CMS ECAL Elba May 2006 R M Brown - RAL 1 The Status of the CMS Electromagnetic Calorimeter R M Brown On behalf of the CMS ECAL Group

CMS ECAL Elba May 2006 R M Brown - RAL 2 Overview  Introduction  Design objectives and technology choices  Description and status:  Crystals  Photo-detectors  On-detector electronics  Off-detector electronics  Laser monitoring system  Mechanical construction and assembly  Pre-shower  Intercalibration with cosmic muons  Construction and installation schedule  Summary

CMS ECAL Elba May 2006 R M Brown - RAL 3 Compact Muon Solenoid ECAL Tracker 4T solenoid Muon chambers HCAL Iron yoke Total weight: 12,500 t Overall diameter: 15 m Overall length: 21.6 m Magnetic field: 4 T

CMS ECAL Elba May 2006 R M Brown - RAL 4 Coloured histograms are separate contributing backgrounds for 1fb -1 ECAL design objectives (electronic, pile-up) High resolution electromagnetic calorimetry is central to the CMS design Benchmark process: H    m / m = 0.5 [  E 1 / E 1   E 2 / E 2    / tan(  / 2 ) ] Where:  E / E = a /  E  b  c/ E Aim (TDR):Barrel End cap Stochastic term: a = 2.7% 5.7% (p.e. stat, shower fluct, photo-detector, lateral leakage) Constant term: b = 0.55% 0.55% (non-uniformities, inter-calibration, longitudinal leakage) Noise: Low L c = 155 MeV 770 MeV High L 210 MeV 915 MeV (   relies on interaction vertex measurement) Optimised analysis

CMS ECAL Elba May 2006 R M Brown - RAL 5 Challenges & Choices Challenges: Fast response (25ns between bunch crossings) High radiation doses and neutron fluences (10 year doses: n/cm 2, 1kGy at  =0 2x10 14 n/cm 2, 50kGy at  =2.6) Strong magnetic field (4 Tesla) On-detector signal processing  0 /  discrimination Long term reproducibility Choices: Lead tungstate crystals Avalanche photodiodes (Barrel), Vacuum phototriodes (Endcaps) Electronics in 0.25  m CMOS Pb/Si Preshower detector in Endcap region Laser light monitoring system

CMS ECAL Elba May 2006 R M Brown - RAL 6 Lead tungstate properties Temperature dependence ~2.2%/ O C  Stabilise to  0.1 O C Formation and decay of colour centres in dynamic equilibrium under irradiation  Precise light monitoring system Low light yield (1.3% NaI)  Photodetectors with gain in mag field But: Fast light emission: ~80% in 25 ns Peak emission ~425 nm (visible region) Short radiation length: X 0 = 0.89 cm Small Molière radius: R M = 2.10 cm Radiation resistant to very high doses

CMS ECAL Elba May 2006 R M Brown - RAL 7 ECAL Layout Barrel: 36 Supermodules (18 per half-barrel) Crystals (34 types) – total mass 67.4 t Dimensions: ~ 25 x 25 x 230 mm 3 (25.8 X 0 )   x  = x Tapered crystals Pointing ~ 3 o from vertex Pb/Si Preshowers : 4 Dees (2/endcap) 4300 Si strips (~ 63 x 1.9 mm 2 ) Endcaps: 4 Dees (2 per endcap) Crystals (1 type) – total mass 22.9 t Dimensions: ~ 30 x 30 x 220 mm 3 (24.7 X 0 )   x  = x ↔ 0.05 x 0.05

CMS ECAL Elba May 2006 R M Brown - RAL 8 Crystal production Crystal delivery determines ECAL Critical Path Suppliers: BTCP (Bogoroditsk, Russia)~ 1100/month SIC (Shanghai, China)~ 130/month ~ 80% of Barrel crystals already delivered (48 950/61 200) Preseries of Endcap crystals: 100 BTCP, 300 SIC  Last Barrel crystal delivery Feb 2007  Last Endcap crystal delivery Jan 2008

CMS ECAL Elba May 2006 R M Brown - RAL 9 Crystal Quality Assurance BTCP SIC Light Yield Automatic control of: Dimensions Optical Transmission Light yield Longitudinal uniformity CERN INFN/ENEA Rome BTCP Transmission at 420 nm

