Scientists used Fermilab's MINERvA neutrino detector to decode a message in a neutrino beam. Image: Fermilab
Humankind is constantly inventing new ways to stay in touch. But in some situations it’s difficult to keep the lines of communication open. A space shuttle’s radio falls silent when the craft slips behind a neighboring planet. A submarine loses contact when deep water blocks signals from the surface.
Scientists recently proved possible a new way to converse when radio waves won’t do. For the first time, physicists and engineers have successfully transmitted a message using neutrinos.
Scientists have for decades contemplated communicating across long distances in a kind of Morse code via neutrinos, ghostly particles that interact so rarely that they can sail through the entire Earth.
“It’s beginning to look more feasible,” said electrical engineer Dan Stancil of North Carolina State University, who proposed the recent neutrino communication test as a side experiment at Fermilab’s MINERvA neutrino detector.
In the early 1980s, Stancil, who was then at Carnegie Mellon University, was intrigued by the idea of using rarely interacting particles for communication. But he was focused on axions, still undiscovered particles predicted by some theories related to dark matter. In 2009, Carnegie Mellon Ph.D. student Jim Downey contacted Stancil, his former professor, to tell him about MINERvA.
The 170-ton MINERvA detector was designed to study neutrino interactions in unprecedented detail, not to function as the receptor in a neutrino telegraph. But luckily for Stancil, the detector sits close to one of the most intense neutrino beams in the world, and that beam is pulsed. Using just over two hours of beam time, scientists were able to manipulate that pulse to convey a message: the word “neutrino.”
NC State electrical engineer Brian Hughes helped write the message in the 7-bit ASCII code computers use to represent characters with a series of 0s and 1s. Fermilab physicist Dave Capista programmed the accelerator that kicks out pulses of neutrinos at Fermilab to represent the number 1 with a pulse of neutrinos and the number 0 with the absence of a pulse. MINERvA scientists tried the program during the time period when they stood to lose the least amount of beam to the experiment – while the accelerator was turned down to half-strength to prepare for a scheduled shut-down.
The physicists were pleased with the results. “It’s impressive that the accelerator is flexible enough to do this,” said Fermilab physicist Debbie Harris, co-spokesperson of the MINERvA experiment.
The detector decoded the message at 99 percent accuracy after just two repetitions of the signal.
The test illustrated that scientists can shape neutrino beams to send messages and that their detectors are capable of reading those messages, at least from 0.6 miles away. However, “to make it interesting, you would want to cover distances,” Stancil said.
Like radio waves, neutrino beams spread out. Moving farther away from the neutrino source is somewhat like driving away from a radio tower: Eventually you lose the signal. Until physicists create more intense beams of neutrinos or build more powerful detectors, the goal of using neutrinos to communicate with people under the sea or outside Earth’s orbit will remain out of reach.
