Si PAD sensor R&D for ALICE FoCal
19 March, 2017.

Motoi INABA
for ALICE FoCal collaboration

Tsukuba University of Technology, Faculty of Industrial Technology.
National University Corporation for the hearing impaired and visually impaired in Japan.

BackgroundP.2 of 29

For one of the ALICE detector upgrade plans, we carried out beam
tests of the FoCal-E PAD detector prototype developed by ORNL at
CERN PS / SPS complexes from 2014 to 2016. The next stage isdevelopment of the original detector with a wider dynamic range.

FoCal-E PAD detector prototype

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FoCal-E PAD detector is the Si-W calorimeter that one module has
4 pairs of tungsten tiles (t = 3.5 mm) and Si-PD sensors (t = 0.5 mm).
1 module (x4)SiSiSiSize: 11.25 x 11.25 mm2 ( = 1.266 cm2 )Si

Si-PD sensor (11.30 mm pitch)
12364 channels

Beam
94 mm

93 mm

WW W W< Side view >62 63 64
93 mm

< Back view >93 mm

FoCal-E PAD detector prototype by ORNL in 2012
P.4 of 29

APV25hybrid

APV25 hybrid
ORNL
summingboard

ORNL
summingboard

A copper shield
IsolatedframesTest of Si-PD

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We are interested in following tests on Si-PDs;(1) V-I characteristics using the electrometer,(2) V-C characteristics using the RLC meter,(3) Dynamic characteristics using the Laser / LED pulsar,(4) Light-incident-position dependence,(5) Cable-length dependence,(6) Estimation of heating and power consumption,(7) Cross-talk check,(8) Radiation durability, etc.
Test results of 3x3 Si-PDs
from Kyushu Univ.

1st test bench for 3x3 Si-PD

P.6 of 29Electrometer3x3 Si-PD from Kyushu Univ.

< Cross section >Probe
PCB with spring-pins
3x3 Si-PD
Cu plate
4 Peltier elements
Cooling fan(Movable)

Nano-step X-Y stage

Fig.1 A cross section of the new test benchV-I characteristics

P.7 of 29

10 ℃< 2[nA]

Tested by
K. Nishimatsu
UG4 student,
Univ. of Tsukuba

V-I characteristics

P.8 of 29

15 ℃< 2[nA]

Tested by
K. Nishimatsu
UG4 student,
Univ. of Tsukuba

V-I characteristics

P.9 of 29

20 ℃< 4[nA]

Tested by
K. Nishimatsu
UG4 student,Univ. of Tsukuba

V-I characteristics

P.10 of 2925 ℃< 7[nA]

Tested by
K. Nishimatsu
UG4 student,
Univ. of Tsukuba

V-I characteristics
30 ℃

P.11 of 29< 20[nA]

Tested by
K. Nishimatsu

UG4 student,
Univ. of Tsukuba

V-I characteristics
35 ℃

P.12 of 29< 30[nA]

Tested by
K. Nishimatsu

UG4 student,
Univ. of Tsukuba

V-I characteristics
40 ℃

P.13 of 29< 50[nA]

Tested by
K. Nishimatsu

UG4 student,
Univ. of Tsukuba

2nd test bench for 8x8 Si-PD

P.14 of 29< Cross section >In the black box
The laser head orLED with optical fibers(Fixed)FPC
PCB with FFC on the Al frame(High Voltage generator)
Si-PD on the W plate(Fixing)
The Cu block and Al base
4 Peltier elements
Power balance of 4 Peltierelements is important.

The water-cooled unit
(Movable)Nano-step X-Y stage
Fig.1 A cross section of the new test benchTest plans for ALICE FoCal-E PAD

P.15 of 29

After the 2nd test bench for new Hamamatsu 8x8 Si-PDs is developed,
we are going to test as follows;(1) V-I characteristics using the electrometer,(2) V-C characteristics using the RLC meter,(3) Dynamic characteristics using the Laser / LED pulsar,(4) Light-incident-position dependence,
Important test points(5) Cable-length dependence,
・S/N・Dynamic range(6) Estimation of heating and power consumption,・Space(7) Cross-talk check,(8) Radiation durability, etc.
Mechanical design(Connectors)(Glueing)

8x8 Si-PD

FPC Type-1

PCB Type-A (Passive elements)
only(1)(2)PCB Type-B ( Analog buffers ) (3)(4)(5)(6)(7)

FPC Type-2 ( On-board buffers )PCB Type-C(5)(6)(7)(8)Assembly

P.16 of 29

HV(6) after W.B.
Signal(5)
Zero-Pressure
FCC (x4)

PCB Type-A (ｘ4)orPCB Type-B (ｘ4)orPCB Type-C (ｘ2)

(4)
(1)
(2)
(3)

Protection film (Mylar film)
Spacer (1.6t FR4)FPC Type-1 or Type-2
Insulated adhesive sheet
Si-PD
Conductive adhesive sheet
W plateAssembly station

The PCB Type-A is designed for the static characteristics test using electrometer.
The PCB Type-B is designed for the dynamic characteristics test using the Laser light.

FPC design
FFC
Bonding pad

P.17 of 29

FPC design

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FFC
Bonding padNew Hamamatsu 8x8 Si-PDs

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We got 10 Si-PDs at the end of January.

Top side

Bottom sideInsulated adhesive sheets

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We imported three types of the double coated tape from 3M U.S.A..
Product
NumberSeries

CarrierThickness

High Temp.
Range

Dielectric
Properties

Resistance

Unit
Price

9495LE

300LSE

Clear
Polyester

0.013mm

93℃

43kV/mm

¥890

¥915

9490LE

300LSE

Clear
PET

0.013mm

93℃

40kV/mm

¥870

¥887

9495MP

200MP

Clear
PET

0.013mm

121℃

54kV/mm

¥780

¥792

Conductive adhesive sheets

P.21 of 29

We also bought three types of the conductive tape as follows.
ProductNumberSeries

CarrierThickness

High Temp.
Range

Adhesiveforce

Resistance

UnitPrice

CN-4490-

Cu/Ni
plated

0.05mm

-

3.9 N/cm

0.050Ω
／mm2¥1,540

X7001-

Cuplanting

0.110mm-

6.6 N/cm

0.015Ω
／25mm2¥1,260AL-25DC-Al-base0.085mm-

3.6 N/cm

0.035Ω
／25mm2¥3,010Cutting of adhesive sheets

Cutting using a machine

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Just after cutting

Ready for assemblingAssembly (1)Insulated adhesive tapes on the bottom side of FPC

P.23 of 29Assembly (2)One side of a tape adheres tothe bottom side of Si-PD

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Another side of a tape adheres tothe Cu plateShipping for wire bonding

Si-PD Just before wire bonding

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Wire bonding
Bonding wire

P.26 of 29

Bonding pad on FPC
FPC
Insulated adhesive tape
Si-PD
Conductive adhesive tape
Cu / W plate< Cross section >Pad of the next cell
Pad of the target cellWire bonding: 72 points / module
FFC
Bonding pad
8x8Si-PD

Si-PDcell

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Material lists and schedule
8x8 Si-PD

P.28 of 29(Delivered)

W plateCu plate

FPC Type-2

FPC Type-1

PCB Type-C

PCB Type-A
Adhesive sheets

Cutting of

1st assembly

adhesive sheets

2nd assembly

Materials forthe test bench
Wire bonding

Wire bonding
for FPC Type-2

22Development

Test using
FPC Type-2of the test bench

TestFebruary 2017

March 2017

April 2017

After May

Thank you for your attention.