Physicists find ways to increase antihydrogen production

May 20, 2015 by Lisa Zyga, Phys.org feature
Antihydrogen consists of an antiproton and a positron. Credit: public domain

(Phys.org)—There are many experiments that physicists would like to perform on antimatter, from studying its properties with spectroscopic measurements to testing how it interacts with gravity. But in order to perform these experiments, scientists first need some antimatter. Of course, they won't be finding any in nature (due to antimatter's tendency to annihilate in a burst of energy when it comes in contact with ordinary matter), and creating it in the lab has proven to be very technically challenging for the same reasons.

Now in a new paper published in Physical Review Letters, Alisher S. Kadyrov, et al., at Curtin University in Perth, Australia, and Swansea University in the UK, have theoretically found a method to enhance the rate of antihydrogen production by several orders of magnitude. They hope that their finding will guide antihydrogen programs toward achieving the production of large amounts of antihydrogen for long confinement times, and at cool temperatures, as required by future investigative experiments.

"Laws of physics predict equal amounts of matter and created after the Big Bang," Kadyrov, Associate Professor at Curtin University, told Phys.org. "One of science's mysteries is where did all the antimatter go? To unravel this mystery, scientists at CERN [the European Organization for Nuclear Research] plan to do gravitational and spectroscopic experiments with antimatter. The simplest example is antihydrogen. However, it is challenging and expensive to create and study antihydrogen in the laboratory."

Antihydrogen is an appealing form of antimatter for scientists to study in part because it is electrically neutral: it consists of an antiproton (a negatively charged proton) and a positron or antielectron (a positively charged electron). Because it's made of just two antiparticles, antihydrogen is also somewhat easier to produce than larger antiatoms.

In 2002, scientists produced antihydrogen in the first dedicated antihydrogen production experiment at CERN, and in 2010 they confined antihydrogen in traps for up to 30 minutes. Eventually, however, the antihydrogen annihilates, such as by impacting the walls of the experimental apparatus or interacting with background gases.

There are a few different ways to produce antihydrogen in the lab, all of which involve colliding or scattering particles off one another. In the new study, the physicists focused on the reaction in which an antiproton is scattered off , which is a bound state consisting of a positron and an ordinary electron. In a sense, positronium can be thought of as a hydrogen atom in which the proton is replaced by a positron. So far, the antiproton-positronium scattering reaction has been investigated mostly when the positronium is in its ground state.

In the new study, the scientists theoretically showed that antiproton collisions with positronium in an excited state instead of the ground state can enhance antihydrogen production significantly, particularly at the lower energies.

"Our calculations show that a very efficient way of producing antihydrogen is to bring together slow antiprotons with positronium, which has been prepared in an excited state, something that is now routine using lasers," Kadyrov said. "It turns out antihydrogen formation increases by several orders of magnitude for positronium in excited states as compared to the due to unexpected low-energy behavior revealed in our calculations."

For the first time, these theoretical results allow for realistic estimates of antihydrogen formation rates via antiproton-positronium scattering at low energies. Because lower energies are more important in experiments than higher energies, the scientists hope that this method will offer a practical way to create cold antihydrogen, which could then be used to test the fundamental properties of antimatter.

"Scientists from the ALPHA, ATRAP, AEgIS and GBAR Collaborations at CERN are working on producing and trapping antihydrogen in sufficient quantities for experiments on the spectroscopic and gravitational properties of antihydrogen," Kadyrov said. "We believe that the efficient mechanism for antihydrogen formation that our research has unveiled could be used to facilitate these investigations."

The scientists plan to investigate this antihydrogen production mechanism more in the future, with the goal to achieve even better results.

"Presently, positronium can be excited to high-energy states, known as Rydberg states," Kadyrov said. "Next we want to investigate antiproton collisions with positronium in such a state. Given the magnitude of the enhancement we have got for the lower excited states, one can expect that the corresponding enhancement would be enormous. This then could open a very promising way of producing low-energy antihydrogen beams for spectroscopic experiments, for example, for measurements of hyperfine splitting in ."

Explore further: CERN experiment produces first beam of antihydrogen atoms for hyperfine study

More information: A. S. Kadyrov, et al. "Antihydrogen Formation via Antiproton Scattering with Excited Positronium." Physical Review Letters. DOI: 10.1103/PhysRevLett.114.183201

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22 comments

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Mark Thomas
2.5 / 5 (8) May 20, 2015
"a method to enhance the rate of antihydrogen production by several orders of magnitude"

New life for antimatter-catalyzed nuclear pulse propulsion?
baudrunner
not rated yet May 20, 2015
Is anti-hydrogen true anti-matter?
TopCat22
1 / 5 (2) May 20, 2015
"One of science's mysteries is where did all the antimatter go?"

