CP with the LHCb detector

1
CP with the LHCb detector

• Ll. Garrido
• Madrid 23/5/2002

• INDEX
• Work done at LHCb (project AEN99-0483)
• Future work for LHCb
• People and institutions involved
• Budget
• Time schedule

2
Work _at_ LHCb

• Electronics of the SPD chamber (design,
  production and installation)
• PMT characterization and test
• MC simulation and physics with SPD

• 6000 pieces

100 pieces
Technical design report approved in February 2001
spd
ps
ecal
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spd
ps
ecal
3
Testing the concept

Warning The MC (GEANT) simulation of the
backsplash may not be reliable. Prediction 1
effect for photons of 30 GeV (log dependence with
the energy)

• Backsplash measurements at the test beam during
  summer 99

Photon123ECAL (magnet ON) Electron 13
(magnet OFF)

• Results (NIM 484A, 351-359) 1 (1.4) effect at
  15 (45) GeV
• About 2 of photons will be flagged as electrons
• About half due to interaction in SPD (nothing we
  can do about it)
• About half due to backscattering in lead
• Charge particle signal dominates.

4
Physics with the SPD

• Main purpose
• Separate photons and electrons at the Level-0
  trigger
• ECAL trigger
• each cell is converted in transverse energy using
  a look-up table
• The highest sum (22 cells) on each front-end
  board (32 channels) are transmitted to the Level
  0 decision unit with the associated preshower and
  SPD information.
• Physics examples
• trigger
• max(Et)gt1.66 GeV
• N(ps)1 N(SPD) 0
• Minibias rejection of a factor 100 in
• electron enhancement
• N(SPD) gt0

5
The SPD electronics ASIC, VFE and FE

• Only 80 of signal in 25 ns
• No dead time on integration

we need a Dual channel
Electronics Review passed March 2001
6
ASIC (I)
Optical microphotography

• Why an ASIC ?
• 6000 channels
• minimal area /ch
• Processing speed 40 MHz
• Power consumption lt 2 W / 64 channels
• Analog Processing Digital Control
• Signal range. 0 to 5 MIP (0 to 650 mV)
• Electronics resolution 5 of 1 MIP
• Dynamic range 40 dB (7 bits)

• 0.8 ?m AMS BiCMOS Technology
• Dual channel
• Fully differential
• SEU and SEL protection
• Triple voting
• Guard rings

• Programmable
• Thresholds per sub-channel
• Subtraction from 0 up to 40 of the signal
• T0 done externally with a delay unit (LAL design)

7
ASIC (II) - Versions
RUN 1 (Sep 2000) Test separate blocs 1 full
channel
RUN 2 (Sep 2001) 4 full channels test ECL vs CMOS
output (tested in beam)

• Offset (Output Zero Error) ltOZEgt 38.6 mV
  ?io 70 mV r.m.s.
• Gain ltVo/Vigt 16.51 (for a typical input
  pulse) ?io 0.091 r.m.s. (0,55)
• Treset 5.5 ns (for 1 V output)
• Noise is about 1 mV r.m.s
• Output range is gt?1V for an arbitrary input
  signal.
• Linearity error is lt 0.5 full scale.

8
ASIC (III)

• RUN 3 (January 2002)
• 1 full channel with digital control
• New tunnable subtractor
• On-chip Digital to Analog
• Converter to program thresholds

• RUN 4 (tomorrow)
• To be sent 24-05-2002 .
• Complete processing channel
• separate blocs digital ctrl
• Works at 3.3 V to reduce power consumption
• Higher gain to meet PMT DC current limit
  requirements.
• Towards final prototype
• Will be tested Sep-Oct 2002

• RUN 5 (November 2002)
• 8 full channels
• Final design Prototype

9
Very Front End Board
Performs Signal Processing
100 Boards
Size 7x12 cm
10
Very Front End Board (II)
Test beam boards

• Sep 2001 RUN 2, 4 full channels/ 4-layer board
• ECL vs CMOS output
• Clock signal distribution
• Power Supply distribution
• June 2002 RUN 2, 4 full channels / 4-layer board
• Improvements in board design
• Signals distribution
• June 2002 RUN 3, 1 full channel and digital
  control/ 6-layer board
• Digital signal distribution vs analog signal
  distribution
• Noise effect vs number of layers

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Front End Board

• Control Unit
• Bus Bridge
• Programmable Delays

1 Control Unit every 4 VFE Boards 5 Control Units
in a Front End Board 6 Front End Boards
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Photomultiplier
Hamamatsu R5900 Multi anode 64 channels
6000 channels Little area Cost per channel Fast
response time
Timer
Trigger System Setup
scan
scintillator
PMT
oscilloscope
Led Pulser
X-Z stage
Computer
Finding the maximum signal (Cathode Profile)
X-Z Scan System
Average Signal Shape
Collaboration with LPC - Clermont-Fd.
13
Simulations

• Simulation of PADs photons arrival time
  distribution at the PMT and its inclusion in the
  LHCb detector simulation, and its comparison with
  cosmic ray test
• Parameters
• Scintillator decay time 2.1 ns
• Scintillator mean free path 0.4 m
• WLS decay time 11.5 ns (Y11)
• WLS mean free path 8m
• White fiber m.f.p 30m
• In-out going angle 26.7º

Normalized signal (25ns windows)
Arrival time (ns)
Data
MC

• Study of the lateral backsplash with EGS4
• Physics of the SPD at the level-0 trigger

14
Towards the massive test
Aiming at a highly automated test of the H7546
characteristics and electronics
Full Characterisation of selected specimens

• To be tested
• 100 PMTs
• 1500 ASICs
• 100 VFE boards
• 5 FE Cards

Automatic Test Bench setup
Automated characterisation and quality control

• PMT
• Absolute gain of all channels
• Linearity test
• Short term stability
• Dark current
• Test on reduced numbers
• Quantum efficiency
• Optical Crosstalk
• Long term stability
• Temperature and magnetic dependence

• ASIC
• offset
• noise
• linearity
• Crosstalk
• Digital path
• Pulse up compensation
• Test on reduced numbers
• Power consumption
• Temperature dependence

• Combined test (asicvfe)
• offset
• Noise in board
• Test pulse
• Linearity with PMT signal

15
People and Task Distribution
People ECM (UB) Electrònica (UB) EALS (URL) R.
Graciani S. Bota X. Vilasis (D. Gascon) A.
Dieguez J.Riera E. Aguilo A. Herms M.
Rosello M. Calvo X. Cano S.Luengo S.
Gomez (URV) (R. Ballabriga) Ll. G.

• ASIC Digital Control UB
• VFE and FE boards EALS
• PMT UB EALS
• PHYSICS UB
• DAHEALSUB

Needs clearly coordination
) in agreement with Santiago we take all the
Spanish DAH and they take all the MO.
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Budget

• Personnel includes D. Gascon (our electronic
  engineer responsible of the
• ASIC), and a post-doc. In addition we request to
  the education programs
• 2 F.P.I and 1 technician
• The contribution specified on the MoU is
• Calorimeter 430 kCHF
• PMTHV 320 kCHF
• Electronics 110 kCHF
• DAH 200 kCHF

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Towards the massive ASIC, boards and PMT test
2003
2004
2005
2002
Massive Joint Test
INSTALLATION
Massive Joint Test
Final Prototype
ASIC
Production
Final Prototype
Production
VFE
PMT
Characterisation
Massive Test
Final Prototype
Production
Test
FE
DAH
switch?