CMS ECAL Elba May 2006 R M Brown - RAL 10 Crystal Radiation Resistance Light loss is characterised by an ‘induced absorption’ Under irradiation at room temperature, a dynamic equilibrium forms between formation and annealing of colour centres.  Light loss saturates at a value that depends on dose-rate CMS specification requires: μ Gy/hr) Under LHC-like conditions for the Barrel (~0.15 Gy/hr)  Light yield loss ≾ 6% initial after irradiation wavelength (nm ) T(%) Verification: BTCP:Use correlation between sharpness of absorption edge and radiation hardness (Check with sample irradiations) SIC: All crystals irradiated by producer 0 5 Light Yield Loss (%)

CMS ECAL Elba May 2006 R M Brown - RAL 11 Photodetectors Barrel - Avalanche photodiodes (APD) Two 5x5 mm 2 APDs/crystal - Gain: 50 QE: ~75% - Temperature dependence: -2.4%/ O C - Delivery complete 40  m Endcaps: - Vacuum phototriodes (VPT) More radiation resistant than Si diodes (with UV glass window) - Active area ~ 280 mm 2 /crystal - Gain (B=4T) Q.E.~20% at 420nm - Delivery ~80%  = 26.5 mm MESH ANODE VPT Delivery & Test status

CMS ECAL Elba May 2006 R M Brown - RAL 12 On-detector electronics Trigger primitives computed on the detector Command & control via token ring Modularity: Trigger Tower (25 channels in Barrel) - 1 Low Voltage Regulation Board (LVR) - 5 VFE Boards (5 channels each) - 1 FE Board - 1 Fibre sending trig primitives (every bunch Xing) - 1 Fibre sending data (on Level1 accept) Trigger Tower (TT) Very Front End card (VFE) Front End card (FE) Trigger Sums Data x12 x6 x1 MGPA Logic 12 bit ADC bits 2 bits HV APD/VPT VFE architecture for single channel VFE x 5 MB FE LVR

CMS ECAL Elba May 2006 R M Brown - RAL 13 On-detector electronics: status ASICs in 0.25  m IBM CMOS Technology Very high yield (typically >85%) ADC MGPA FENIX Status: All ASICS procured and tested All systems for 30 SMs are tested & burned-in Full Barrel set available for most components Endcap components following close behind 30 MeV 45 MeV View of a SuperModule (SM) showing on-detector electronics Noise distribution for 1700 channels of SM13

CMS ECAL Elba May 2006 R M Brown - RAL 14 Off-Detector electronics Clock & Control System (CCS) Data Concentrator Card (DCC) Trigger Concentrator Card (TCC) Status: CCS finished for whole ECAL DCC in production for Barrel TCC for Barrel: Production started TCC For Endcaps: Schematic finished First board by September LV Power supplies: ~60% of Barrel ordered (rest soon) Order for Endcaps in 2007

CMS ECAL Elba May 2006 R M Brown - RAL 15  at APD when electronics is powered-up (Worst case: Bottom Supermodule) Cooling &Temperature Stability  Power dissipation of Barrel on-detector electronics ~160 kW  Combined temperature sensitivity of (crystal + APD):  Stabilise temperature to better than ± 0.05 O C  Chilled water at 50l/s Water manifold and pipes on SM Cooling bars in direct contact with electronic cards

CMS ECAL Elba May 2006 R M Brown - RAL 16 Laser light monitoring (1) The Solution: Damage and recovery during LHC cycles tracked with a laser monitoring system 2 wavelengths are used: 440 nm and 796 nm Light is injected into each crystal Normalisation given by PN diodes (0.1%) 0.95 Correlation between transmission losses for scintillation light and laser light The Problem: Colour centres form in PWO under irrad n Transparency loss depends on dose rate Equilibrium is reached after a low dose Partial recovery occurs in a few hours Simulation of crystal transparency evolution at LHC ( L =2x10 33 cm -2 s -1 ) - based on test beam irradiation results

CMS ECAL Elba May 2006 R M Brown - RAL 17 Laser light monitoring (2) APD Light is injected through fibres into the front (Barrel) or rear (Endcap) of each crystal 440 nm 796 nm An optical switch directs light to one half-supermodule or one quarter Dee at a time Resolution before irrad n / after irrad n and correction

CMS ECAL Elba May 2006 R M Brown - RAL 18 Construction: Barrel Sub-module: 10 crystals Super-module: 1700 crystals 2 Regional Centres: CERN and Rome Module: 400/500 crystals Assembly status: 26/36 bare SMs assembled 15/36 SMs completed Production rate 4/month Bare SMSM with cooling

