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Fraser
2004-Dec-21, 06:47 PM
SUMMARY: An international team of researchers have recently launched a huge balloon, the size of a football field, in Antarctica. The instrument, called BESS-Polar launched from McMurdo Station on December 13, and will spend at least 10 days at an altitude of 39 km (24 miles); at the edge of space. The experimenters hope that BESS-Polar will be able to detect any evidence of antimatter created during the Big Bang. And as a bonus, if the instrument can find low-energy antiprotons, it would be evidence of radiation from evaporating black holes, predicted by Stephen Hawking.

View full article (http://www.universetoday.com/am/publish/search_antimatter_antarctica.html)

What do you think about this story? Post your comments below.

antoniseb
2004-Dec-21, 07:34 PM
There are quite a few balloon borne projects in Antarctica. There's another one [for example] which is looking for high energy neutrinos coming up from the ice. This is a pretty special place for cosmological studies.

dave_f
2004-Dec-21, 08:02 PM
Originally posted by antoniseb@Dec 21 2004, 02:34 PM
There are quite a few balloon borne projects in Antarctica. There's another one [for example] which is looking for high energy neutrinos coming up from the ice. This is a pretty special place for cosmological studies.
I remember this one mission specifically: mapping the microwave radiation above Antarctica. I'm not a big fan of the images on this specific site (it took me a while just to find this link), but the data was very striking. The microwave radiation picture gives the impression of a boiling cauldron.

http://www.astro.caltech.edu/~lgg/boomerang_front.htm

One thing I've always been curious of: If we take multiple pictures of the microwave background radiation over time, would the images "move"? Are the changes that occurred that close to the big bang fast enough to be able to detect?

antoniseb
2004-Dec-21, 08:31 PM
Originally posted by dave_f@Dec 21 2004, 08:02 PM
One thing I've always been curious of: If we take multiple pictures of the microwave background radiation over time, would the images "move"? Are the changes that occurred that close to the big bang fast enough to be able to detect?
Since the CMB is redshifted by a factor of tens of thousands, the speed at which any changes happening would be observed is slowed down by a factor of tens of thousands. Changes should be happening, but it will be a long time before we have equipment sensative enough to detect the changes, and it will take a long time for sufficient change to occur that we could notice it.

Nige
2004-Dec-22, 01:44 PM
can i ask a question. how can you collect antiprotons as they would come into contact with matter and would destroy themselves?

Greg
2004-Dec-22, 06:23 PM
An even better question would be: can we construct an antimatter trap and begin collecting these antiprotons as raw material for high-energy uses and experiments? I realze that the technology isnt available now, but I envision such floating particle collectors here and in space in the distant future providing fuel for spacecraft.

Greg
2004-Dec-22, 06:37 PM
Ok, I will take the logic of my last thought one step further. If antiprotons are a ubiquitous and self-renewing source of power, then it is safe to assume that a technologically advanced civilization in another galaxy may have realized this long ago. By now they may have gotten particuarlly good at collecting these antiprotons at their source. So maybe what we should be looking for to detect advanced alien life is a lack of the expected amount of antiprotons emanating from a distant galaxy. If every galaxy has a SMBH (proportional to its size) and they all decay antiprotons, then every galaxy should produce a predictable amount of the stuff. If the output is shockingly low from one then the cause can be easily inferred.

antoniseb
2004-Dec-22, 06:39 PM
Originally posted by Nige@Dec 22 2004, 01:44 PM
can i ask a question. how can you collect antiprotons as they would come into contact with matter and would destroy themselves?
You don't so much collect them as observe the gamma rays from when they do annihilate.

I understand that there have been experiments that have trapped anti-protons that were created in accelerators, but not many, and not for long.

dave_f
2004-Dec-22, 10:01 PM
Originally posted by antoniseb+Dec 22 2004, 01:39 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (antoniseb &#064; Dec 22 2004, 01:39 PM)</td></tr><tr><td id='QUOTE'><!--QuoteBegin-Nige@Dec 22 2004, 01:44 PM
can i ask a question. how can you collect antiprotons as they would come into contact with matter and would destroy themselves?
You don&#39;t so much collect them as observe the gamma rays from when they do annihilate.

I understand that there have been experiments that have trapped anti-protons that were created in accelerators, but not many, and not for long.[/b][/quote]
Magnetic fields are handy for trapping charged anti-particles, though not that many of them. That&#39;s probably a good thing. :)

antoniseb
2004-Dec-22, 10:05 PM
Originally posted by dave_f@Dec 22 2004, 10:01 PM
Magnetic fields are handy for trapping charged anti-particles, though not that many of them.
One of the real puzzles for technology is how to keep anti-hydrogen trapped when the anit-proton and positron have joined to form an anti-atom.

Any predictions as to how long till we make our first anti-Helium?

