Presentation is loading. Please wait.

Presentation is loading. Please wait.

Performance of the LHCb Vertex Locator Thomas Latham (on behalf of the LHCb VELO group) 11/06/20111TIPP 2011 - Chicago.

Published byHilda Gilbert Modified over 7 years ago

Similar presentations

Presentation on theme: "Performance of the LHCb Vertex Locator Thomas Latham (on behalf of the LHCb VELO group) 11/06/20111TIPP 2011 - Chicago."— Presentation transcript:

1 Performance of the LHCb Vertex Locator Thomas Latham (on behalf of the LHCb VELO group) 11/06/20111TIPP 2011 - Chicago

2 Introduction to LHCb 11/06/2011TIPP 2011 - Chicago2 LHCb is a dedicated experiment for flavour physics at the LHC, in particular: – Study of CP violation in beauty and charm decays – Search for New Physics in loop processes – Complementary to direct searches at ATLAS and CMS Detector requirements: Efficient trigger for leptonic and hadronic final states Excellent vertex finding ability Extremely good tracking efficiency and particle identification

3 The LHCb detector 11/06/2011TIPP 2011 - Chicago3 Interaction Point in the VELO LHCb σ(pp → H b X) = ( 75 ± 5 ± 13 ) µb Phys. Lett. B 694, 209-216 (2010) Angular acceptance: 15 mrad < θ < 250 mrad

4 The Role of the VELO 11/06/2011TIPP 2011 - Chicago4 b-hadrons have lifetime of O(10 -12 )s Relativistic boost means average flight distance of ~1cm VELO has to precisely locate both primary and secondary vertices Forms essential part of higher level trigger Also a principal tracking device

5 VELO Design 2 retractable detector halves 11/06/2011TIPP 2011 - Chicago5

6 VELO Design 2 retractable detector halves 11/06/2011TIPP 2011 - Chicago6

7 VELO Design 2 retractable detector halves 21 modules (+ 2 pile-up) per half Each module has r and φ sensor Detectors in secondary vacuum 11/06/2011TIPP 2011 - Chicago7

8 VELO Design 2 retractable detector halves 21 modules (+ 2 pile-up) per half Each module has r and φ sensor Detectors in secondary vacuum Separated from LHC vacuum by 300µm foil Foil also guards against RF pickup from beam 11/06/2011TIPP 2011 - Chicago8

9 Sensor Design 11/06/2011TIPP 2011 - Chicago9 2 semi-circular sensor designs – r and φ measuring 300µm n-on-n silicon 2048 strips per sensor 8.2mm inner radius of active silicon Cooled by evaporative CO 2 system – Operating temperature of -30°C

10 VELO Views 11/06/2011TIPP 2011 - Chicago10 Beam-eye view of open VELO Close-up of RF foil VELO modules

11 VELO Performance! 11/06/2011TIPP 2011 - Chicago11

12 Signal and Noise 11/06/2011TIPP 2011 - Chicago12 Overall S/N as per design, > 20 Noise on strips increases with strip length, hence with radius of r strips Noise levels also differ between 3 different types of φ strips: – inner – routed over outer strips – outer – w/ overlaid routing lines – outer – no overlaid routing lines

13 Spatial Alignment 11/06/2011TIPP 2011 - Chicago13 VELO moved for each LHC injection Precise knowledge of alignment critical for lifetime measurements Proceeds in 3 stages: – Sensors within modules – Module to module within half – Inter-half alignment Uses residuals from track fit Module and sensor alignment known to better than 4µm Inter-half stable over time to better than 5µm

14 Hit Resolution 11/06/2011TIPP 2011 - Chicago14 Measure residual of cluster to track made without that cluster Correct for track uncertainty Bin in both strip pitch and projected track angle Best resolution < 4µm !

15 Primary Vertex Resolution 11/06/2011TIPP 2011 - Chicago15 Randomly split tracks into two sets Fit two vertices and measure their separation With 25 tracks per vertex: – x resolution = 13.1µm – y resolution = 12.5µm – z resolution = 71.1µm Approaching design levels

16 Impact Parameter Resolution 11/06/2011TIPP 2011 - Chicago16 IP = distance of closest approach of track to PV Important variable for identifying long lived particles such as B mesons Contributions from PV and hit resolutions plus multiple scattering IP resolution improved with data based alignment Some disagreement with simulation remains – Under investigation Preliminary

17 Material Budget 11/06/2011TIPP 2011 - Chicago17 Use detector model in simulation to estimate material budget Total material budget 0.221X 0 Material before 1 st measurement 0.032X 0

18 Self Imaging 11/06/2011TIPP 2011 - Chicago18 Use vertices of hadronic interactions with material to map VELO Requires precise vertex measurements – Exactly what VELO was designed for! Key features (sensors, RF foil etc.) stand out clearly Preliminary comparisons between data and MC indicate good agreement

