But his experimental runs weren’t producing nearly the amount of antimatter particles he expected.

Breathing heavily, tasting the sour leftovers of coffee in his mouth, Dumenco crawled into the beam-tube alcove. For the fifth time in an hour, he traced a complicated logic-flow diagram with a thin finger. The diagram outlined the complex interconnections, the feedback mechanisms, and the fault-tree circuitry of his experiment.

And he couldn’t find what was wrong.

Nicholas Bretti, his graduate student assistant, always grumbled that Dumenco did too much of the “grunt work” himself, but the truth was Dumenco didn’t have a terribly high opinion of Bretti’s competence, or his scientific intuition, or his imagination for solving unexpected problems.

Fermilab had few holdout scientists who tried to do everything by themselves. In the era of Big Science, breakthrough technical papers were more likely to carry dozens and dozens of coauthors. In March 1995, when international teams of experimenters at Fermilab had announced the long-awaited discovery of the top quark, each technical paper cited 450 names! Probably everyone down to the custodians and cafeteria workers, Dumenco snorted. Physics by lemmings!

He preferred working alone; that way he knew he could trust everyone around him.

He wheeled a metal tool cart into position and unfolded a sturdy stepstool beneath the beam tube. Dumenco used a hand tool to remove an access port in front of the foil target. Detectors stood dull and dormant, waiting for an experiment to begin. A portable radiation detector sat in place on the cart, occasionally sounding a click from the natural background level.

The painted white walls and sealed concrete floor gave the experimental target chamber a cold, sterile feel-like a newly constructed sewer. Rugged instruments protruded from ports in the beam itself, shielded from the radiation that scattered during a high-energy impact. Superconducting magnets and capacitors covered portions of the beam pipe.

Inside the beam line itself, Dumenco’s antimatter “sieve” stood ready to measure the flux of antiprotons in the stream, recording each blip on computers in the main control room, which was located behind gates, fences, and safety interlocks.

But the detectors simply weren’t encountering as many antimatter particles as he expected. It was all so straightforward, and it had worked years before-so what was wrong now? The nuclear resonances excited by the gamma-ray laser should generate orders of magnitude more p-bars than any other production method, but he had measured only a few million antiparticles. He should have found billions upon billions more. Even that amount would be measured in tenths of milligrams, but it was more antimatter than had ever been produced in the free world.

His diagnostics had to be malfunctioning.

He tried to concentrate on the intricate diagram, but he had difficulty blocking out the background chugging of vacuum pumps, the hum of electronics, the stealth of shadows.

As he stood precariously on his stepstool, Dumenco looked behind him, but the long, empty tunnel responded only with an oppressive silence. He hated the constant uneasiness of feeling like someone was watching him. He had been free for years, and his family was safe, but still the fear hadn’t gone away.

Putting the logic-flow diagram aside, Dumenco rubbed his eyes. Numerous steaming cups of coffee had been unsuccessful in masking his tiredness. In times like these he longed for Luba and the children. He had been alone so long.

Alone with his work. When he was deepest in thought, trying to unravel the most intricate details of a physics problem, the memories of his family came the strongest.

He stretched higher, grunting and wedging himself into the crawlspace where he shined a small flashlight into the beam tube. He decided to take another look at the crystalline wafers that made up part of the detector.

Dumenco shuffled around on the stepstool and peered toward the experimental cavity. Small discs were arranged at various angles to the incoming beam, some with shiny surfaces, some with a wafered texture. Braids of thin fiberoptic wires lay in twisted bundles, carrying data to diagnostic units throughout the shunting area before forwarding impulses to a gigantic farm of supercomputers that analyzed the millions upon millions of particle collisions. Here in the target area, the staff placed their “oh shitski” tests-high-risk, little-understood experiments used only when the particle beam was diverted from the racetrack and dumped into the shunt area.

As Dumenco traced the connections, he heard a loud click from somewhere in the shunting bay. The lights flickered. The distant, low-frequency drone of the accelerator changed-and before Dumenco could react, he heard a muffled explosion off in the distance, down the tunnel and outside the bay.

The lights in the tunnel blinked; the air-conditioning sighed to a stop. Magenta emergency lights flared on simultaneous with automatic alarms triggered by Continuous Air Monitors.

Startled, not yet terrified, Dumenco scrambled out of the beam tube as the air crackled indistinctly around him. He lost his footing on the stepstool, stumbled, then dropped from above, falling to his knees on the concrete floor. A siren wailed, running up and down the scale.

Then he heard ominous, frenzied clicks from the radiation monitor, like popcorn.

Dumenco crouched on the floor, his knees bent and his hands spread out on the cold concrete. What had happened? He tried to think, but his attention was fixed on the rotating light.

Within seconds, the radiation detector relaxed to a much quieter series of clicks. The rotating alarm light bathed the shunting bay with a magenta strobe, which then switched to amber. Use caution. Okay to enter.

With sweat prickling at the back of his neck, Dumenco looked up at the experimental cavity. He had been standing inside only moments earlier.

Magenta: Extreme danger. Radiation hazard.

He had heard an explosion. If an accident in the Main Ring had caused a beam dump, the stream of high-energy particles would have crashed into the experimental target area. Right here, where he was.

“Don’t panic,” Dumenco whispered to himself, proud to note that he had not slipped back into his native Ukrainian. “Keep calm and try to reconstruct the events.”

Shaky, getting back to his feet, he stumbled down the concrete tunnel, toward the locked gates and the exit to the cold October night. He still clutched his logic-flow diagram, and the rotating amber light splashed blotches of yellow across the pages.

He had been bombarded with an immense amount of radiation. He had a pen in his pocket-he could calculate the dosage in seconds if he could just collect his thoughts. He had dropped from the cavity quickly, but even sub-microseconds would have been much, much too long. It had all happened in an instant.

With shaking hands he jotted down the formulas: Bragg deposition, rad to rem conversion, Q quality factors…

How could this have happened? A mere accident, right when he was about to make a breakthrough on the dangerous Soviet work he had sworn never to repeat? A mere accident, right when he was likely to be nominated for the Nobel Prize? When his grad student Bretti was gone on vacation, when Dumenco himself was conveniently working late and alone in the experimental target area?

The accelerator had too many interlocking safety features, even with the Main Injector construction. He himself had checked the integrity of the protection mechanisms, even with the temporary bypasses.

It couldn’t have been an accident.

Dumenco continued to scribble calculations, literally on the back of an envelope, and arrived at a range of possible exposures. It felt as if his heart had crawled into his throat. He tried to swallow but couldn’t.