ICHEP – Beijing, China Aug 16-22, 2004Professor Priscilla Cushman, University of Minnesota...

ICHEP – Beijing, China Aug 16-22, 2004 Professor Priscilla Cushman, University of Minnesota

Performance of the multi-channel Hybrid Photodiodes Performance of the multi-channel Hybrid Photodiodes for the CMS HCAL for the CMS HCAL

Professor Priscilla CushmanProfessor Priscilla CushmanUniversity of MinnesotaUniversity of Minnesota

The US-CMS HCAL Collaboration

Fermilab Florida State Purdue Notre Dame University of Illinois (Chicago) University of Mississippi University of Maryland Rochester University of Minnesota


HCAL

The CMS Tile/Fiber Hadronic CalorimeterThe CMS Tile/Fiber Hadronic Calorimeter

HB

HE

HO


Reading out the Towers of Tiles with WLS fiber and HPD’sReading out the Towers of Tiles with WLS fiber and HPD’s

4 Tesla Magnetic Field


The CMS Hybrid PhotodiodeThe CMS Hybrid Photodiode

Tube Fabrication by DDelft EElectronic PProducts (Netherlands) Subcontracts: Canberra (Belgium): diodes Schott Glass (USA): fiber optic windows Kyocera (Japan): vacuum feedthru/ceramic carrier

19-channels 5.4mm each

• 12 kV across 3.3 mm gap with Vth < 4 kV => Gain of 2200

• 200 m Silicon PIN diode array, T-type, 80 V reverse bias

PIN Diode arrayCeramic feedthrough

Fiber-OpticWindow

Photocathode

e


Larger active area: Less room for HV connection, possible field distortions

Minimize gap: Improve tube components

This has been a development projectThis has been a development project (the tube)

HV coax cable : Reliability and compatibility with RBX

RBX mountings and cookies must be rubber insulated

Gold-plated pins: Enables us to use ZIF sockets - questions of gold diffusion

FIBERS

Plate

HPD

Plate Cookie

Ring HV Cable

Electronics Interface Board


Custom Pixel Design: 19 ch (towers) and 73 ch (short stacks)

This has been a development projectThis has been a development project ( the diode)

2 side-contacts (100 nm thick Al)

Bump-bonded vacuum feedthru

n++ contact

n++ n++p+ p+ p+ p+ p+

n+ bulk (200 m thick)

AR (16 nm sputtered Si)Metal (25 nm AL)Barrier (25 nm SiO2)

Higher pinout density: wire-bonds =>glass feedthrus => ceramic from Kyocera

Alignment to 50 m: manufacturer tolerances tightened, new measurement procedures

Improved rise time: Thinner silicon: 200 m replaces 300 m

Guard ring and drain structure: lower leakage current and better uniformity for edge pixels

Lower depletion voltage and better control of process: higher breakdown voltage

Surface aluminization and edge traces: Reduce negative crosstalk: 300 /sq => 1.7 /sq

Antireflective coating: Reduce positive crosstalk from reflected light


300 m thick 200 m thick

Pulse width can be shortened by reducing wafer thickness d Pulse width can be shortened by reducing wafer thickness d or by increasing bias voltage, Vor by increasing bias voltage, Vbb

Drift time is approximately given by

and the shape of the plateau mirrors the internal electric field

bV V

dd

2

0lim


Crosstalk in non-Aluminized 73-ch tube (B=1.5)

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

200 250 300 350 400

time[ns]

I/50o

hms[

mv]

pixel 36pixel 35pixel 34pixel 33pixel 37 /100

Crosstalk in Aluminized 73-ch tube (B=1.5)

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

200 250 300 350 400time[ns]

I/50o

hms[

mv]

pixel 36

pixel 35pixel 34

pixel 33pixel 37 /100

AC Crosstalk eliminated by Aluminization and edge tracesAC Crosstalk eliminated by Aluminization and edge traces

33 34 35 36 37

Pixels in center row

Positive crossstalk now observed !


photoelectrons

Light

Re-emitted photoelectrons

APD views reflected light

pe backscatter focussed by B

Light injected thru fiber

Test Confirms Reflected Light produces optical crosstalkTest Confirms Reflected Light produces optical crosstalk

DIODE ARRAY

FIBER OPTIC & PHOTOCATHODE


Study Problem at Minnesota, then export technology to DEPStudy Problem at Minnesota, then export technology to DEP

IMD - optical modeling package for multilayer structures

(by David L. Windt, http://cletus.phys.columbia.edu/windt/idl)Model

Data monochrometer

PIN diode

Samples: glass slides with various coatings (PECVD)