19 Velo Radiation Damage Studies LHCb VELO HOT! First Strip only 8mm from LHC beam Outer strip 40mm Maximum Fluence predicted at 14TeV 1.3x10 14 1MeV n eq /cm 2 /2 fb -1 Strongly non-uniform dependence on 1/r 1.9 and station (z) Clear observation of radiation damage IV, CCE, noise versus voltage Annealed at 20 C over shutdown n-on-n sensor Noise vs Voltage Obtained from CCE vs Voltage 11/06/201119TIPP 2011 - Chicago

20 Summary VELO has operated extremely well from day one Operations becoming smoother over time Performance is close to design parameters – Best hit resolution < 4µm – best at LHC! Improvements already made based on 2010 data will reap further benefits for the LHCb physics programme this year Outlook: – Still some room for improvements – work ongoing – Challenges to come from radiation damage First evidence for radiation damage now seen – Replacement VELO under construction 11/06/2011TIPP 2011 - Chicago20

21 BACKUP 11/06/2011TIPP 2011 - Chicago21

22 Time Alignment Nominal LHC bunch spacing 25ns Fine tune timings of front end chips Aim for – Maximum signal/noise – Minimum spillover Sensors individually tuned to account for differences in – Time of flight – Cable length 11/06/2011TIPP 2011 - Chicago22

23 Cluster Finding Efficiency 11/06/2011TIPP 2011 - Chicago23 Only 1 bad chip out of 1344! Efficiency generally extremely good Most inefficiencies understood

24 Velo Radiation Damage Studies Tips of VELO sensors expected to type invert in next months of LHC running LHCb VELO HOT! Middle station Far station TDR Prediction First Strip only 8mm from LHC beam Outer strip 40mm Maximum Fluence predicted at 14TeV 1.3x10 14 1MeV n eq /cm 2 /2 fb -1 Strongly non-uniform dependence on 1/r 1.9 and station (z) 11/06/201124TIPP 2011 - Chicago

25 Velo Radiation Damage Monitoring 1.Current vs applied bias Voltage (IV) -Taken weekly -Current increases with bulk damage, linearly related to fluence -Does not study depletion voltage 2.Noise vs applied bias Voltage -Taken monthly -Sensors decrease capacitance and hence noise when depleted, so sensitive to depletion voltage at least during early running 3.Charge Collection Efficiency vs applied bias voltage -Direct measure of physics relevant parameter -Can study rad. damage as function of position -Requires beam data so only taken a few times per year -April 2010 (~0), April 2011 (40 pb -1 ) Expectation: Depletion voltage of VELO sensors around 40-80V originally. Depletion voltage decreases with fluence till type inversion 11/06/201125TIPP 2011 - Chicago

26 IV Studies Example sensors showing bulk damage Annealed at 20 C over shutdown n-on-n sensor VELO n-on-n, contains one n-on-p module 11/06/201126TIPP 2011 - Chicago

27 Noise vs Voltage Measure voltage required to get noise to reduce by a specified fraction of the total depleted/undepleted change in noise Outermost strips on R sensor less irradiation Ratio ~ 1, i.e. no change in V (noise min) Innermost strips on R sensor most irradiation Ratio < 1, i.e. change in V(noise min) 11/06/201127TIPP 2011 - Chicago

28 Charge Collection Efficiency (CCE) Blue – tracking sensors – at full bias voltage Red – test sensors – bias voltage ramped – 10V steps, 0V-150V – Rotate through patterns, fully automatic scan procedure Tracks fitted through tracking sensors – Charge collected at intercept point on test sensors measured as function of voltage Non-zero suppressed data taken so full charge recorded – Can study regions of sensor 11/06/201128TIPP 2011 - Chicago

29 Charge collection efficiency vs Voltage measured. Voltage at which CCE is 80% extracted 80% chosen as gives best agreement unirradiated with depletion Here, averaged over all sensors, there is dependence of fluence on Z position Region sizes chosen so that fluence varies by factor two in each region Fluence expected to change as 1/r^{1.9} Errors on plot are error on mean from all sensor average Charge Collection Efficiency (CCE) 11/06/201129TIPP 2011 - Chicago

30 Same info. plotted for all regions, all modules Lines are fits to all modules 11/06/201130TIPP 2011 - Chicago

Download ppt "Performance of the LHCb Vertex Locator Thomas Latham (on behalf of the LHCb VELO group) 11/06/20111TIPP 2011 - Chicago."

Similar presentations

LHCb Alignment 12 th April 2007 S. Viret Coseners Forum « LHC Startup » 1. Introduction 2. The alignment challenge 3. Conclusions.

LHCb Alignment 12 th April 2007 S. Viret Coseners Forum « LHC Startup » 1. Introduction 2. The alignment challenge 3. Conclusions.
Impact parameter studies with early data from ATLAS

Impact parameter studies with early data from ATLAS
IAP-PAI 25/05/20051 CMS Si Rad. Hardness Introduction Damage in Si Neutron tests => Beam => Irrad. Setup.

IAP-PAI 25/05/20051 CMS Si Rad. Hardness Introduction Damage in Si Neutron tests => Beam => Irrad. Setup.
June 6 th, 2011 N. Cartiglia 1 “Measurement of the pp inelastic cross section using pile-up events with the CMS detector” 1 2 4 3 8 5 6 7 How to use pile-up.

