Atom Interferometry for Nuclear Reactions

In summary, atom lasers could be very useful for making ultra-precise measurements, including at the quantum scale.
  • #1
sanman
745
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Recently, we've heard about research into storing anti-hydrogen as a BEC. Atom lasers are touted for their potential to make ultra-precise measurements, including at the quantum scale, because of their small DeBroglie wavelengths in comparison to light.

Once, I emailed Dr Wolfgang Ketterle immediately after he was awarded the Nobel Prize, and asked him about whether Bose-Einstein Condensate could be used to somehow achieve nuclear fusion. He good-naturedly replied back, chuckling that no, it was not possible, because the density of the BEC is far too low.

Alright, a single BEC/superatom might not be able to do this, but what about 2 or more BECs in relative motion to each other -- ie. 2 atom lasers made to interfere with each other?

My point in speculating about this idea, is that so far in our attempts at achieving nuclear fusion, we have been trying to get a bunch of particles to collide with each other. But what if you could manipulate matter as a wave, and make two such waves very sharply interfere with each other?

What if you had 2 very "powerful" atom lasers -- in this case, "power" would probably refer to mass throughput or KE -- which would be configured to maximize collisions between their respective atoms resulting in nuclear reactions.

If fusion reactions wouldn't produce enough power, then could atom lasers be used for conveniently producing matter-antimatter collisions?

http://arxiv.org/PS_cache/cond-mat/pdf/0511/0511113v3.pdf
 
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  • #2
sanman said:
My point in speculating about this idea, is that so far in our attempts at achieving nuclear fusion, we have been trying to get a bunch of particles to collide with each other. But what if you could manipulate matter as a wave, and make two such waves very sharply interfere with each other?
sanman,

Quantum mechanics doesn't work like that. You can't "get around" or "get over" the
Coulomb barrier by some type of "interference".

In essence, the waves of a particle can only interfere with other waves from the SAME
particle - not other particles. Remember the magnitude of the wave function gives the
probability density function for finding the particle at a given point in space in the limit
of the Born approximation.

You don't get a modification of the probability because another particle's wave function
happens to overlap. There has to be some type of interaction potential for that to
happen. It's like two radio waves of different frequencies that criss-cross in space.

Just because at some point in space, one radio wave is "+" and the other wave is "-";
doesn't mean that the two waves annihilate each other. Nope - they pass right
through each other.

You do consider the quantum mechanical wave nature of the problem when you
compute the reaction cross-section; because one considers the "tunneling" of the
Coulomb barrier.

Dr. Gregory Greenman
Physicist
 
  • #3
Hi Greg, that wasn't quite what I was saying.

Clearly you can overcome Coulombic repulsion using momentum. The purpose of using the atom lasers is to have colliding streams of atoms (each of these atoms having momentum), but where the collision of the atoms isn't a hit-and-miss affair, and is instead more coherently organized.

The momentum or kinetic energy is what breaches the Coulomb barrier, the interference or synchronization is what keeps you on target. What's the point of 2 oncoming atoms having lots of momentum or KE, if they miss? Every miss is a wasted opportunity.

That's why I said atom laser, because atom laser means moving atoms, but moving in a coherent manner, just like coherent light moves in a coherent manner. Lasers can be synchronized.
 
  • #5
sanman said:
The momentum or kinetic energy is what breaches the Coulomb barrier, the interference or synchronization is what keeps you on target. What's the point of 2 oncoming atoms having lots of momentum or KE, if they miss? Every miss is a wasted opportunity.
sanman,

I don't think you are going to be able to control the trajectory of the
individual ions to the point where you can dictate a collision.

No - just make and confine a plasma of the requisite density and temperature;
and you will have all the collisions you need.

For example, in a nuclear fission reactor, we don't control whether or
not an individual neutron hits a nucleus or not. The collisions are all
stochastic. Besides, the number of collisions number in the thousands
of billions - you aren't going to be able to control that many particles.

But what's more - you don't have to.

Dr. Gregory Greenman
Physicist
 
  • #6
But Greg, all those wasted collisions are what make the reactors so hazardous and heavy. All those dangerous neutrons and the shielding/blanketing they necessitate.

Photonic lasers of course all travel at C.
But with atom lasers we can control how fast the atoms travel. So what is the limit on how fast the atoms in an atom laser can be made to travel?

