Mark Megahan
Something really odd is going on in Antarctica. Cosmic rays are behaving in ways that scientists weren’t expecting. Some groovy new gear noticed freaky radiation moving in the wrong direction. They went to study the rays coming in, then were astonished to see rays going out.
Cosmic confusion
The Antarctic Impulsive Transient Antenna or “ANITA” as the researchers like to call it, hangs suspended from a balloon, high above the south pole. Twice in the past two years it picked up a really strange signal.
It’s looking for radiation from space and once in a while picks up “cosmic rays coming from a direction no one expected: inside the earth.” Call the police, because that seems to break the laws of physics.
They thought it was a glitch in the equipment or something, until the effect was confirmed by another team. Cosmic rays were also spotted “by a surface-based Antarctic neutrino detector called, sensibly enough, IceCube.” Back in September, a paper was submitted by a pair of astrophysicists at Penn State.
Derek Fox was astounded. This “model doesn’t make much sense” he agrees, but the ANITA result kept nagging at him, “so I started checking up on it.” His office neighbor and paper co-author Steinn Sigurdsson helped brainstorm “more plausible explanations than the papers that have been published to date.”
They couldn’t think of any. Next, they looked for similar cosmic ray events and found three. Those are the ones that went through the IceCube project neutrino detector. By combining the data from both projects, “the Penn State scientists started getting excited.” Whatever the particle is that’s making the machines beep is a really rare one.
“Whatever kind of particle is flying up and away from Earth has a less than 1-in-3.5 million chance of being any of the particles predicted by the Standard Model.” It was once the opinion of all the aerodynamics experts that bumblebees couldn’t fly because of wing loading too. These sorts of conundrums require looking at old problems from new directions to solve.
High energy particles
The thing about cosmic rays is that they’re “supposed to come from out there somewhere, not here.” Our planet “is bombarded with them all the time.” The first guess was that some were “slamming into the earth on one side and somehow making it out the other.”
They may be high energy but they’re too wide to fit through the gaps, having “wide cross-sections that lead to their demise by causing them to crash into matter inside the Earth.”
Neutrinos can go through because they’re “low-energy” but the problem is they aren’t related to cosmic rays. Both ANITA and IceCube “track neutrinos indirectly by detecting their remains.” That leads them to think what they’re seeing is “a new kind of particle.”
They first considered “the elusive ‘sterile neutrino,’ first hinted at by evidence captured in the mid 1990s at the Liquid Scintillator Neutrino Detector at Los Alamos.” Its described as “a weird kind of high-speed neutrino that simply passes through matter without any interaction.” Wrong. Nobody could make that theory fly.
Then, last spring Chicago’s FermiLab captured new signs that it might exist. Physicists came unglued. “The sterile neutrino would break the Standard Model if confirmed, which is one of the things that make MiniBoonE’s data exciting.” It’s not settled yet. The pseudo cosmic rays could be dark matter.
Even more promising is the theory that it’s a missing particle predicted by the standard model but not yet identified. If so, a likely candidate has been found. “specifically the partner of the Standard Model’s tau leptons.” Under the normal way of naming things, they’d be “stau sleptons.”
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