1. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Detector Control and Safety System for the Electromagnetic Calorimeter of CMS Design Requirements for the CMS ECAL Specifications of the ECAL DCS Detailed specifications of the ECAL Safety System ECAL SS prototype - Test-beam results Predrag Milenovic CMS Belgrade Group

2. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Large Hadron Collider CMS ATLAS ALICE LHC: 27 km Circum., ~100m underground CERN

3. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Compact Muon Solenoid MUON BARREL CALORIMETERS Silicon Microstrips Pixels ECAL Scintillating PbWO4 crystals Cathode Strip Chambers (CSC) Resistive Plate Chambers (RPC) Drift Tube Chambers (DT) Resistive Plate Chambers (RPC) SUPERCONDUCTING COIL IRON YOKE TRACKER MUON ENDCAPS HCAL Plastic scintillator/brass sandwich

4. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey ECAL design criteria Physics goal Physics goal - The discovery of the Higgs at the LHC H→ γγ The favourable channel for low mass Higgs search: H→ γγ Design criteria: High energy (and angular) resolution: Barrel: Stochastic term (a): 2.7%, Constant term (b): 0.5%, Noise term (c): 150 – 220 MeV Hermetic, granular Compact, operated inside a 4T magnetic field. Challenging radiation environment with an integrated dose:  10 13 neutrons/cm 2 and 1 kGy at  = 0 to 2×10 14 neutrons/cm 2 and 50 kGy at  2.6. Fast response for 40 MHz bunch crossing rate.

5. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Choices, Constraints, Challenges Crystals – PbWO 4 –Short X 0 and R M –Fast light output (80% in 25ns) –Low light yield –Temp. sensitivity – -2.2%/ O C Photodetectors – APDs,VPTs –Gain – 50(10). –QE – 80%(15%) @ 420 nm –Temp. sensitivity – -2.4%/ O C Constraints: –Very hostile radiation environment at LHC; –4T solenoidal magnetic field of CMS; –Low room-temperature scintillation yield of PbWO 4 ; –Temperature dependence of crystal light yield and APD response. Need to stabilise crystal volume temperature to 0.1 o C

6. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Temperature Stability Issue All 0.25  electronics runs at 2.5V. 0.45 A/channel 1 A/board Radiation hard regulator has a drop out voltage of 1.5V Total heat power dissipated in the whole calorimeter ~300 kW Crystal light yield decreases by 2.2%/ o C & APD gain decreases by 2.3%/ O C. Removing all excess heat is critical for the stable operation of the detector. Systems of crucial importance for the ECAL: Cooling system & Cooling system & Detector Slow Control System Detector Control System (DCS)

7. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey ECAL DCS Design Objectives: temperature stabilityExact monitoring of the crystal and APD temperature stability (18.0 o C ± 0.1 o C) air humidityMeasurement of the air humidity in the supermodule Safety system for automatic FE electronics disconnectionSafety system for automatic FE electronics disconnection (due to cooling problems, overheating of electronics, water leakage, over-voltage/over-current in FE) Development of the control software (sensors, HV, LV, cooling, safety…) Foreseen Difficulties: Sensors ~100m away from the readout electronics, not accessible, large radiation dose present in ECAL DCS Subsystems (independent on the DAQ): –Precision Temperature Monitoring (PTM) –Humidity Monitoring (HM) – Collaboration of research groups: ETHZ, Protvino and Belgrade ECAL Safety System (ESS) ECAL Safety System (ESS)

8. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Full system autonomy in all aspects; Independent, continuous temp. monitoring of the ECAL VFE + FE environment in both ECAL SM + EE; Precision : 0.2 o C Archiving of temp. data and system information for analysis of the detector status and ESS performance; Reliable hardwired interlocks with ECAL HV and LV Power Supply systems; External Alarm Interfaces with ECAL Cooling system, Water leakage detection system, as well as interfaces with general CMS DSS and LHC TCR; Prompt reaction on any external alarm or critical change of temperature inside the ECAL by issuing, in a proper time sequence, Warnings and Alarms to: 1. HV System Crates (hardwired interlocks), 2. LV System Crates (hardwired interlocks), 3. System Operator (soft PVSS Warning and Alarm messages); Radiation tolerance in accordance with CMS radiation dose specifications; Maximum possible level of robustness, reliability, safety and maintainability; ECAL Safety System

9. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Schematic layout Three interconnected system layers: ESS FE Layer Temperature conversion and channel multiplexing - ESS FE Layer, ESS PLC Layer Data acquisition, data processing and interlock generating - ESS PLC Layer, ESS Soft Layer System monitoring and system control - ESS Soft Layer Several external interfaces to: ECAL Low Voltage, ECAL High Voltage and ECAL Cooling systems, Input from Water leakage detection system CMS Detector Safety System (DSS), LHC Technical Control Room (TCR).

10. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey ESS Sensor Location 288 + 64 SMD, 470 Ohms In total 288 + 64 SMD, 470 Ohms NTC NTC thermistors (EPCOS) positioned in pairs at each measurement point ( “twin” sensors ). Sensor 1 Sensor 2 Connector Screw hole 8 / EB SM 8 / EE quadrant Sensors to be calibrated to relative precision of 0.1 o C with calibration setup developed by Belgrade group PSI irradiation PSI irradiation: Sensors irradiated to 4-5 times EE dose – EPCOS sensors behaved perfectly

11. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey FE Electronic components Rad-tolerant Max4582:  TTL/CMOS compatible  Temperature Range  0°C - 70°C  On-resistance  150 Ohms at 5V  Off-leakage current  1nA at 25°C  Low Distortion  Low crosstalk NTC 680 Ohms Resistant Bridge Front-End ASIC: IBM 0. m 100 + 30% spares ordered (with LHC cryo group) Bi-directional three-level programmable Internal Current Source (1  A, 10  A and 100  A), Differential Amplifier, gain = 50 (adjustable), input range: -50mV – 50mV, output range: 0 - 5V, Analog switches, 8 measurement modes of the chip, controlled by the Ck0, Ck1 and Ck2 bits, Removes ASIC voltage offsets, thermocouple effects, power supply & ambient temperature dependencies RBFE ASIC

12. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey FE Electronic components Custom-made MUX + ‘RBFE’ test board, irradiated at PSI: No problem, irradiated at ~ 10 6 x CMS balcony flux, and about 300 x CMS balcony dose  Tests in Belgrade: very satisfactory, could basically clock at 1 ms with 2x better resolution.  Has current generator at 500 μA  Need only (power, signal) 5V Programmable Microcontroller test board, irradiated at PSI: No problem, irradiated at ~ 10 6 x CMS balcony flux, and about 300 x CMS balcony dose  Purpose :  Control of MUXs and RBFE setup, Control of the communication (RS485), does ADC  Has watchdog timer, automatic RESET in case of blocking  Possibility to send remote RESET  Memory checksum sent: Control against SEU

13. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey FE Layer – ESS Unit Modular systemESS Units Modular system - Independent ESS Units Redundant readout Redundant readout - 4 SM or one Endcap 12 in total units needed for (EE+EB+EB+EE) Radiation tolerant Radiation tolerant can sustain radiation levels orders of magnitudes higher than those expected on the CMS balconies Redundant architecture - maximum reliability Redundant architecture - maximum reliability - minimum possible loss of temp. information from the inside of ECAL Reliability analysis Reliability analysis (for 4 designs) This layout with 8 RBFEs/4SM has smallest prob. to loose large number of modules in case of component failure Functional layout of ESS Unit in control of four ECAL Super Modules

14. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey H4-Beamline, CERN ECAL Test Beam Real-life testReal-life test of "almost" complete integrated system: –Readout: –Readout: (PbWO 4 +APDs+VFE(100xFPPA or 50xMGPA)+FE(L1,3μs)) –Slow Control (DCS) and Monitoring: LV, HV and Laser monitoring Cooling and temperature stability DCS subsystems: PTM, HM and ECAL SS –Online/Offline software Validation of pre-calibration strategy (reproducibility and transferability to CMS in-situ) Evaluation of effective detector performance (linearity, resolution, noise, stability) with new electronics design

15. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Energy (GeV) Energy Resolution(%) ECAL Test-beam results with final electronics Resolution(mm) Energy (GeV) 1 mm Position 0.6% at 50 GeV. 0.85 mm at 50 GeV. Target calorimetry resolution achieved with new electronics design!

16. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey ECAL Test-beam results with final electronics In situ:Fast intercalibration based on  symmetry in energy flow 2% in few hours Energy/momentum of isolated electron from W→ e in 2 months Energy/momentum of isolated electron from W→ e in 2 months Absolute energy scale from Z ee Absolute energy scale from Z → e + e - Test Beam LY Labo LY corr  = 4.05% Test Beam LY – Labo LY corr Lab4 % Relative channel calibration can be obtained from Lab with a precision of 4 % We cannot calibrate every crystal with an electron beam. Obtain a first calibration point from component data: crystal light yield, APD & PA gain.

17. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey RS 485 connection ESS test-beam setup with SM0 SM0

18. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey ESS test-beam results with SM0 ECAL SS (FE + Interface) PCBCalibration curve for one ESS sensor Noise dependence on RBFE position (ΔL ~ 40m) Noise distributions ~0.04°C ~0.025°C

19. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey ESS test-beam results with SM0

20. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Oscillations of temperature of the air inside and outside of the SM0 are correlated! Cooling problems ! Cooling water temp. too high -> ESS interlock ! -> LV off ! Cooling problem solved ! LV On ! Cooling problems ! LV On ! ESS interlock ! System performance satisfactory !!! ESS test-beam results – Example

21. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Back-up slides

22. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Three interconnected system layers: ESS FE Layer Temperature conversion and channel multiplexing - ESS FE Layer, ESS PLC Layer Data acquisition, data processing and interlock generating - ESS PLC Layer, ESS Soft Layer System monitoring and system control - ESS Soft Layer Several external interfaces to: ECAL Low Voltage, ECAL High Voltage and ECAL Cooling systems, Input from Water leakage detection system CMS Detector Safety System (DSS), LHC Technical Control Room (TCR). Schematic layout RS485

23. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey  TSS FE is modular system made of ESS Units as independent modules, all identical  Each TSS unit has its own, independent and redundant power supply; redundant readout  Each TSS unit provides redundant readout for four SM or one Endcap. There are 12 in total (1+5+5+1) units needed for (EE+EHB+EHB+EE) There will be at least 3-5 spare TSS units (about 16-24 spare entries in total);  TSS units can be interconnected in order to be controlled in parallel by the same PLC Control Signals --> possibility for parallel readout of several EB Super Modules and reduces the cabling between the Counting Room and the ESS Racks on the balconies; Redundant architecturemaximum reliability  Redundant architecture of the ESS readout unit : provide maximum reliability, so that, in the case of malfunction of any internal electronic components, the unit still works properly with minimum possible loss of temperature information from the inside of ECAL  All the electronic components of ESS FE Units have been shown (recent tests at PSI) that they can sustain radiation levels orders of magnitudes higher than those expected on the balconies... ESS FE Layer

24. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey FE Layer – ESS Rack Rack Layout of ECAL SS on CMS Blaconies Panel Layout of ECAL SS Unit

25. CMS ECAL DCS, Belgrade Group Four Seas Conference, 5-10 September 2004, Istanbul, Turkey Conclusions and Outlook