1. Richard Jacobsson, CERN
The LHCb experiment
Brazil
USA
Poland
Finland
Ukraine
France UK
Germany
Switzerland
Italy
Netherlands
PRC
Romania
Russia
Spain
Richard Jacobsson, CERN

2. Richard Jacobsson, CERN
Outline
Physics motivation
LHCb at LHC
The LHCb detector
Front-End electronics
Timing and Fast Control (TFC)
DAQ
Conclusions
Richard Jacobsson, CERN

3. Richard Jacobsson, CERN
Physics motivation 1
Ultimate questions:
Matter - Anti-matter imbalance in the Universe
CP violation a la Standard Model not sufficient Least tested aspect of the Standard Model
Flavor physics : More accurate Standard Model measurements in this sector (some parameters known with an accuracy level of only O(30%)
Flavor Changing Neutral Currents? (Not in SM)
New physics beyond the Standard Model
More CP violation
Richard Jacobsson, CERN

4. Physics motivation 2 u c t d s b
Yukawa couplings involve quarks from different generations ==> eigenstates of the weak interaction not the same as the mass eigenstates
= V Lcc = 2-1/2g (u, c, t)L gm V W+m + h.c. d
s b d’
s’ b’
Vud Vus Vub
Vcd Vcs Vcb Vtd Vts Vtb
VCKM = W-
That is b c
Kobayashi and Masukawa
1973
VCKM not diagonal. The structure of the charged current coupling is
u c t
d s b
t b c s u
Richard Jacobsson, CERN

5. Richard Jacobsson, CERN
Physics motivation 3
In addition, introducing complex phase into the three-generation mass
matrix generates CP and T violation in weak interaction---> (too) small in SM
==> So far, only observed in K mesons (1964)
Supersymmetry, left-right symmetric model, leptoquark, …all extensions
have strong influence.
AIM: Measure flavor parameters as accurately as possible
Ex: Unitarity conditions (V+CKMVCKM = 1) Wolfenstein parametrization:
VudVub + VcdVcb + VtdVtb = 0
1-l2/ l Al3(r-ih)
-l 1-l2/2 Al2 Al3(1-r-ih) -Al2 1
VCKM ~ Re a b g
(1-l2/2)V*ub/(l|Vcb|)
r(1-l2/2)
Vtd/(l|Vcb|) Im
Richard Jacobsson, CERN

6. Richard Jacobsson, CERN
Physics motivation 4
|Vcb|, |Vub|, |Vtd| ==> r and h ==> calculate a, b, g
Also measure directly a, b, g from CP asymmetries:
b + g from B0d p+p- (background B0d K+p-)
b from B0d J/y Ks
g from B0d D0K*0, D0K *0 ,D01K*0
B0d - B0d and B0s - B0s oscillations
Rare b-decays
Richard Jacobsson, CERN

7. Richard Jacobsson, CERN
LHCb
LHC is the most intensive source of Bu, Bd, Bs and Bc and b-baryons
1012 b-pairs per year (75 kHz)
Branching ratios of interesting channel
5 Hz interesting events
LHCb emphasis:
B decay reconstruction
Particle identification (K/p: ~1GeV/c < p < 150GeV/c)
Trigger efficient for both leptonic and hadronic final states. (ATLAS and CMS: no real particle ID and only with lepton triggers
Richard Jacobsson, CERN

8. Richard Jacobsson, CERN
LHCb detector 1
Richard Jacobsson, CERN

9. Richard Jacobsson, CERN
LHCb detector 2
Spectrometer:
A single-arm spectrometer covering qmin = ~15 mrad (beam pipe and radiation) to qmin = ~300 mrad (cost optimisation) i.e. h = ~1.88 to ~4.89
has an equal bb acceptance
as a large central detector.
Locally tunable luminosity
Richard Jacobsson, CERN

10. Richard Jacobsson, CERN
LHCb Detector 3
Calorimeters
Tracker
Coil
Yoke
Shielding plate
RICH-1
~20m
Muons
Vertex
RICH-2
Richard Jacobsson, CERN

11. Richard Jacobsson, CERN
LHCb Trigger (L0)
High PT
leptons
photons
hadrons
muons
Pile-up
veto
Level-0
decision unit
40 MHz crossing rate
1 MHz accept rate
Richard Jacobsson, CERN

12. Richard Jacobsson, CERN
LHCb trigger (L1)
Purpose
Select events with detached secondary vertices
Algorithm
Based on special geometry of vertex detector (r-stations, -stations)
Several steps
track reconstruction in 2 dimensions (r-z)
determination of primary vertex
search for tracks with large impact parameter relative to primary vertex
full 3 dimensional reconstruction of those tracks
Technical Problems:
1 MHz input rate, ~4 GB/s data rate, small event fragments, latency restrictions CN SN y CN
Computing Node SN
Source Node
Richard Jacobsson, CERN

