ATLAS SLHC Upgrade

Background

After ten years operation the ATLAS inner detector components (the core of ATLAS) will have become degraded by intense radiation. After this time the Large Hadron Collider will be upgraded to increase the intensity of particle collisions by ten-fold.

A new upgraded inner detector is required to allow continued detection, data acquisition at the higher rate and to withstand the higher radiation environment. A programme of work is considering ways to create the new inner detector.

Technical challenges:

Ten times radiation tolerance
Increased heat generated by front end read-out electronics
More read-out channels, higher density, faster, more data
Cable density must not increase

Front-end electronics and DAQ

Higher data rates and channel density require new front-end electronic read-out components.

Prototype strip-detector read-out hybrid.

PPD staff have helped to design front-end components and have tested these in the laboratory.

Powering

One in a series of serial powered hybrids tested successfully.

Power has traditionally been delivered independently to each of the many thousands of modules within particle detectors. In future, the increased numbers and density of modules means this is not practical. Two techniques are being considered to solve the problem.

DC to DC conversion: Power is delivered at a high voltage and low current (thinner wires). The power is converted to the low voltage required within each module.
Serial powering: Power is again delivered at a high voltage, but modules are connected in series so each module has the correct operating voltage.

The merits of each technique are being considered and circuits have been built to test/demonstrate how they might work. Related issues also require careful thought and analysis such as increased electrical interference, radiation tolerance, size of extra components and reliability implications. Fully engineered prototype sub-systems comparing and demonstrating options will be manufactured in coming months.

PPD staff have moved the serial powering technique from at idea, through printed circuit boards with commercial components to demonstrating complete powering sub-systems on a chip. Staff have also made big contributions to the design of supporting electronics including protection mechanisms and AC-coupled interfacing.

Cooling

The electronic components generate significant heat. Many options for cooling have been considered including the cooling fluid, tube material and dimensions, joints and structure.

Understanding the consequences of a catastrophic pipe burst.

PPD staff have created a laboratory to test options in detail, including pressure testing, heating, cooling, thermal shock and cycling facilities.

Mechanics

A program of work to consider mechanical issues and options in the new inner detector is under way.

A draft design - crossection of a stave showing hybrids, support and cooling pipes.

PPD have managed STFC staff working on the project and have made prototype mechanical structures.