The Soudan Iron Mine in Northern Minnesota is home to several experiments in particle physics and cosmology. I’ve written about one of the projects there, known as the Cryogenic Dark Matter Search (CDMS). Another experiment is Main Injector Neutrino Oscillation Search (MINOS), which detects muon neutrinos produced at Fermilab in Northern Illinois. MINOS is about 48 feet long, and contains 6000 tons of steel layered between scintillators. The entire detector had to be lowered down a narrow mine shaft piece by piece and then assembled on site.
Little Neutral One
Radioactive decay is where the atom of an unstable element can decay into another type of element, releasing energy in the process. One process by which this can occur is known as beta decay. When beta decay occurs an element such as caesium decays to barium. This process releases an electron, first known as a beta particle, hence the term beta decay.
Kick Me
Pulsars are neutron stars, formed when a large star explodes as a supernova. Because of this, one would expect a pulsar to lie within the surrounding supernova remnant, and to move at the same relative speed. But this is not the case with the Guitar Nebula. It seems that something must have caused the pulsar to move at great speed relative to the remnant. Given it a kick, as it were, hence the term pulsar kick (or neutron star kick). Given the mass of a neutron star (greater than that of our Sun) the only thing that could have provided such a kick would be the supernova itself.
Not Like the Others
The nature of dark matter is one of the greatest mysteries in modern astrophysics. Actually that isn’t quite true. We do know of one type of dark matter, and we’ve even detected this dark matter in experiments on Earth. This particular type of dark matter is more commonly known as neutrinos.
Mine Over Matter
Minnesota’s Soudan Underground Mine State Park is a former iron mine. Because of the orientation of the hematite, the mine had to go deep, and by the time of its close as an active mine in 1962 they were mining more than 2000 feet below ground level. Given its depth, and the geology of the region, the lower levels of the mine are well shielded from cosmic rays, which makes it a perfect location for sensitive experiments such as the search for dark matter. This is why it’s the location for the Cryogenic Dark Matter Search (CDMS).
Easing Tension With Neutrinos
a new paper published in Physical Review Letters gives a measure of neutrino mass, and it does so by alleviating the tension between cosmological parameters.
Factor of Three
When we discovered the Sun created its heat and light through nuclear fusion, we found that it emitted only a third of the neutrinos expected. The solution to that mystery led us to the discovery that neutrinos have mass.
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