Status and prospects of the LHCb Experiment

Status and prospects of the LHCb Experiment

Neville HarnewUniversity of Oxford

Beauty 2002, Santiago de Compostela

21st June 2002

On behalf of the LHCb Collaboration

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France:FR Annecy, Clermont-Ferrand, CPPM Marseille, LAL Orsay

Germany:DE Tech. Univ. Dresden, Phys. Inst. Univ. Heidelberg, KIP Univ. Heidelberg, MPI Heidelberg,

Italy:IT Bologna, Cagliari, Ferrara, Firenze, Frascati, Genoa, Milan, Univ. Rome I (La Sapienza), Univ. Rome II (Tor Vergata)

Netherlands:NL NIKHEF

Poland:PL Cracow Inst. Nucl. Phys. & Tech. Univ, Warsaw Soltan Inst.

Spain:ES Univ. Barcelona, Univ. Santiago de Compostela

Switzerland:CH Univ. Lausanne, Univ. Zürich

UK:GB Univ. Bristol, Univ. Cambridge, Univ. Edinburgh, Univ. Glasgow, IC London, Univ. Liverpool, Univ. Oxford, RAL

CERN

Brazil:BR UFRJ, CPBF

China:CN IHEP(Beijing), Tsinghua Univ.

Russia:RU BINP, INR, ITEP, IHEP, PNPI

Romania:RO IFIN-HH (Bucharest)

Ukraine:UA Inst. Phys. Tech. (Kharkov), Inst. Nucl. Research (Kiev)

Technical Espoo-Vantaa Inst. Tech. (Finland), Geneva Engineering School (Switzerland)Associates: CEFET-RJ (Brazil)

The LHCb Collaboration (45+3 institutes)

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OUTLINE

Introduction The LHCb experiment

Status of the experiment Detector optimization

LHCb-light Trigger strategy

Physics prospects Measurement of angle Importance of high statistics

Summary and conclusions

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Standard Model predicts large CP

violating asymmetries for B mesons

CP violation predicted in many (often v.rare) decays need large samples of

Bd, Bu, Bs mesons, B baryons

Need consistency checks

Physics motivation of LHCb

Unitarity TrianglesUnitarity Triangles

Bd0

Bd0

Bd0 DK*0

BS0 DSK

Bd0 D*

BS0 DS

Bd0 J/ KS

0

BS0 J/

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CP violation in 2007

|Vtd/Vts|

|Vub/Vcb|

(sin2) ~ 0.02 (world average)

(sin2) ~ 0.1 () ~ v.large ? |Vtd/Vts| from mS

by CDF & D0 limited by theory

|Vub/Vcb| from b->u by BaBar & Belle

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Advantage of LHC

bb angular distributionbb angular distribution LHC Luminosity <L>LHCb = 2 x1032 cm-2 s-

1

bb = 500 b inelastic ~ 80 mb

1012 bb / 107 s (or 1 million per 10s)

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LHCb Experiment (“classic”)

Acceptance 10 – (250) 300

mrad (non) – bending plane

Particle ID -K separation

1<p<150 GeV/c Vertexing

Proper time resolution

43 fs Bs -> Ds(K)

30 fs Bs -> J/

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Status of construction & design

Experimental area Magnet VELO RICH Tracking system Calorimeter Muon system Re-optimization of the detector

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Experimental area

Pit 8:DELPHI dismantling completed. Necessary modification work started.

POINT 8 - UX85 March 2002

Pillar

Head Wall

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Magnet Warm magnet Al conductor ∫B.dl ~ 4 Tm

All contracts placed and signed Production well underway

Bending of the Al conductor

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~1 m

VErtex LOcator

Si strip detectors, single sided, read-out 220 m thick, 1800 wedges.

Now 21 stations mounted inside the vacuum tank. ~200k readout channels.

Vertex detector crucial in ALL time-dependent CP violation studies. Si detectors

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VELO test beam

radial azimuth

Test beam Reconstruction of Primary Vertex using 2d tracks

z ~ 79 m

Test beam Reconstruction of Primary Vertex using 2d tracks

z ~ 79 m

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RICH System 2 RICH detectors 3 K separation 3-80 GeV/c 2 K separation 1-150 GeV/c

Aerogel C4F10 CF4 L 5 85 167 cm n 1.03 1.0014 1.0005 242 53 32 mrad 0.6 2.6 4.4 GeV K 2.0 9.3 15.6 GeV

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Photon detection with HPDs

-20 kV

CF4

Aerogellarge rings

C4F10

small rings1024 pixel prototype 1024 pixel prototype

Prototype 1024-pixel HPD (LHC speed) being developed

Major review end June 2002

Backup MAPMT

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And in reality …

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RICH-2 Engineering Design

3-D CAD model Assembly of

Prototype window

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Power of particle ID

Purity = 84% ; Efficiency = 90%

B +-

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LHCb Inner & Outer Tracking

Outer tracker Straw tubes 5mm

diameter, occupancy <10%

3m Prototype installed in HERA-B

Inner tracker Now full silicon soln. Tests in progress

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ECAL – Shashlyk type (+ preshower)

5952 cells 25 X0 , 1.1depth

E/E = 0.10/sqrt(E) + 0.01

Mass production started, ~30% modules produced.

