Posted on 02/21/2005 6:26:33 PM PST by wagglebee
Scientists are using cosmic ray detectors to uncover the secrets of the earliest large metropolis of the Americas.
Archaeologists and nuclear physicists are working together to measure the passage of muons, subatomic particles from deep space, through the 2,000-year-old Pyramid of the Sun to discover whether it was a mausoleum or a ceremonial monument.
They believe the experiment will lead them to burial chambers, the American Association for the Advancement of Science conference was told. Many experts believe that the pyramid, the third largest in the world, holds the mysteries of the pre-Aztec Teotihuacan civilisation.
Arturo Menchaca-Rocha, the director of the physics institute at the National Autonomous University of Mexico, is leading a team using muon detectors in a tunnel 26ft below the base of the 215ft-tall pyramid.
Dr Menchaca-Rocha said: "In spite of its fame, little is known about this, one of the largest pyramids in the Americas, or even about the people who built it 2,000 years ago. Excavations have shown no identifiable internal structures of the kind uncovered in the nearby Pyramid of the Moon, which are also a relatively common feature in other pre-hispanic monuments in Mesoamerica.
"It has been a long-standing archaeological question as to whether the pyramid might have been used as a burial place.
"It is the perfect place for such as experiment. If we detect more particles than expected coming from one part of the building, it means that there must be a hole in that direction."
The ancient city of Teotihuacan, whose first inhabitants settled in the area as far back as 800BC, was the first large metropolis in the Mesoamerica.
It became the capital of a complex civilisation, which at its peak was made of up of an estimated 100,000 people, that lasted until it was abandoned around the seventh century for unknown reasons. Numerous excavations have failed to shed light on who founded and governed the city.
When the Aztecs found it empty, they decided the whole area was inhabited by supernatural beings. Teotihuacan means "place of the gods" in Nahuatl, the Aztec's native tongue.
Archaeologists have been unable to uncover the original name of the city. Nor do they know who founded the civilisation, how it was government and why the city was abandoned.
The stepped Pyramid of the Sun, 740ft on each side and 215ft high, was built in the second century AD. In spite of its importance, excavations have failed to answer the pyramid's central mystery - was it a mausoleum or a ceremonial monument. Archaelogists believe the keys to shedding light on the origins and political leadership of Teotihuacan civilisation could lie in burial chambers deep inside the giant pyramid.
The interaction of cosmic rays with the atmosphere creates a continuous shower of muons - tiny, charged particles that travel dozens of miles in the millionth of a second that they exist.
They strike the Earth's surface at a rate of about 10,000 per square metre per minute and pass through most materials almost unhindered.
A given amount of a known material will absorb a precise proportion of muons that can be calculated and will deflect them in a particular pattern.
A muon detector, which uses thin wires to pick up electrical charges from the tiny particles, has been put in a tunnel 26ft beneath the Pyramid of the Sun. By this summer six will be in operation. The experiment will take a year.
Dr Menchaca-Rocha calculates that chambers should be present if the detector counts fewer less than 100 particles every second.
Kanetada Nagamine, of the KEK Muon Science Laboratory in Japan, told delegates at the conference about his research into using muon radiography to predict volcanic eruptions.
American researchers from the Los Alamos National Laboratory in New Mexico described how they were working on using the technique to detect smuggled nuclear materials in vehicles and cargo containers.
IIRC he worked on the "Second Pyramid". The Great Pyramid is known to have a variety of chambers but comparitively few chambers had been found in the Second Pyramid. Alvarez described in his autobiography how he received a call during the experiment that positive results had been found, but after travelling all the way back to Egypt, he found that the results were due to an experimental error known as "double binning".
"In truth, he succeeded in proving that there were no hidden chambers in the Great Pyramid."
Waaaaah! Are too! It's just that they're lined with an alien material unknown to science that threw off his instruments.
Question: Since muons seemingly pass through everything, pretty much, how do you detect one?
Muons have an electromagnetic charge. As they pass by atoms, they can strip off electrons. The free electrons and ionized atoms can be detected in a number of ways.