Research in photonic lasers is trying to make them more powerful.
I presume the analogy for atom lasers would be to try and make them have more KE.
High-KE atom lasers might be more useful in practical applications, because they would allow you to direct a large amount of KE in a precisely controlled way.
 
  • #7
sanman said:
But Greg, all those wasted collisions are what make the reactors so hazardous and heavy. All those dangerous neutrons and the shielding/blanketing they necessitate.
The collisions in nuclear processes are inherent in the nature of the process. What makes reactors so 'potentially' hazardous is the high levels of energy involved. The confinement systems - pressure vessels and piping of a fission reactor system or confinement magnets and vessel for a fusion reactor - require massive strutures.

Laser systems are equally massive. Just look at the Shiva system, and now the National Ignition Facility.
http://www.llnl.gov/nif/

http://www.llnl.gov/etr/pdfs/12_94.1.pdf

Photonic lasers of course all travel at C.
But with atom lasers we can control how fast the atoms travel. So what is the limit on how fast the atoms in an atom laser can be made to travel?

Research in photonic lasers is trying to make them more powerful.
I presume the analogy for atom lasers would be to try and make them have more KE.
High-KE atom lasers might be more useful in practical applications, because they would allow you to direct a large amount of KE in a precisely controlled way.
The term 'photonic laser' is redundant.

Particle beams and lasers require a lot of energy input compared to the useful energy produced. Trying to use lasers or beams on an atomic level is inherently inefficient and counter productive. One CANNOT control nuclear collisions on a nuclear level, let alone the atomic level. Just look at the cross-sectional dimension of a laser beam!
 
  • #8
sanman said:
But Greg, all those wasted collisions are what make the reactors so hazardous and heavy. All those dangerous neutrons and the shielding/blanketing they necessitate.
sanman,

BALONEY! What "wasted collisions" are you talking about - that's NONSENSE!

Reactors are NOT hazardous. The neutrons have NOTHING to do with
the reactors being heavy. The fuel - Uranium - is the heaviest naturally
occurring element. Additionally, the reactor has heavy shielding. However,
the bulk of that is to shield gammas not neutrons.

Photonic lasers of course all travel at C.
But with atom lasers we can control how fast the atoms travel. So what is the limit on how fast the atoms in an atom laser can be made to travel?

As Astronuc points out - the term "photonic lasers" is redundant. ALL lasers;
which stands for Light Amplified by Stimulated Emission of Radiation are based
on Photons; i.e. "light". Even their predecessor the MASER - for Microwaves
Amplified by Stimulated Emission of Radiation are ALSO photons.

You don't have "coherent laser beams" of particles - that's NOT a laser.

Particle accelerators get nucleons up to 99.999..% of the speed of light;
which is the ultimate speed limit.

Research in photonic lasers is trying to make them more powerful.
I presume the analogy for atom lasers would be to try and make them have more KE.

There's NO SUCH THING as an "atom laser". Lasers are based on the process
called "stimulated emission" - that is one photon can trigger the release of
another photon and the two photons will be in phase. There's no analogous
process for atoms - "atom laser" is a NONSENSE term.

High-KE atom lasers might be more useful in practical applications, because they would allow you to direct a large amount of KE in a precisely controlled way.

There are already machines that do that - and they are NOT lasers.

Cyclotrons, synchrotrons, and other particle accelerators are used in
nuclear physics research. Plasma torches are used to cut metal, diamond...
many materials very precisely.

Dr. Gregory Greenman
Physicist
 
  • #9
Cutting things is not the purpose that I was alluding to.

I'm saying that BECs-in-motion (aka "atom lasers") would allow us to collimate and collide greater numbers of nuclei with greater frequency, and greater accuracy.

Nuclei could be targetted at each other with less chance of missing, and therefore make more efficient use of inputted energy.http://www.npl.washington.edu/AV/altvw97.html (scroll to section on atom lasers and 4-wave mixing)

While optical lasers produce light of a single wavelength with the waves all in phase, atom lasers produce a beam of atoms, all with exactly the same velocity and all the matter waves in phase (i.e., coherent). The first atom laser produced its atom beam as a spreading pulse, as the atoms of a Bose-Einstein condensate (see Analog March-96.) were simultaneously ejected from the trap that held them.
Look, a low-mass particle, whether in motion or at rest, is going to have some jiggle to it -- the DeBroglie wavelength, a quantum effect due to the buffeting of the dynamic vacuum. So if you're trying to collide it with a similarly low-mass particle, then that jiggle is going to create some uncertainty on whether you get a collision or not.

