Because of the numbers of detector components the trusses will hold, they must be precisely measured and aligned when they are first assembled.

"When we put all the detectors onto this big frame," Diehl said, "we have to make sure they don't bump into each other and get into each other's way."

Enter John Greenwood and his digital camera, called the "V-Star." The $70,000 unit uses CCD technology, and records extremely high-resolution images (6.3 megapixels, about 20 to 30 times the resolution of most CCD cameras) onto a hard drive that pops out of the camera and into a desktop computer. The camera is one of about a dozen or so in existence.

"It's already paid for itself with the time we've saved and the things we've been able to do with it," said Greenwood, assistant leader of the Lab's alignment and photometrology group.

Greenwood and a surveying crew, including O'sheg Oshinowo, John Kyle and Ed Dijak, recently spent a Friday evening attaching 150 precision-measured reflecting targets onto the huge steel structure, then photographing it from several angles at night with an intense, fast flash. The reflectors show up as white dots in the black-and-white images. Scanning software resolves the centers of the targets within 1/100 of an inch; under ideal conditions, V-Star is precise to within 1/1000 of an inch.

Most surveying of this type is done indoors, but the assembled EMC truss won't fit anywhere indoors except in its final placement at DZero. Shooting outdoors, especially with snow on the ground, meant shooting at dusk so the ambient light would not overwhelm the reflections from the targets.

"It was about 12 degrees the night we surveyed the first truss," Greenwood said. "We're waiting for a little warmer weather to do the second one."

Denisov's detector work must be nearing the finish before the weather gets much warmer. The trigger detectors, or scintillation counters, must be installed in May under the current schedule. They'll be assembled into eight units called "octants," which will then be affixed to the trusses.

The scintillators have been built and tested at the Russian high energy physics laboratory IHEP Protvino. The mini-drift tubes, gas-filled wire detectors which mark the positions of passing muons to within a millimeter, are being built at Dubna in Russia. Denisov said the Russian components have been arriving on schedule, with the last drift tubes waiting to be shipped in heated containers as soon as the severe Russian winter is past its peak.

The big truss project brings into focus the small world of particle physics, across the U.S.A. and back in the (former) U.S.S.R.

Greenwood is from California, born into a surveying family. He says his surveying work was in his backyard, his first paid surveying job came at the age of 10, and declares that he's in his sixth decade of surveying.

Denisov came easily and enthusiastically to science, with parents who were both particle physicists. He was dazzled by the space explorations and lunar expeditions of the late 1960s and 1970s. He said when he was in high school, "everybody wanted to go into the space program." The difference: it was the Soviet Union space program, with heroes like Yuri Gagarin instead of John Glenn. Denisov grew up near the Protvino lab now producing the scintillation counters.

Diehl is from Maine, and his speech is pure angular New England. His wife, Brenna Flaugher, is a physicist at CDF, DZero's rival detector across the Tevatron ring. They know it's unrealistic to try to keep professional secrets from each other.

"Our deal," said Diehl, "is that if we overhear something that's going on, we have to hear it from at least one other person before we can talk about it at our experiments."

So if they weren't before, the details of the end truss project are now fair game for Flaugher and CDF.