CMS ECAL Elba May 2006 R M Brown - RAL 19 Construction: Endcaps Production status All mechanical parts delivered Endcap crystal production starts in summer 2006 Backplates successfully test mounted on HCAL Dee (½ endcap): 3662 crystalsSupercrystal: 25 crystals

CMS ECAL Elba May 2006 R M Brown - RAL 20 Preshower detector Rapidity coverage: 1.65 < |  | < 2.6 (End caps) Motivation: Improved  0 /  discrimination 2 orthogonal planes of Si strip detectors behind 2 X 0 and 1 X 0 Pb respectively Strip pitch: 1.9 mm (63 mm long) Area: 16.5 m 2 (4300 detectors, 1.4 x10 5 channels) High radiation levels - Dose after 10 yrs: ~ 2 x10 14 n/cm 2 ~ 60 kGy  Operate at -10 o C

CMS ECAL Elba May 2006 R M Brown - RAL 21 Status of Preshower Detector Micromodules Ladders System motherboards - production finished by end 2006 System Tests Ongoing - 8 ladders shown here Mechanics All ES “complete disc” elements ready for installation at end 2006 (before the beam pipe) Off-Detector Readout Electronics First module already prototyped – 12-channel optical receiver (optoRx) Production completed ~September 07 D.Barney Pre-series underway Production by mid 2007 Preshower on schedule for installation at end of 2007

CMS ECAL Elba May 2006 R M Brown - RAL 22 Mip deposits ~250MeV (increase APD gain from 50 to 200) Cosmic Muon Test & Calibration Cosmic muons  Each SM operated with cosmic rays for ~1 week  Intercalibration: 1-3% (stat) depending on η Muons through full crystal Event: 4161 Cry: 168 Status: 10 SM Calibrated

CMS ECAL Elba May 2006 R M Brown - RAL 23 During assembly, all detector components are characterised Thus the relative calibration c i of each channel may be estimated: Where:LY is crystal light yield, M and  Q are gain and quantum efficiency of the photo-detectors c ele is the calibration of the electronics chain Intercalibration from Laboratory Measurements  = 4.2% Test beam vs Lab Intercalibration Ratio: Test beam/Lab

CMS ECAL Elba May 2006 R M Brown - RAL 24 Barrel construction schedule Reduced time 3→2months EB+ Surface Installation EB- Surface Installation (12/18) EB- U’ground Installation (6/18) EB+ EB-

CMS ECAL Elba May 2006 R M Brown - RAL 25 Supermodule Installation Insertion at point 5 2 SMs inserted 27 April for magnet test SM Rails on HB+ Gap HB+/HB- ~ 1mm ECAL Barrel installation

CMS ECAL Elba May 2006 R M Brown - RAL 26 Endcap Construction Schedule  Assembly plan assumes last EE crystal delivered end Jan 08.  Aim is to have Endcaps installed for 2008 Physics Run  All cables and services are already installed  Goal: D1 Sept07, D2 Nov07, D3 Jan08, D4 Apr08 ECAL Endcap installation

CMS ECAL Elba May 2006 R M Brown - RAL 27 Summary  High resolution electromagnetic calorimetry is a central feature of CMS  The construction of the Barrel ECAL is in the final phase  All mechanical components are delivered for the Endcap ECAL  Crystal delivery sets the schedule for both Barrel and Endcap  The Pre-shower detector is on course for completion as planned  Supermodules are being commissioned and calibrated with cosmic rays  The CMS ECAL will meet its design goals – see next talk!

CMS ECAL Elba May 2006 R M Brown - RAL 28 Spares

CMS ECAL Elba May 2006 R M Brown - RAL 29 Calibration strategy Lab measurements Pre-calibration GeV Reference pre-calibration of few SM with 50/120 GeV electrons in test beam (<2%) Finally: calibration to < 0.5% with W  + e in ~2 months Test Beam LY Lab LY Test Beam LY – Lab LY  = 4.0% Initial pre-calibration by ‘dead reckoning’ based on lab measurements (~4%) In-situ calibration Precision with 11M events Limit on precision  Inter-calibration precision %  -symmetry w/jet trigger (E T > 120 GeV) Fast in-situ calibration based on principle that mean energy deposited by jet triggers is independent of  at fixed  (after correction for Tracker material) (~2-3% in few hours) Z  e + e Barrel  -ring inter-calibration and Z  e + e cross-calibration (~1% in 1 day)