Has PAMELA Already Seen Dark Matter?

August 25, 2009 by Miranda Marquit PAMELA

Enlarge

PAMELA is launched onboard a Resurs-DK1 Russian satellite by a Soyuz rocket in June 2006.

(PhysOrg.com) -- Back in 2006, PAMELA (a Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) was launched with the purpose of detecting cosmic radiation and looking for clues pointing to dark matter. And now it's possible that PAMELA might have already spotted dark matter.

Earlier this year, PAMELA sent data about high energy positrons -- a higher presence of them than originally expected. Speculation is that these positrons might have been generated by annihilations. Annihilations are collisions between particles that result in high amounts of energy.

Philipp Mertsch, a researcher at Oxford University in England, is working on figuring out how to detect dark matter, using information from PAMELA. He was interviewed by the Oxford Science Blog about dark matter, and how to test if these positrons represent the results of dark matter:

If dark matter is made of new elementary particles (and antiparticles) created in the then these will occasionally annihilate with each other in the dense environ of our Galaxy. Most of the energy released like this goes into or gamma-rays but a small fraction is released as energetic positrons into the cosmic radiation.

Subir Sarkar, who is also working on this project, goes on to point out that one of the problems is distinguishing between positrons and protons. The team at Oxford has devised a test to determine the source of the protons, and Sarkar offers this on the Oxford Science Blog:

Measuring the ratio of the flux of nuclei compared to carbon nuclei can therefore discriminate between the dark matter and pulsar source models on the one hand and the nearby cosmic ray accelerator model on the other hand.

While this ratio is being measured right now, there is a larger experiment slated to run next year, so the test can be better carried out. It will be interesting to see what comes back. Dark matter is of great interest to astrophysicists who contend that most matter in the universe is actually dark matter. Additionally, the presence of dark matter, and knowing what it is composed of, could answer questions about how our universe came into being -- and how it is evolving.

© 2009 PhysOrg.com


print this article email this article download pdf blog this article bookmark this article     Stumble it Digg this share on Facebook retweet share on Reddit add to delicious
Rate this story - 3.7 /5 (15 votes)

Rank Filter

Move the slider to adjust rank threshold, so that you can hide some of the comments.


Display comments: newest first

  • Alexa - Aug 25, 2009
    • Rank: 2.2 / 5 (10)
    These positrons may originate from distant pulsars, too.
    http://physicswor...ws/40065

    But I'm rather convenient with the dark matter origin of most of antimatter observed, as it supports AWT well.

    http://aetherwave...ter.html
  • Shootist - Aug 25, 2009
    • Rank: not rated yet
    Well if the gamma is 511GeV, then yes, it was caused by annihilation, otherwise NO.
  • Alexa - Aug 25, 2009
    • Rank: 3.4 / 5 (5)
    PAMELA found an excess of positrons from 10%u2013100 GeV range in the cosmic ray, but value 511MeV (not GeV) is relevant only for anihilation of electrons and positrons at rest. High speed collisions are producing gamma rays of arbitrary energy scale.
  • superhuman - Aug 26, 2009
    • Rank: 3.4 / 5 (5)
    Has PAMELA Already Seen Dark Matter?

    No, PAMELA has seen positrons and no amount of theoretical spin can turn them into dark matter.
  • Torbjorn_Larsson_OM - Aug 26, 2009
    • Rank: 1 / 5 (2)

    Measuring the ratio of the flux of boron nuclei compared to carbon nuclei can therefore discriminate between the dark matter and pulsar source models on the one hand and the nearby cosmic ray accelerator model on the other hand.


    That discrimination is all well and good in itself of course, but this is a confession that the article's claims of dark matter detections this way is an oversell. And indeed, the mundane hypothesis is that pulsar sources explains the observations, and this would be a good test of that.

    "aether"?

    Aether was rejected 1887 with Michelson's and Morley's experiments.

    "no amount of theoretical spin can turn them into dark matter"

    But these things are exactly what theory and experiments are good for, obtaining natural mechanisms explaining observations. And _that_ knowledge is much older than relativity even.
  • Alizee - Aug 27, 2009
    • Rank: 3 / 5 (4)
    .Aether was rejected 1887 with Michelson's and Morley's experiments...
    This is widespread religion of scientific community, which opens door for free thinkers, like me. Particle environment behaves differently in sparse and dense state. Sparse aether spreads energy in longitudinal waves while dense aether spreads energy in transversal waves. Single experiment cannot disprove both variants at the same time, this is virtually impossible.
  • HeyZeuss - Sep 01, 2009
    • Rank: 3 / 5 (1)
    " Aether was rejected 1887 with Michelson's and Morley's experiments..."


    It was only the rigid Aether model that M+M experiments contradicted. They regarded that experiment and their and others later ones as PROVING that a fluid aether reference frame for EM waves was correct. Superfluid it seems actually. Hence transverse EM waves.

August 25, 2009 all stories

Comments: 7

3.7 /5 (15 votes)
  • Stumble this up

  • Digg this

  • share this

  • hide
  • Related Stories

  • Dark matter: Physicists may have found piece of the puzzle
    created Apr 01, 2009 | popularity not rated yet | comments 0
  • Physicists on the prowl for dark matter
    created Jul 23, 2009 | popularity not rated yet | comments 0
  • Is Dark Matter a Source of High Energy Gamma Rays?
    created Dec 08, 2006 | popularity not rated yet | comments 0
  • Is dark matter composed of sterile neutrinos?
    created Jan 15, 2007 | popularity not rated yet | comments 0
  • High-energy Electrons Could Come from Pulsars -- or Dark Matter
    created May 05, 2009 | popularity not rated yet | comments 0



  • hide
  • Relevant PhysicsForums posts

  • moment of inertia and friction
    created 6 hours ago
  • two-dimensional collision
    created 9 hours ago
  • The acceleration of mass using light
    created 11 hours ago
  • Badminton
    created 12 hours ago
  • More from Physics Forums - General Physics

Other News

In the Brain, Seven Is A Magic Number

In the Brain, Seven Is A Magic Number

Physics / General Physics

created 15 hours ago | popularity 4.3 / 5 (20) | comments 6

Having a tough time recalling a phone number someone spoke a few minutes ago or forgetting items from a mental grocery list is not a sign of mental decline; in fact, it's natural.


Scientists react as they stand in front of a screen at CERN

First atoms reported smashed in Large Hadron Collider (Update)

Physics / General Physics

created 17 hours ago | popularity 4.7 / 5 (24) | comments 11

Two circulating beams on Monday produced the first particle collisions in the world's biggest atom smasher, the Large Hadron Collider (LHC), three days after its restart, scientists announced.


New tool for helping pediatric heart surgery

Physics / General Physics

created 3 hours ago | popularity not rated yet | comments 0

A team of researchers at the University of California, San Diego and Stanford University has developed a way to simulate blood flow on the computer to optimize surgical designs. It is the basis of a new tool that may help ...


Straightening messy correlations with a quantum comb

Straightening messy correlations with a quantum comb

Physics / Quantum Physics

created 18 hours ago | popularity 4.8 / 5 (8) | comments 0

Quantum computing promises ultra-fast communication, computation and more powerful ways to encrypt sensitive information. But trying to use quantum states as carriers of information is an extremely delicate ...


Visual assistance for cosmic blind spots

Visual assistance for cosmic blind spots

Physics / General Physics

created 18 hours ago | popularity 4.3 / 5 (3) | comments 0

A bit of imagination on the part of a measuring instrument wouldn't be a bad thing. It could help to add data from areas where the instrument is unable to measure. However, it must do so constructively. In ...