1. The Detector Control System for the ATLAS SemiConductor Tracker
Assembly Phase
Anna Sfyrla
University of Geneva
on behalf of the ATLAS SCT collaboration
IEEE, Rome 2004
SCT
DCS

2. The ATLAS SemiConductor Tracker (SCT)
9 disks
1.53 m
9 disks
4 barrel layers
Silicon surface: ~62 m² -> 4088 modules
-> ~6.3 million readout channels
* ~760 cables & ~2400 fibers required to transfer information from these channels
* Cooling System keeping electronics, modules and cables at low temperature
* Hundreds of sensors providing information about the environmental parameters
the coherent and safe operation of the detector demands a stable Detector Control System
Module
SCT Building Block
Constructed by 4 p-n strip silicon detectors
& FE electronics
768*2 strips & active length of mm

3. DCS DCS Detector Control System (DCS)
Detectors are complicated systems with huge number of parameters to be monitored and controlled
-> Powerful DCS is needed to ensure their safe and coherent operation!
Actions
Handling
Warnings
Alarms
Errors
DCS
Interaction
with
LHC Accelerator
and
External Systems
Interaction
with other
Subdetectors
Hardware
and
Software
Interlocks
Common Architecture for all the LHC experiments (Joint Controls Project – JCOP)
DCS
Distributed Back-End (BE) System
Running on PCs
Front-End (FE) Systems
(sensors, controllers…)
CANbus
Supervisory Control and Data Acquisition System (SCADA)
-> PVSS II
Hierarchical organization
simulates the natural mapping of the experiment
Final State Machine (JCOP)
States and transitions handling
Embedded Local Monitor Board (ELMB)
Standard Analog&Digital I/O
Radiation hard – Low power consumption

4. Subdetector Control Station
DCS Hierarchy
Global
Control Station
Subdetector Control Station
Local
Control Station
PCs
PVSS Projects
Communication
FE System
Hardware

5. SCT DCS Hardware Cooling System System common for SCT and Pixels
Radiation Damage = f(Temperature) -> operational temperature of the two detectors: -7°C
Initial testing and warm startup at temperatures ~ +15°C
Thermal stability better than 2 °C and tolerance to thermal shocks
-> flexible cooling system required!
Cooling System
Evaporative fluorcarbon system
Liquid C3F8
non-flammable
non-conductive
radiation resistant
Controlled by Programmable Logical Controllers (PLCs)

6. SCT DCS Hardware Environmental System
Temperature sensors (NTC thermistors)
temperature in the outlets of the cooling pipes
temperature near the edge of the support structure
air temperature inside the detector
Humidity sensors (Xeritron)
humidity inside the detector
Thermal Enclosure
Detector in controlled environmental conditions
Monitoring of temperature, humidity and pressure
Schematic Layout of the Interlock System
All sensors monitored by software
Cooling sensors monitored by
additional hardware interlock
All sensors monitored by software
Cooling sensors monitored by
additional hardware interlock
BBIM : Building Block Interlock Monitoring
IBOX : Interlock Box
IMatrix: Interlock Matrix
SIC : System Interlock Card
CC : Crate Controller
PS : Power Supplies
OPT : Optical Decoupling
BBIM Crate with the IBOXes

7. SCT DCS Hardware Power Supplies System
Provide the modules with power and slow control signals
Provide the DCS with current, voltage and temperature information from the modules
Low Voltage (LV) card
Controls 4 channels
Outputs Logical Signals for the FE electronics
Analogue Voltage (Vcc) and
Digital Voltage (Vdd) for the hybrid
VCSEL Voltage and
PIN bias Voltage for the optical
communication of the module
High Voltage (HV) card
Controls 8 channels
Provides bias voltage to the detector
Crate Controller (CC)
ELMB based interface for the
Communication of the LV and HV cards
Power Pack (PP)
Redundant powering of the crates
System Interlock Card (SIC)
Interface between PS and Interlock

8. Power Supplies Diagnostic Panels
PS GUI
Power Supplies Diagnostic Panels
Overview Panels
Global Monitoring of a crate

9. SCT supervisor : PS Project
SCT DCS BE System
Projects’ Features
Monitoring and Control of all possible values
Additional functionalities where needed
(IV curves, dew point calculation…)
PVSS archiving for storing running conditions & trending for plotting parameters’ values
Configuration files for loading & storing system information
Warnings and Alarms from ENVR and Cooling systems propagated to the PS system
(Distributed Projects)
- Temperature & Humidity Limitations
- Voltage & Current Limitations
DAQ & DCS Communication (DDC)
The two projects are sharing common databases
Final State Machine (FSM)
ATLAS Subdetector Supervisor : Common Infrastructure Control Station (CIC)
SCT supervisor : PS Project

10. SCT Assembly SCT Assembly proceeding in: Oxford (Barrels)
Liverpool & NIKHEF (Endcaps)
Modules on Barrels and Endcaps
Complete DCS chain
Evaporative cooling system
Interlock system installed
Power Supplies installed
-> System set tested successfully
Pictures taken at Oxford, by Georg Viehhauser. More about assembly at Oxford in his talk.

