Transcript LHCb Introduction

July 13-25, 2000, Hanoi, Vietnam
Aurelio Bay
Institut de Physique
des Hautes Energies
[email protected]
SM
from Dm:
t
b
(1-r)2+h2
W
Im
d
d
W
t
b
~ (1-r)2 + h2
r2+h2
from BXu+ln
~Vtd
B0
B0
~Vub
W
b
g
t
t
W
J/Y
Ks
B0
Re
CP Asym ~ sin[2(b+fnew )]
The Unitary Triangle
+ New FCNC
from Dm:
(1-r)2+h2 + rnew
+
b
r2+h2 =
cte
from BXu+ln
Unchanged
d
d
NEW
FCNC
B0
b+fnew
b
~ (1-r)2 + h2 + rnew
t
t
W
N
E
W
b+fnew
SM + New FCNC
from Dm:
(1-r)2+h2 +rnew
Im
t
b
W
d
d
t
b
b
r2+h2
Unchanged
d
NEW
FCNC
d
from BXu+ln
+
W
b
~ (1-r)2 + h2 + rnew
B0
B0
~Vub
W
g
b+fnew
t
t
W
J/Y
Ks
B0
N
E
W
Re
CP Asym ~ sin(2(b+fnew))
The Unitary Triangle
g from Bd  D*-np+, D*+np-, etc.
CP in BJ/Y Ks ~ 2(b + fnew)
From
Bd  D*+ np vs Bd  D*+ np
Bd  D*- np vs Bd  D*- np
2(b + fnew) + g
g
Idem with Bs decays:
compare the two
g determinations
(then combine them)
2 ( dg + fsnew )
from CP in Bs  J/y f
2 ( dg + fsnew ) - g from CP in Bs  Ds-K+, Ds+ K-
g
We want to measure g, we need to select hadronic decay channels,
we want to study the Bs system, have K/p separation, access to Br < 10-7….
LHCb overlook
• BABAR, BELLE, CLEO-III, CDF, D0, HERA-B will test CKM at the O(l3) level.
• LHCb is a second generation experiment for CP violation studies in the B and Bs
meson systems. The goal is to obtain precise and overconstrained determination of
CKM elements, including terms beyond O(l3). This will permit to detect deviations
from the Standard Model description and thus to probe New Physics.
• Second generation means:
– High statistics is needed to study Bu,d,s decays with Br < 10-7
– Excellent proper time resolution
– Excellent particle identification
– Efficient and flexible triggering scheme, including a selection on hadrons.
• High statistics can be obtained by LHCb because
– B production cross section at 14 TeV:
– LHCb running luminosity:

sbb ≈ 500 mb
2 1032 cm-2 s-1
Rate(bb) = 105 sec-1 : 0.5% total inelastic
LHCb
Magnet
dipole
non-bending
plane view
LHC beams
collide here
Vertex
Locator
x
z
10 m
Open geometry with (quite)
easy access to (almost) all
components
  [15, 300] mrad
h  4.9, 1.9]
20 m
LHCb bending plane
Vertex Locator (VELO)
[mm]
Z
80 cm
s impact parameter
100
10
0
-20
sz ≈ 40 mm resolution on
interaction point
0.1
1
Pt [GeV]
retract by
3 cm during
beam setup
0 0.8
4 cm
• ≈ 200 mm Si single-side
• R and f measuring planes
• 220 kchannels, analogue R/O, S/N =15
prototype of R measuring 1/2 plane
Design work on front-end chip (DMILL
and sub-micron technolgies) in progress
10
RICH
pixel HPD
Gas C4F10
K–p separation > 3 s
1<p< 100 GeV/c
Aerogel
Threshold Aerogel C4F10 CF4
[GeV/ c ]
0.6
2.6
4.4
p
K
2.0
9.3
15.6
Gas CF4
0
large
aerogel
rings
small
C4F10
CF4 rings
RICH R&D
Photodetectors options:
HPDs and multianode PMTs
• single photoelectron resolution
•QE = 17% @ 400 nm
• spatial resolution ~1 mm
• large area ~2.9 m2, active: ~ 70%
 325 kchan. binary readout
• B stray field up to 100 gauss
• radiation dose < 3kRad/year
1 p.e.
pedestal
2 p.e.
3 p.e.
4 p.e.
threshold
Pion beam:
large rings in aerogel
and small rings in C4F10
DEP prototype pixel HPD
Other Systems
Magnet: Warm dipole 4 Tm - 4.2 MW - 1450t TDR ok
Tracker
Inner: (40x60 cm2) triple GEM , Si 3 stations sp/p = 0.3 % [5 , 200] GeV/c
2
s
(M
)
=15
MeV/c
B->pp
Outer: straw-tube drift chambers
s(MD->KKp) = 4 MeV/c2
Calorimeter (design completed)
Pre-shower sandwich Pb - scintillators
s (E) 10%

