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Anti Proton - Non Proton reaction


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Alright, I have a basic understanding about anti hydrogen - hydrogen annihilation reaction. But what exactly happens if an anti hydrogen atom stumbles into anything else like a deuterium, tritium of helium atom?

From my limited understanding, antimatter favor to to react with its anti-particle. So if a single anti hydrogen strikes a helium 4 atom, the anti proton reacts with a proton in the helium core and it positron reacts with an electron in the helium. The remainder, a proton with 2 neutron and 1 electron (=Tritium atom) should fly away the opposite direction. Correct?

If so, would this be a useful property which we can use for propulsion/energy production. Instead of a neutral Helium, we could strip the outer electron, and the antimatter reaction would be (besides the standard proton antimatter product) be a highly directed tritium ion, which we could directly use for propulsion using a magnetic nozzle, correct?
Edited by FreeThinker
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This might not be the most scientific way to put it, but wouldn't the remaining nucleus (or even the nucleons) just be blown apart? The energy released by the annihilating proton/anti-proton pair should exceed the binding energy oft the Tritium nucleus considerably.

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You've got it right in that an anti-proton wants to react with a proton. But the specifics of actual "anti-atom" annihilating with each other I think would be far less clear-cut. For example, one the positron has annihilated one of the helium's electrons, does it release enough energy, in the appropriate manner, to eject the other electron? If there is still an electron present around the helium, it will strongly repel the remaining anti-proton.

And if the anti-proton manages to interact with the helium nucleus, the remaining particles will likely be flying in all directions seperately, it is not likely that a complete tritium nucleus will be left over, and if it were, it is unlikely to still have the leftover electron bound to it.

If I recall correctly, there are proposed propulsion mechanisms that are similar to the method you propose, ie: using magnetic fields to direct the high-energy products of annihilation reactions as an exhaust, but it isn't the perfect energy source that we might sometimes imagine - a significant amount of energy produced by annihilation comes in a form that cannot be directed (uncharged particles, gamma rays) and so cannot contribute to propulsion, the engine will also be intensely radioactive, which means heavy shielding amongst other complications.

As always, head on over to project rho for a decently up-to-date skivvy on proposed propulsion methods, and a decent primer on antimatter propulsion:

http://www.projectrho.com/public_html/rocket/enginelist.php

On which this interesting link, amongst others, can be found:

http://www.dtic.mil/dtic/tr/fulltext/u2/a160734.pdf

 

 

 

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Antiprotons consist of up and down antiquarks. So they can react straight with all baryons consisting of up or down quarks, like protons and neutrons. Annihilation of protons release about one GeV per particle and binding energies of nuclei are less than 10 MeV per baryon. I would guess that a nucleus which reacts with an antiproton will shatter to several fragments.

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It also depends on the energy of the collision. There are numerous allowed variations that don't involve anti-proton/proton annihilation (or indeed any annihilation at all). These include elastic scattering and the formation of positronium and antiprotonic helium amongst others [1].

 

References:

[1]  S. Jonsell, P. Froelich, S. Eriksson, and K. Strasburger, “Strong Nuclear Force in Cold Anithydrogen-Helium Collisions”, Phys. Rev. A, vol. 70, no. 6, p. 62708, 2004.

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12 hours ago, Hannu2 said:

Antiprotons consist of up and down antiquarks. So they can react straight with all baryons consisting of up or down quarks, like protons and neutrons. Annihilation of protons release about one GeV per particle and binding energies of nuclei are less than 10 MeV per baryon. I would guess that a nucleus which reacts with an antiproton will shatter to several fragments.

Ok, so an antiproton reacting with a helium atom would result in 1 proton and 2 neutrons?

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It will annihilate with the first met barion, turning into 3 pairs of pi-mesons (each consists of u and d quarks), blowing the rest of the nucleus aparts. The pi-mesons will result into electron (if ~p + n), neutrinos and photons.

Edited by kerbiloid
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Alright but what percentage of total energy will be turned into neutron energy and what will be the effect on percentage charged particles on the reaction. I need to determine if helium or anything else could be a viable alternative for protons in my antimatter reactor

Edited by FreeThinker
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This link gives this link on the theme (see prev/next also), but can't say at once if there is a simple visible number in this extensive sheet.
 

