The pixel hybrid photon detectors The pixel hybrid photon detectors - - PDF document

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The pixel hybrid photon detectors The pixel hybrid photon detectors f or the f or the LHCb LHCb- RI CH project

• RI CH project

Thierry GYS Thierry GYS On behalf of the On behalf of the LHCb LHCb- RI CH group

• RI CH group

CERN, Geneva, Switzerland CERN, Geneva, Switzerland

Pixel 2000 Pixel 2000

I nt ernat ional Workshop

• n Semiconduct or Pixel Det ect ors

f or Part icles and X-Rays J une 5-8, 2000 Port o Ant ico, Genova, I t aly

• T. Gys - Pixel 2000

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Outline of the talk Outline of the talk

• I nt roduct ion

I nt roduct ion

The LHCb det ect or The RI CH count ers Overall RI CH syst em requirement s

• The pixel hybrid phot on det ect or

The pixel hybrid phot on det ect or

Descript ion Full-scale 61-pixel HPD prot ot ypes Laborat ory and beam t est measurement s Ceramic carrier designs Binary f ront end elect ronics Expect ed det ect ion ef f iciency Back-scat t ering and charge sharing ef f ect s

• Conclusions and perspect ives

Conclusions and perspect ives

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The The LHCb LHCb detector detector (top view) (top view)

LHCb is a single-arm spect romet er wit h a f orward angular coverage f rom 10 t o 300 mrad, dedicat ed t o precision st udies of CP asymmet ries and of rare decays in t he B-meson syst em Part icle ident if icat ion over t he moment um range 1-150 GeV/ c will be achieved by t wo Ring I maging Cherenkov count ers

ht t p:/ / lhcb.cern.ch/ geomet ry/ images/ lhcb-x.gif

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The RI CH 1 counter The RI CH 1 counter

Aerogel

I mperial College London

• G. Barber et al.

ht t p:/ / lhcb.cern.ch/ rich/ images/ rich1_schemat ic.gif

Mechanical design st udies Schemat ic view

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The RI CH 2 counter The RI CH 2 counter

Spherical mirror Photo detectors Flat mirror

ht t p:/ / lhcb.cern.ch/ rich/ images/ rich2_schemat ic.gif CERN EP-TA2

• P. Wicht et al.

I NFN Genova

• S. Cuneo et al.

Mechanical design st udies Schemat ic view

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Overall RI CH system Overall RI CH system requirements requirements

• Phot on det ect ion

Phot on det ect ion

~2.9 m2 t ot al surf ace Granularit y: 2.5 × 2.5 mm2 Act ive area coverage ≥ 70 % (~325’000 channels) Single-phot on sensit ivit y (λ = 200-600 nm)

• Environment

Environment

Magnet ic st ray f ield:

≤ 30 gauss (RI CH1) ≤ 100 gauss (RI CH2)

Radiat ion dose:

≤ 3 kRad/ year

• Read-out

Read-out

Maximum occupancy:

≤ 10 %

BCO ident if icat ion (τp ≈ 25 ns) High L0-t rigger rat e (1 MHz)

• Phot o-det ect ors

Phot o-det ect ors

Pixel-HPDs: baseline solut ion

cross-f ocussing geomet ry binary pixel readout (t his t alk)

Mult i-anode PMTs: backup solut ion

met al channel dynodes analogue readout

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Main f eat ures: Main f eat ures: Close collaborat ion wit h indust ry Quart z window wit h t hin S20 pK (∫QE•dE≈0.77eV) Cross-f ocussing opt ics (t et rode st ruct ure):

• De-magnif icat ion by ~5
• 50 µm PSF (~250 µm at window level)
• Act ive diamet er 75 mm (81.7 % t ube coverage)

⇒ ~450 t ubes f or overall RI CH syst em

• 20 kV operat ing volt age (~5000 e– [eq. Si])

32×32 pixel sensor array (500 µm×500 µm each) Encapsulat ed binary elect ronics readout chip

Pixel- HPD description Pixel- HPD description

ht t p:/ / www.cern.ch/ ~gys/ LHCb/ PixelHPDs.ht m

Schemat ic view

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Full- scale 61- pixel Full- scale 61- pixel HPD prototypes HPD prototypes

Preliminary t est s at t he f act ory were sat isf act ory: Preliminary t est s at t he f act ory were sat isf act ory: 20 kV high volt age operat ion 17% QE @ λ = 400 nm Si det ect or leakage current : ≤1 nA per pixel

ht t p:/ / www.cern.ch/ ~gys/ LHCb/ PixelHPDs.ht m

Manuf act ured by DEP B.V. (The Net herlands)

ht t p:/ / www.dep.nl/ prodline/ a182.j pg

3D schemat ic view Act ual prot ot ype

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Full- scale 61- pixel Full- scale 61- pixel HPD prototypes ( HPD prototypes (cont’d cont’d) )

Single phot oelect ron response: Single phot oelect ron response: Signal-t o-noise rat io ≈ 11 @ 20 kV wit h ext ernal analogue VA2 readout (τp=1.2 µs)

(E. Albrecht et al., NI M A 411 (1998) 249)

E- opt ics perf ormance: E- opt ics perf ormance: Conf irmed Laborat ory measurement s Laborat ory measurement s

• E. Albrecht et al.

