Very Forward Instrumentation of the

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Very Forward Instrumentation of the Linear
Collider Detector
On behalf of the
Wolfgang Lohmann, DESY
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Old Kernel
New Members
Univ. of Colorado, Boulder, AGH Univ., INP
Jagiell. Univ. Cracow, JINR, Dubna, NCPHEP,
Minsk, FZU, Prague, IHEP, Protvino, TAU, Tel
Aviv, DESY, Zeuthen
Vinca Institute of Nuclear Sciences,
Belgrade Royal Holloway, London, BNL, Brookhaven,
NY, LAL, Orsay

• Luminometer
• BeamCal
• PhotoCal

Goal-Design and RD for
see PRC RD 01/02 (2002)
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Current design (Example LDC, 20 mrad)
Luminometer
TPC
HCAL
ECAL
BeamCal
Technology Tungsten/Si (C) sandwich
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Challenges
Fast, robust and reliable
Detector performance

• High granularity and multi-channel (104)
• High occupancy machine and physics backgrounds
  
• High radiation environment (radiation hard
  sensors/electronics)
• Readout of every bunch (fast electronics, fast
  analyzes, high volume storage)
• High precision alignment

r
IP
z
15000 ee- per BX ? 1020 TeV 10 MGy per year
Align
µm Dr
100µm DZ
?L/L10-4
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Measurement of L
Events
L N / s
N
Count Bhabha events
From theory
Q, (rad)
Max Min
25 cm 10 cm R
80 mrad 33 mrad ?
Goal Precision 10-4
Requires theoretical cross-section with the
necessary precision contacts to theory groups in
Zeuthen, Cracow, Katowice theory groups (two loop
calculation)
DESY-PRC2006
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Systematic Effects
Beam polarisation
2
e
Bunch charge effects
e-
e
Deflection of Bhabhas due to the field of the
opposite beam shifts q
e-(q0)
0.5 shift in the lumi measured
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Occupancy
LumiCal
Remnant background from Beamstrahlung
background from two photon events (under work)

• x cm

Bhabha signal
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LumiCal, present understanding
Maximum peak shower
Every second ring
10 cylinders (?)
64 cylinders 120 sectors 30 rings
60 cylinders (?)
Strip
Pad
e-
Strip Performance Pad Performance Parameter
25 25 Energy resolution
2.1 10-5 rad 3.5 10-5 rad q resolution
10-3 rad 10-2 rad f resolution
2.1 10-7 rad 1.5 10-6 rad D q
3720 (with bonding sectors) 13,320 (without bonding) 25,200 Electronics channels
15 layers (z)
11 layers (z)
4 layers (z)
DESY-PRC2006
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BeamCal
Low angle electron veto Background suppression
in search channels. e.g.
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BeamCal
Determination of beam parameters from
beamstrahlung depositions on BeamCal
2 mrad
20 mrad
Question how many sensor planes are really
needed?
Full GEANT4 simulation Parameters sx and sy
Seems sufficient to read out a few planes only (
around 10 X0)
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BeamCal sensor tests
Shower particles energy spectra
2X0
6X0
Energy deposition from beamstrahlung pairs in
BeamCal. 10-20 TeV and more depending on the
beam parameters.Dose of up to 10MGy/a
Test of sensors in an electron beam of 10 MeV
energy (DALINAC, TU Darmstadt)
20X0
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GEANT4 Simulation
Deposited energy density
Deposited energy inside the sensor
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The Setup
exit window of beam line
collimator (IColl)
Faraday cup (IFC, TFC)
sensor box (IDia, TDia, HV)
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Measurement of reference spectra
Sr90
ADC
diamond
delay
Sr90 source
Scint.
discr
PM1

Gate
discr
PM2
Preamplifier
signal
Sensor box
Trigger box
typical spectrum of an E6 sensor
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PROGRAM

• 2 samples from E6
• 1 MGy
• 5 MGy
• 2 samples from IAF
• 1 MGy
• 5 MGy
• 2 Si samples
• both drew high currentsafter 50 kGy.

E6_4p after 5 MGy
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Results
Beam current, set to 10, 20, 50 and 100
nA, (Faraday cup)
Si sensor, 10 nA (ECAL standard)
high leakage current after 50 kGy
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Results
Diamonnd sensor (produced by E6)
Diamond sensor (produced by Fraunhofer IAF)
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The Testbeam Crew
not on the photo W.Lange
Thanks to INTAS, Worldlab and the TU Darmstadt
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Readout- the challenges

• - 5 bunch trains per second (5 Hz)
• - 3000 bunches within one train
• - One bunch every 300ns, 150ns possible
• - Each bunch to be registered
• High dynamic range (110k)
• 10 bit ADC
• Data per train 1 Gb
• (transmission during train 1 Tb/s, during
  break 3 Gb/s)
• Radiation hardness to be considered
• Compact detectors low power little space for
  multi-channel
• electronics

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DESY PRC Report May 2006
People signing the 2006 PRC report (60)
2006
2006
2008
DESY-PRC2006
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Conclusions

• From similations Design of calorimeters in the
  forward
• region relatively advanced
• However, many topics not yet addressed or
  completed
• (cross talk, occupancy, pile-up of events .)

• Radiation hard sensors not yet understood
• - we consider backup materials, like special
  silicon and GaAs
• Read-out electronics will be a challenge
• -different from standard calorimeters, fast
  digitisation
• and processing, large amount of raw data
• Effort on hardware development will be
  increasend!