WBS 4.0 The Electromagnetic Calorimeter

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WBS 4.0 The Electromagnetic Calorimeter

• Roger Rusack
• The University of Minnesota
• US-CMS L2 ECAL Manager

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Outline
Subsystem overview Problems and Solutions Current
Status Changes Concerns
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The construction
Supermodule
ECAL Barrel and Endcaps
Services
VFE Modules
Grid
36 supermodules 1700 crystals per
super-module 20,000 crystals in endcap
Crystals
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VFE readout
Electro-optics
Avalanche photodiode
Bit-serializer
FPPA
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Calibration

• Seven month period of operation in 2006 at low
  luminosity. CMS goal to observe the Higgs.
• At low luminosity physics channels for
  calibration are limited by rates.
• Need to start with crystals calibrated to 1.
• Calibrate every crystal in beam between now and
  installation.

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Calibration Schedule

• Module 0 tests October Novemebr 2001 to debug
  whole calibration process.
• Supermodule calibration
• SM1 3.5 months in 2002.
• SM2 to SM11 2002.
• SM12 to SM24 and DEE1 2003
• SM25 to SM36 and DEE2 2004
• Sufficient to remeasure 10 SMs in 2004.
• Fits with V31 planning.
• Install in SX5 EB (SM1 SM18) in 8/2004.
• Install in UX5 EB (SM1 SM18) in 11/2004.

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Issues at last Review

• Crystal production.
• Supermodule Mechanics
• APD Radiation hardness
• Honeywell Bit-serializer

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SM Construction Schedule
Initial pace set by APD production.
Calibration of supermodules paced by electronics
delivery at start.
Production of crystals sets the pace of the
supermodule construction at the end.
Module 0 tests paced by electro-optic components.
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Crystals

• Improvements to the crystal process increased
  rate of production.
• New method 2-crystals per boule.
• All Russian crystals to be made this way.

36 mm
64 mm
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Crystal Boules
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Crystal Production
Crystal Production
Crystal Production
Supermodule Construction
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Mechanics

• Major problems last year Prototype grid failed
  tolerance requirements.
• Tolerance is critical for barrel assembly.
• Major redesign of the way grid is made.
• Dropped idea of welding three pieces together.
• Now simpler bolted solution.
• Better cooling.
• 2 of 4 module prototypes delivered and meet
  specifications.
• Have on order parts for SM1 and SM2.
• Problem solved

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Mechanics
Grid are made by 3 bolted pieces
Alveola are now tied on their front face
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Bit-Serializer
Last year two failed runs at Honeywell and then
3 safe mode run failed. Three strikes and
Switched to CERN solution Giga-optical link.
Made in 0.25 m process.
Cheaper
Bit error rate test in the 800Mbit/s G-Link mode
20 hours error free transmission Problems with
VCSEL driver Mods for ECAL. Submission May
2001 Will not be ready for Module 0
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Electro-Optics

• We need this component in final form for the 2001
  calibration test.
• Used to send output of serializer to upper level
  readout.
• Slow getting components from Methode
• Started second parallel development with Spinner
• Major Issues May 2000.

Methode
Spinner
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FPPA2000 (UHF1x)
40 MHz Multi-ranging sample-and-hold Intersil
UHF-1X process Joint Lyon-Princeton (LBL)
design 1000 parts made. Early results look good.
Detailed studies on large quantity now at Lyon.
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FPPA
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FPPA
Circuit functions as designed.Noise level is 4
higher than anticipated. OK for module 0 tests
will need another engineering run
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APDs

• Problem all last year with radiation damage.
• APDs survival goal is 0.1 level to ensure
  energy resolution required to observe the Higgs.
• 5 failure rate seen in proton beam at PSI.
• Requirements 21013 neutrons/cm2 and 10 kGy
  gammas over 10 years.
• Proton beam delivers full dose in 2 hours.
• Changes
• Compared neutron with protons. With neutrons 100
  survival.
• Effect of ionizing dose is rate dependent.
• Improve APD design

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Radiation Damage to APDs
Current
Time
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Changes to APDs
Increase gap
Move n in away from p
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Californium Source
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Neutron Irradiation
135 irradiated so far
Every APD has survived neutron irradiation
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Monitor

• TiSaphire laser pumped by a NdYLF laser.
• Light output at 440 or 490 nm.
• Used to monitor changes to the crystal response
  between calibration cycles.
• Two lasers required to ensure continuous
  operation during supermodule calibration.
• Ship first laser August 01
• Second one early 2002.

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Monitor Light Source
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Cost estimate changes
Major cost changes.
Honeywell to IBM switch. (640k)
Peter Denes -- Princeton to LBL. 350k Extra
engineering effort. 100k Spinner development
contract 110k Productization of
FPPA 150k Californium cost change 75k
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L2 and L3 milestones.
Delays in mechanics and APD and Electronics in
production ML2 - Module 0 complete - 8 month
delay. ML2 - SM1 completed 15 month delay.
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Concerns

• Points to watch in near future.
• Production of the electro-optics components for
  Module 0.
• Production start of FPPA.
• Bit-serializer and SEU effects.
• Establish procedures for electronics radiation
  hardness QA/QC.
• Readiness for calibration.