Antimatter atom trapped for first time

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17 November 2010 Last updated at 13:07 ET
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Antimatter atom trapped for first time, say scientists
By Jason Palmer Science and technology reporter, BBC News

Antimatter atoms have been trapped for the first time, scientists say.

Researchers at Cern, home of the Large Hadron Collider, have held 38 antihydrogen atoms in place, each for a fraction of a second.

Antihydrogen has been produced before but it was instantly destroyed when it encountered normal matter.

The team, reporting in Nature, says the ability to study such antimatter atoms will allow previously impossible tests of fundamental tenets of physics.

The current "standard model" of physics holds that each particle - protons, electrons, neutrons and a zoo of more exotic particles - has its mirror image antiparticle.

The antiparticle of the electron, for example, is the positron, and is used in an imaging technique of growing popularity known as positron emission tomography.

However, one of the great mysteries in physics is why our world is made up overwhelmingly of matter, rather than antimatter; the laws of physics make no distinction between the two and equal amounts should have been created at the Universe's birth.
Slowing anti-atoms

Producing antimatter particles like positrons and antiprotons has become commonplace in the laboratory, but assembling the particles into antimatter atoms is far more tricky.

That was first accomplished by two groups in 2002. But handling the "antihydrogen" - bound atoms made up of an antiproton and a positron - is trickier still because it must not come into contact with anything else.

While trapping of charged normal atoms can be done with electric or magnetic fields, trapping antihydrogen atoms in this "hands-off" way requires a very particular type of field.

"Atoms are neutral - they have no net charge - but they have a little magnetic character," explained Jeff Hangst of Aarhus University in Denmark, one of the collaborators on the Alpha antihydrogen trapping project.
Continue reading the main story
“Start Quote

I'm delighted that it worked as we said it should... it shows that the dream from many years ago is not completely crazy”

End Quote Professor Gerald Gabrielse Harvard University

"You can think of them as small compass needles, so they can be deflected using magnetic fields. We build a strong 'magnetic bottle' around where we produce the antihydrogen and, if they're not moving too quickly, they are trapped," he told BBC News.

Such sculpted magnetic fields that make up the magnetic bottle are not particularly strong, so the trick was to make antihydrogen atoms that didn't have much energy - that is, they were slow-moving.

The team proved that among their 10 million antiprotons and 700 million positrons, 38 stable atoms of antihydrogen were formed, lasting about two tenths of a second each.
Early days

Next, the task is to produce more of the atoms, lasting longer in the trap, in order to study them more closely.

"What we'd like to do is see if there's some difference that we don't understand yet between matter and antimatter," Professor Hangst said.

"That difference may be more fundamental; that may have to do with very high-energy things that happened at the beginning of the universe.

"That's why holding on to them is so important - we need time to study them."

Gerald Gabrielse of Harvard University led one of the groups that in 2002 first produced antihydrogen, and first proposed that the "magnetic bottle" approach was the way to trap the atoms.

"I'm delighted that it worked as we said it should," Professor Gabrielse told BBC News.

"We have a long way to go yet; these are atoms that don't live long enough to do anything with them. So we need a lot more atoms and a lot longer times before it's really useful - but one has to crawl before you sprint.

Professor Gabrielse's group is taking a different tack to prepare more of the antihydrogen atoms, but said that progress in the field is "exciting".

"It shows that the dream from many years ago is not completely crazy."

*****

I haven't been keeping up with physics/chemistry research lately, but since I started school again I've resumed rummaging around for news. It's an rather light read but interesting; I remember reading Asimov's book on particle physics and he talked about antimatter like it was a dream and that was only twenty years ago, it's great to see progress. Also, good to see CERN paying out dividends.

[Chaotic Neutral]

I thought they already did this? Oh well, any steps towards the next super-batteries are good.

[open_sketchbook]

I'm not sure it'd be a good idea to have anti-matter batteries lying around, lest somebody buys a bunch of coppertops and blows up a city.

[Sarevok]

They only stored 38 atoms out of millions of positrons and anti protons produced. This is for sake of studying antimatter. Not a feasible means of antimatter based energy storage.

[Lord of the Abyss]

I thought they already did this?

They've trapped and held positrons and antiprotons in the past; what's new in this is that they've momentarily trapped a whole atom. That's bigger, more complex and quite a bit harder because as the article points they are neutrally charged.