The matter and antimatter created by the big bang annihilated each other and made energy. The energy was so high that it condensed into the solid regular matter we have today based on the following ratio.

E=Mc2
or
M=E/c2

TimLong2001
1 / 5 (1) May 20, 2015
Supersymmetry exists inside the dipole photon.
antialias_physorg
5 / 5 (5) May 20, 2015
New life for antimatter-catalyzed nuclear pulse propulsion?

Hardly. The amount of energy needed to create these buggers is still way, way, WAY more than the reaction would yield,
Creating antimater as fuel is a no-go scenario. any way you slice it you put a lot mor energy in than you get out (not to mention that storing it is a real doozy)

Is anti-hydrogen true anti-matter?

Each of the constituents (the antiproton and the positron) are already antimatter. There is no such thing as "fake antimatter".

The matter and antimatter created by the big bang annihilated each other and made energy. The energy was so high that it condensed into the solid regular matter

Erm...that makes no sense on any level whatsoever. It violates all kinds of symmetries for a start.
Mark Thomas
2.4 / 5 (8) May 20, 2015
"The amount of energy needed to create these buggers is still way, way, WAY more than the reaction would yield."

That's true, but my comment was directed to a form of spacecraft propulsion, not energy production. The beauty of antimatter-catalyzed nuclear pulse propulsion (which is somewhat of a misnomer because the antimatter is destroyed) is a very tiny amount of antimatter can trigger a fission-fusion reaction in BB-sized pellets of deuterium and tritium surrounded by uranium. In theory, nanograms of antimatter can take you to Mars and back in few months and about 10 pounds of the stuff will get you to Alpha Centauri in a lifetime. Antimatter storage is an issue, but I understand the biggest problem is producing enough antimatter and the article above recited major improvements. BTW, your comment surprised me because I thought it was common knowledge that the best starships are powered by antimatter. :-)
MaxwellsDemon
2 / 5 (8) May 20, 2015
Baryogenesis, dark energy and dark matter: three enormous cosmological mysteries defying resolution. I'm thrilled that this technique may pave the way for a new era of precision antimatter experiments - any new insights could crack open a world of unanticipated physics beyond the Standard Model and perhaps give us a good start on solving all three of these bizarre and potentially related puzzles.
MaxwellsDemon
1 / 5 (7) May 20, 2015
And while I absolutely love to see the enthusiasm that so many people have for a revolution in manned spaceflight, I think we need to remember that what we need most right now is new understanding – once we have that, then we can work on new applications…like novel propulsion methods...
Mark Thomas
1 / 5 (6) May 20, 2015
"what we need most right now is new understanding – once we have that, then we can work on new applications…like novel propulsion methods"

How can you be certain that better propulsion won't turn out to be instrumental in unraveling the mysteries of dark matter and dark energy?
big_hairy_jimbo
5 / 5 (1) May 20, 2015
@AntiAlias, I think the reference to TRUE antimatter is that positronium, while being anti-matter, isn't a REAL anti ATOM. Whereas an anti-proton / anti electron combo is, in the fact it makes Anti Hydrogen.
This is my understanding of TRUE anti matter anyway.

Now just how does an Anti electron and an electron end up in a stable bound state (positronium) without annihilating?
DarkLordKelvin
2.3 / 5 (9) May 20, 2015
@AntiAlias, I think the reference to TRUE antimatter is that positronium, while being anti-matter, isn't a REAL anti ATOM. Whereas an anti-proton / anti electron combo is, in the fact it makes Anti Hydrogen.
This is my understanding of TRUE anti matter anyway.

Now just how does an Anti electron and an electron end up in a stable bound state (positronium) without annihilating?

The same way an electron and a proton do .. it's the same problem, quantum mechanically .. only the reduced mass is different. Note that it is not stable and decays by annihilation into gammas .. the most stable form has a half-life of less than a microsecond in its ground energy state (higher energy states can exist for longer before annihilating).
antialias_physorg
5 / 5 (3) May 21, 2015
a very tiny amount of antimatter can trigger a fission-fusion

How's that supposed to work?
Mark Thomas
1 / 5 (5) May 21, 2015
"How's that supposed to work?"