13. Sub-Farm Controllers (SFC)
LHCb Read-out
LHC-B Detector
Data
rates
VDET TRACK ECAL HCAL MUON RICH
40 MHz
Level 0
Trigger
40 TB/s
1 MHz
Level-0
Front-End Electronics
Level-1
Timing
&
Fast
Control L0
Fixed latency
4.0 ms
1 TB/s
40 kHz L1
Level 1
Trigger
1 MHz
LAN
Front-End Multiplexers (FEM)
Front End Links
6 GB/s
Variable latency
<1 ms RU RU RU
Read-out units (RU)
Throttle
Read-out Network (RN)
6 GB/s
SFC
SFC
Sub-Farm Controllers (SFC)
Variable latency
L2 ~10 ms
L3 ~200 ms
Control
&
Monitoring
Storage
50 MB/s
Trigger Level 2 & 3
Event Filter
CPU
CPU
CPU
CPU
Richard Jacobsson, CERN

14. Front-End electronics
Richard Jacobsson, CERN

15. Richard Jacobsson, CERN
CERN TTC system 1
Developed in the CERN RD12 project: Timing, Trigger and Control distribution system
Used by all LHC experiments
Transmitting two channels multiplexed
Low latency 40 MHz
Encoded long and short broadcasts
Richard Jacobsson, CERN

16. Richard Jacobsson, CERN
CERN TTC system 2
LHC: Distribute LHC clock (40.08 MHz) and
LHC orbit signal ( kHz) to experiments
over fiber with minimal jitter (~8ps RMS)
Experiments: Distribute clock, trigger and control commands to the
detectors over fiber with minimal jitter
Prevessin Control Room
Experimental hall
Richard Jacobsson, CERN

17. Timing and Fast Control 1
Richard Jacobsson, CERN

18. Timing and Fast Control 2
Experiment orchestra director
Readout Supervisor
Clock, trigger and command distribution and support partitioning
TFC switch
Throttle feed-back
Throttle Ors and Throttle switches (L0 & L1)
Richard Jacobsson, CERN

19. Timing and Fast Control 3
- Trigger controller
Trigger controller
Throttles
- ECS interface
ECS interface
ECS L0
- L0 distribution (TTC) L1
- L1 distribution (TTC)
- Clock distribution(TTC)
TTC encoder
Ch A/B
LHC clock
Readout Supervisor:
- Module
- Auto-trigger generator
Trigger generator
- Reset/cmd generator
Reset/command
generator
- “RS Front-End”
RS Front-End
L0/L1
DAQ
Richard Jacobsson, CERN

20. Timing and Fast Control 4
Richard Jacobsson, CERN

21. Richard Jacobsson, CERN
LHCb DAQ 1
Readout Units (RUs)/Front-End Multiplexers (FEM)
Multiplex input links (Slink) onto Readout Network links (RU) or Slink (FEM)
Merge input fragments to one output fragment
Destination assignment for Readout Network
Readout Network
provide connectivity between RUs and SFCs for event-building
provide necessary bandwidth (6 GB/sec sustained)
Subfarm Controllers (SFCs)
assemble event fragments arriving from RUs to complete events and send them to one of the CPUs connected
dynamic load balancing among the CPUs connected
CPU farm
execute the high level trigger algorithms
execute reconstruction algorithm
Processing needs: ~100 kSI95, i.e. ~1000 processors
Note: There is no central event manager
Read-out Network (RN) RU
6 GB/s
50 MB/s
Variable latency
L2 ~10 ms
L3 ~200 ms
Control
&
Monitoring
LAN
Read-out units (RU)
Timing
Fast
Front End Links
Trigger Level 2 & 3
Event Filter
SFC
CPU
Sub-Farm Controllers (SFC)
Storage
Throttle
Front-End
Multiplexers
(FEM)
Richard Jacobsson, CERN

22. Richard Jacobsson, CERN
LHCb DAQ 2 - RU
Two alternative approaches to Readout Unit/FE Multiplexer
1. Customized hardware
Richard Jacobsson, CERN

23. Richard Jacobsson, CERN
LHCb DAQ 3 - RU
2. Software driven Readout Unit on IBM network processor
The IBM NP4GS3 is a network processor designed for wire-speed switching/routing and frame manipulation
It can handle over 4.5 Million packets per second on 4 1-Gigabit full duplex links
It is fully software programmable
Richard Jacobsson, CERN

24. Richard Jacobsson, CERN
LHCb DAQ 4 - RU
Readout Unit implementation
DAQ RU
IBM NP4GS3
Phy RN CC - PC
PCI
Ethernet
ECS
Mem
GbE
FEM
GMII
Switch Bus
DASL
Richard Jacobsson, CERN

25. Richard Jacobsson, CERN
LHCb DAQ 5 - FEM
Front-End Multiplexer implementation
Richard Jacobsson, CERN

26. Richard Jacobsson, CERN
LHCb DAQ 6 - SubFarm
Sub Farm Architecture
Richard Jacobsson, CERN

27. Richard Jacobsson, CERN
Conclusions
Exciting years ahead with design and flavor physics
Two TDRs submitted (September 2000)
Calorimeters
RICHes
Building the LHCb readout system is progressing well
DAQ TDR end of the year, a lot of work ahead
Timing and Fast Control
Richard Jacobsson, CERN

28. Richard Jacobsson, CERN

29. Richard Jacobsson, CERN
LHCb RICHes
RICH1:
5cm aerogel n = 1.03, GeV
4 m3 C4F10 n = , GeV
RICH2:
100 m3 CF4 n = , GeV
HPD
Richard Jacobsson, CERN