posted on Jun, 28 2013 @ 11:50 PM
A $2-billion experiment on the International Space Station has released the first data from its unprecedented census of the charged subatomic
particles whizzing by Earth. Although the results, presented April 3 at a seminar at CERN in Geneva, largely confirm previous observations,
researchers hope they will lead to discovering the identity of dark matter, an invisible form of matter that outweighs normal matter in the universe
by more than 5 to 1.
The Alpha Magnetic Spectrometer is the latest and most ambitious attempt to uncover the identity of dark matter by looking for cosmic rays, which are
charged subatomic particles cruising through space. Theoretical physicists have proposed that dark matter could be made up of exotic particles that
can slam into and annihilate each other, creating detectable cosmic rays such as electrons and their antimatter partners, positrons.
This first batch of AMS results, published April 3 in Physical Review Letters, encompasses about 25 billion particles detected over the course of a
year and a half, including 6.8 million measurements of the electrons and positrons that could come from dark matter. AMS improved the precision of
earlier data, detected particles at higher energies than previous instruments and found that the particles arrive in equal amounts from all
But none of the new data give clues to the positrons’ source, said Katherine Freese, a theoretical astrophysicist at the University of Michigan in
Ann Arbor. The trajectories of these charged particles can change as they move through magnetic fields, she said, making it difficult to determine
where the particles began their journey. Her bet is that rapidly spinning stars called pulsars produce positrons and fling them across the galaxy
using extremely strong magnetic fields. “It will take a while to sort this out,” she said.
In the mid-1990s, physicists got a first peek at cosmic rays that could have resulted from dark matter annihilation. The High Energy Antimatter
Telescope, a cosmic ray detector attached to a high-altitude balloon, found an unexpectedly high number of positrons, a result that seemed to jibe
with the idea that dark matter annihilation creates these charged particles. In the last five years two space-based detectors, PAMELA, for the Payload
for Antimatter Matter Exploration and Light-nuclei Astrophysics, and the Fermi Gamma-ray Space Telescope, have found even more decisive evidence of
Unfortunately for dark matter hunters, the specifics of the probes’ observations do not match up well with theories that predict cosmic rays
resulting from dark matter annihilation. Along with electrons and positrons, dark matter annihilation should produce other signals like extra
antiprotons (protons’ antimatter siblings), gamma rays and radio waves. But detectors have found no evidence of any of those signals.
Wait there is hope check this out.
DENVER — Ultracold crystals designed to catch particles of dark matter deep underground have come up with three potential detections, physicists
reported April 13 at a meeting of the American Physical Society.
The researchers do not have enough evidence to say they have discovered dark matter particles, but the finding qualifies as a rare clue in the
frustrating quest to understand the universe’s most elusive substance.
Theoretical physicists have put forth some ideas for particles that might constitute dark matter, including one called a weakly interacting
massive particle, or WIMP. The hope is that even though dark matter doesn’t often interact with regular matter, WIMPs may do so occasionally.
The experiment that made the newly reported detections is designed to pick up the signal of a WIMP as Earth passes through the galaxy’s sea of dark
matter. The Cryogenic Dark Matter Search consists of a network of silicon and germanium crystals cooled to near absolute zero. It sits in the Soudan
Underground Laboratory in Minnesota, a former iron mine more than 700 meters beneath the surface.
If WIMPs exist, one should very occasionally slam into the nucleus of a silicon or germanium atom, causing a release of energy and a detectable
vibration in the crystal. The hundreds of meters of earth above the experiment prevent other particles, such as protons and neutrons, from reaching
the crystals and triggering a false positive.
McCarthy reported that between July 2007 and September 2008, two of the experiment’s 11 silicon crystal detectors picked up three signals consistent
with those expected from WIMP interactions. If the signals were caused by WIMPs, McCarthy estimates the dark matter particle would weigh in at about
10 times the mass of the proton, well below many theoretical estimates. The results also appear in a paper posted online April 15 at arXiv.org.
While the crystals’ underground setup provides plenty of shielding, some non-WIMP particles, such as electrons on the crystals’ surface, can cloud
the results. The CDMS researchers say it’s extremely unlikely that three events would show up from non-WIMP sources.
There is a lot of research going on in and off the world looking for the key to explaining or at least identifying Dark Matter. Some call it DAMA
others call it WIMPs (bad name) anyway there are those out there trying to understand and explain the universe and even though I do not understand
everything they are doing by a long shot I get the gist of it.
Dark matter is what confounds so many it does for myself the idea that is there but having no clue as to what it is made up of. You could become
philosophical about it.