But with a BEC-superatom, you've got the mass of multiple atoms concentrated into a single superatom, and so it's going to have much less jiggle, since the dynamic vacuum can't buffet its heavier mass as easily. So that means you can aim that superatom more precisely when trying to achieve a collision with another oncoming superatom. So you're much more likely to achieve a collision.

Chemical reactions have been achieved by colliding opposing streams of atom laser beams. Each input/collision stream consisted of a chemical reagent in BEC form, while a 3rd (output) stream was generated, made of the chemical reaction product.

So then the question becomes one of trying to accelerate your superatoms to enough velocity to overcome Coulombic repulsion, so that collisions become meaningful for nuclear reaction purposes. It's a question of relative velocity for the colliding beams.

How fast does a superatom have to be traveling relative to another superatom it's colliding with, in order to overcome the Coulombic barrier? Let's assume a superatom of Deuterium.
 
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  • #11
It is unfortunate that a professional would use the term 'atom laser', when it has nothing to do with lasers. One is talking about a monoenergetic and coherent beam of atoms colliding with some fixed target or opposing beam.

One still cannot avoid scattering - it is inherent in the physics of particle interaction. One cannot control atoms in the keV range down the level of the radius of a nucleus, and the atom is several orders of magnitude larger.

Using atoms involves a more complex interaction than using nuclei.
 
  • #12
When we try to collide atoms with each other for fusion purposes, we like to exploit the Coulombic shielding that neutrons cause, so that we can more easily obtain the collision. That's why we like D and T over H. Ideally, you'd like the neutrons to be positioned on the forward-facing sides of your respective nuclei as they rush to hit each other, so that they will provide the Coulombic shielding.

But we're forced to rely upon statistical effects, because we can't control which way nuclei are oriented as they hit each other. Or can we?

With BECs and atom lasers, our atoms are all in phase with each other. What works for one will work for all, because they're all synchronized. With atomic interferometry, we could play with the beams and adjust some parameter like beam path (just like Michelson-Morley did) until we get our atom beams colliding in just the right way. We'll know that we've calibrated our colliding beams optimally, once we observe optimal reaction products (ie. nuclear reaction products)

I'm wondering if this might even be useful for muon-catalyzed fusion? After all, we want our muons to diatomically bind with hydrogen nuclei in the most efficient way, so that the short-lived muons will catalyze the most nuclear fusions possible before they die. BEC hydrogen is about the most dense hydrogen you can get, which might facilitate the muons visiting the most hydrogens possible. Just another thought.
 
  • #13
Astronuc said:
One still cannot avoid scattering - it is inherent in the physics of particle interaction. One cannot control atoms in the keV range down the level of the radius of a nucleus, and the atom is several orders of magnitude larger.

But according to the concept of "matterwave", the properties of the atom beam have cyclical periodicity. There is a wavelength.

How can you control a laser beam of photons to etch pits on a DVD? The laser beam has the wave properties.
How can you do laser interferometry? Lasers have those wave properties.

In the case of an atom laser, the wavelength is far smaller than the wavelength of light, because of the higher mass of the atoms. Likewise, those atoms have kinetic energy.

Exactly what is the relationship between kinetic velocity of the atoms, and their uncertainty/imprecision?
Does acceleration automatically cause decoherence? What is the critical threshold of beam decoherence below which we cannot obtain sufficient numbers of nuclear collisions between our opposing atom laser beams?

When you say 'scattering' -- in 4-way mixing of atom beams that scattering is a result of collision. Fine, we don't have to mind scattering of the reaction products, after our collisions have been achieved.
 
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  • #14
Nextly, why couldn't you apply photonic lasers to further optimize collision conditions between the atoms of opposing atom laser beams?

We know that femtosecond/attosecond-pulse lasers are capable of distorting the electron cloud of an atom. Doing so could have an effect on the orientation of the charged nucleus. What if you could synchronize/arrange your photonic lasers (femtosecond/attosecond-pulse) to interact with the atom laser beams and manipulate the orientation of their nuclei, in order to optimize their chances of breaching the Coulomb barrier?