10 nm Ag120 nm SiO2

8 nm A-SiH15 nm Ag50 nm SiO2

16 nm A-SiH25 nm Al25 nm SiO2

Some OptionsMinnesota test slides

14 nm a-SiH 25 nm Al 25 nm SiO2


Quality Assurance: Can process 40 tubes/monthQuality Assurance: Can process 40 tubes/month

fail passReturn to DEPReturn to DEP

Bake-out at 10 kV for 2 weeks

Evaluate >600 tubes, automated procedure, complete web-accessible databaseEvaluate >600 tubes, automated procedure, complete web-accessible database

Alignment measurements for 50 micron tolerance

Leakage current for each pixel and guard ring @ 80V2-D response scans (10kV, 80 V), HV gain, bias curve

crosstalk checks alignment

DC Station Machine custom ring

Single pe spectra per pixel

To FNAL for installation in readout boxes

Viking Station Lifetime: Q, Cf252, HV

High Rate and B-Field tests

subset

DC crosstalk Optical xtalk in each pixel in B-field.

AC crosstalk Recorded scope traces of AC xtalk for nn pixels

capacitance vs biasCap Station


Samples from DC StationSamples from DC Station

Pixel Number Dark Current

1 8.6827e-0092 9.2811e-0093 2.4709e-0084 8.6967e-0095 8.995e-0096 2.2894e-0087 8.2391e-0098 2.1001e-0089 9.1783e-00910 2.2305e-008

11 1.36793e-00812 8.7693e-00913 2.0977e-00814 3.0818e-00815 1.78352e-00816 7.1035e-00917 7.2061e-00918 8.2694e-00919 7.2356e-009

Total Current 2.6605e-007


Precision RegistrationPrecision Registration

• Test fixture = Standard Mount + metal plate with 3 alignment holes

• Scan to find centroid of alignment holes

• Same scan finds pixel intersections above and below metal piece by iterative sector equalization• Machine shop uses measured x, y, to produce Custom Ring

• Each ring is registered to its HPD via alignment pins such that Readout Module and Cookie (Notre Dame and FNAL) can be universal

Stabilized light source

HP

D

Mou

nt

Scanning Table

Integratingsphere Focussing

optics

Green filter

Metal alignment

plate

FIBERS

Plate

Alignment Pins

Plate

HPDRing HV Cable

Electronics Interface Board


Initial Alignment Scan Final Alignment

Production #

SQ

RT(d

X2

+dY2

+dTheta

2)

0

0.05

0.1

0.15

0.2

0.25

0 50 100 150 200

Initial Alignment

Final Alignment

Alignment Procedure to 50 m is effective

50 microns


AC Station: Viking chip serial readout at 10 MHz

HPD +interface card

AC-Coupling2 chip

128 channel PARepeater card

Laptop with ADC card

128 Mu

ltiplexer

ShaperSample& hold

10 MHzreadout


Individual spectra for each pixel from AC StationIndividual spectra for each pixel from AC Station19-channel tube at low light levels19-channel tube at low light levels


AZ0139031 HPD List Search Results

HPD Serial Number

Date Time QE at 480

QE at 520

QE at 560

Global Status

AZ0139031 2003-01-08 18:10:48 null null null Failed

AZ0139031 Bias Curve Search Results

HPD Serial Number

Scan Date Scan Time High Voltage Data File Bias Curve Status

AZ0139031 2001-11-15 10:35:45 739 BV(2C)AZ0139031.dat AZ0139031bvgraph.gif Passed

AZ0139031 Dark Currents Search Results

HPD Serial Number

Scan Date Scan Time

Bias Voltage

High Voltage

Summed Current

Pixel Current

Bias Current

Data File DCGraph Status

AZ0139031 2001-11-15 10:43:22 80 0 2.193e-09 2.17e-09 5.4069e-09 DCAZ0139031.dat

AZ0139031dcgraph.gif

Passed

AZ0139031 Viking Search Results

HPD Serial Number

Scan Date Scan Time Viking File Pixels Status

AZ0139031 2002-03-26 14:09:40 az0139031VIK.raw AZ0139031vikgraph.gif Passed

AZ0139031 High Voltage Curve Search Results

HPD Serial Number

Scan Date Scan Time Bias Voltage Data File Response Curve Status

AZ0139031 2001-11-15 10:44:10 80 HV(2C)AZ0139031.dat AZ0139031hvgraph.gif Passed

Database http://hcal-up.hep.umn.edu

http://hcal-up.hep.umn.edu/researchhpds/AZ0139031/BV(2C)AZ0139031.dat

http://hcal-up.hep.umn.edu/researchhpds/AZ0139031/AZ0139031bvgraph.gif


Tracking and Grading ProceduresTracking and Grading Procedures

Grading is done through the database Contract specifications for each test must be met.Failing one test Tube returned to DEP

http://hcal-up.hep.umn.edu/grading

Trending Plots show specification compliance vs time(see following plots for examples)

