Cosmic Ray / Auger Obsevatory Working Now

Seldom can I report science news not already known in English. Local newspaper's (Folha) reporter has full-page report on the Auger Cosmic Ray observatory being constructed in the very dark (moonless) Argentine "pampas region." 1000 of the planned 1600 Cerenkoff radiation tanks have been placed into operation. They are separated from each other by 1.5 Km, and powered by solar cell /battery system with GPS time* of UV Cerenkoff flash in the 1000 water tanks is sent to processing center by cell phones. (Each tank is 1.5m tall and 3.5m in diameter and has three UV sensitive photo detectors.) Thus, the angle of primary ray is known.

The primary rays of interest have 99.999,999,999,999,999,999,999,9% of the speed of light! To make this understandable to Brazilian readers, this is said to be the same as the energy in Guga's fastest serve of a tennis ball. (Guga is a well-ranked Brazilian tennis star who seems to be past his peak now.) The water tank array covers 3 thousand square Km. The rays of most interest come to each square Km between 10 to 100 years on average. No one has the slightest idea how they are made or where they come from.

Surrounding the water tank array are four optical telescopes, called "eyes" that continuously monitor the sky over the tank array looking for the very faint atmospheric Cerenkoff. Each eye is six sub telescopes and seems to send light to 440 separate photo-detectors. Few details about them are given in the text, except they can detect a 4W “Christmas tree light” at 15Km. Two photos of them are shown. One makes me think the primary mirrors are a close packed array of small hexagon mirrors. The other photo has a small "fly eye" like structure at what may be the focus of a much larger circular annulus of adjacent almost square mirrors. I think this "fly eye" structure houses the 440 detectors and the 24 small nearly square mirrors in the circular annulus send different parts of the sky (superposed?) on to the 440 detectors. (Possible as most of the sky is dark and the optical system may just be refining the precession of the incident direction known from the timing of water tank signals. Stars would be relative static and their atmospheric shimmer would not correlate well with both the loction given by water tank array data and the GPS timing - Just guessing. You know what a mess a reporter can make of physical facts he does not really understand.)

A lot of the above is report's text augmented by my knowledge of the physics. - It is an exciting time. One of the great mysteries of physics is hopefully going to get good data soon. Search and tell us more/ correct my guesses.
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*The tanks "know" where they are. The location of the GPS satellites is always known (as a function of time). In this system, the GPS is being used as a very high precision clock. Since GPS is able to measure locations to sub meter errors, it means that the time is known to accuracy of the interval that the satellite requires to move less than a meter (I think).

 

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http://www.auger.org/observatory/observatory.html

Here is a link to the Pierre Auger Cosmic Ray Observatory website. It is one of the latest projects to study the ultra high energy cosmic rays. The HiRes Observatory in
Utah was one of the first, later replaced by the Fly's Eye in Utah. Japan's Akeno Giant Air Shower Array is another newer project studying the UHE cosmic rays.

Of particular interest are the rare cosmic rays with kinetic energies over 10&sup2 0; eV.
The last I read, only about a dozen cosmic rays of those energies have been detected so far, at both Fly's Eye and Akeno. 10&sup20; eV is equal to the kinetic energy of a tennis ball travelling at 340 miles per hour, much faster than Guga's serve! They are of
particular interest because they may cause Einstein's Theory of Special Relativity to be
reformulated. Cosmic rays with energies over 5 x 10&sup19; eV are theorized to interact
with the photons of the cosmic microwave background radiation, losing energy through the interaction. According to present theory, cosmic rays with energies over that cutoff cannot travel over 150 million light years without losing so much energy so as to fall below 5 x 10&sup19; eV by the time they reach Earth. But the Ultra High Energy cosmic rays are believed to come from events billions of light years away, possibly from a black hole 'eating' a neutron star, or the collision of two neutron stars creating a new black hole in the process.

 

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I have read the colorful comparison of an already detected cosmic ray having had the kinetic energy of a major league fastball.

Anyone who has ever had the sensation of being momentarily dazed for no apparent reason might now have some idea of what might have happened.

 

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Quick exercise for you:

If a cosmic ray (say a lithium nucleus, with mass 10^-26kg) with the KE of a Lleyton Hewitt first serve (say 50 grams at 50m/s) interacted with your hand, would you feel it?

(hint - momentum)

 

Slow witted exercises only for the old man, please.

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If a major league fastball interacted with my hand, I would feel it and, even after all these years, I would catch it.

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( hint - the old man does still has excellent reflexes and coordination ).

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I'm sure you would!

But... is that because of its kinetic energy, or because of its momentum? Or something else again?

 

"Or something else again?"?

I understand momentum and kinetic energy. If you are privy to arcane knowledge of physics having escaped great minds for five centuries and more, please share now.

 

Methinks you're reading too much into my post...

 

I have read that also. In Brazil, where article I quoted from was written, they do not play baseball, so I guess a fast tennis ball was as close as the author could come.