Duane
2004-Dec-22, 10:07 PM
And there are experiments underway to try and preserve them for longer in hopes of using the energy produced when they annihilate. It is a field that is still in its infancy, so it will be interesting to watch it develope.

Matter-antimatter drive anyone? ;)

downunder
2004-Dec-23, 02:34 AM
I&#39;ll take a bet that they&#39;ll never find a low energy anti-proton :)

Hawking radiation will only be strong enough to create either a proton or anti-proton in the final moments of a mini BH. Also, there&#39;ll be a 50/50 chance which type happens to escape so virtually all of them will annihilate soon after.

Greg
2004-Dec-23, 05:35 AM
That said, there are still thouands of anti-proton hits according to this article during the duration of the balloon&#39;s flight in Canada. Over a long period of time that can add up if we devise a way to effectively collect and trap them. And the best thing is that it is freely provided for us and has a much higher specific impulse than nuclear or fusion propulsion.

Greg
2004-Dec-23, 05:36 AM
Specifically I envision fully autonomous deep space collecting stations which could refuel spaecraft on long distance missions.

sk_astroman
2004-Dec-30, 02:22 PM
Originally posted by dave_f+Dec 22 2004, 10:01 PM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (dave_f @ Dec 22 2004, 10:01 PM)</td></tr><tr><td id='QUOTE'>
Originally posted by antoniseb@Dec 22 2004, 01:39 PM
<!--QuoteBegin-Nige@Dec 22 2004, 01:44 PM
can i ask a question.* how can you collect antiprotons as they would come into contact with matter and would destroy themselves?
You don&#39;t so much collect them as observe the gamma rays from when they do annihilate.

I understand that there have been experiments that have trapped anti-protons that were created in accelerators, but not many, and not for long.
Magnetic fields are handy for trapping charged anti-particles, though not that many of them. That&#39;s probably a good thing. :) [/b][/quote]
yes i was also read an article that magnetic fields can trap the anti-particles.

construction of a vessle that can trap the anti-particles is very difficult and very expensive also. it is possible in future.

qraal
2005-Jan-02, 09:14 PM
Hi UT

Anti-protons are not coming from space only the gamma-ray photons from their annihilation. Hence no harvesting. They&#39;re long gone. The flux of Primordial Black Holes blowing up is probably also very small too else we&#39;d see the detonations all over the gamma-ray sky - and no, they are not the cause of Gamma-Ray Bursts. That&#39;s been ruled out - GRBs are too far away and too energetic to be PBHs.

Antimatter, currently, can only be made in accelerators. Current designs aren&#39;t optimised for catching antimatter. A few improvements would increase their efficiency by orders of magnitude, but would still be terribly inefficient. Making a-matter is only worthwhile if used as a trigger for a net energy releasing reaction like fusion.

If we had immense solar arrays built out in space by self-replicating machinery then making bulk antimatter for whatever use might become feasible. Considering that making a mere gram requires 1.8*10^14 Joules of energy - ten times the current global energy use if it takes a second - and current inefficiency multiplies that by ~ 10^6-10^5... well you can see we have a long way to go before anything can be powered by straight a-matter/matter reactions.

I used to ask "why can&#39;t it be made via converting matter into it" - which is an SF dream, but rather unlikely. Both types of particles in regular matter - leptons and baryons - have conservation laws about the number of particles. This is a fact observed time and time again in particle accelerators and everywhere that particle physics can be observed in action, like high-energy cosmic-rays etc.

BUT at some point far, far back in time some natural process did violate the conservation of particle symmetry in order to create a net presence of matter in the Universe. It was however pretty inefficient - 1/10,000,000 excess of matter over antimatter - and today is probably only happening (if at all) in the extreme particle environment inside neutron/quark stars. The spontaneous "burning" of baryons by this process might explain the short duration GRBs and/or anomalies in the detonation of supernova.

If that&#39;s what it takes to occur naturally I&#39;m pretty sure we won&#39;t be emulating it for a long time yet. However what we might be doing soon is making monopoles - "particles" with single magnetic poles - and these are known to catalyse proton-decay (http://www.npl.washington.edu/AV/altvw01.html) in most particle theories. Who needs antimatter if you can do that?

qraal

qraal
2005-Jan-02, 09:32 PM
Hi UT

Here&#39;s a very interesting web-book on Baryon Asymmetry - the current preponderance of matter over antimatter - which discusses all the physics I&#39;ve mentioned in my last post: Baryon Asymmetry (http://socrates.berkeley.edu/~morey/baryontalk/introduction.html)

...I&#39;m having a good read myself. Apparently there will be an experiment on the ISS that will try to catch stray anti-nucleii (helium will be the significant one) for 3 years. Currently none found by its prototype or cosmic ray watching.

qraal