PDA

View Full Version : X-rays reinvented



Snoop
February 23rd, 2005, 11:28 AM
WASHINGTON -- Scientists at Los Alamos National Laboratory have developed a muon* cosmic ray screening device that can accurately detect smuggled nuclear weapons and materials in any vehicle or container, the nuclear lab reported Tuesday.

The device would provide, according to Los Alamos officials, an enormous advantage over X-ray scanning equipment, which can generate dangerous amounts of radiation and cannot penetrate lead containers and other shielding.

http://www.chicagotribune.com/technology/chi-0502230171feb23,1,4094016.story

*Quick definitions (Muon)

noun: an elementary particle with a negative charge and a half-life of 2 microsecond; decays to electron and neutrino and antineutrino. Together with the electron, the tauon and the neutrinos, it is classified as part of the lepton family of fermions. WOW

My question is this: who came up with the name cosmic rays?

Fyshhed
February 23rd, 2005, 02:20 PM
Well to answer the question of the premise, I have to think it would be the guy who inspired the writing of H.G. Wells' The War of the Worlds way back when death rays were the only rays people imagined. All the real death rays have cooler names nowadays, like Gamma and UV rays. ;)

FruitandNut
February 24th, 2005, 05:22 AM
All this gadgetry is fine, just so long as the geezer monitoring the monitors is alert, up to the job and interested. At the end of the day it is usually the human element fouling up that allows unwelcome things to happen.

It is very likely that Pearl Harbour and 9-11 would have had very different outcomes if the human element had been up to scratch.

Snoop
February 24th, 2005, 08:05 AM
This pretty much explains it - at least NASA says so: http://helios.gsfc.nasa.gov/cosmic.html

"Particles that bombard the Earth from anywhere beyond its atmosphere are known as cosmic rays. Cosmic rays don't take pretty pictures, but studying the quantity and type of these particles helps us to understand the acceleration processes involved and to measure the composition of the Sun, as well as sources at the far distant reaches of the galaxy.

Cosmic rays include:
Galactic Cosmic Rays -- coming from outside the solar system
Anomalous Cosmic Rays -- coming from the interstellar space at the edge of the heliopause
Solar Energetic Particles -- associated with solar flares and other energetic solar events


The term "cosmic rays" used to include X-rays and gamma rays, which are well covered in Imagine the Universe!"

Cosmic Rays: What Are They?
Cosmic rays are the atomic nuclei (mostly protons) and electrons that are observed to strike the Earth's atmosphere with exceedingly high energies. Cosmic rays can be over 1021eV, which is a billion times more energetic than high energy particles created on earth in the most powerful particle accelerators. They are moving at nearly the speed of light.
They were first discovered by Victor Hess, during a balloon flight. Although Hess did not know what the particles were or where they came from, he observed a source of radiation (which he thought, at the time, were gamma-rays). He noticed that there was more radiation the higher up he rose and concluded that the Earth could not therefore be the source of the emission. This was the first time that an external source of energetic particles had been discovered. Cosmic Rays have been widely observed since then and are found just about everywhere in our Galaxy. The big question is: how and where are normal protons and electrons accelerated to these tremendous energies?

http://imagine.gsfc.nasa.gov/docs/features/topics/snr_group/cosmic_rays.html

Snoop
April 5th, 2005, 06:04 PM
Does anyone know if it is possible to see through the scratch off lottery tickets with this technology - or any other technology. I really think the scratch offs are vulnerable. There used to be a machine called a flouroscope that could see through that lead based paint? Oh well, I have to trust the sellers I guess.

FruitandNut
April 7th, 2005, 01:23 AM
Does anyone know if it is possible to see through the scratch off lottery tickets with this technology - or any other technology. I really think the scratch offs are vulnerable. There used to be a machine called a flouroscope that could see through that lead based paint? Oh well, I have to trust the sellers I guess.

A dentist friend and myself tried using the intense light/fluoroscope that is used to 'fix' dental adhesive. We got tantalisingly close to cracking the MacDonald scratch cards! The 'weakest' side is the reverse.

Snoop
March 17th, 2006, 09:30 AM
I knew this topic wouldn't die - consider this an x-ray of the universe.