P.S.
Though, probably exact nucleon type would effect only in the number of electrons (negligible for your purpose) and kinds of neutrino and photons (even more negligible).
So, probably you could just presume that ~p+2p+2n will result into 1p+2n or 2p+1n with 0.5 probability. And then you have equal p+n plasma cloud with only 50% of charged particles or so.

Upd: https://physics.stackexchange.com/questions/74106/how-is-the-energy-distributed-in-a-proton-antiprotion-annihilation

Edited by kerbiloid
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1 hour ago, kerbiloid said:

This link gives this link on the theme (see prev/next also), but can't say at once if there is a simple visible number in this extensive sheet.
 

P.S.
Though, probably exact nucleon type would effect only in the number of electrons (negligible for your purpose) and kinds of neutrino and photons (even more negligible).
So, probably you could just presume that ~p+2p+2n will result into 1p+2n or 2p+1n with 0.5 probability. And then you have equal p+n plasma cloud with only 50% of charged particles or so.

Upd: https://physics.stackexchange.com/questions/74106/how-is-the-energy-distributed-in-a-proton-antiprotion-annihilation

 
 

Alright but what percentage of the overall energy will be carried by the neutrons? From my understanding most of the energy goes into the smallest particles, the heavier the particle ,the less kinetic  energy. it receives. It does have to be precise, just some educated estimated will do ...

Edited by FreeThinker
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28 minutes ago, FreeThinker said:

Alright but what percentage of the overall energy will be carried by the neutrons? From my understanding most of the energy goes into the smallest particles, the heavier the particle ,the less kinetic  energy. it receives. It does have to be precise, just some educated estimated will do ...

I feel like the question is far too simple for the physics that it relates to...

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12 minutes ago, p1t1o said:

I feel like the question is far too simple for the physics that it relates to...

Yes I understand this might be a question that doesn't concern physics but I hate to use the unwritten rule and make something up. But perhaps we can make some educated generalizations like, the heaver the atom, the more energy will be converted to neutron energy which will embrittle the reactor. Thinking about this futher, it might be a very good mehod to create a very powerful neutron bom, creating much more neutrons than an ordinary fission neutron bom. Simply combining an antiproton and uranium atom should do the trick

Edited by FreeThinker
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2 hours ago, FreeThinker said:

Alright but what percentage of the overall energy will be carried by the neutrons? From my understanding most of the energy goes into the smallest particles, the heavier the particle ,the less kinetic  energy. it receives. It does have to be precise, just some educated estimated will do ...

 

13 minutes ago, p1t1o said:

I feel like the question is far too simple for the physics that it relates to...

Yeah, I mean with anything like this, even when you simplify it the results tend to obey some form of distribution, there will not be one particular energy that is the magic answer.

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17 minutes ago, FreeThinker said:

Yes I understand this might be a question that doesn't concern physics but I hate to use the unwritten rule and make something up. But perhaps we can make some educated generalizations like, the heaver the atom, the more energy will be converted to neutron energy which will embrittle the reactor. Thinking about this futher, it might be a very good mehod to create a very powerful neutron bom, creating much more neutrons than an ordinary fission neutron bom. Simply combining an antiproton and uranium atom should do the trick

Well what we can say with a high degree of confidence is that the total mass-energy of the system before and after annihilation will be conserved, as will the total charge of the system.

Im not sure if neutron embrittlement would be a limiting factor, there are larger worries present. Possible that the high temperature environment would "anneal" any neutron embrittlement, but whether or not this is true is non-trivial to work out.

As for some kind of 4th-gen enhanced radiation warhead, again, its too complex to say "Combine uranium with antiprotons will liberate more neutrons than a thermonuclear device of comparable mass" or the opposite.

But if its for sci-fi, and you aren't going fully 100%  "hard" sci-fi, then I suppose its vaguely plausible, to create this device with antiprotons and uranium. Since practical research with AM is very limited, who can say you are definitely wrong? For details about neutron embrittlement of an AM reactor, I would just look  into how it is dealt with in real-life fission reactors, and modify that context to your needs.

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Probably, there isn't a definite answer at all, as the results would depend a lot on exact conditions, including the initial speed of injected antiprotons, geometry, density and temperature of the fusion fuel layer and so on.