June 6 th, 2011 N. Cartiglia 1 “Measurement of the pp inelastic cross section using pile-up events with the CMS detector” How to use pile-up.
Jet and Jet Shapes in CMS

Jet and Jet Shapes in CMS
Solid State Detectors- 4 T. Bowcock 2 Schedule 1Position Sensors 2Principles of Operation of Solid State Detectors 3Techniques for High Performance Operation.

Solid State Detectors- 4 T. Bowcock 2 Schedule 1Position Sensors 2Principles of Operation of Solid State Detectors 3Techniques for High Performance Operation.
LHC SPS PS. 46 m 22 m A Toroidal LHC ApparatuS - ATLAS As large as the CERN main bulding.

LHC SPS PS. 46 m 22 m A Toroidal LHC ApparatuS - ATLAS As large as the CERN main bulding.
For high fluence, good S/N ratio thanks to: Single strip leakage current I leak  95nA at T  -5C Interstrip capacitance  3pF SVX4 chip 10 modules fully.

For high fluence, good S/N ratio thanks to: Single strip leakage current I leak  95nA at T  -5C Interstrip capacitance  3pF SVX4 chip 10 modules fully.
Striplet option of Super Belle Silicon Vertex Detector Talk at Joint Super B factory workshop, Honolulu 20 April 2005 T.Tsuboyama.

Striplet option of Super Belle Silicon Vertex Detector Talk at Joint Super B factory workshop, Honolulu 20 April 2005 T.Tsuboyama.
1 The LHCb Vertex detector 15/9/2003 Physics –Goals –Properties and consequences LHCb –Overview of the detector Vertex –Specifications –Silicon stations.

1 The LHCb Vertex detector 15/9/2003 Physics –Goals –Properties and consequences LHCb –Overview of the detector Vertex –Specifications –Silicon stations.
Jornadas LIP, Dez. 2005 P. Martins - CFTP-IST The NA60 Silicon Vertex Telescopes Dimuon measurements Dimuon measurements Vertex telescope used in: Vertex.

Jornadas LIP, Dez P. Martins - CFTP-IST The NA60 Silicon Vertex Telescopes Dimuon measurements Dimuon measurements Vertex telescope used in: Vertex.
The ATLAS Pixel Detector - Running Experience – Markus Keil – University of Geneva on behalf of the ATLAS Collaboration Vertex 2009 Putten, Netherlands,

The ATLAS Pixel Detector - Running Experience – Markus Keil – University of Geneva on behalf of the ATLAS Collaboration Vertex 2009 Putten, Netherlands,
Jeroen van Hunen The LHCb Tracking System. May 22, 2006 Frontier Detectors for Frontier Physics, Elba, 2006. Jeroen van Huenen 2 The LHCb Experiment LHCb.

Jeroen van Hunen The LHCb Tracking System. May 22, 2006 Frontier Detectors for Frontier Physics, Elba, Jeroen van Huenen 2 The LHCb Experiment LHCb.
1 Performance of the LHCb VELO Outline LHCb Detector and its performance in Run I LHCb Detector and its performance in Run I LHCb VELO LHCb VELO VELO performance.

1 Performance of the LHCb VELO Outline LHCb Detector and its performance in Run I LHCb Detector and its performance in Run I LHCb VELO LHCb VELO VELO performance.
Radiation Damage in the CMS Strips Tracker Christian Barth on behalf of the CMS Tracker Collaboration.

Radiation Damage in the CMS Strips Tracker Christian Barth on behalf of the CMS Tracker Collaboration.
Tracking at LHCb Introduction: Tracking Performance at LHCb Kalman Filter Technique Speed Optimization Status & Plans.

Tracking at LHCb Introduction: Tracking Performance at LHCb Kalman Filter Technique Speed Optimization Status & Plans.
Martin van Beuzekom, STD6 14 th September 20061 Outline: Introduction to LHCb and VErtex LOcator (VELO) Status of VELO Beamtests Upgrades Summary LHCb.

Martin van Beuzekom, STD6 14 th September Outline: Introduction to LHCb and VErtex LOcator (VELO) Status of VELO Beamtests Upgrades Summary LHCb.
G. Eigen, LISHEP2011, Rio de Janeiro, July 5 th, 20112 Outline Introduction Introduction ATLAS detector and performance Vertex and impact parameter resolution.

G. Eigen, LISHEP2011, Rio de Janeiro, July 5 th, Outline Introduction Introduction ATLAS detector and performance Vertex and impact parameter resolution.
The LHCb VErtex LOcator Olaf Behrendt on behalf of the VELO group Novosibirsk, 29.02.08.

The LHCb VErtex LOcator Olaf Behrendt on behalf of the VELO group Novosibirsk,
Chris Parkes First results from the LHCb Vertex Locator Act 1: LHCb Intro. Act 2: Velo Design Act 3: Initial Performance for LHCb VELO groupVienna Conference.

Chris Parkes First results from the LHCb Vertex Locator Act 1: LHCb Intro. Act 2: Velo Design Act 3: Initial Performance for LHCb VELO groupVienna Conference.

Similar presentations

Ads by Google