11. SCT Integration Final Assembly Site: CERN
Dedicated facility for the Inner Detector Assembly and Integration
SR1 Building
A Crate installed in the Rack Area
Thermal Enclosure - All the cables are installed in the barrel support structure

12. Acceptance Tests Fitted with Cooling Pipes and Environmental Sensors
Single Barrel – Full Barrel – Endcap Acceptance Tests
-> Verification of the proper function of each component
after transportation and before final assembly
700 cables and 2400 fibers installed in defined mapping and tested
2 cables with defects
No faults in the fibers
Long term tests in all the DCS components
Thermal Enclosure monitoring
Detector Environmental monitoring
Cooling monitoring
Permanent use of the Power Supplies Project
Disk Sector with modules mounted on
Fitted with Cooling Pipes and Environmental Sensors
Monitoring of up to 6 modules successful
DCS Chain in the ATLAS Testbeam
Modules powered using the PS DCS;
System working!
> IV of 1 module using the PS
Project (September 2004)
Temperature monitoring using the Envr Project
PVSS Trending Tool used
SCT Testbeam 2004

13. DCS Performance Tests
Immediate Communication between the distributed projects (Ethernet Speed)
-> Messages exchanged immediately
0.9ms separation between the messages in the long PS CANbus cable (100% Occupancy);
60% CANbus Occupancy;
11 crates on a CANbus;
-> 4s between each readout of all the parameters (11crates x 1500parameters/crate).
6s needed to switch off a crate
- result reproducible many times;
- still the same if more than one crates switched off simultaneously
Good Performance is an important issue since the system gets more and more complicated
- for single barrel acceptance tests up to 15 crates used simultaneously;
- for full barrel acceptance tests up to 44 crates used simultaneously;
- 355 environmental sensors mounted on the four-barrel system;
- later, disks integrated…

14. Conclusions & Future Plans
SCT Module Production reaching an end
Module assembly on Barrels & Endcaps underway
BE & FE DCS Systems ready for acceptance tests
Extensive DCS Testing & Upgrading Vital
for the security and performance of the Detector
…Looking forward to testing the SCT fully assembled!
Looking forward to see such pictures…
…not only in simulations!

15. Some More Stuff…

16. The Large Hadron Collider (LHC) at CERN
7 TeV beam energy
27 km circumference
operating luminosity 1034cm-2s-1
bunch spacing 25ns -> ~23 collisions per bunch crossing

17. The ATLAS Inner Detector
Muon Spectrometer
Inner Detector
Calorimeter
The Muon Spectrometer
Toroidal field configuration, field over a large rapidity range
2 barrels and endcap
The Calorimeter
Electromagnetic Calorimeter (ECAL) (Liquid Argon)
Hadronic Calorimeter (HCAL) (Liquid Argon)
Scintillator Calorimeter (TileCAL)
The Inner Detector
Cylindrical cavity, 6.8m length and 2.2 m diameter
Axial field of max strength 2Tesla - superconductiong solenoid in front of the ECAL
Precision tracking, 2ndary vertex detection, good time resolution vs big amount of material (FE electronics, power cables, colling pipes…)

18. The SemiConductor Tracker (SCT)
Detector Requirements
pseudo-rapidity coverage: 2.5
small angle stereo in order to avoid ambiguities
each detector to provide resolution of 20 μm in r and 700 μm in z
two-hit resolution of the order of 200 μm
each detector at least 97% efficiency
all layers to operate for full lifetime of ATLAS
5.6 m
1.04 m
9 disks
1.53 m
9 disks
4 barrel layers
Silicon surface: ~62 m² -> 4088 modules
-> ~6.3 million readout channels
* ~760 cables & ~2400 fibers required to transfer information from these channels
* Cooling System keeping electronics at low temperature
* Hundreds of sensors providing information about the environmental parameters
the coherent and safe operation of the detector demands a stable Detector Control System
Module
SCT Building Block
Constructed by 4 p-n strip silicon detectors & FE electronics
768*2 strips & active length of mm

19. Subdetector Control Systems
DCS Hierachical View
Global
Control System
Subdetector Control Systems
Local
Control Systems
PCs
PVSS Projects
Communication
FE System
Hardware

20. Thermal enclosure – the two sides
…and a cooling pipe

21. ELMB Stuff… Motherboard - Back Side Block Diagram
Motherboard - Front Side
ELMB card