Maybe you would extrapolate ICAN-II project which looks more or less close.

http://www.astronautix.com/i/ican.html

http://ffden-2.phys.uaf.edu/213.web.stuff/Scott Kircher/fissionfusion.html

https://translate.google.ru/translate?sl=ru&tl=en&js=y&prev=_t&hl=ru&ie=UTF-8&u=http%3A%2F%2Fnuclphys.sinp.msu.ru%2Fantimatter%2Fant21.htm&edit-text=

(As the antimatter is used here mostly to heat the reaction mass, not to split every atom, probably you could extrapolate D+T to 4He)

Edited by kerbiloid
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On 4/18/2017 at 1:57 AM, FreeThinker said:
Alright, I have a basic understanding about anti hydrogen - hydrogen annihilation reaction. But what exactly happens if an anti hydrogen atom stumbles into anything else like a deuterium, tritium of helium atom?

From my limited understanding, antimatter can only react with its anti-particle.

That's actually completely wrong. Matter-antimatter reactions can happen with many different pairs of particles. The only rule is that all conserved quantities are, well, conserved.

Lets start with the fact that proton isn't elementary. It's made up of a crap ton of particles and antiparticles. I'm going to let that sink in for a moment.

Ok, so the interior of a proton is filled with quarks, antiquarks, and gluons. Gluons are massless, so they are their own antiparticles, just like photons. And together with quarks and antiquarks all of this mess is a constantly bubbling soup of quantum probability with new pairs of quarks and antiquarks constantly created and destroyed. However, no matter at what point you do the counting, there are always going to be precisely 3 quarks without an antiquark pair, and these are known as valence quarks. Moreover, in a proton, these are going to be two up quarks and a down quark. These two flavors of quarks (yes, they are actually called flavors) are different from each other in their electric charge and isospin. Both of these quantities are conserved, and really, what makes a proton a proton. In contrast, neutron will have two down quarks and one up quark. All other quark compositions are highly unstable but do have corresponding particles.

With all of this in mind, you can probably see that annihilation event isn't going to be a clean affair. In proton-antiproton collision, all of these particles will start interacting with each other. Quarks from one hadron will start annihilating with anti-quarks from another, all the while new pairs are still being created out of quantum vacuum. But what's interesting is that there is now an anti-up quark for every up quark and an anti-down quark for every down quark. So they can all find each other and annihilate the proton and anti-proton completely. Can, but usually don't. The moment proton and anti-proton meet, the amount of energy released blasts the whole thing apart while the annihilation is still in process.

One possible outcome is that two valence quarks meet, say a down quark met its anti-down match. Lots of energy released, new particles could be created, but among remains are the old valence quarks. And suppose an anti-up quark got blasted out with a down quark. And the up quark with the anti-down. These are pi mesons, aka pions. (Or rho mesons, depending on their spin.) For simplicity, lets say they are pions. π+ and a π-, with charges +1 and -1 respectively.

So with up quark not having a corresponding anti-up in the π+, do we expect it to never decay? No, actually, pions have a very short half-life and a number of possible decay modes. The most direct is for the up quark to annihilate with the anti-down quark. That leaves us with an uncomfortable remainder carrying not only energy but electric charge. What can it be? Well, there are some options, but the most likely product of anti-up and down quark annihilation is a W+ boson carrying the charge and a photon carrying some of the energy, recoil momentum, and counter-balancing the spin of the W. Photon's stable, we're good. But not the W. That needs to decay. And just like its origin, it produces a pair of particles that aren't each other's antiparticles. Most likely case in pion decay chain is an anti-muon and a muon neutrino. These are also two flavors of the same kind of particle. But nonetheless, they aren't a particle-antiparticle pair. Neutrino flies off. Anti-muon decays again. This time, finally, to stable particles. Positron (anti-electron), electron neutrino, and a muon anti-neutrino. All with considerable energy.

 

This is just one branch of one possible chain in proton-antiproton annihilation. Which brings us now to a question of what happens if anti-proton encounters something else, like a neutron, instead? Well, all of the rules from above apply. Anti-quarks will look for quarks, not necessarily of the same flavor, and neutron has these. So there will be an annihilation event. Just like before, it's going to blast the quark-antiquark mix into a bunch of new particles, and these will eventually decay to some stable particles. After everything calms down, you'll just have a bunch of photons, various flavors of neutrinos, and maybe leftover positron until that encounters something interesting.

