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R Lambert, LHCb RICH PD07, 28th June 2007 1 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH collaboration

R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

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Page 1: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 1

The LHCb Pixel Hybrid Photon Detectors

Robert W. Lambert, University of Edinburgh

On behalf of the LHCb RICH collaboration

Page 2: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 2

Outline

Introduction: LHCb and Particle ID

Hybrid Photon Detectors (HPDs)

HPD Manufacture

Testing and Results

RICH Installation Progress

Summary

Page 3: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 3

LHCb

LHCb will examine CP-violation in B-mesons [1] Why is there a matter-antimatter asymmetry in the universe? What are the reasons for the parameters in the Standard Model? Is there physics beyond the Standard Model?

Page 4: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 4

LHCb @-100m

RICH 1MagnetRICH 2

Page 5: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 5

RICH 1 and RICH 2

Ring Imaging CHerenkov (RICH) detectors [2] Relativistic charged particles in a medium radiate light Characteristic cone angle, cos = 1/n

RICH 1(Vertical)

RICH 2(Horizontal)

MA

GN

ET

TT

T1-T

3

Page 6: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 6

Cherenkov Imaging

Rings reconstructed Velocity Cone angle ≡ Ring radius Combine with momentum to get Particle ID

RICH 1 for 1 < p < 60 GeV/c RICH 2 for p < 100 GeV/c

~20 hits/ring~4 hits/ring

~25 hits/ring

Page 7: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 7

Ideal Cherenkov Spectra

0.1

1

10

100

1000

100 300 500 700Wavelength [nm]

Ab

sorp

tion

[cm

-1] .

0.0

0.2

0.4

0.6

0.8

1.0

# o

f ph

oto

ns

[arb

. un

its] .

Absorption Water

Absorption OxygenRICH 1 C4F10

RICH 1 Aerogel

Requirements

Stringent requirements for RICH photodetectors– 2.6 m2 detector plane

– Single-photon sensitive

– 65% active area overall

– 80% for cylindrical devices

– Cherenkov Spectrum

– 2.5 mm x 2.5 mm granularity

– 25 ns Clock <25ns response

– 40 MHz Clock 40 MHz read out

– Trigger decision 4s data buffer

– Photon yield High Signal:Noise

– 5-10 year lifetime

– Radiation tolerant 30 krad

– Fringe magnetic field

C4F10

200-600nm

Page 8: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 8

Hybrid Photon Detectors

484 Hybrid Photon Detectors HPDs required [3]+ Photocathode (S20)+ Silicon sensor+ Binary read-out chip

120

mm

87 mm

8192Vacuum

Electrode

Photoelectrons

Solderbump bonds

Ceramic Carrier

Binaryelectronicschip

Photon

Photocathode (S20)at -20kV

Si Sensor8192 pixels

QuartzWindow

Page 11: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 11

HPD ProductionHPD production status as of 18th June 2007

0

100

200

300

400

500

600

1-Jan-05 2-May-05 31-Aug-05 30-Dec-05 1-May-06 30-Aug-06 29-Dec-06 29-Apr-07

Qu

anti

ties

HPDs required

Spare HPDs required

HPDs delivered

Total tested

Production

Testing

536 / 550 HPDs Produced

18th June 2007

519 / 536 HPDs Tested

Page 12: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 12

PDTF

Photo-Detector Test Facilities 2 centres (2 stations each) Test 1 HPD/site/day 506 of 519 HPDs pass Failures Replaced.

Page 13: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 13

PDTF Tests

Check out every function of the HPD, from the ground up

Readout ChipConnectionsCommunicationsDAQReadoutDead ChannelsNoisy ChannelsMaskingResponsesThresholdNoise

PhotocathodeDark CountResponse to lightQuantum Efficiency

HPD BodyDimensionsHV StabilityVacuum Quality

Electron OpticsImage SizeImage CentreHV StabilityField Distortions

Silicon SensorIV CurveEfficiency (Backpulse)

Page 14: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 14

Silicon Sensor

PDTF perform a bias scan of each sensor Measures sensor quality

Leakage Current at 80V

0

50

100

150

200

250

300

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

Leakage Current [A]

Fre

qu

en

cy

, HP

Ds Contract

Typical 1A

H527009, 0.46 A leakage at 80V

Operating Point, 80V

Ramp-up

Ramp-down

Page 15: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 15

Readout Chip

Low number of faulty channels Average 0.15% dead channels << 5% specification Average 0.02% noisy channels << 5% specification

