CMS MicroTCA

The CMS Experiment at the Large Hadron Collider at CERN is one of four experiments investigating the state of matter under conditions not seen since shortly after the universe was created.

The LHC

The Boston University Electronics Design Facility is building next-generation readout electronics for the CMS experiment at CERN in Geneva, Switzerland. CERN is the home of the Large Hadron Collider, the world's largest machine!

The LHC is currently circulating bunches of protons at 7 TeV. To put that in everyday terms, the total energy of one bunch of protons is about 110 kJ, which is enough energy to lift a typical 200T diesel locomotive 50 meters in the air!

Instead of lifting locomotives, the protons collide head-on, recreating conditions which have not existed since shortly after the big bang. New particles such as the elusive Higgs Boson may be created, giving us a unique understanding of how all matter achieves it's mass.

Each collision produces hundreds or thousands of secondary particles, which are captured by a huge underground detector (4 stories high). The detector is essentially a 3-dimensional digital camera, which takes a 100 Mega-pixel 3D photo 40 million times per second! That's something like 5,000 Gigabytes per second.

Data, data and more data!

What happens to all this data? Each event ("photo") is examined by a trigger system to see if it contains any potentially interesting particle interactions. If the trigger sends an accept ("yes") signal, the data is send to a "farm" of computer servers for further processing and storage. Much of this processing is performed by Xilinx FPGAs on boards built at Universities (including Boston University) and labs worldwide.

The current generation of readout electronics for a portion of the CMS detector called HCAL (Hadron Calorimeter) was built using the VMEbus standard at Boston University. Shown here is one of 32 "crates" of electronics. As you can see, a lot of cables are required to carry data between electronics modules. Incidentally, one HCAL electronics crate contains about 56 Xilinx FPGAs, mostly from the Spartan-3 and Virtex-2 families.

Upgrades!

Upgrades are currently underway to increase the energy and intensity of the LHC beams, producing up to 10 times as much data. The current electronics will be replaced starting next year with new electronics built using the new telecommunications standard MicroTCA.

A MicroTCA board (example shown to the right) is a small board which typically contains one or two large FPGAs and a connector to the backplane in the crate. Each module can transfer up to 20 Gigabytes per second to other modules via the backplane. Newer Xilinx FPGAs are ideal for use in MicroTCA modules, as they contain high-speed serializer/deserializer blocks which can directly interface to the backplane.

The EDF is supplying AMC13 modules for use in MicroTCA crates throughout CMS. See www.amc13.info for details.


Prototype MicroTCA Hub Card designed in the EDF

Display of particle tracks resulting from 7 TeV proton collision at the LHC