Martin van Beuzekom, STD6 14 th September 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

Martin van Beuzekom, STD6 14 th September 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

Martin van Beuzekom, STD6 14 th September 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)

Martin van Beuzekom, STD6 14 th September 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)

Martin van Beuzekom, STD6 14 th September 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

Martin van Beuzekom, STD6 14 th September 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

Martin van Beuzekom, STD6 14 th September 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 – MHz = 80 Gbit/sec –Special hybrids (4 times #signals)

Martin van Beuzekom, STD6 14 th September 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

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

Martin van Beuzekom, STD6 14 th September 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

Martin van Beuzekom, STD6 14 th September 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

Martin van Beuzekom, STD6 14 th September Testbeam performance 2004: Single sided module with 200  m sensor Characterized (final) sensor + (final) Beetle S/N 16 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 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

Martin van Beuzekom, STD6 14 th September 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 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

Martin van Beuzekom, STD6 14 th September 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 1x > 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)

Martin van Beuzekom, STD6 14 th September 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

Martin van Beuzekom, STD6 14 th September 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

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

Martin van Beuzekom, STD6 14 th September Reduce material in VELO BTeV planned sensors in primary vacuum Beam (mirror) current via wires/strips Cryo pumping against outgassing Totem 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

Martin van Beuzekom, STD6 14 th September 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