This image processor is not your typical digital camera. It took 6 years to 20 people and $6 million to build the 'Regional Calorimeter Trigger' (RCT) which will be a component of the Compact Muon Solenoid (CMS) experiment, one of the detectors on the Large Hadron Collider (LHC) in Geneva, Switzerland. The RCT will fill several racks of space in order to process 4 trillion bits of information per second while analyzing a billion proton collisions per second. The camera is currently tested at the University of Wisconsin at Madison before being shipped to Geneva in June to participate in the first experiments in 2007.
Before focusing on the RCT, let's briefly look at the physics behind the CMS experiment.
When protons crash in a collider, an event that occurs over the span of two-billionths of second, the particles they create are so short lived that they cannot be observed directly.
According to Pamela Klabbers, [a UW-Madison scientist leading the effort to build the superfast image processor,] all of this happens, says Klabbers, in less than two billionths of a second, and scientists need to determine if that ephemeral moment is of interest and record it.
This is why the Regional Calorimeter Trigger was built. Here are some short details.
The Regional Calorimeter Trigger will be capable of processing 4 trillion bits of information per second, in essence taking "a picture of the structure of the collisions 40 million times per second," says Klabbers, who has been working to build the device at UW-Madison with 20 other people for the past five and a half years.
The Regional Calorimeter Trigger is composed mostly of custom-designed and built circuit boards integrated into crate-like structures that will be in a series of racks 8 to 9 feet tall. The components are scheduled to be shipped to Geneva in June and should be up and running by the end of 2006 in anticipation of the LHC’s first experiments planned for 2007.
Below is a "close up view of integrated circuits on a summary card, one of 300 such parallel processing computer cards to be mounted into 18 crates to collectively create a massive image processor capable of analyzing one trillion bits of data per second. A summary card does the final processing of data and drives that information to the next processing level." (Credit: Jeff Miller/UW-Madison). Here is a link to related pictures.
But you may prefer to browse through this presentation from which I've extracted the two slides below. The first one describes the algorithms to be used (Credit: UW-Madison).
This other one shows the RCT crate (Credit: UW-Madison).
As this camera is not yet assembled in Switzerland, I'll leave the last word to Pamela Klabbers.
For Klabbers, who spends most of her time in Switzerland, it won’t be possible to relax until the first working tests of the Regional Calorimeter Trigger show that it will work as advertised: "Until I see everything working right, I will be apprehensive."
Sources: Terry Devitt, University of Wisconsin at Madison, February 6, 2006; and various web sites
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