1.%
ECAL Shashlik type, 25 X0
E
E
HCAL Fe + scintillating tiles, 5.6l
s (E) 0%

 %
E
E
R/O by wave-length shifting fibers and PMTs
MUON
Resistive Plate Chambers (RPC) +
Wire and Cathode Pad Chambers
(WPC/CPC) for high rate regions
Joint Calorimeter Test
preshower
ECAL resolution %
0
ECAL Shashlik
30
20
40
GeV
HCAL resolution %
20
HCAL Fe+scintillating tiles
10
0
0
50
100
150
200 GeV
LHCb Trigger Efficiency
for reconstructed and
correctly tagged events
BdJ/y(ee)KS + tag
BdJ/y(mm)KS + tag
BsDsK + tag
BdDK
Bdp+p- + tag
L0(%)
m e h
17 63 17
87 6 16
15 9 45
all
72
88
54
42
50
56
81
81
92
24
36
28
14
76
48
83
30
where the lepton
trigger is important
8
70
L1(%) L2(%) Total(%)
where the hadron
trigger is important
Tags considered (so far):
– muon or electron from other b-hadron b  lepton
– charged kaon from other b-hadron b  c  s
Overall tag efficiency = 40%
Overall mistag rate = 30%
Trigger System
LHC: 40 MHz
L0:1 MHz
High PT muons
High PT electrons
High PT hadrons
L1:40 KHz
Latency: 4 ms
L0
decision
unit
Output:200 Hz
< 2 ms
L1 Trigger
3D reconstruction
of secondary
vertices
Pileup Veto
Running
luminosity
2 x 1032
~30 %
~10%
B0  p+ pInelastic pp interactions
hadron trigger
threshold
L2+L3 Trigger
Full event
information
Mass, decay time resolutions and particle ID
Bs-Bs oscillations with BsDsp
Measurements of Dms
with a significance >5:
up to  ps-1 (xs  7)
Bs  DsK
separation from
Bs  Dsp
Dms  30 ps-1
without RICH
with RICH
DsK
Mass(DsK)
sm = 11 MeV/c2
Dsp
Dsp
DsK
5.2
5.3
5.4
5.5
5.6
GeV/c2
5.2
5.3
5.4
5.5 GeV/c2
LHCb CP Sensitivities in 1 year
Parameter

2b+g
Channels+c.c.
No of events
s(1 year)
Bdpp
5k @DP/T = 30°, |P/T|=0.200.02, =90° 2-5
Bd0  r p
1k
@ =50°
5
Bd  D*(incl.)p
260k
@2b+g=0
12
BdJ/YKs
100k
<0.6
Bs DsK
2400
8(Dms=15ps-1) - 12  (45ps-1)
Bd  DK*
400
10
Bs  J/Y
50k
0.6
b
g-2dg
g
dg
Bs oscillations
xs
Bs  Dsp
Rare Decays
Bs  mm
Bd K0* mm
Bd  K* g
See yellow Book
35k
up to 75 (5s)
11
4500
26k
CERN 2000-004 !
s/b=3.5
s/b=16
s/b=1
LHCb schedule (and conclusion)
1998 Technical Proposal
2000
2001
2002
1999 LHCb approved
Magnet
RICH, Calorimeters
Outer Tracker
Muon System
Vertex Detector
Inner Tracker
L0 & L1 Trigger, DAQ
Technical
Design
Reports
Computing
2003
Magnet installation
2004
2005
Detector and DAQ installation
LHCb ready for LHC « day one »
and for many years of B physics
at “nominal LHCb luminosity”