1. Martin van Beuzekom, STD6 14 th September 20061 Outline: Introduction to LHCb and VErtex LOcator (VELO) Status of VELO Beamtests Upgrades Summary LHCb Vertex Locator: present and future Martin van Beuzekom On behalf of the LHCb VELO group Liverpool University

2. Martin van Beuzekom, STD6 14 th September 20062 LHCb overview Large Hadron Collider pp collisions: √s = 14 TeV bunch crossing every 25 ns LHCb Studies physics of b-flavoured hadrons (CP violation) B-hadrons produced at small angles –-> Single arm forward spectrometer 10 – 300 (250) mrad in bending plane (non bend.) Luminosity 2·10 32 cm -2 s -1 interaction region

3. Martin van Beuzekom, STD6 14 th September 20063 Vertex Locator 2 retractable detector halves –Range 3 cm each 23 silicon microstrip modules / side Silicon modules in secondary vacuum Modules separated from beam vacuum (10 -9 ) by 300  m Alu foil (RF box) –Maximum allowed diff. pressure 5 mbar –Shield against beam induced EMI Innermost strip 8 mm from beam (2 mm)

4. Martin van Beuzekom, STD6 14 th September 20064 Silicon sensor details 42 mm 8 mm 300  m thick sensors n-on-n, DOFZ wafers 42 mm radius AC coupled, double metal 2048 strips / sensor Pitch from 40 to 100  m Produced by Micron Semiconductor  -measuring sensor (radial strips with a stereo angle) R-measuring sensor (45 degree circular segments)

5. Martin van Beuzekom, STD6 14 th September 20065 Module construction Kapton hybrid Carbon fibre Thermal Pyrolytic Graphite (TPG) 4 layer kapton circuit Heat transport with TPG Readout with 16 Beetle chips 128 channels, 25 ns shaping time, analog pipeline 0.25  m CMOS no performance loss up to 40 Mrad Yield > 80 % Beetle

6. Martin van Beuzekom, STD6 14 th September 20066 Silicon microstrip modules 21 stations with R-  geometry –Fast R-Z tracking in trigger farm –Overlap of right and left det. halves –Total of 176k strips 2 stations with R-sensor for PileUp trigger VELO sensors PileUp sensors RF-foil Fine pitch kapton cables Carbon fibre base

7. Martin van Beuzekom, STD6 14 th September 20067 n = # pp interactions/crossing Pile Up (veto) trigger LHCb luminosity PileUp system detects multiple interactions Vetoes Level-0 trigger –Increases physics output –Multiple interactions complicate Level-1 trigger (CPU-farm) Factor 3 reduction in #crossings with multiple interactions 2 R-sensors, prompt binary readout –Combine 4 strips in 1 to reduce # inputs –2048 “bits” @ 40 MHz = 80 Gbit/sec –Special hybrids (4 times #signals)

8. Martin van Beuzekom, STD6 14 th September 20068 PileUp continued Each vertex bin corresponds to a small wedge in the R A -R B correlation plot Each “track” is represented by a point Histogramming of Z-vertex –determine # vertices with FPGAs –find 1 st peak, mask hits, find 2 nd peak –Algorithm highly pipelined ( ~ 80 Bunch crossings) true tracks all combinations 2 vertices

9. Martin van Beuzekom, STD6 14 th September 20069 LHCb status Installation progressing, first collisions expected in fall 2007

10. Martin van Beuzekom, STD6 14 th September 200610 Status @ Interaction point Vacuum vessel installed May 2006 –Vacuum controlled by PLC –Movement system controlled by PLC Thin (2 mm) exit foil mounted in Aug 2006 Vacuum qualification ongoing Detector installation early 2007

11. Martin van Beuzekom, STD6 14 th September 200611 CO 2 cooling T=-30 ºC T ~ -5 ºC 2 phase CO2 cooling system Low mass Radiation hard Non toxic Silicon modules in parallel 1 mm Ø stainless steel capillaries Pressure up to 70 bar Large  T over TPG + interface heat load max. 30W

12. Martin van Beuzekom, STD6 14 th September 200612 Testbeam performance 2004: Single sided module with 200  m sensor Characterized (final) sensor + (final) Beetle S/N 16 Spillover @25 ns < 25 % Resolution ~4  m November 2006 Aim for a complete detector half (21 mod.) Module production in Liverpool at full speed Delivery 4 modules per week Major effort! August 2006 3 double sided modules Full electronics chain with final electronics ADCs, Timing, Fast & Slow Control Data taken for many sensor and chip settings Analysis ongoing Beetle Frontend pulseshape

13. Martin van Beuzekom, STD6 14 th September 200613 VELO Upgrades Why: Limited lifetime of VELO due to high radiation dose –( 1.3x10 14 n eq /cm 2 /year) Improve (impact parameter) resolution –Displaced vertex trigger Increase statistics –Readout of complete LHCb detector @ 40 MHz How: Different sensor technology/geometry Reduce material in VELO Move closer to beam –Currently 8 mm, goal 5 mm (min. allowed by accelerator ) –Up to 36% resolution improvement Increase luminosity (not SLHC) –Level-1 computing power

14. Martin van Beuzekom, STD6 14 th September 200614 Radiation environment Radiation environment for current design Strongly non-uniform Dependence on radius and z-position Max fluence 1.3x10 14 n eq /cm 2 /year Define as 1 LHCb-year Expected (useful) lifetime ~3 years assuming nominal luminosity no accidents Far station Middle station With upgrades 5 mm strip radius -> 2.5x increase Luminosity to 1x10 33 -> 5x increase Fluence 1.7x10 15 n eq /cm 2 /year Only possible with Different sensor technology and/or smaller strips or pixels (Syracuse group)

15. Martin van Beuzekom, STD6 14 th September 200615 Radiation Hard Technologies 5..6 LHCb-years p-on-n MCz Assume required CCE min. 60 % Single sided processing R&D by Glasgow group Magnetic Czochralski

16. Martin van Beuzekom, STD6 14 th September 200616 Radiation Hard Technologies- II n-on-p Presentation by Gian-Luigi Casse > 20 LHCb-years High resistivity p-silicon Single sided processing Very high bias voltage R&D by Liverpool group

17. Martin van Beuzekom, STD6 14 th September 200617 Radiation Hard Technologies- III 3D - sensors Extremely radiation hard Low bias voltage Very promising Complex processing R&D by Glasgow group

18. Martin van Beuzekom, STD6 14 th September 200618 Reduce material in VELO BTeV planned sensors in primary vacuum Beam (mirror) current via wires/strips Cryo pumping against outgassing Totem (@LHC) 150  m Inconel (Ni-Cr) foil 1 mm from beam Radiation length of total VELO: 19 % X 0 Largest contribution from RF-foil and sensors Thin sensors (200  m) already tested extensively Thinner RF-foil is under investigation

19. Martin van Beuzekom, STD6 14 th September 200619 Summary Construction of LHCb VErtex LOcator is well underway –Mechanics, vacuum, motion system installed –Cooling system steadily progressing –Silicon module production at full speed Next deadline is half detector for November testbeam –Detector (sensors) installation early 2007 Already starting to think about upgrades –Limited lifetime of VELO –More radiation hard sensors –Reduce material to improve performance