[PeZook]

I'm not sure it'd be a good idea to have anti-matter batteries lying around, lest somebody buys a bunch of coppertops and blows up a city.

Trying to build a bomb out of antimatter batteries would be like constructing a nuke using medical isotopes and a whole bunch of smoke detectors

If anybody would ever make such a battery, the amounts used would be absurdly miniscule. Just encase it in a shell that will contain an explosion if containment fails - it's not like your cell phone needs 20 megatons worth of energy to run.

For comparison, a 1kg Lithium-Ion battery carries about 900 kilojoules of energy, or the equivalent of 0,00000005 grams of antimatter (well, more, since there's inefficiencies involved etc.)

[Sarevok]

However it should be noted that there are proposals for using minute amounts of antimatter to initiate nuclear fusion. If this holds true it may be possible to nuclear weapons without require fissile materials.

[Solauren]

I'd like to know what kind of Anti-Matter atom's they've captured. It's probably only Antihydrogen, however.

This also makes me wonder something....

Assuming we had enough Antihydrogen, could we create a Anti-matter Fusion reactor, and create Anti-Helium or heavier?

[Bottlestein]

^ Anti-hydrogen isn't for "fusion" or "antimatter/matter based energy plants/bombs/engines" or whatever - that would be laughably inefficient given the ground state energy of stored antimatter.

The anti-hydrogen is to see how the magnetic dipole of the anti-neutron scales as the energy state of the anti-neutron is increased. What they are trying to demonstrate is at high energies, some quarks have "more stable" magnetic properties than their corresponding anti-quarks. This would explain why there is so much more matter in the universe than antimatter.

[General Trelane (Retired)]

Anti-hydrogen isn't for "fusion" or "antimatter/matter based energy plants/bombs/engines" or whatever - that would be laughably inefficient given the ground state energy of stored antimatter.

And here I thought Solauren was simply speculating about using fusion simply to generate heavier antimatter for research purposes and not for "antimatter/matter based energy plants/bombs/engines". Looking back at his post again, I still think the same thing, so I'm not seeing what you're seeing.

The anti-hydrogen is to see how the magnetic dipole of the anti-neutron scales as the energy state of the anti-neutron is increased. What they are trying to demonstrate is at high energies, some quarks have "more stable" magnetic properties than their corresponding anti-quarks. This would explain why there is so much more matter in the universe than antimatter.

The term "hydrogen", without any qualifiers, is normally assumed to be protium. Likewise, antihydrogen would be antiprotium, which only has an antiproton and a positron. There are no antineutrons present in this antihydrogen, so your assumption is way off base--at least until they make antideuterium, which wasn't done in this test. This article gives more information:

Researchers at CERN have created and trapped antihydrogen in an attempt to study the underpinnings of the standard model of physics. Antihydrogen is made of antiparticles, specifically an antiproton and a positron, instead of the proton and an electron that are present in natural hydrogen. It has the same mass but opposite charge of its normal matter counterparts.

[...]

Production begins by creating antiprotons, which are slowed down by the Antiproton Decelerator at CERN, then stored in the magnetic Penning trap and further cooled. Positrons are supplied by a radioactive sodium-22 source and then cooled as well. These two antiparticles are then allowed to mix and, if this is done at low enough energies, they combine to form antihydrogen.

So why did you bother to mention antineutrons?

[Serafina]

So why did you bother to mention antineutrons?

Probably because he wanted to point out what's one of the eventual goals of this experiment. They are just not there yet.

[Bottlestein]

Likewise, antihydrogen would be antiprotium, which only has an antiproton and a positron. There are no antineutrons present in this antihydrogen, so your assumption is way off base...

They don't make one anti-protium, dude. During the collision anti-neutrons are generated, as are a host of other particles caused by decay events. They can't store these (anti-neutrons) yet - the goal is to get a good idea of the dipole behavior of anti-protium and the decay particles - so they can figure out the possible dipole behaviors of the anti-neutron.

[someone_else]

Assuming we had enough Antihydrogen, could we create a Anti-matter Fusion reactor, and create Anti-Helium or heavier?