So as your colliding atoms approach each other, the femtosecond/attosecond pulses would arrive, distorting their electron clouds so that they bunch up between the nuclei to provide more shielding, thus allowing the colliding nuclei to successfully overcome the Coulomb barrier and fuse.

That way, you're bringing multiple physics tricks into play at once, to get you to the goal. You're using photoelectric effect (cloud distortion), you're using wave nature of matter (mass-superpositioning for jiggle reduction and trajectory refinement), so that you can fight Coulomb's Law.
 
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  • #15
http://www.nist.gov/public_affairs/releases/n99-09.htm [Broken]

"...We can now look forward to the analogous development of quantum atom optics," Phillips says. Another possible application is the amplification of matter waves, making a beam of atoms more intense by creating additional atoms that are exact copies of those in the original beam.

Okay, so making an atom laser beam more intense would mean having more nuclei traveling in that beam, which would hopefully increase the possibility of nuclear collisions. With more nuclei being in phase with each other along the beam trajectory, it could allow us to synchronize their collision trajectories to maximize the collisions between the opposing beams.
 
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  • #16
http://www.laserfocusworld.com/display_article/292386/12/ARCHI/none/News/ATOM-OPTICS:-Slow-helium-source-is-first-step-toward-atom-interferomete" [Broken]

The Texas researchers used an atomic-beam source developed by Uzi Even at Tel Aviv University (Tel Aviv, Israel) to generate a monochromatic pulsed beam of helium and neon atoms traveling at 511 m/s. Despite the rapid motion of the atomic pulses, atoms within each 10 µm pulse (a few millimeters in length) moved only a few meters per second relative to each other, yielding an equivalent temperature of about 50 mK within each pulse.

So you guys were talking about tokamak plasma having a low density, but if a fast-moving atom beam pulse has an internal temperature of 50mK, that sounds like it corresponds to a high density. Of course we'd want to have the most intense beam possible, to maximize the number of nuclei smacking into each other. The more crowded our collision zone is, the better.
 
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  • #17
http://www.iop.org/EJ/abstract/0295-5075/78/6/60003"

Abstract. It is demonstrated that a Stern-Gerlach interferometer including a special transverse phase shifter can generate an atomic beam of a small diameter (few tens of nm). Calculations carried out in a coherent regime confirm this point. They also show that the device is almost insensitive to velocity dispersion and that the required mechanical accuracy is quite accessible. Due to the peculiar transverse amplitude distribution (of the Lorentz type), the spreading of the generated beam profile is very small compared to that given by a circular diaphragm or a Gaussian profile of comparable initial diameter. This is a key property as regards applications, e.g. in atom lithography and surface probing.

PACS numbers: 03.75.-b, 03.75.Be, 39.20.+q

Print publication: Issue 6 (June 2007)
Received 19 January 2007, in final form 1 May 2007
Published 24 May 2007

Okay, so a few tens of nanometers is still quite a lot of dispersion relative to the radius of an atomic nucleus. But when you're talking about a whole lot of atoms traveling down that beamline, you might achieve quite a number of collisions within that cross-sectional area.

The greater your beam velocity and the greater your beam intensity, the more your atomic throughput ("power"), and the more collisions you could expect.
 
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  • #18
sanman said:
When we try to collide atoms with each other for fusion purposes, we like to exploit the Coulombic shielding that neutrons cause, so that we can more easily obtain the collision. That's why we like D and T over H. Ideally, you'd like the neutrons to be positioned on the forward-facing sides of your respective nuclei as they rush to hit each other, so that they will provide the Coulombic shielding
sanman,

WRONG! Neutrons DON'T sheild the Coulomb force.

Your concept of having the neutronn on the "forward facing" side is also NONSENSE!

You have to think of the neutrons in the nucleus as if they were in ORBITS - the
"Tinker-Toy" model of the nucleus where the protons and neutrons are represented as
discrete balls is WRONG!

Neutrons don't shield the Coulomb force. What is happening is that the strong nuclear
force is MUCH more powerful than the Coulomb force - but it is short range. The idea
is to give the particles enough energy so that by the time the Coulomb force stops them;
they are close enough so that the strong nuclear force can "overpower" the Coulomb
force and fuse the two particles into a single nucleus. The strong nuclear force can do
this after all - it's what is holding the nucleus together - a nucleus that may have many,
many protons - all of which are repelling each other.

Neutrons bring with them a certain amount of nuclear "binding energy". Protons also
bring nuclear "binding energy" - but they also bring Coulombic "unbinding energy".