Here's some recent news about the origin of the universe. It seems the initial expansion was huge and fast, and now it is more stable. At least that's what I think they are saying:

NASA images offer details about design of the universe

Probe 'confirms suspicions' of events after Big Bang, UBC professor says


PETTI FONG

<!-- Summary --><!-- dateline -->VANCOUVER<!-- /dateline --> -- You may be reassured to know, as physicist Mark Halpern of the University of British Columbia has just learned, that the universe is behaving exactly as it should.
New images from a NASA space probe that Prof. Halpern and scientists from throughout the United States designed and launched five years ago, have provided evidence of what happened 13.7 billion years ago.
<!-- /Summary -->Prof. Halpern looked back in time to capture the split second when a mass the size of a pebble expanded exponentially over and over to become the universe, after the Big Bang.
And he saw what he expected to see.
<SCRIPT type=text/javascript ads="1">aPs="boxR";</SCRIPT><SCRIPT type=text/javascript>var boxRAC = fnTdo('a'+'ai',300,250,ai,'j',nc);</SCRIPT>
"The simplest version of this fairy tale that is our universe is now dramatically more secure," Prof. Halpern said.
"What surprised me is how incredibly well the simple picture fits. It seems we understand a lot about the universe that until now has been just about guesses. Things are the way we believed they should be."
Cosmic microwave background radiation is the radiant heat left over from the Big Bang and first observed in 1965 by astronomers. From the properties of the radiation, scientists can learn the physical conditions of the universe at its beginning stages.
Images released yesterday detected the earliest light seen yet from the Big Bang afterglow, providing new evidence that the universe grew suddenly in less than a trillionth of a second.
The current picture shows blue and green cool spots, yellow and red hot spots and white slashes to indicate polarization, which tell scientists how material was moving in the beginning when the universe formed.
The information pinpoints when the first stars formed and provides new details about events that transpired in the first trillionth of a second. It's from quantum fluctuations that stars, planets and the galaxies formed.
Mike Nolta, a postdoctoral fellow at the Canadian Institute for Theoretical Astrophysics in Toronto, said the images are a relic left over from the beginning of the universe.
"There was an expectation we would see what we're seeing. It basically confirms our suspicions," he said yesterday.
For the past three years, the satellite has continuously observed the cosmic background radiation that lingers from the universe's sudden forceful beginnings billions of years ago from a distance of 1.6 million kilometres away from Earth.
From their observations, scientists were able to report the age of the universe as 13.7 billion years, give or take a few hundred million, and the age of the universe when stars first began to shine, 400 million years later, again with the cushion room of a few million either way.
Prof. Halpern and 12 other U.S. scientists around began the project, but it has since expanded to include a group of 20 physicists who continuously monitor and analyze the patterns and signals received.
Over the past three years, scientists have been able to identify that just 4 per cent of the universe is composed of ordinary familiar atoms.
Researchers have still not been able to identify 22 per cent of the universe, which they call "dark matter."
"It's not atoms, so it remains a mystery. It's some other stuff that doesn't give off light. We know it doesn't bump into other matter, but it gives us something to think about," Prof. Halpern said.
A remaining 74 per cent of the universe is another mysterious substance called dark energy.
Each new piece of the puzzle in determining the origins of the universe is done for pure curiosity, according to Prof. Halpern.
"It's not going to help us understand weather patterns or other things like that," he said.
But reassuringly, the latest images indicate the universe will last even longer than scientists predicted.
Also, its expansion is accelerating, rather than slowing down.
"I used to say the universe will last forever and people would say, 'How do you know that?' " Prof. Halpern said. "Now I can say it will last at least many tens of billions of years and the universe we know will last forever or at least as long as forever means."


http://www.theglobeandmail.com/servlet/story/LAC.20060317.BCSCIENTIST17/TPStory/National

Turtleflipper
March 17th, 2006, 06:56 PM
I think the expansion of the universe is a constant. Called the Hubble constant. I'm not sure if he got a noble prize or not. He should have though. That sucker is useful. Although he didn't get the numbers even close to right, so.....

Anyway, it wasn't fast to slow. I posted the whole "1 early light-year equals way more light-years now" in the other cosmology thread. Now if the universe expanded at rate x, which we will say is 100 m/ph (as in we are getting 100 miles of increase objectiivly per hour, though relativily we're stationary). Rate x will change because of the stretching of space-time, from an objective veiwer's way of seeing, to become 100,000 m/ph (agian, in terms of spatial warping increasing objective distance), because although the universe is only going at the velocity of 100 m/ph, the relative distance a mile counts as, is being stretched to 100,000 times its normal length.
So, with that, we can see that Rate x dosen't change. And the universe is always expanded at the current rate. It just looks faster back then because from our way of looking, a light-year was so much bigger in the good-ole' days then our modern, stunted light-year.

Snoop
April 16th, 2006, 11:04 AM
I am still amazed by the amount of activity in the universe (although most of the events are many thousands of years old). I recently saw a show on TV about Gamma Rays (http://www.msnbc.msn.com/id/6994277/) - they actually are like molecular bullets (after they pass through our atmosphere) that can alter our chromosomes over time. Shearly a chance event, but this is how mutations happen.

This a series of photo's featuring nebulae (http://photoshow.comcast.net/watch/Yx4xM8nP) (click for a musical photo show including all 13 photo's)

FruitandNut
April 16th, 2006, 12:53 PM
The universe is a massive fireworks and lights show.