Noisy pixels

0

50

100

150

200

250

300

350

400

0 15 30 45 60 75 90 105 120 135 150

Number of noisy pixels (out of 8192)

Fre

qu

en

cy

, HP

Ds

Dead pixels

0

20

40

60

80

100

120

140

160

180

0 15 30 45 60 75 90 105 120 135 150

Number of dead pixels (out of 8192)

Fre

qu

en

cy

, HP

Ds

Specification< 400

Specification< 400

Page 16: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 16

Sensor + Readout

Thresholds and noise Threshold scan performed on all 8192 pixels ~85% sensor efficiency, Typical signal is 5000 e-

Thresholds

0

20

40

60

80

100

120

140

160

600 800 1000 1200 1400 1600 1800 2000

Average pixel threshold [e-]

Fre

qu

en

cy

, HP

Ds

Electronic Noise

0

20

40

60

80

100

120

140

160

50 70 90 110 130 150 170 190 210 230

Average electronic noise [e-]

Fre

qu

en

cy

, HP

Ds

<N> = 145 e-<T> = 1063 e-

Page 17: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 17

HV Stability

PDTF perform a HV scan of each HPD Measures HV stability Pulsed LED used at each voltage step

H527009, a typical HPD H527009, 200k events, LED run

Operating Point, 20kV

Backscatter

Reflections

Page 18: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 18

Vacuum Quality

Ion-feedback (IFB), afterpulse Ionisation of residual gas atoms, particularly He, produces afterpulse At 20 kV, IFB measures the vacuum quality

Residual Gas Ionised

Ion liberates many

secondary electrons

Secondaries measured after characteristic delay

1

2

3

Delayed Ion Feedback

0

50

100

150

200

250

300

350

400

450

500

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Ion-feedback [% of peak # of photoelectrons]

Fre

qu

en

cy

, HP

Ds Specification

< 1%

<IFB> = 0.03%

Page 19: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 19

Dark Count

Thermionic emission, noise, and IR-sensitivity produce Dark Count Specification 5 kHz cm-2

Average 2.6 kHz cm-2 ≡ 0.003 hit / event / HPD in LHCb

Dark Count from 5 Million triggers

0

50

100

150

200

250

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Dark Count [kHz cm-2]

Fre

qu

en

cy

, HP

Ds

Specification < 5kHz cm-2

H520009, 5M events, 2.0 kHz cm-2

Page 20: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 20

Quantum Efficiency

QE is a function of wavelength, large improvement seen Independent measurements: photocurrent from known light level DEP improved the QE with each batch (i.e. with time)

Quantum Efficiency with wavelength and batch

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600 700 800 900 1000

Wavelength, l / nm

QE

(DE

P),

hq(l

) / %

1 23 44b 56 78 910 1112 1314 1516 1718 1920 2122 ExpectedMin Spec Typ Spec

H527009 Quantum Efficiency

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0 100 200 300 400 500 600 700 800 900 1000

Wavelength l / nm

QE

, hq, (

no

un

its

)

DEP Results

PDTF Results 18.05.06

PDTF Results 03.06.07

Increasedover time

Decreasedover time

Expectation from preseries

Agreement across

measurements

Page 21: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 21

S QE dE

0

10

20

30

40

50

60

70

80

90

100

0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4

S QE dE [eV]

Fre

qu

en

cy

, HP

Ds

SQE dE

S QE dE, integrate improvement in QE across energy Cherenkov light has flat energy spectrum 24% relative increase in S QE dE over expectations from preseries

QE(DEP), hq(E), Summary

0

5

10

15

20

25

30

35

40

45

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Energy, E / eV

QE

(DE

P),

hq(E

) / %

DEP Average

DEP Min

DEP Max

Min Spec

Typ Spec

Expected

Vertical bars are standard deviation, no error is included.Green and Red curves are extrema, no single HPD has this curve

Expectation from preseries

Page 22: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 22

HPDs in use

HPDs fulfil or exceed all requirements for the LHCb RICH

Excellent performance demonstrated in testbeam scenarios

Ring from Pions, over 3 HPDs

124k events, with C4F10

Fre

qu

en

cy

, th

ou

sa

nd

s o

f e

ve

nts

Hit spectrum, 124k events

Hit Count in expected region of ring for 1 HPD

signal

pedestaland noise

PRELIMINARYIn agreement withexpected yields

Page 23: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 23

HPD Integration

HPDs -> Columns+ Magnetic Sheilds+ Level-0 Data Processing+ LV power distribution+ HV power distribution

HPD

L0

LV

HV

Page 24: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 24

RICH 2 Installation

Page 25: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 25

Summary

484 HPDs are required for the LHCb RICH

536 HPDs have now been produced 519 tested at PDTF with 506 passes Excellent results overall 24% relative improvement in QE will directly improve photon yields

RICH is now under installation and commissioning RICH 2 fully populated with HPDs

LHCb is getting ready for data….