So neutrons - because they increase the nuclear force without adding to the repulsion
forces - can act like a nuclear "glue". Neutrons DON'T shield the Coulomb force - they
provide more nuclear force to overcome the Coulomb force.

Dr. Gregory Greenman
Physicist
 
  • #19
sanman said:
With BECs and atom lasers, our atoms are all in phase with each other. What works for one will work for all, because they're all synchronized. With atomic interferometry, we could play with the beams and adjust some parameter like beam path (just like Michelson-Morley did) until we get our atom beams colliding in just the right way.
sanman,

NOPE - your concept of how the quantum mechanics of colliding beams works is just
plain WRONG!

You CAN NOT DO what you are suggesting.

The only reason you can do what Michaelson and Morley did is because you essentially
have photons that are interfiering with THEMSELVES!

If you take a Michaelson and Moreley interferometer, and increase the length of one
of the legs so that the difference between the lengths of the two legs exceeds the
"coherence length" of the photons - then you STOP getting interference effects because
you are no longer having the same photons interfere with themselves.

http://en.wikipedia.org/wiki/Coherence_length

You are essentially applying principles of wave interference that are good for photons
that are interfering with themselves; to a regime where you have discrete particles that
do NOT share the same wavefunction.

Dr. Gregory Greenman
Physicist
 
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  • #20
sanman said:
W
I'm wondering if this might even be useful for muon-catalyzed fusion? After all, we want our muons to diatomically bind with hydrogen nuclei in the most efficient way, so that the short-lived muons will catalyze the most nuclear fusions possible before they die.
sanman,

Any given muon can only catalyze exactly ONE fusion reaction!

This is NOT like a catalyst that can be used over and over again.

Muons are a ONE SHOT catalyst - so this is all NONSENSE!

Dr. Gregory Greenman
Physicist
 
  • #21
Here is a reply from Dr William Phillips, 1997 Nobel Prize Winner in Physics
http://www.britannica.com/eb/article-9110823/William-D-Phillips

I have not considered this question carefully, but it seems highly
unlikely that atom lasers will be applicable to nuclear fusion for
fusion energy. The problem is that for fusion to occur, you need to
overcome the coulomb barrier that keeps nuclei apart. To do that you
need lots of energy, and atom lasers have extremely small energy per
particle. Acceleration of atoms in an atom laser is no easier than
with other atomic beams, so I see no reason why atom lasers would be
useful.

I have a vague recollection that some years ago there was a proposal
to use atom lasers for the conversion of nuclear waste into something
less dangerous. The idea was that the atom laser could stimulate
some kind of nuclear reaction. While not done with the idea of
producing fusion energy, the idea has some similarity. That idea
never went anywhere, as far as I know, probably for the same reason.
If you are really interested, you might find something written about
that proposal, but I cannot recall any more details about it and
cannot direct you to any resources.

>Hi Dr Phillips,
>
>My friends and I were having a debate on the
>PhysicsForums website, and I was wondering if you
>could settle it for us:
>
>https://www.physicsforums.com/showthread.php?t=176946
>
>I am arguing that atom lasers could be adapted for
>achieving nuclear collisions for fusion energy
>purposes, but others are disagreeing with me. I'm
>arguing that the extremely low DeBroglie wavelength of
>coherent matter could permit extremely fine-precision
>targetting of opposing atom laser beams, to maximize
>the number of nuclear collisions between them. This
>would all be done under vacuum conditions, naturally.
>
>As someone who has published work in the field of atom
>optics, what is your opinion?

Dr Phillips then also further replied:

Here is a web page that references the ideas (the Baser) for nuclear
waste disposal. I know nothing about the reliability of this.


http://www.cs.cmu.edu/~dst/ATG/index.html
 
  • #22
Morbius said:
sanman,

Any given muon can only catalyze exactly ONE fusion reaction!

This is NOT like a catalyst that can be used over and over again.

Muons are a ONE SHOT catalyst - so this is all NONSENSE!

Dr. Gregory Greenman
Physicist

I'm sure that this isn't true. IIRC, a single muon can catalyze an average of 103 nuclear D-D fusion reactions before it decays/dies. Let me find a reference:
http://en.wikipedia.org/wiki/Muon-catalyzed_fusion
The highest success rate achieved in the lab has been on the order of about 100 reactions or so per muon.