LHCb Calorimeters

HCAL – Tile calorimeter 1468 cells 5.6 E/E = 0.80/sqrt(E) + 0.1 Module 0 built and tested Mass production started

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Muon system

Outer region RPCsRate < 1kHz/cm2 Muon system

5 stations 900 MWPCs 480 RPC

chambers Production in

preparation

Inner & outer region MWPC

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Detector optimization LHCb material budget increased significantly since

Technical Proposal. LHCb has been reoptimized. Beampipe Al -> Be-Al alloy

possibility of first beampipe cone all Be VELO reduced number of stations 25 -> 21 & thinner Si

Was 0.19 X0 (0.04 0) ; Now 0.18 X0

RICH-1 composite mirror and mirror support outside acceptance. Was 0.14 X0, (0.05 0) ; Now 0.085 X0

Tracking stations from 9 -> 4 Now 0.27 X0, (0.11 0) ; Now 0.12 X0

Trigger optimization : B-field to provide PT information.

New RICH-1 design required by presence of B-field.

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LHCb Light

No tracking stations in magnet region

“Vertical” RICH-1

RESULT : an improved detector

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LHCb Light tracking

Reduce tracking stations:-

Track efficiency and ghost rates improved with fewer secondary interactions.

Preliminary conclusions

B +- sample

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LHCb trigger system

high PT muons high PT electrons high PT hadronshigh PT / 0

pile-up veto

Level-0 decision unit

Muon System Calorimeter Systempile-upvertex

detector40 MHz

Level-1 trigger unitVELO

1 MHz

All the detector Higher Levels

40 kHz (up to 100 kHz)

Level-0

Level-1Vertex trigger

Levels-2&3

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Optimized Level-1 trigger

Include Level-0 information B improved

by factor 2

Add pT information Allow to work at

low o/p rates (5-40) kHz

High signal efficiencies

Work in progress :B

0

0.05

0.1

Signal efficiency 1.00.2 0.4 0.6 0.8

Min

imu

m b

ias

rete

nti

on

TP L1 algorithm L1 with

L0 info

L1 with pT info

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B field in VELO region Si station TT1 has 10% of

By

Momentum resolution using VELO tracks & TT1 S(1/p)~0.2p + 0.01/GeV

B-field in RICH-1 region

VELOVELO

RICH1RICH1

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Major re-design of RICH-1 2-mirror geometry Magnetic shielding

box Retain Aerogel & C4F10

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LHCb Physics performance

Importance of redundancy Importance of particle ID Importance of BS modes Importance of high statistics Performance summary table

Re-optimization of LHCb currently in progress. All performance figures are pre - detector optimization.

Measurement of

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Measurement of angle (1)

Expect 2400 events in 1 year of data taking

Depends onand

strong phase diff.

( )

Bs -> Ds K+-

4 Rate asymmetries measure angle

Theoretically clean

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Measurement of (2)

ACP = Adircosmt + Amixsinmt ~5k events per year in each

channel Invoke U-spin symmetry &

relate and KK coefficients to extract

(Fleischer CERN-TH/2000-101) ~ 5 – 10o [theory]

From Bd , Bs KK

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Measurement of (3)

4 Time-dependent decay rates

Relies on efficient hadron trigger

CP asymmetry very small (need large statistics)

- Inclusive D* reconstruction ~ 500 k events/year with S/B~5- Add D*a1 channels ~ 360 k events/year- Get from B->J/ Ks

(2 + ) in degrees

(2

+

) in

deg

rees

1 year 5 years

Bd D , DMeasures 2+

( )

Assumes perfect knowledge (blue) and 10% uncertainty

(red) in ||

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LHCb sensitivity per year : ~ 10O

Determination of from the measurementof 6 time-integrated decay rates :

Bd D0 K*0 , Bd D0 K*0 , Bd D0CP=+1 K

*0

Bd D0 K*0 , Bd D0 K*0 , Bd D0CP=+1 K

*0

K+- K- + K+-,

+-

Visible BR’s ~ 10-810-7

Measurement only possible with forwarddetector with particle ID

Bd D0 K*0 signalFrom Bd0 D0 K*0

Measurement of (4)

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B -> J/ Ks

world(sin 2) ~ 0.02 by 2006

What will LHCb bring to this topic ? STATISTICS !

LHCb(sin 2) ~ 0.02 in 1 year

True precision measurement of this parameter

Eg. Fit for direct CP-violating contribution

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C h a n n e l T r i g g e r E f f i c i e n c y E v e n t y i e l d S e n s i t i v i t y m o d e s

0dB 3 0 % 6 . 9 k 2 1 0

3 ,DB 0d 3 3 % 7 2 5 k 8

m o d e s 0s

0d KJB 3 6 % 4 5 . 6 k

m o d e s

KDB s0s 2 8 % 2 . 4 k

0*00

d KDB 2 1 % 0 . 4 k

0dB 2 0 % 1 . 3 k d o w n t o

0sB o s c i l l a t i o n s

s0s DB 2 8 % 3 4 . 5 k u p t o x s ~ 9 0

m o d e s

JB 0s 3 8 % 4 4 k 0 . 6 o

O t h e r d e c a y s 0

sB 9 5 % 1 0

0*0d KB 8 % 2 6 k

LHCb performance

64%

35%

45% Performance figures are for: 1 year’s

running Reconstructabl

e events

Event yields are for tagged events

Performance figures are currently being re-evaluated.

Pre

limin

ary

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After 1 year of LHCb (2008)

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or maybe …

… maybe will provide a surprise

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Summary

LHCb will perform a precision study of CP violation. A probe for physics beyond the SM.

Redundancy of measurements in many channels. Good particle ID, vertexing, and efficient & flexible trigger essential.

Detector construction has started and progressing well. Good balance of advanced and proven technologies.

LHCb will be ready for data-taking at LHC startup in 2007.