On your second "momentary dazed" I can report that I have personally, unaided by instruments detected a cosmic ray. I was in sleeping bag in desert near Los Alamos one summer eve when there was supposed to be a good metor shower (I did in fact see one every three or four minutes at the peak before falling asleep.)

I was far from any artificial lights well dark adapted, when a flash of light occured. I don't know in which eye, but Chrenkoff radiation from a cosmic ray is the most obvious explaination for this flash. Twice at other times in my life, I have "seen" bright spots, well localized, appear in the dark. The first time I briefly thought it a luminous bug on the ceiling, but it moved as I moved my direction of gaze, so I immediately knew it was in my eye. I wrote up a report on it and sent it to the Wilmer Eye clinic of JHU, but they did not reply. This bright spot lasted several minutes. I think an optic nerve ruptured or something like that as it was very small point of appearant light in a dark room. The cosmic ray flash was very brief, very bright (seemed to be white) , and global.

 

I want to vote for Pete's "something else"

If a cosmic ray of that energy were to pass thru your hand, I think that there would be a lot of charged particles produced and some would interact with your nerves. I think you would feel something like a mild electric shock. - Just guessing.

I did not feel any thing when I experienced the flash of light, but perhaps it distracted me. Also the energy of a particle that can make Cherenkoff radiation inside your eye is much less.

 

I have also experienced very brief flashes of light on a few ocasions. They have all been identical: a point of light appearing and disappearing instantaneously, and with eyes opened and also closed. I remember that astronaughts have reported the same phenomena and it has been explained as cosmic ray strikes. With me there has been no nerve sensation, and the brightness has been identical; bright enough to easily notice in daylight or in a well lit room.

Pete's "something else" was just too inscrutable for me. I have enough trouble guessing the answer, but when I must also guess the question, the game is over for me before it can begin.

In respect to "something else", there have also been a few times when I have experienced a brief electric shock sensation somewhere or the other with no recognizeable reason. They have been consistent in strength, what I would speak of as just strong enough to be noticed but not painful, just certainly distracting. Now that I know what was meant, I can easily add my agreement that a fairly powerful cosmic ray could seemingly cause nerve sensation.

 

My take on the interaction of a cosmic ray with universal photons:

Suppose a particle is expelled from a distant source at a high subluminal velocity. As it whizzes along, it is struck by photons overtaking it and also hitting it head on. Relative to the particle, the rear-ending photons are red shifted, therefore having a lower kinetic energy available. The head on photons are relatively blue- shifted with a coincidingly greater amount of kinetic energy available. The particle should steadily suffer a reduction of kinetic energy, therefore a lowering of velocity. At a little under .5 c, the rear-ending and head on kinetic energy transfers should stabilize in equilibrium, with the particle then maintaining a steady cruising speed.

My conjecture can be proved or disproved by researching our decades of cosmic ray observational data to see if there is a big spike of velocities in the range of .5 c.

 

I am quite sure that a cosmic ray passing thru the eye should not be perceived as a "point of light" but as a global flash. Thus, I am not sure what you are referring to.

I also mentioned that I have twice had very well defined small points of light that were definitely some process in my eye (not my brain or the room) as they were fixed in location wrt my point of fixation and I had the presence of mind in the minute or so tht they lasted to intentionally move the point of fixation around in the room. (I was still in bed and the room was with enough light for me to see things in the room.) I am nearly sure that they had somethhing to do with a hyper active rod or cone, but they had little color, so I suspect a rod cell was dying etc.

 

I do not quickly see why this should be true. Also it is from the entire forward and rearward hemispheres that one must consider this. Perhaps a search of "Compton Sacttering" will turn up some results. You are talking about Compton Scattering off a moving charge, so use "moving" or better "moving charge" etc in your search to get only a few thousand Hits.

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I clearly remember reading astronaut reports of brief light flashes in which their descriptions were identical to what is these posts of mine. And I clearly remember that the official explanation was that of cosmic ray strikes in their eyes. However, it is the least of my concern whether I have, or, have not, personally detected a cosmic ray under any circumstance. Or, whether you have, or, have not.

Regarding your admission that you do not quickly see why my .5c conjecture could be so: if it doesn't work at first, try it again. No pain, no gain. Think about carefully and for sufficient time and perhaps you will get it.

You are correct that the entire hemispheres are to be considered. I am in the habit of not having to explain obvious truths and therefore unfortunately sometimes omit things which then mystifies those who chronically need to be spoon-fed.

 

I agree it is not very important to have personnally detected cosmic rays without insturments, but I think it interesting that one can do so. I believe in lots of things I have only instrumental evidence for.

I hope you have a spoon handy for "spoon feeding" me. I thought about it, a little, along the following lines:

If a charged particle (or a rocket ship) has velocity v wrt to a spectral distribution incident upon it that was identical frequency distribution when leaving the source, assumed to be isotropically surounding the the particle, then even if v is small the spectral distribution on the forward end will still be blue shifted and that on the tail will be red shifted.