Up till now the deal-breakers have been inadequate antimatter production and storage, but the concept came from a Penn State University professor way back in the early 1990s. In short, antiprotons are readily absorbed by a compressed U-238 pellet to initiate a hyper-neutronic fission process that rapidly heats and ignites the D-T core in the pellet. Read the following 1999 article on the NASA website and take a good look at Figure 1: http://ntrs.nasa....0316.pdf

You didn't really think we'd be stuck in the solar system forever did you? Go boldly.
Whydening Gyre
5 / 5 (6) May 21, 2015
Now just how does an Anti electron and an electron end up in a stable bound state (positronium) without annihilating?

By keeping a good distance from eachother?
matthew_deward
1 / 5 (2) May 22, 2015
Even if it is improbable or impossible, I still want to know what antihydrogen dioxide would look like.
DarkLordKelvin
1 / 5 (5) May 22, 2015
Even if it is improbable or impossible, I still want to know what antihydrogen dioxide would look like.

1) I suppose you meant: anti-dihydrogen monoxide?

2) It would look just like regular water ... until it came into contact with regular matter, in which case it would look very, very bright, very, very briefly ;)
MaxwellsDemon
1 / 5 (7) May 28, 2015
"what we need most right now is new understanding – once we have that, then we can work on new applications…like novel propulsion methods"

How can you be certain that better propulsion won't turn out to be instrumental in unraveling the mysteries of dark matter and dark energy?


How are we supposed to devise "better propulsion" methods without new physics understanding? The horse goes before the cart, Mark. You can look at every advancement in the history of propulsion and see that the understanding of physical principles always precedes their practical application....which is what makes fundamental research so crucial for human technological progress.
MaxwellsDemon
1.5 / 5 (8) May 28, 2015
You didn't really think we'd be stuck in the solar system forever did you? Go boldly.

Now I see where you're coming from, but that horse can't run.

It's a proven physical fact that the reaction propulsion principle, even using idealized scenarios for antimatter production, would be inadequate for a manned exosolar mission to the nearest star:
http://www.circlo...nic.html

We need a *new motive principle* to reach the stars. And pure research is the means for discovering new propulsion principles.
Mark Thomas
1 / 5 (6) May 28, 2015
"How are we supposed to devise "better propulsion" methods without new physics understanding?"

This assumes we've maxed out our propulsive capabilities to the extent of our understanding of the laws of physics. This is very far from true. We haven't even flown a nuclear thermal rocket engine such as the type tested in the U.S. in the 1960s. Although the ACMF and AIM antimatter concepts are more than 20 years old, to my knowledge we haven't even tested them once. Here is link to a NASA paper on antimatter propulsion from 1999. http://ntrs.nasa....0316.pdf

We should run with the physics we've got and not sit around waiting for decades/centuries for something better to drop into our laps. We know nuclear fission works, let's use it for spacecraft propulsion. We have good reasons for believing antimatter-catalyzed micro fusion-fission (ACMF) will work too, so let's explore this possibility.
Mark Thomas
1 / 5 (6) May 28, 2015
MaxwellDemon, look, there is no doubt physics research should continue. Absolutely. No doubt at all. But outside of the 1968-1972 timeframe, people haven't even left Low Earth Oribit (LEO). While it would be wonderful, we don't need a breakthrough in fundamental physics to do better. It's been over 42 years, is there a particular reason we should continue to wait? Let's use modern materials and techniques and start flying the nuclear thermal rocket engines of the type developed decades ago. Maybe by the 2030s we'll get around to implementing ACMF ideas from the 1990s.
MaxwellsDemon
1 / 5 (6) May 29, 2015
Mark, you said:

You didn't really think we'd be stuck in the solar system forever did you? Go boldly.


There are real, insurmountable, and well-understood problems for interstellar spaceflight using reaction propulsion, even antimatter/ antimatter-assisted reaction propulsion systems. We're not going to get to the stars that way.

We could exit the solar system and probably fly out to the Oort cloud…maybe take some samples of the interstellar medium…but we're not going to get to any exosolar body of real significance using antimatter reaction propulsion.

I'm all for manned exosolar exploration. But I understand the need for a totally novel new motive principle to get the job done.

Do you?
big_hairy_jimbo
not rated yet Jun 03, 2015
Hey I think developing a propulsion system to allow us to roam our own solar system at will, will keep us occupied for sometime!!!! There is more than enough to investigate in our own backyard.

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