If you really start digging into particle physics, we don't even talk about creation/annihilation events. The quantity of interest is a vertex. There is very little difference between electron scattering and electron-positron production. They are both vertices with two electron currents and one photon current. The only difference is time-ordering, and that's a fairly flimsy thing at these energies. Likewise, two particles of different flavor being annihilated is similar to a flavor-changing weak interaction. So if there is a way for particle A to become particle B, then A can annihilate with anti-B. And that opens up a whole bunch of possible combinations.

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@K^2  So to sum it up, if you allow an anti-proton to react with anything else than a single proton, you end up with with a big mess of unpredictable interesting particles physics, or is it?

What about if we allow antiproton reactor with a hydrogen molecule (H2), will the second proton particle absorbs some of the annihilation energy? then the question would be, how much, on average by percentage?

 

Edited by FreeThinker
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11 minutes ago, FreeThinker said:

@K^2  So to sum it up, if you allow an anti-proton to react with anything else than a single proton, you end up with with a big mess of unpredictable interesting particles physics, or is it?

What about if we allow antiproton reactor with a hydrogen molecule (H2), will the second proton particle absorbs some of the annihilation energy? then the question would be, how much, on average by percentage?

 

From what I've read, even if you only allow a single proton and anti-proton to come into contact, there's no guarantee.

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53 minutes ago, K^2 said:

<snippa-snippa>

That would explain why I have heard the term "Quark-gluon plasma" to describe the debris produced by an annihilation.

 

27 minutes ago, FreeThinker said:

What about if we allow antiproton reactor with a hydrogen molecule (H2), will the second proton particle absorbs some of the annihilation energy? then the question would be, how much, on average by percentage?

 

How much of the kinetic energy supplied by the cue ball, on average by percentage, does the black ball receive during a break in a game of pool?

It can vary wildly depending on initial conditions, which in the context of your question, vary wildly with time. So the answer is "unknown", at least without extensive mathematical treatment. Extensive.

It could be zero percent, or it could absorb enough energy to blast it into its constituent pieces. On average over a large number of events? I have no idea. So little AM has been produced and successfully experimented with, that it is possible that this is still an open question. Its not something that you can estimate with classical physics, and quantum things are very hard to make intuitive guesses at.

Edited by p1t1o
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13 minutes ago, p1t1o said:

That would explain why I have heard the term "Quark-gluon plasma" to describe the debris produced by an annihilation.

 

How much of the kinetic energy supplied by the cue ball, on average by percentage, does the black ball receive during a break in a game of pool?

It can vary wildly depending on initial conditions, which in the context of your question, vary wildly with time. So the answer is "unknown", at least without extensive mathematical treatment. Extensive.

It could be zero percent, or it could absorb enough energy to blast it into its constituent pieces.

 

For the sake of argument lets assume the initial condition is the antipartice has sufficient or ideal amount of speed when it hit the Hydrogen atom. Now what happens next on average?

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54 minutes ago, FreeThinker said:

For the sake of argument lets assume the initial condition is the antipartice has sufficient or ideal amount of speed when it hit the Hydrogen atom. Now what happens next on average?

What orientation is the H2 molecule in?

What frequency is the H-H bond vibrating at?

What is the temperature of the system?

What is the proton energy state?

What are the quark-gluon conditions like within each proton AND antiproton?

Is the H2 molecule rotating?

Dont forget the Heisenberg uncertainty principle!

Precisely what angle and attitude will the collision have?

What is the electric and magnetic environment present?

Is there an electron involved? What is its energy level? Where is it in its probability cloud?

 

This sh** is COMPLEX, you cant give meaningful answers with such broad starting conditions - and even if you gave precise conditions, a reasonable answer would still be very difficult to guess at without actually knowing how to work out the answer.

It seems like I should be able to say "Ooh it will be around the 35% mark or thereabout I would imagine", but you really, really cant do that sort of thing at these kinds of scales, in this realm of physics.

