End-Cap Data Acquisition

US Muon Software Workshop
Tufts University

Kevan Hashemi
Brandeis University
24 May 2007

This talk on the web at:
http://www.bndhep.net/ATLAS/MSW_07/Index.html

Introduction
LWDAQ Architecture
End-Cap DAQ Architecture
Hardware Components
Control Components
Control Architecture
People
ARAMYS
Readout Rate
Status

Introduction

End-Cap Alignment System:

The ATLAS muon spectrometer has three parts:
- Barrel
- End-Cap, A-Side
- End-Cap, C-Side
End-cap alignment system measures geometry of end-caps.
The A-Side system measures geometry of A-Side End Cap.
The C-Side system measures geometry of C-Side End Cap.
Brandeis University designed and provided for the end-cap alignment:
- Long-Wire Data Acquisition System (System Specification)
- All alignment sensors and light sources (Device Catalog)
- Image analysis code (Command Reference)
- TCP/IP-Based data acquisition software (User Manual).

Barrel Alignment System:

Barrel alignment system measures barrel geometry.
NIKHEF designed and manufactured barrel alignment electronics.
Barrel and end-cap electronics are incompatible.

LWDAQ Architecture

Long-Wire Data Acquisition (LWDAQ) supports cables up to 130 m.
Each LWDAQ Driver performs one DAQ action at a time.

End-Cap DAQ Architecture

Hardware Components

≈ 5000 devices in end-caps.
- BCAM (camera combined with laser diode point sources)
- RASNIK Masks (IR-illuminated chessboard pattern)
- RASNIK Cameras
- Thermometers
≈ 800 10-socket multiplexers in end-cap wheels.
≈ 150 patch panels on rims of end-cap wheels.
≈ 100 8-socket drivers in USA15.
≈ 5000 white (branch) cables, each up to 10 m long in end-caps.
≈ 800 blue (root) cables, each up to 130 m long, in cable runs.
5 VME crates in Rack 1.
2 Linux PCs and 1 screen in Rack 2.

Control Components

Component, Location, Communication:

Conditions Database, Anywhere, Internet
ATLAS Slow Controls, Anywhere, Internet
ARAMYS Geometric Reconstruction, Anywhere, Internet
Linux PCs, USA15, Internet and Alignment Ethernet.
VME-TCPIP Interfaces, USA15, VME Backplane and Alignment Ethernet.
LWDAQ Drivers, USA15, VME Backplane and LWDAQ Protocol.
Alignment Devices, End Caps, LWDAQ Protocol

Control Architecture

LWDAQ Drivers:
- receive commands (eg. Flash, Read, Sleep) over VME Backplane
- control devices over long cables
- flash lights, read out images
VME-TCPIP Interfaces:
- receive commands (eg. Flash, Read, Sleep) over Alignment Ethernet
- pass commands to LWDAQ Drivers over VME Backplane
- send images over Alignment Ethernet
Rack-Mounting Linux PCs:
- receive commands (eg. Run, Stop, Reset) over Internet
- run LWDAQ Software
- send commands (eg. Flash, Read, Sleep) over Alignment Ethernet
- receive images over Alignment Ethernet and analyze
- serve alignment measurements to Internet
ATLAS Slow Controls:
- sends commands (eg. Run, Stop, Reset) over Internet
- downloads alignment measurements over Internet
- stores alignment measurements in Conditions Database
ARAMYS Reconstruction:
- reads alignment measurements from Conditions Database
- determines end-cap geometry
- uploads geometry to Conditions Database

People

Christoph Amelung (CERN)
- Wrote ARAMYS Geometric Reconstruction program
- Checks calibration of alignment devices at CERN
- Full-time installing and alignment system at CERN
James Bensinger (Brandeis University)
- Leader of USA end-cap alignment effort
- Designed proximity cameras and calibration systems
- Half-time at CERN installing alignment system
Andrei Dushkin (Brandeis University)
- CAD drawings, layout, and integration of alignment system
- Frequently at CERN installing alignment system
Joe Rothberg (University of Washington)
- Interface between ATLAS Slow Controls and End-Cap Alignment System
Kevan Hashemi (Brandeis University)
- Wrote LWDAQ Software.
- Designed all end-cap alignment electronics and the BCAM
- Rarely at CERN.

ARAMYS

Takes as input:

alignment device calibration constants (from Brandeis University).
measurements of alignment bars (from Freiburg University).
definition of end-cap geometry, including alignment bars and muon chambers.
arrangement of alignment devices upon geometry.
latest alignment measurements.
most-recently valid alignment measurements.

Produces as output:

locations of all device mounts
location of chambers
location of wires
sagitta correction map
deviations from nominal positions
worste-performing sensors

Also applied to:

sub-sets of end-cap, such as a single big wheel
optical calibration-checking stands

Readout Rate

Time-Consuming Steps:

image capture by LWDAQ Driver: 50 ms/image
image transfer by LWDAQ Driver over VME Backplane: 50 ms/image
image transfer by VME-TCPIP Interface over Alignment Ethernet: 400 ms/image
image analysis by Linux PC: 50 ms/image (average of BCAMs and RASNIKs)
geometric reconstruction by ARAMYS: 5 minutes/end-cap.

Geometry Update Process:

Each Linux PC handles one end-cap, running in parallel.
Each Linux PC captures and analyzes one image at a time.
Each end-cap cycle captures ≈5000 images.
geometric reconstruction takes place in parallel.

Total Geometry Update Time Now: 50 min.

Slowest step is image transfer by VME-TCPIP Interface, 400 ms/image.
New version this year, will transfer images at 150 ms/image.

Total Geometry Update Time Expected: 30 min.

Status

Now running big wheel alignment in ATLAS hall from USA15.
Reconstruction is self-consistent to better than 100 μm.
Harware working well across 130-m cables.
LWDAQ Sotware working well on Big Wheel.
Expect no problems scaling to full end-cap.
Will deliver faster VME-TCPIP Interfaces this year.
Even with faster interfaces, update time will be 30 min.
One outstanding hardware problem, discovered during installation:
- Some RASNIK masks over-heat when left on for ten hours.
- Power surges and data acquisition errors can turn them on by mistake.
- We have to be careful to turn everything off every few hours.