NI M A 442 (2000) 164

Pulsed LED spect rum

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Full- scale 61- pixel Full- scale 61- pixel HPD prototypes ( HPD prototypes (cont’d cont’d) )

Beam t est s Beam t est s

ht t p:/ / lhcb.cern.ch/ rich/ images/ RI CH_prot o_layout _pixel_clust er.gif ht t p:/ / www.cern.ch/ ~gys/ LHCb/ PixelHPDs.ht m

Full-scale RI CH1 prot ot ype 61-pixel HPD clust er

• E. Albrecht et al.

NI M A 442 (2000) 164

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Full- scale 61- pixel Full- scale 61- pixel HPD prototypes ( HPD prototypes (cont’d cont’d) )

Accumulat ed Accumulat ed Cherenkov Cherenkov rings rings

• E. Albrecht et al.

NI M A 442 (2000) 164

Tube f igure of merit : Tube f igure of merit : N0 ≈ 225-250 cm-1

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Ceramic carrier designs Ceramic carrier designs

1st HPD prot ot ype: 1st HPD prot ot ype: Commercial 61-pixel anode Ext ernal VA2 readout (τp = 1.2µs) ~65 f eed-t hroughs Final HPD prot ot ype: Final HPD prot ot ype: Cust om 1024-pixel anode I nt ernal binary readout (τp = 25ns) ~100 f eed-t hroughs + Bake-out compat ibilit y (5h @ 350°C) + Power dissipat ion (≤0.5 W f or binary elect ronics)

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Ceramic carrier designs Ceramic carrier designs ( (cont’d cont’d) )

Manuf act ured by Kyocera (J apan) ALI CE-LHCb chip wit hin carrier cavit y ~100 f inger bond pads (out of 360) used Cust om Pin Grid Array carrier f or t he ALI CE- LHCb chip

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Binary f ront end electronics Binary f ront end electronics (baseline specif ications) (baseline specif ications)

Full readout chip Super-pixel Sub-pixel 500µm × 500µm area 10 sub-pixels ORed t oget her Digit al FE elect ronics:

• 20 delay lines (4µs)
• 16-deep FI FO de-randomizing buf f er

⇒ reduced occupancy seen by analogue FE and lower noise 32 × 32 super-pixel array 16mm × 16mm act ive area 40MHz readout clock ⇒ ~800ns readout t ime complying wit h LHCb L0 t rigger rat e (1MHz)

ht t p:/ / nicewww.cern.ch/ ~lebwshop/ LEB99_Book/ Tracker/ Wyllie.pdf See also cont ribut ion of W. Snoeys (t his workshop)

50µm × 500µm area Analogue FE elect ronics:

• Dif f erent ial amplif ier (250 e– noise)
• Shaper (25 ns peaking t ime)
• Discriminat or (2000 e– aver.,

30 e– spread wit h 3-bit adj ust )

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Expected detection ef f iciency Expected detection ef f iciency

• Pedest al: 250 e– RMS noise
• Cut : 2000 e– aver., 30 e– RMS spread
• Signal: 5000 e– @ f ull energy

+ 18 % back-scat t ering ⇒ ~90 % det ect ion ef f iciency Pedest al Cut Signal

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Back- scattering and Back- scattering and charge sharing ef f ects charge sharing ef f ects

7µm RMS lat eral spread (300 µm-t hickness, 90 V bias) Not signif icant if Ecut< E0/ 2 Charge sharing 18% probabilit y < E> = E0/ 2 Reduced ef f ect if low cut Back-scat t ering

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Conclusions and perspectives Conclusions and perspectives

• Prot ot ype t ubes and elect ronics

Prot ot ype t ubes and elect ronics

Close collaborat ion wit h indust ry:

reliabilit y easier t ransit ion t o product ion

Binary elect ronics implies:

lower cost simpler readout archit ect ure, dat a t ransmission

and processing

• Successf ul R&D result s

Successf ul R&D result s

Elect ron opt ics provide large t ube act ive area High quant um ef f iciency phot o-cat hodes Cherenkov air and gas rings successf ully det ect ed in

var ious LHCb RI CH prot ot ypes

Test pixel elect ronics provides opt imized det ect ion

ef f iciency, same perf ormance expect ed wit h f ull chip

• Current and f ut ure R&D work

Current and f ut ure R&D work

HPD prot ot ype wit h encapsulat ed ALI CE-LHCb chip

(milest one wint er 2000)

LHCb-RI CH Technical Design Report

(submission aut umn 2000)

Final LHCb chip and ceramic carrier design

(submission spring 2001)

Final HPD prot ot ype

(complet ion wint er 2001)