Pixel 2000 Pixel 2000 I nt ernat ional Workshop on 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 The pixel hybrid photon detectors The pixel hybrid photon detectors f or the LHCb LHCb- RI CH project - RI CH project f or the Thierry GYS Thierry GYS On behalf of the LHCb LHCb- RI CH group - RI CH group On behalf of the CERN, Geneva, Switzerland CERN, Geneva, Switzerland 1
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 � T. Gys - Pixel 2000 2
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 ht t p:/ / lhcb.cern.ch/ geomet ry/ images/ lhcb-x.gif 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 T. Gys - Pixel 2000 3
The RI CH 1 counter The RI CH 1 counter Aerogel Schemat ic view ht t p:/ / lhcb.cern.ch/ rich/ images/ rich1_schemat ic.gif Mechanical design st udies I mperial College London G. Barber et al. T. Gys - Pixel 2000 4
The RI CH 2 counter The RI CH 2 counter Photo I NFN Genova Schemat ic S. Cuneo et al. detectors view Flat mirror Mechanical Spherical design st udies mirror CERN EP-TA2 P. Wicht et al. ht t p:/ / lhcb.cern.ch/ rich/ images/ rich2_schemat ic.gif T. Gys - Pixel 2000 5
Overall RI CH system Overall RI CH system requirements requirements � Phot on det ect ion Phot on det ect ion � � ~2.9 m 2 t ot al surf ace � Granularit y: 2.5 × 2.5 mm 2 � Act ive area coverage ≥ 70 % (~325’000 channels) � Single-phot on sensit ivit y ( λ = 200-600 nm) � Environment Environment � ≤ 30 gauss (RI CH1) � Magnet ic st ray f ield: ≤ 100 gauss (RI CH2) ≤ 3 kRad/ year � Radiat ion dose: � Read-out Read-out � ≤ 10 % � Maximum occupancy: � BCO ident if icat ion ( τ p ≈ 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 T. Gys - Pixel 2000 6
Pixel- HPD description Pixel- HPD description Schemat ic view ht t p:/ / www.cern.ch/ ~gys/ LHCb/ PixelHPDs.ht m 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 µ m PSF (~250 µ m 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 µ m × 500 µ m each) Encapsulat ed binary elect ronics readout chip T. Gys - Pixel 2000 7
Full- scale 61- pixel Full- scale 61- pixel HPD prototypes HPD prototypes Manuf act ured by DEP B.V. (The Net herlands) 3D schemat ic view ht t p:/ / www.dep.nl/ prodline/ a182.j pg Act ual prot ot ype ht t p:/ / www.cern.ch/ ~gys/ LHCb/ PixelHPDs.ht m 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 T. Gys - Pixel 2000 8
Full- scale 61- pixel Full- scale 61- pixel HPD prototypes (cont’d cont’d) ) HPD prototypes ( Laborat ory measurement s Laborat ory measurement s Pulsed LED spect rum E. Albrecht et al. NI M A 442 (2000) 164 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 ( τ p =1.2 µ s) (E. Albrecht et al., NI M A 411 (1998) 249) E- opt ics perf ormance: E- opt ics perf ormance: Conf irmed T. Gys - Pixel 2000 9
Full- scale 61- pixel Full- scale 61- pixel HPD prototypes (cont’d cont’d) ) HPD prototypes ( Beam t est s Beam t est s Full-scale RI CH1 prot ot ype ht t p:/ / lhcb.cern.ch/ rich/ images/ RI CH_prot o_layout _pixel_clust er.gif E. Albrecht et al. NI M A 442 (2000) 164 61-pixel HPD clust er ht t p:/ / www.cern.ch/ ~gys/ LHCb/ PixelHPDs.ht m T. Gys - Pixel 2000 10
Full- scale 61- pixel Full- scale 61- pixel HPD prototypes (cont’d cont’d) ) HPD prototypes ( Accumulat ed Cherenkov Cherenkov rings rings Accumulat ed E. Albrecht et al. NI M A 442 (2000) 164 Tube f igure of merit : Tube f igure of merit : N 0 ≈ 225-250 cm -1 T. Gys - Pixel 2000 11
Ceramic carrier designs Ceramic carrier designs 1st HPD prot ot ype: 1st HPD prot ot ype: Commercial 61-pixel anode Ext ernal VA2 readout ( τ p = 1.2 µ s) ~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 ( τ p = 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) T. Gys - Pixel 2000 12
Ceramic carrier designs Ceramic carrier designs (cont’d cont’d) ) ( Manuf act ured by Kyocera (J apan) Cust om Pin Grid Array carrier f or t he ALI CE- LHCb chip ALI CE-LHCb chip wit hin carrier cavit y ~100 f inger bond pads (out of 360) used T. Gys - Pixel 2000 13
Binary f ront end electronics Binary f ront end electronics (baseline specif ications) (baseline specif ications) Full readout chip 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) Super-pixel 500 µ m × 500 µ m area 10 sub-pixels ORed t oget her Digit al FE elect ronics: •20 delay lines (4 µ s) •16-deep FI FO de-randomizing buf f er ⇒ reduced occupancy seen by analogue FE and lower noise Sub-pixel 50 µ m × 500 µ m 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 ) ht t p:/ / nicewww.cern.ch/ ~lebwshop/ LEB99_Book/ Tracker/ Wyllie.pdf See also cont ribut ion of W. Snoeys (t his workshop) T. Gys - Pixel 2000 14
Expected detection ef f iciency Expected detection ef f iciency Pedest al Cut Signal •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 T. Gys - Pixel 2000 15
Back- scattering and Back- scattering and charge sharing ef f ects charge sharing ef f ects Charge sharing 7 µ m RMS lat eral spread (300 µ m-t hickness, 90 V bias) Not signif icant if E cut < E 0 / 2 Back-scat t ering 18% probabilit y < E> = E 0 / 2 Reduced ef f ect if low cut T. Gys - Pixel 2000 16
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) T. Gys - Pixel 2000 17
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