One method would be to have a series of wires held at a high voltage in some easily ionized gas, such as argon or neon. As the passing muon leaves a trail of ionized gas molecules in its wake, the molecules drift in the vicinity of the wires and are attracted to them. The charge is deposited on the wires, which gives a measurable signal on the wires. Trace a curve through the wires with signals on them, and it shows the path of the muon. This is called a wire chamber.
Another method, more common for muons, is to wait for the ions to recombine with the electrons that were stripped from them, which results in the emission of light. This process is called "scintillation". The light can then be collected with a photomultiplier tube. A typical scintillation counter would consist of a series of rods made of a very special plastic that is very clear, and which ionizes easily.
So why are muons so much better at passing through matter than other charged particles? Well, for one thing, they have a long lifetime. The only charged particles that last longer are electrons and protons. Electrons and protons do travel through matter, and can be measured by the detectors I described, but they don't go as far, and for different reasons.
Electrons have very little mass, which makes them emit energetic photons very easily (a process called "Bremsstrahlung"--German for "braking radiation"). Muons, being more than two hundred times heavier, don't do that as readily.
Protons, being heavier still, also don't suffer much Bremsstrahlung, but they are subject to the strong nuclear force. Every time a proton smacks into an atomic nucleus, it either bounces off at some angle, or it breaks the nucleus apart. Nuclei are pretty small, but there sure are a lot of them, so naturally a proton will suffer many interactions as it passes through matter. Muons, by contrast, are totally blind to this force.
Lord, your world is so big and my brain is so small.
Great summary. Thanks a million.
I won't ask you to turn the thread into physics 101, even though I can't for the life of me figure out why muons are blind to the strong nuclear force.
Thanks wags, looks like blam just barely beat ya to it. :')
This one goes into the GGG catalog though, obviously, and I'll ping the other one. Thanks again!
Cosmic Rays To Solve Ancient Mexican (Pyramid) Mystery
Scotsman | 2-21-2005 | John von Radowitz
Posted on 02/21/2005 12:26:52 PM PST by blam
http://www.freerepublic.com/focus/f-news/1348047/posts
Please FREEPMAIL me if you want on, off, or alter the "Gods, Graves, Glyphs" PING list --
Archaeology/Anthropology/Ancient Cultures/Artifacts/Antiquities, etc.
The GGG Digest -- Gods, Graves, Glyphs (alpha order)
Teotihuacan (northeast of Mexico City) where this pyramid is located existed around 200 BC to 600AD not much is known about the builders and their civilization, the Aztecs and Tenochtitlan (present day Mexico City) did not really come on the scene until 1200-1300AD. Calling the Pyramid of the Sun pre-Aztec is only correct in that it was built long before the Aztec emergence but that's the only connection.
Thank God they ended it.
When you consider the elementary particles, you see that they fall into two groups: force particles that have integer spin and which carry a force (such as photons, gravitons, gluons, Z particles, and the like, collectively known as "bosons") and matter particles that have half-integer spin and which do not carry a force (collectively known as "fermions").
These fundamental fermions--the "matter" particles--are further split into two kinds: quarks and leptons. There are six kinds of quarks, and six kinds of leptons. These two groups mirror each other in all sorts of ways, so that it seems each type (or "flavor") of lepton has a corresponding flavor of quark, and vice-versa. Nobody knows why that's the case. There's some symmetry there we haven't discovered yet.
The main difference between the quark and lepton families is that the quarks carry "color" charge, while the leptons do not. The color charge is the charge associated with the strong nuclear force. If a particle has color charge, then the strong force can push it around, but if not, then the strong force has no handle on it. (This is exactly analogous to electromagnetism: if a thing is charged, then it can be moved around with an electrical field, but if it isn't, then it can't.)
So the answer to your question is this: muons are leptons, and as such, they have no color charge, so the strong nuclear force can't move them around. Protons, on the other hand, are made of quarks, so even though the protons themselves are colorless, the strong nuclear force does have a handle on the proton's constituents.
Once again, thanks a million.
I don't think they even knew all of that when I was in college back in the 70s.
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