Excel spreadsheet updated and emailed to CERN financial monthlyOnly pay for the cumulative number of approved tubes


Spec: R < 3 Ohms

Resi

stance

in O

hm

s

0

2

4

6

8

10

12

14

16

0 50 100 150 200

AC x-talk Spec: pixels/input pixel < 3%

Production #

% o

f in

put

light

0

5

10

15

20

25

30

35

40

0 50 100 150 200

Silicon resistivity and aluminized traces now under control

DEP now requires testing resistance of the aluminized traces before releasing the tubes

readout 8

and 18

Illuminate center pixel1 2 3


DC x-talk Spec: Pixels/Input Pixel < 4%

%

of

inpu

t lig

ht

0

1

2

3

4

5

6

7

8

0 50 100 150 200

single worst pixel

All pixels

Anti-reflective coatings are reasonable

HPD

Permanent 0.3 T field isolates optical crosstalk from backscatter.

magnet

magnet

illuminated pixel

Production #


Lifetime under HV and Light

PIN reference diodes

1.0 mm diam. WLS fibers

Blue LED’sPixel 11

HPD

Pixel 9

Lifetime Monitoring Stations monitor current (PIN diodes, HPD) and temperature

Integrated Charge: (10 CMS years = 3 C over 25.6 mm2 pixel at high

Expose to accelerated rate: Pixel 9 at 327 nA plus control pixel at CMS rate: Pixel 11 at 37 nA

Surface scans done before and after exposure distinguish between photocathode degradation and silicon damage.


Light off

1011

9

Steady LightLight injected into 2 pixels. Run over more than 2 years

3.4 C0.4 C

13.7 C 1.6 C

19.1 C 2.2 C

Integrated Q

pixel 9 pixel 11

Pixel (led) – Pixel 10 Pixel 10

Percent change in response (gain*QE)


Radiation Damage

Radiation Damage: (10 CMS years = 5 x 1010 n/cm2 in worst region)

Expose samples to Cf 252

1997: Oak Ridge: Early HPD version to 1013 n/cm2 Remote operation at very high flux Monitor current, characterize before and after irradiation

Result: No change in gain up to 5x1012 n/cm2, Monotonically increasing leakage current consistent with silicon

Still worked even at 10 A of leakage current!

2001, 2003: Minnesota: new HPD to >1011 n/cm2

Low flux drawer instrumented similar to Lifetime Test Light injection, in situ gain curves, reference diode

Result: Leakage current will rise at rate of 7 nA/yr in the worst location


2004 Test Beam at CERN

HO

HB

HE

ECAL

HO

beam

beam

Wedge tests going on now


Tracking a single channel in 4 Readout Modules

100

1000

10000

100000

0 200 400 600 800 1000 1200 1400 1600

Ch

arg

e (

fC)

RM1mean

RM2mean

RM3mean

RM4mean

CALmean

Occasional changes in LED levels

The PIN diode for HB1 flaked out for a whileThe HV was changed from 8kV to 10kV

Two Months of operation at the test beam – monitored by led


HO Response to Muons: Select high Gain*QE tubes and run at 10 kV

Ped. RMS Peak – Ped pe S/N

Ring 0 0.95 fC 5.0 fC ~18 pe 5

Ring 1 0.91 fC 3.7 fC ~13 pe 4

Ring 2 0.92 fC 2.5 fC 9 pe <3


Special layer-by-layer readout for the testbeam showsLongitudinal Development of a 150 GeV Pion shower in HB

HCAL alone HCAL + ECAL

layer

layer

Barrel section (HB) will be run at 8 kV for stability & lifetime


ConclusionsConclusions

8 years ago, no existing technology could satisfy our specifications.

Development project was initiated with one Company - DEPwith backup plans which included Hamamatsu and Litton

Quality Assurance from the start can discover unanticipated problems timely feedback creates new solutions – specifications may change

Our yield under new specifications is only 60% but graded under original specs, it is closer to 80%

Photosensor fulfills all CMS HCAL requirementsas well as lifetime, stability, and operation in radiation field.

They are currently operating as expected in the Test Beam

All tubes will be manufactured and tested by February 2004.

ICHEP – Beijing, China Aug 16-22, 2004Professor Priscilla Cushman, University of Minnesota...

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Transcript of ICHEP – Beijing, China Aug 16-22, 2004Professor Priscilla Cushman, University of Minnesota...