Would be surely fun to see. But why should we do that? To have anti-iron tanks where we can store anti-matter with a trivial containemnt requirements since iron is magnetic? (as per Wong's idea)
Are there other good reasons to fuse antimatter atoms to synthetize heavier anti-elements?

[General Trelane (Retired)]

Likewise, antihydrogen would be antiprotium, which only has an antiproton and a positron. There are no antineutrons present in this antihydrogen, so your assumption is way off base...

They don't make one anti-protium, dude. During the collision anti-neutrons are generated, as are a host of other particles caused by decay events. They can't store these (anti-neutrons) yet - the goal is to get a good idea of the dipole behavior of anti-protium and the decay particles - so they can figure out the possible dipole behaviors of the anti-neutron.

Sorry, but I'll take the word of the ALPHA Collaboration over yours any day. Your reply only serves to reinforce my suspicions.

[Bottlestein]

^ Are you trying to claim anti-neutrons aren't produced? Which part of the ALPHA Collaboration page do you believe contradicts this? I like the vague citation this time rather than the exact passages used previously

Ditto the "suspicions" that aren't voiced

[General Trelane (Retired)]

^ Are you trying to claim anti-neutrons aren't produced?

No, I'm calling you on your bullshit posing. If you recall, you stated:

The anti-hydrogen is to see how the magnetic dipole of the anti-neutron scales as the energy state of the anti-neutron is increased. What they are trying to demonstrate is at high energies, some quarks have "more stable" magnetic properties than their corresponding anti-quarks. This would explain why there is so much more matter in the universe than antimatter.

Here you were pretending expertise that you simply don't have, and I'm tired of that bullshit. The ALPHA collaboration makes it very clear what they are trying to accomplish by trapping antihydrogen:

The quest for antihydrogen is motivated by the current failure of physical theories to completely describe the universe as we see it. There are a number of fundamental problems in modern physics that remain to be addressed, and for which CERN has also built the new Large Hardon Collider. An overarching problem is that the theory of the very small, quantum mechanics, and the theory of the very large, Einstein’s general relativity, are not fully compatible. This means, for example, that we cannot achieve a complete, self-consistent, description of black holes (Barceló et al. 2009). In fact, we do not really know if they truly exist in the form that Einstein’s theory predicts, as the extreme conditions in some black holes require a quantum mechanical version of gravity, which we do not have. But it is not only black holes that pose problems. Even more extreme conditions existed in the early universe, directly after the Big Bang. It is thought that conditions in the early universe provided the origin of the current asymmetry between matter and antimatter.

[. . .]

To date no experiment has measured any part of the antihydrogen spectrum, or even detected photons interacting with antihydrogen. However, CPT symmetry has been tested in other cases. Measurements have been done on the bound state of a positron and an electron, called positronium, and on helium atoms where one electron has been replaced by an antiproton. None of these investigations have detected a violation of the CPT theorem. However, antihydrogen would be the first pure antimatter system to be probed, and hydrogen is the simplest and one of the best studied atoms of all, making detailed comparisons with antihydrogen one of the most sensitive probes of the CPT theorem (Shore 2005). It is expected that no violations of CPT will be found. If a violations were found, it would be sensational.

and

The ultimate goal of both the ALPHA and ATRAP collaborations is the comparison of the transition from the ground state to the first excited state in antihydrogen with that in hydrogen. The upper state that will be addressed is the 2s state, which has the same angular momentum as the ground (1s) state such that a single photon cannot induce this transition. This causes the upper state to be very long lived (122ms), and therefore the energy difference between the two states is very well defined. This is therefore an ideal candidate for detailed measurements. Furthermore, this transition has been probed in both trapped hydrogen atoms (Cesar et al. 1996) and in a beam (Niering et al. 2000), with the latter achieving a precision of about one part in 10^14.

There are of course a number of other transitions in antihydrogen which are worth investigating, as different transitions depend in different ways on the interactions of the constituents, and therefore probe different facets of CPT symmetry. Some of these are likely to be carried out before the precision laser spectroscopy detailed above and one particular measurement deserves a few extra lines.

