Titanium in Cosmic Rays
In the stream of cosmic rays, particles flying toward us from the depths of the Galaxy, titanium is rare. Its nuclei are almost indistinguishable from iron: both are heavy, and both leave similar tracks in detectors.
Cosmic nuclei reveal their energies
High above the Antarctic ice sheet, a balloon with a detector floated for twenty days. It caught tiny particles that had been traveling toward us for millions of years from distant stellar explosions. Now scientists have sorted through the catch and reported how much energy the protons and nuclei of different elements carried.
Cosmic Surprise: Iron Behaves Differently
In the stream of charged particles flying toward us from the depths of the Galaxy, iron turned out to be the odd one out. The ATIC-2 instrument, lifted on a balloon over Antarctica, compared how the fraction of nuclei from sulfur to chromium relative to iron changes with energy.
The Earth’s Neutrino Confession: IceCube Reads the Planet in the Language of Weak Interactions
Earth is a closed book for those accustomed to leafing through pages with light. But to neutrinos, the invisible particles born in cosmic rays and barely remembering the prediction of Pauli, our planet is a braille script: each kilometer of depth presses its relief into their…
Neutrino Tomography of Earth: A New Look at the Planet's Interior
For almost a century, seismology has been the planet’s chief X-ray, probing the interior through elastic waves. But neutrinos, ghost particles predicted by Wolfgang Pauli, offer a different perspective.
The Milky Way Speaks the Language of Neutrinos
Deep beneath the ice of the South Pole, nearly two and a half kilometers down, an unusual telescope is at work. It is not pointed at the sky but through the Earth. Its quarry: neutrinos, nearly elusive particles that pass through planets and stars without interacting with anything.