New research could help develop gamma ray lasers and produce fusion power

May 01, 2010
Image shows the ultra-high vacuum target chamber used in the experiment. Credit: David Cassidy, UC Riverside.

Positronium is a short-lived system in which an electron and its anti-particle are bound together. In 2007, physicists at the University of California, Riverside created molecular positronium, a brand-new substance, in the laboratory. Now they have succeeded in isolating for the first time a sample of spin polarized positronium atoms.

Study results appear this week in the journal .

Spin is a fundamental and intrinsic property of an electron, and refers to the electron's . Spin polarized are atoms that are all in the same spin state. A collection of spin polarized positronium atoms is needed to make a special form of matter, called the (BEC). The BEC, predicted in 1924 and created in 1995, allows scientists to study atoms in a unique manner.

"We achieved our result by increasing the density of the positronium atoms in our lab experiment," said David Cassidy, the lead author of the research paper and an assistant researcher working in the laboratory of Allen Mills, a professor of physics. "At such a high density, positronium atoms get annihilated simply by interacting with each other. But it turns out that not all the positronium atoms get annihilated under these conditions."

Cassidy explained that positronium atoms come in two types - say, an up type and a down type. The positronium atoms are only annihilated when an up type meets a down type. Two atoms of the same type do not affect each other.

"So if you have 50 percent ups and 50 percent downs and you squeeze them all together they will totally annihilate and turn into gamma rays," he said. "But if you have, for example, about 66 percent ups and 33 percent downs, then only half of the ups will be destroyed. You will get a load of - but in the end you will be left with only one type of atom - in this case, up atoms.

"This is an important development for making the BEC," Cassidy said, "because you have effectively purified your sample of positronium. And you need a pure collection of spin aligned atoms to make the BEC."

When atoms are in the BEC state, they are essentially stopped (or they move extremely slowly), facilitating their study. Non-BEC atoms on the other hand whiz around at very high speeds, making them harder to study.

"There are fundamental processes that can be looked at in new ways when you have matter in the BEC state," Mills said. "Having Bose-condensed atoms makes it easier to probe the way they interact under certain conditions. Moreover, to have motionless positronium atoms is an important aspect for making something called a gamma ray laser, which could have military and numerous scientific applications."

According to Mills and Cassidy, the new research could lead also to the production of fusion power, which is power generated by nuclear fusion reactions.

"The eventual production of a positronium condensate could help us understand why the universe is made of matter and not antimatter or just pure energy," Cassidy said. "It could also one day help us measure the gravitational interaction of antimatter with matter. At present, nobody knows for sure if antimatter falls up or down."

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User comments : 20

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Shootist
2 / 5 (4) Apr 30, 2010
I don't see how one collimates radiation the wavelength of which is less than the diameter an atom.
Megadeth312
1 / 5 (3) Apr 30, 2010
What the hell is Positronium. Someone provide details on how electrons and positrons can be bound together?

(why don't they annihilate??)
Alizee
Apr 30, 2010
This comment has been removed by a moderator.
Parsec
5 / 5 (2) May 01, 2010
I don't see how one collimates radiation the wavelength of which is less than the diameter an atom.


The gamma rays emitted by a group of positronium atoms stimulate the annihilation of other atoms in a wave, causing a narrow beam of gamma rays to emitted from the far edge. 142ns is actually quite a long time compared to the lifetime of para-positronium.
zuggerjack
1.6 / 5 (7) May 01, 2010
I'm sure this new research will produce beneficial fusion power, just as space solar power satellites will beam down high intensity microwaves to supply us with cheap energy from space. Instead both projects will be converted into weapons of mass destruction by USA defense contractors, exactly as David Kagan wrote about in his best-selling book Sunstroke regarding SSP.
GaryB
3 / 5 (4) May 01, 2010
What the hell is Positronium. Someone provide details on how electrons and positrons can be bound together?

(why don't they annihilate??)


If you watch the movie "Avatar", you'll get the idea.
Skeptic_Heretic
5 / 5 (2) May 01, 2010
What the hell is Positronium. Someone provide details on how electrons and positrons can be bound together?

(why don't they annihilate??)