Page 26: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 26

References

1. LHCb collaboration, LHCb Technical Proposal, CERN-LHCC-98-004 LHCb, 20th February 1998

2. LHCb collaboration, LHCb RICH, Technical Design Report 3, CERN-LHCC-2000-037 LHCb, 7th September 2000

3. T. Gys, LHCb RICH, “Production of 500 pixel hybrid photon detectors for the RICH counters of the LHCb,” NIM A 567 (2006), pp. 176-179

Page 27: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 27

Backup

Additional slides hereafter

Page 28: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 28

Physics and Photons

RICH crucial to separate Kaons and Pions [1] Similar hadrons, different in mass Contribute to different physics Important to separate

Signal Bd +-

Page 29: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 29

HPDs Realised

Hybrid Photon Detectors

Quartz window

thin metal Photocathode (S20)

20kV acceleratingpotential

Photoelectric effectproduces electrons

Pixelated anode8192 pixels

500 m x 62.5 m

Amplifier, Thresholder, Buffer, Read out

87 mm

120

mm

Page 30: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 30

HPD Production

HPD production status as of 18th June 2007

0

100

200

300

400

500

600

700

1-Jan-05 1-Apr-05 1-Jul-05 30-Sep-05 30-Dec-05 31-Mar-06 30-Jun-06 29-Sep-06 29-Dec-06 30-Mar-07 29-Jun-07

Qua

ntiti

es

HPDs required

HPDs delivered

Anodes required

Anodes delivered

Spare HPDs required

Spare anodes required

Anodes

HPDs

536 / 550 HPDs Produced

18th June 2007

Page 31: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 31

HPD tests at PDTFs - 15th May 2007

0

100

200

300

400

500

600

01/10/05 30/01/06 31/05/06 29/09/06 28/01/07 29/05/07

Date

# o

f H

PD

s

Delivered Scotland

+30 days

+60 days (~contract limit)

Scheduled

Total tested

PDTF Progress

15th May 2007

519 / 550 HPDs tested

Page 32: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 32

QE at PDTF

Uses existing Darkbox PC at -100V, focussing cathodes at -100V, Anode at ground

Quartz-tungsten halogen lamp

(6V, 50 W)LOT Oriel

Fused silica lensf = 50 mm,

diam. = 25.4 mm

IR-blocking filter(Schott KG-5)

bandpass filter (+- 10 nm FWHM)

lamp housing

Calibrated photodiode(Newport 818-UV unbiased)

HPD

hq(HPD) = hq

(pd) * I(HPD) / I

(pd)

I pd (pA) I HPD (pA)

ND filter (where required)

Shutter/iris combination

Shutter/iris combination

100V

RL

Page 33: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 33

HPD categories

150

260

5640

13

0

50

100

150

200

250

300

A+ A B E F

Fre

qu

en

cy

, HP

Ds

Results Summary

HPD Quality Assurance 506 of 519 tubes pass

A+: Exceeds key specifications. A specifically recommended HPD

A: Pass all aspects of tests

B: Falls beneath contracted specifications, but still recommended for use in the RICH

E: HPD qualified for use in the RICH, but is flagged with an issue

F: Clear failure of HPD, such that it is unusable in the RICH. HPD returned to DEP if possible for replacement

HPDswith higherdarkcount

HPDs with high leakage current and with >1% dead pixels

Page 34: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 34

HPD electron optics

Reliable manufacture 73% of centres within 1 pixel of chip centre standard deviation of image size ~ ¼ pixel

Distribution of image centres

-1500

-1000

-500

0

500

1000

1500

-1500 -1000 -500 0 500 1000 1500

X Deviation from centre of Chip [m]

Y D

ev

iati

on

fro

m c

en

tre

of

ch

ip [

m]

