2- 3 MHztype “D”, D.C.(ΔV=2V) ≈ 1 MHz

dynamic measurements-5


dynamic measurements-6

Measurements performed in a climatic chamber (with humidity control)The amplifier was located outside the chamber, connection via a special 18 GHz ft50 Ω cable

Temperature Dependences - 1

dVBD /dT ≈ 78 mV/C


1x1mm 2x2mm 3x3mm (3600 cells) 4x4mm (6400 cells)

Circular(1.2 mm – diameter)

increased fill factor: 40x40mm => 44%50x50mm => 50%100x100mm => 76%;

last batch

Array



Noise and charge resolution

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

3.5E+06

29 30 31 32 33 34 35

5C GAIN

5C Dark Coun

30.5

31

31.5

32

32.5

33

-1.50E-08 -1.00E-08 -5.00E-09 0.00E+00

Pulse Area (Vs)

1x1mm2 SiPM with 40x40m2 cells

0.0E+00

1.0E+06

2.0E+06

3.0E+06

4.0E+06

5.0E+06

30 31 32 33 34 35

20C GAIN

20C Dark count

T=5C

T=20C

resolution limited by electronic noise

Charge spectra at differentVoltages with the same light Intensity (pulsed)

3.5p.e.

5p.e.

6.5p.e.

8p.e.

9.5p.e.

First signal and noise characteristics of the last devices



T956 devices packaged with and without protective resin for test

VBD~ 31 V

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28 June 2007G. Pauletta: ALCPG 20071 Tests of IRST SiPMs G. Pauletta Univ. & I.N.F.N. Udine Outline...

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