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More news from PI: UHECR are likely protons from AGN's

  1. Nov 8, 2007 #1
    Dr. A. Chou of the Auger Ultra High Energy Cosmic Ray detector announced today that the last three years of partial information has been analysed to show at the 95% confidence level, UHECR's are caused by protons from Active Galactic Nuclei.

    Dr. Chou presented his data to the conference on quantum gravity at the Perimeter Institute for Theoretical Physics.
     
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  3. Nov 8, 2007 #2

    ZapperZ

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    See the link to the press release that I posted in the Astrophysics forum.

    Zz.
     
  4. Nov 8, 2007 #3

    marcus

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    Thanks for the link. It is an important story. When Science comes out tomorrow I hope you or someone will post exerpts---if of interest---in case the access is "subscribers only".

    Starkind the workshop is turning out well, and a lot of us are evidently enjoying your reports! This is the second breaking news you have passed along. Gives an idea of the atmosphere there (overandabove summaries of the talks presented)

    I'll copy ZapperZ's post since it gives an idea of how his outfit connects with Auger.

    BTW a couple of years ago I kept hearing Lee Smolin talking about the results to be expected from Auger---and the potential importance of Auger and the orbital gammaray observatory GLAST.
    At first I didn't know what he was talking about because it sounded like he was referring to O. J. SIMPSON------"O.J. will do this...O.J. will do that." It took me a while to catch on that it was just the correct French pronunciation of Auger.
     
  5. Nov 8, 2007 #4
    Looks like Zapper Z scooped me by twelve minutes. I waited until I could get Dr. Chou to reassure me that it was ok to send this news to PF, or maybe I would have been first! No matter. I am also glad to see the end of an embargo.

    Yes, Auger is pronounced very much like "O. J.", except the J has a little hint of "dsh" in front of it, the tip of the tounge a little forward and flatter on the hard pallete. Not a consonent that occurs in English. In fact it took me a while to realize they were talking about the name which I had previously seen in print.

    Another long day, and more tomorrow.

    Thanks,

    S
     
  6. Nov 9, 2007 #5
    Last edited: Nov 9, 2007
  7. Nov 9, 2007 #6

    ZapperZ

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    One can only hope that all of the publicity they're getting (it seems that they made the cover of Science) would give them some clout in trying to get Auger North to be built. I heard rumors several months back from people who were part of that collaboration that Auger North is in trouble of not getting funded, at best, significantly below the level that they had asked for.

    A ridiculously puny percentage of what the US spent in Iraq would have funded all of Auger North.

    Zz.
     
  8. Nov 9, 2007 #7

    marcus

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    That is disturbing news.

    We should probably all try to educate ourselves more about this new kind of telescope----one that you cannot launch into orbit because it uses the earth's atmosphere as a giant particle detector.

    If someone wants to give a thumbnail sketch of how Auger works I suspect it would be a welcome help.

    Christine, thanks for the Science magazine link! Following your link I get a page which has the following link to a FREE ABSTRACT accessible to non-subscribers
    http://www.sciencemag.org/cgi/content/abstract/318/5852/938

    this abstract would even be worth copying here in part, I think
     
  9. Nov 9, 2007 #8

    ZapperZ

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  10. Nov 9, 2007 #9

    marcus

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    Good suggestion Zapper! I wrote the following before I saw your post.

    Christine, Starkind, ZapperZ please correct me if I am wrong. A quick overview to get us up to speed on an important development.


    The air-shower telescope is a TOTALLY NEW type of telescope maybe the first really new kind (to such a radical extent) since Galileo.

    there are several examples of this new telescope concept in operation, that have appeared in the last 3 years or so---so we may be at the beginning of a new development. The MAGIC telescope is air-shower type and there are others.

    Previous telescopes normally collect an image made of the primary photons arriving from the source---they can work at various wavelengths including radio but this is generally the idea.

    By contrast, the air-shower type does not receive the arriving particles themselves, it PLOTS THEIR TRACKS BY RECORDING SECONDARY AND TERTIARY PARTICLES in a huge cube of atmosphere above the telescope.

    well some shape of volume of air. a cube is easy to say and imagine.

    There has been a lot published about Auger during the past year or two.
    Articles describing the project, with pictures. We could get links. Maybe Wikipedia has an article. If anyone has a general description to recommend please do.

    The basic idea, I think, is that the real detector is this big volume of air above the equipment. So the incoming primary stuff is INFERRED from tracks.

    MAGIC telescope in the Canaries is currently just a single optical dish, which works by imaging the Cherenkov radiation coming from high speed secondary particles produced by one gammaray photon.

    By correlating the tracks left by individual arriving particles one can pinpoint the source!
    ==========================

    Here is some of the abstract which one can get using Christine's link:
    Science 9 November 2007:
    Vol. 318. no. 5852, pp. 938 - 943
    DOI: 10.1126/science.1151124

    Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10^19 electron volts and the positions of active galactic nuclei (AGN) lying within ~75 megaparsecs. ...The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. ...

    Observatorio Pierre Auger, Avenida San Martín Norte 304, (5613) Malargüe, Mendoza, Argentina. E-mail: auger_collaboration2@fnal.gov

    ======EDIT======
    Excellent article on this in PHYSICS WORLD, just released today
    http://physicsworld.com/cws/article/news/31764
     
    Last edited: Nov 9, 2007
  11. Nov 9, 2007 #10

    ZapperZ

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    The Auger Telescope actually consists of 2 types of detectors, at least the one in the pampas of Argentina. The inner detectors are all water tank cherenkov detectors. This is similar to the detectors that are used for neutrino detection (IceCube, Amanda, etc). Surrounding these cherenkov detectors on the outer perimeter are the fluorescence detectors. These detects the electrons that are produced when the cosmic rays passed through the atmosphere. It turns out that for the fluorescence of electrons in N2, more than 1/2 of the main intensity of fluorescence light comes from electrons in the 7 to 14 MeV range of energy. Since the accelerator facility that I work with actually have an operating range within those energies, and since we can produce very good quality electron beams (low energy spread, low transverse momentum spread), it was why we were selected to do the fluorescence calibration.

    Zz.
     
  12. Nov 9, 2007 #11

    marcus

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