Image Radii

0

10

20

30

40

50

60

70

80

90

100

6000 6150 6300 6450 6600 6750 6900 7050 7200

Image Radius [m]

Fre

qu

en

cy

, HP

Ds

1 Pixel

Page 35: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 35

Peak QE

QE peaks at ~270 nm Consistent improvement of QE with batch, All production HPDs are over specifications

<QE> @ 270 nm (per batch)

25

27

29

31

33

35

37

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22batch no.

av

era

ge

QE

at

27

0n

m [

%]

<QE(270nm)> per batch

running <QE(270nm)>

Peak Quantum Efficiency

0

10

20

30

40

50

60

70

80

90

100

20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0 38.0

QE at 270 nm [%]

Fre

qu

en

cy

, HP

Ds

ContractMinimum20.0%

<QE> = 30.9%

Page 36: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 36

Backpulse

Efficiency of hit detection, hSi

Pixel chip efficiency important for reconstruction Probability that the chip registers a hit, given a photoelectron has struck Comparing the number of photoelectrons seen by the chip (via normal

chip readout) to the number arriving at the backplane of the Si sensor.

We measure: hsi = (87±2)%.

Fit to charge spectrum at backplane

1 electron

2 electrons3 electrons

4 electrons

5 electrons

Page 37: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 37

Afterpulse

Ion Feedback from Strobe Scan Consistently low, indicating excellent vacuum in all tubes Single HPD, H546002, displayed IFB and dark-count anomalies

Strobe Scan H524004

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 100 200 300 400 500

Delay [ns]

Hit

s P

er

Ev

en

t

Raw hits

Clusters

Poisson estimate

Ion Feedback x 100

Very low IFB <<1%

Delayed Ion Feedback

0

50

100

150

200

250

300

350

400

450

500

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Ion-feedback [% of peak # of photoelectrons]

Fre

qu

en

cy

, HP

Ds Specification

< 1%

<IFB> = 0.03%

Page 38: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 38

Source Sites

HPD sourced from around the world !

Item Source Location Test Location

Readout Wafer IBM France CERN Switzerland

Sensor Canberra Belgium CERN Switzerland

Carrier Kyocera Japan CERN Switzerland

Gold Plating CERN Switzerland CERN Switzerland

Bump-Bonding VTT Finland CERN Switzerland

Packaging HCM France CERN Switzerland

Quartz Window China, Lithuania

Assembly DEP Holland PDTF Scotland

Page 39: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 39

QW Reflections

As predicted by naïve CAD approximations 75% of light reflected off Chromium coating TIR at QW-Air interface ~20% reflection at QW-PC interface

Page 40: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 40

Reflective Effects

Activating QW reflections and Chromium reflections 8.0% more hits (naïve estimate would predict ~11%)

Improved Geometrical Description

1.5 M events, 4,992,419 Hits

Reflections Activated

1.5 M events, 5,393,100 Hits

Page 41: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 41

Backscatter

Only ~85% of all real photoelectrons produce digital hits Thermal effects Thresholding effects Backscatter effects

+ ++

--

-+ -- +

- + - +

Normal Case~5000 e-h pairs

Thermal absorptionv. few e-h pairs, Damage to lattice

Charge Sharing.<5000 e-h pairsper pixel

Backscatter.Smaller amountof energy deposited

Electron “may”Fall back ontoSi sensor

Si Sensor

Page 42: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 42

RICH in UV

Below 200 nm photon yield is limited by absorption of air

Transmittance, Absorption and QE

0.1

1

10

100

1000

100 1000Wavelength [nm]

Ab

sorp

tion

[cm

-1] .

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Tra

nsm

itta

nce

or

QE

[no

un

its] .

Absorption Water (/cm)Absorption Oxygen (/cm)Transmittance window HPDMean QE prototype pixel HPDAerogel Filter

Page 43: R Lambert, LHCb RICHPD07, 28th June 20071 The LHCb Pixel Hybrid Photon Detectors Robert W. Lambert, University of Edinburgh On behalf of the LHCb RICH

R Lambert, LHCb RICH PD07, 28th June 2007 43

Expected Spectra

Folding in the expected QE

Cherenkov spectrum for RICH radiators

RICH 1, C4F10 RICH 2, CF4 RICH 1, Aerogel

Wavelength [nm]

Ch

ere

nk

ov

Ph

oto

ns