That is, I think there is a "photon drag" on any movement, regardless of v, if the photon flux field is isotropic and of the same spectral distribution at the source.

For example, suppose the particle is moving inside a pure atomic hydrogen gas cloud with uniform temperature, and only the Hydrogen lines (Lyman, Balmer, etc. series) are present. Then as it runs into Hβ photons they will appear blue shifted and as the Hβ photons catch it, they will be red shifted - I.e. a net drag. What is true of Hβ is true for all lines etc for a continium.

What is wrong with this arguement, if you disagree and want to defend your original "balance at near 0.5c" claim?

 

My original Gedanken was thought out and then posted prior to my second cup of coffee. Subsequent reflection has enabled me to have doubts about its validity. However, the concept that a massive particle originally having a particular velocity will, as it transits universal space, enjoy drags and propulsions , seems to my second coffee cupped mind to have possible validity.

After proper reflection, it does occur to me that .5c may be a flawed concept.

It seems likely that net photon drag would brake a speeding particle. Perhaps rear ending photons would balance oncoming photons at 0 c. But, then a particle would be, as they said on Star Trek, dead in space. How, then, would it continue on its way and finally get here into a cosmic ray detector?

Have you entertained any conjectures on this subject?

We have mountains of evidence that there are massive cosmic rays, yet, both photon drag and actual "aerodynamic drag", due to collisions with other interstellar massive particles, should both brake them and stop them "dead in space".

By the way, thanks, this was an interesting thread for you to have posted.

 

Normally I would not "gloat" but your "need to spoon feed me?" comment makes me do a little of it. Anyway I am glad we now agree that there is a "photon drag" for cosmic rays to overcome.

Yes, on the average a collision with another particle in route to Earth should slow down the high-energy cosmic ray, but this is not always true. For example, fast particle A, hit from the side (think 90 degree broadside, but not only this) by fast particle B can result in one of them, post collision, having more energy than pre collision. (It would be more massive if you are an old guy like me who still likes to speak of "relativistic mass" even if the younger physicist look down on their elders for doing so.) That is, some of the high-energy cosmic rays may be in the "Maxwellian tail" of a collisional distribution. I am just speculating, and think wrongly, as this idea is too obvious to be the missing explanation. I mainly mention it to counter your idea that collisions must cause "aerodynamic drag."

Thanks. It is seldom that science news is first reported in Brazil, although thanks to stupid (MHO) right-wing & religious political pressure related to stem cells etc., Brazil is at least the equal to US in some areas of Genetics etc. (A Brazilian team's work made the cover of Science last year. - Some Asian countries are far ahead.) If you are interested in how the US needs to learn from others, take a look at the new thread I started today on "Fuel Choices, Global Warming, & Pollution" in the Science & Citizen forum.

 

Believe me, I have no bias about any nation in regard to science, and am glad of any person in any nation helping science truth to be discovered and published.

Somebody did me again! Enjoy your gloating in a hurry, because your next opportunity is zooming in, if my personal history holds true to form. I am very proud of my natural talent to give somebody something to gloat about. Just don't think you are unusual.

This cosmic ray thing might be serious. I may become tempted to try to contrive some statistics about how much how many very fast particles are slowed to a standstill, on the average, on their way here, and then, try to elaborate on what could make a stationary particle show up here in a detector as if it were a 340 MPH tennis ball.

I am going to try to dig up some reliable astronomy estimates on how many cosmic ray strikes we enjoy per day or whatever, and start from there. Do you perhaps already know of a good source of such info?

I am invisioning a case of where we might have a kind of a sphere of "dead" cosmic rays around the solar system, and when one happens to be struck by a gamma photon and kicked our way again, it is close enough to get here before it gets braked again. If you know of such a theory already having been published, I TOLD YOU to be ready to hurriedly gloat again.

PS: I am indeed an old man who is comfortable speaking in terms of "relativistic mass", etc., although I have some SERIUOS doubts about the Relativities. However, I am not a fanatic one way or the other about the validity or invalidity of the Relativities, and am sincerely seeking the truth about which way the cards fall on the issue.

 

Well, people can build cloud chambers at low cost that will detect the occasional cosmic ray. I have also seen the flashes of light accompanied sometimes by a sensation of heat. Anything that carries that much of a punch is going to knock photons loose all the way through a human body, so it's likely to cause a sensation somewhere, like being shocked or stuck with a pin. Actually, it is going to literally blow holes through tissue, holes less than a thousandth of an inch in diameter. They blow holes through glass. The human retina is able to detect just one photon at a time, so it's not at all fantastic to suppose that a person can see a cosmic ray impact on their retina. The same thing can happen on a digital camera, if anyone leaves one turned on in a dark room or container. A similar thing happened to film used to take pictures near Chernobyl. There are nice bright flashes of light on that video every so often, and my 10 year old nephew asked if those were because of radioactivity.