When you remove almost all kinetic energy from the particles they can become bound through other force interactions, strong and weak nuclear force, etc. As Alizee pointed out, the timescales for existence are incredibly small, however, the research above is attempting to lengthen that timescale for existence by ultracooling thereby removing all velocity and allowing from extended existence.
Shootist
4 / 5 (4) May 01, 2010
I'm sure this new research will produce beneficial fusion power, just as space solar power satellites will beam down high intensity microwaves to supply us with cheap energy from space. Instead both projects will be converted into weapons of mass destruction by USA defense contractors, exactly as David Kagan wrote about in his best-selling book Sunstroke regarding SSP.


And? This is obvious to most anyone.

It all started with Prometheus. You have heard of fire? Arch-type and all that, wot, wot?
brentrobot
2.3 / 5 (3) May 01, 2010
I wonder how much positronium can be be put into something the size of a bullet. That could make for one bitchen anti tank weapon.
Slotin
1.2 / 5 (21) May 01, 2010
I wonder how much positronium can be be put into something the size of a bullet.

I see, a millitary guy...;-\ Well, a grain of 100% antimatter should be enough - why to dilute it by some electrons and make it unstable in such way..?
Skeptic_Heretic
3 / 5 (2) May 02, 2010
I wonder how much positronium can be be put into something the size of a bullet.

I see, a millitary guy...;-\ Well, a grain of 100% antimatter should be enough - why to dilute it by some electrons and make it unstable in such way..?

Bigger boom.
billyswong
1 / 5 (1) May 02, 2010
Why does "fusion power" matters here?
Alizee
May 02, 2010
This comment has been removed by a moderator.
Doug_Huffman
1 / 5 (2) May 02, 2010
Better than a weaponized Gamma-ray laser? Hah, better in every way than a neutron bomb! I don't recall Gamma-rays inducing any significant radioactivity in materials and do recall, I do know, that the majority of my personal exposure is from Gamma radiation. How difficult will it be to deliver 5000 RAD sec^-1 at unlimited distances?

Crispy critters driving their tanks, airplanes, spaceships or crouched behind their keyboards.
Skeptic_Heretic
2 / 5 (2) May 02, 2010
Why does "fusion power" matters here?

We can capture that energy release. Meaning the fuel would have an E value of 1. Our only losses would be in transmission and capture. Particle antiparticle annihilation is one manner of "fusion" research. In reality the term to be used was nuclear, not fusion.
jsa09
3 / 5 (1) May 02, 2010
Fusion power cannot be achieved from annihilation, that would be a different power source.

Fusion power comes from fusing atoms into a different atom. matter/anti-matter power would be much better power than fusion power in the sense that it would have less byproducts.

+ve + -ve = E whereas with fusion you have atom + atom = bigger atom + E.
malapropism
not rated yet May 02, 2010
How do they make the anti-particles in the first place?

I was under the impression that the process was so energy intensive to do this, that the payback from anti-matter annihilation would not be worthwhile?
Shaffer
5 / 5 (1) May 03, 2010
Why does "fusion power" matters here?


It doesn't. I Has Cheezburger.
rbrtwjohnson
not rated yet May 03, 2010
Ostentatious method involving laser to produce fusion power, I think it is superfluous. Electrostatic acceleration, when wisely used, can be much more efficient, consuming much less energy.
kevinrtrs
1 / 5 (3) May 05, 2010
Science is great! Such vigorous discussion!

Now, if you consider how much effort it takes for teams of physicists, electrical ,chemical and mechanical engineers to create a stable fusion environment, does it not seem ludicrous that cosmologists can propose that extreme low-density dust clouds can simply collapse into themselves and form fusion engines known as stars? [please spare me the useless arguments of low temperatures and gravity doing the work - it is just not enough, finish and klaar]

Makes the mind boggle, doesn't it?
frajo
5 / 5 (2) May 05, 2010
does it not seem ludicrous that cosmologists can propose that extreme low-density dust clouds can simply collapse into themselves and form fusion engines known as stars?
No. Can you offer a better explanation?
Skeptic_Heretic
5 / 5 (2) May 05, 2010
does it not seem ludicrous that cosmologists can propose that extreme low-density dust clouds can simply collapse into themselves and form fusion engines known as stars?

Not if you understand Boyle's Law, typically taught to 4th graders.