Dark Matter hit the news this week for the second time recently – hot on the heels of another suggestive but hardly conclusive report (see earlier posts Nov. 17, 2010 and just the other day, April 8, 2013 ) on data from the International Space Station and its alpha magnetic spectrometer team led by MIT physicist Sam Ting.
This time the hints of WIMPs, or Weakly Interactive Massive Particles, is detection of three cosmic something or others that kicked their way through the deeply chilled silicon and germanium crystals of the Cryogenic Dark Matter Search. The CDMS detector's builders tucked it into the Soudan Mine underground laboratory in Minnesota. The newest one is often called Super CDMS, as it has better crystals than the germanium-only in previous models in the mine. There, cosmic rays seldom interfere and wispy things such as neutrinos and dark matter particles better stands out against the near-blank background.
It may be an exaggeration to say the new results hit the news with a sharp smack. The paper announcing them was put up on the archive physics server April 13. The first news stories I can find emerged two days laters, a few from reporters who learned of it first hand as in physical presence at the American Physical Society meeting in Denver. Yesterday and today a train of other news stories have run. Most are fairly small. That is sensible for an incremental advance that doesn't yet settle the mysterious nature of this dark matter stuff that has been suspected for many years due to a pervasive excess of gravity in the cosmos but is yet to get definitive details to its character. None of the new results rise to that statistical benchmark of 5 sigma (about one chance in 2 million of being random chance) significance at which physicists tend to nod their heads with vigor. These reach about three sigma – better than 99 percent. That's just enough to get a fairly enthusiastic approval for the next experiment.
Stories, more or less in chronological order with those datelined Denver noted – one is always heartened to see instances when reorters went out looking for news:
- Nature Newsblog – Alexandra Witze (April 15): Another dark-matter sign from a Minnesota Mine ; A dash of bracing technical detail on how the gizmo works, along with context with other underground detection efforts but no mention of the data from space.
- Symmetry Magazine (Fermilab and Slac, Apr 15) Kathryn Jepson: Underground experiment sees possible hints of dark matter ;
- BBC (from Denver, Apr 15) Jason Palmer : Dark matter experiment CDMS sees three tentative clues ; Palmer commendably quotes some of the top gray beards in the cosmic baffler dept, including the dark matter hunt – Stanford's Blas Cabrera and UC Berkeley's Bernard Sadoulet.
- Science News (Denver, April 15, ) Andrew Grant : Dark matter detector reports hints of WIMPs ;
- Space.com (Denver, Apr 15) Stephanie Pappas: Hints of Dark Matter Possibly Seen ; Hmm, gotta sound a redundancy in headline alert. If they are only hints, that in itself means that the truth has only possibly been seen. Don't need to say both. Pappas's story itself does a fine job sorting through sigmas and other explanations of what she calls "statistical hiccups" and that's a good way to put it.
- New Scientist (Denver, Apr 15) Valerie Jamieson: Tentative dark matter hits fit with shadow dark sector ;
- Sky & Telescope (Apr 16) Camille Carlisle: Homing in on Dark Matter ; Nice acknowledgment to readers they may recall just reading about dark matter and along comes this.
- … have been lots more as word got around from Denver.
Grist for the Mill: SuperCDMS Collaboration Press Release ; Fermilab Today Press Release ; Texas A&M Press Release ; Poster PDF ; Paper PDF ;
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