There is a reason "they" spend million and millions on enormous colliders - because sometimes to know something you actually have to go and do it. 

In other words, you need to talk to someone who works with antimatter and individual protons at a professional level, and you may need to go through a large amount of higher education to understand the answer.

If it was a classical physics problem, many people on this site would be able to work out a pretty decent treatment of the problem and perhaps calculate accurate and well-characterised answers, or by analogy to a similar known problem, give very illuminating comparisons.

But at this scale, in the quantum realm, this cannot be done in the same way. Protons are not solid spheres that bounce and collide in nice predictable ways. Even the concept of them being "particles" is an approximation, they are not actually little round balls in any real sense.

 

If all of that sounds rather negative, hear this - that you even know enough to ask very hard questions is a pretty good starting point :wink:

 

 

 

Edited by p1t1o
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13 minutes ago, p1t1o said:

If all of that sounds rather negative, hear this - that you even know enough to ask very hard questions is a pretty good starting point :wink:

 

Thanks for your long answer, I guess there is no alternative than to find scientific paper and try to make some sense from it

I found paper about Antiproton collision with molecular hydrogen (March 7 2017), perhaps it can give me some answers I can use for my approximation for an Antimatter reactor simulator

Edited by FreeThinker
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3 minutes ago, FreeThinker said:

Thanks for your long answer, I guess there is no alternative than to react scientific paper and try to make some sense from it

I found paper about Antiproton collision with molecular hydrogen, perhaps it can give me some answers I can use for my approximation for an Antimatter reactor simulator

That is unfortunately the long and short of it. 

 

However, if it is a simulation you are attempting to build, that does grant you some freedom if your goals are a little flexible.

It will be very difficult to write a perfect simulator, you wont be reproducing results from CERN any time soon.

But since it is a simulator, and thus by definition, an approximation, you are free to define said approximation as you see fit.

Set out known assumptions and set out what you are going to show, and you still might be able to generate some interesting data, even if it isnt the exact solution you were looking for at first.

For example:

Let us assume that protons are small physically spherical objects

Let us assume that one particle labelled "antiproton" will consume another particle labelled "proton" (and vice versa) and will produce X number of smaller particles moving at speed Y from the origin of the collision.

Here is what happens when we fire an "antiproton" into a mass of ten thousand "protons".

 

Now this only resembles reality at a very basic level, however some statistical information coming from it might be valid. Such as observing how the number of subsequent collisions increase as a function of the number of "antiprotons" you inject. You wont really be simulating the exact results of using real antiprotons and protons, but you will see the sort of numerical things that happen when you do things with large numbers of particles, it can give a general "gist" of what happens when particles start exploding amongst themselves, that sort of thing.

Like when a military simulator cannot properly simulate modern missiles because the technical spoecifics are classified, but you can still get a good/realistic picture of what happens to the air battle when you, say, double the number of available weapons, or aircraft. The specific data might be inaccurate, but the overall picture still gives an illustrative idea.

 

Im not sure if that is clear, see what Im getting at?

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24 minutes ago, FreeThinker said:

Thanks for your long answer, I guess there is no alternative than to find scientific paper and try to make some sense from it

I found paper about Antiproton collision with molecular hydrogen (March 7 2017), perhaps it can give me some answers I can use for my approximation for an Antimatter reactor simulator

You have to be careful even then, from my quick skim the method used in that paper is based on semi-classical assumptions. That's great for scattering and ionisation at low-ish energies (which are the two things the paper is looking at), but doesn't take into account the effects of the strong force, weak force or annihilation.

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22 hours ago, FreeThinker said:

What about if we allow antiproton reactor with a hydrogen molecule (H2), will the second proton particle absorbs some of the annihilation energy? then the question would be, how much, on average by percentage?

On average, cross-section of a proton divided by surface area of a sphere with radius equal to inter-atomic distance. But I suspect variance will be rather high. Most of the energy will be carried away by relatively few high energy particles. Picture trying to hit a pea with a shotgun from across a football field while blind-folded. If you hit it, won't be much left of a pea, but your odds aren't great.

What I don't know is how much low-energy radiation is released. Anything in 1eV range is likely to be absorbed, causing that proton to go flying, but not terribly fast. These are ordinary chemical energy ranges.

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