As was discussed in §1 antimatter is a child of quantum field theory. We do not, however, have a quantum version of Einstein’s general theory of relativity which describes how the curving of space-time gives rise to the ‘illusion’ of gravity. What Einstein’s theory essentially says is that space-time curves proportionally to the local energy density (or rather the energy-momentum tensor). Matter is very energy-rich (recall the famous equation), thus it curves space. Antimatter is equally energy-rich. We therefore speculate that antimatter will curve space in the same way as matter. This, however, has never been tested, so we do not know now antimatter will behave in space-time curved by matter. Testing this is a test of the weak equivalence principle which states that all bodies, irrespective of their composition, fall at the same rate in a gravitational field.

and again:

The creation of the first low energy antihydrogen atoms in 2002 has spurred a massive increase in the interest in antimatter physics and the race is now on to try to trap the anti-atoms and compare them with their matter counterparts. This research is challenging, as the temperature of the antihydrogen formed must be much lower than in the original experiments in 2002 in order for it to be magnetically trapped. Further complications arise from the fact that no appropriate way seems to exist to slow and cool the atoms to aid in trapping, such that the experimenters are forced to make the atoms inside the neutral trap. This feat has only recently been accomplished.

However, in spite of the difficulties, the physics payoff of a successful comparison of hydrogen and antihydrogen can be very large indeed. If any difference is found between the properties of these two the call is out to reformulate quantum field theory, one of the most successful theories of the twentieth century and the foundation of much modern physics.

They make no mention of antineutrons at all. That's not to say that work won't be done on that, but this particular experiment is content with trapping antihydrogen so as to study it and compare the results to normal hydrogen. Your posing that it's really to study antineutrons doesn't change that.

Are you trying to claim anti-neutrons aren't produced? Which part of the ALPHA Collaboration page do you believe contradicts this? I like the vague citation this time rather than the exact passages used previously

I was giving you some wiggle room, but you're doing it all wrong. I never claimed anti-neutrons weren't produced. No amount of wiggling on your part will change that. I was calling you out for your bullshit posing while at the same time giving you an out. You didn't take it. Sucks to be you.

You claim to know something, and I give you the information to allow you to correct yourself, but you have to be right, so you twist and turn to try to evade the point. This is not about antineutrons. No one is saying they're not produced in this experiment. You're saying that the purpose of this experiment is one thing, but the experimenters themselves blow you away. Normally, I really wouldn't care, but to top it off, you enter this with a you're-so-stupid-and-I'm-so-smart attitude that rubs me the wrong way. At least, that's how this opening sentence reads to me:

^ Anti-hydrogen isn't for "fusion" or "antimatter/matter based energy plants/bombs/engines" or whatever - that would be laughably inefficient given the ground state energy of stored antimatter.

That was in response to someone who was speculating about antimatter fusion for the purpose of creating heavier antimatter elements. No, I don't need suspicions of your motives; your infantile posing is plain for all to see.

[Bottlestein]

^ So you bothered to posture but not actually google " anti neutron magnetic moment"

Here's a hint: the Graemer and Ghandi paper - the very first hit on Google demonstrates exactly what my post stated.

Also - don't use the word "CPT violation" if you don't know what it means

[Sarevok]

Erm bottlestein what does anti neutrons have to do here ? The article very clearly states what is the purpose anti hyddrogen containment. It did not mention the word "neutron" even. As for CPT symmetry if you are as educated as you posing to be you would know by now how antimatter figures into this. The stated purpose of the experiment is to see if anti matter is indeed a mirror image of normal matter or not.

[General Trelane (Retired)]

^ So you bothered to posture but not actually google " anti neutron magnetic moment"

Way to miss the point.

Here's a hint: the Graemer and Ghandi paper - the very first hit on Google demonstrates exactly what my post stated.

Here's a hint: learn to get the point. Wait, let me back up: learn to read.

Also - don't use the word "CPT violation" if you don't know what it means

I guess you didn't notice the quote block?

You have completely and utterly missed the point. This leads me to two possibilities: (1) that you can't read, or (2) that you're desperate to avoid admitting you're full of shit. Sarevok spelled it out simply, so that addresses (1). As for (2), let's stomp on the bag and get back to your original assertion (again):

The anti-hydrogen is to see how the magnetic dipole of the anti-neutron scales as the energy state of the anti-neutron is increased. What they are trying to demonstrate is at high energies, some quarks have "more stable" magnetic properties than their corresponding anti-quarks.

I have shown you proof from ALPHA that this is plain wrong. I can't wait to see how you'll avoid this in your next response. Now I have to go change my shoes.