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Decades-old Scientific Paper May Hold Clues To Dark Matter
sciencehabit writes: Here's one reason libraries hang on to old science journals: A paper from an experiment conducted 32 years ago may shed light on the nature of dark matter, the mysterious stuff whose gravity appears to keep the galaxies from flying apart. The old data put a crimp in the newfangled concept of a 'dark photon' and suggest that a simple bargain-basement experiment could put the idea to the test. The data come from E137, a "beam dump" experiment that ran from 1980 to 1982 at SLAC National Accelerator Laboratory in Menlo Park, California. In the experiment, physicists slammed a beam of high-energy electrons, left over from other experiments, into an aluminum target to see what would come out. Researchers placed a detector 383 meters behind the target, on the other side of a sandstone hill 179 meters thick that blocked any ordinary particles.
Available for free: 2.5E36 high-energy electrons (~ 10GeV - 100 GeV). Last used in 1982, kept in a pet-free, smoke-free particle accelerator.
Local pick-up only; bring your own magnetic container.
* do NOT contact me with unsolicited services or offers
My favorite character from ST:NG are Data.
~(xkcd)
The collective noun for data is set: one talks about a set of data in the same way that one talks about a herd of cows. Data is just a normal nominative plural, not a collective noun.
I got about 1 paragraph into the article before it became obvious that the author had no clue what the hell he was talking about. Maybe the old paper was better, but I don't have the patience to try to find out. From TFA:
They would interact only through the feeble weak nuclear force—one of two forces of nature that ordinarily flex their muscle only within the atomic nucleus—and could disappear only by colliding and annihilating one another
So many things wrong just in that sentence
1) Weakly Interacting Massive Particles (WIMPs) do have very low interaction cross sections (read: rates). There's sometimes an unfortunate ambiguity in the fact that phycisists have no imagination and gave two of the fundamental forces the names Strong and Weak. To say something interacts Weakly means that it interacts by exchange of W or Z bosons, not just that it has a low rate. However the WIMP interaction cross section has been known to be sub-Weak by several orders of magnitude for decades.
2) The Weak force's most obvious manifestation is in the production or absorption of neutrinos (beta decay or inverse beta decay) in a nucleus, but that's certainly not the only place it shows up; it's the mechanism for neutrino-electron scattering, muon decay, and a whole bunch of other stuff up to driving supernova explosions
3) Self-annihilation is the vanilla model for WIMP transformation, but there are plenty of sundaes-with-cherries-on-top models like self-interacting dark matter, which is discussed about 2 sentences later. Also, the chi is the symbol for the supersymmetric neutralino, often equated to a vanilla WIMP, and is not at all specific to the self-interacting dark matter model.
In short, cbtfaij;dr (can't bother to find an intelligent journalist; don't read)