I'm wondering if muons could catalyze the fusion better if coupled to a BEC superatom?
 
  • #23
sanman said:
I'm sure that this isn't true. IIRC, a single muon can catalyze an average of 103 nuclear D-D fusion reactions before it decays/dies. Let me find a reference:
http://en.wikipedia.org/wiki/Muon-catalyzed_fusion
No. One is not going to get 103 reactions before a muon decays - half-life ~ 2 microseconds or so. One might be fortunate to get a d and t or d traveling nearly parallel (highly improbable, but could happen) and the muon just happens to pass by at the right moment (even more improbable). One is lucky to get one reaction.

One needs a better reference than a Wikipedia article.

I'm wondering if muons could catalyze the fusion better if coupled to a BEC superatom?
:rolleyes:

Dr. Phillips may be recalling accelerator driven transmutation - and that is not based on 'atomic lasers'.


How can you control a laser beam of photons to etch pits on a DVD?
This is something entirely different. One should look at the size of those 'pits' on a DVD in comparison with an atom. And one is simply changing the optical properties (reflectivity) of the surface - it either reflects or does not. It's on/off - hence a digital (binary) system - and the laser is fixed in the vertical and azimuthal - sliding back and forth radially. This is also low power stuff.

I think one is mixing apples, oranges and bananas here.
 
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  • #24
Morbius said:
sanman,

NOPE - your concept of how the quantum mechanics of colliding beams works is just
plain WRONG!

You CAN NOT DO what you are suggesting.

The only reason you can do what Michaelson and Morley did is because you essentially
have photons that are interfiering with THEMSELVES!

If you take a Michaelson and Moreley interferometer, and increase the length of one
of the legs so that the difference between the lengths of the two legs exceeds the
"coherence length" of the photons - then you STOP getting interference effects because
you are no longer having the same photons interfere with themselves.

http://en.wikipedia.org/wiki/Coherence_length

You are essentially applying principles of wave interference that are good for photons
that are interfering with themselves; to a regime where you have discrete particles that
do NOT share the same wavefunction.

Dr. Gregory Greenman
Physicist

Regarding decoherence of a laser, may I point out that the more massive atoms are less vulnerable to decoherence from quantum effects (ie. propagation through the vacuum) than the far lighter photons are.

So I would see superatoms as having far greater decoherence length than photons.

Atom lasers have been shown to have interference patterns -- these occur when they are interfering with themselves.

An atom laser beam can be split, and then re-collided with itself.
 
  • #25
Astronuc said:
No. One is not going to get 103 reactions before a muon decays - half-life ~ 2 picoseconds or so. One might be fortunate to get a d and t or d traveling nearly parallel (highly improbable, but could happen) and the muon just happens to pass by at the right moment (even more improbable). One is lucky to get one reaction.

One needs a better reference than a Wikipedia article.

:rolleyes:

Muons have a lifespan of over 2 microseconds:

http://en.wikipedia.org/wiki/Muon

"The muon (from the letter mu (μ)--used to represent it) is an elementary particle with negative electric charge and a spin of 1/2. It has a mean lifetime of 2.2μs, longer than any other unstable lepton, meson or baryon except for the neutron."
Dr. Phillips may be recalling accelerator driven transmutation - and that is not based on 'atomic lasers'. This is something entirely different. One should look at the size of those 'pits' on a DVD in comparison with an atom. And one is simply changing the optical properties (reflectivity) of the surface - it either reflects or does not. It's on/off - hence a digital (binary) system - and the laser is fixed in the vertical and azimuthal - sliding back and forth radially. This is also low power stuff.

I think one is mixing apples, oranges and bananas here.

I don't think you read his comments properly, as they were supporting your side not mine. He was saying that (current) atom lasers don't have enough KE to overcome Coulombic repulsion.

But I'll disagree with him, as I don't feel there is any fundamental barrier to making the BEC move fast enough for nuclear collision purposes.

The whole point of my suggestion of atom lasers for nuclear reactions, is to increase the probability of collisions, rather than depending on the stochastics of mean free path.
Here you would create an anti-free path, by seeking to overlap 2 mutually opposing trajectories as fully as possible.
And this is where the coherence of the colliding atoms comes in, because superpositioning them will give them less quantum jiggle, and synchronizing their jiggle with those of the matter they're colliding with would increase the chances of collision further still.

If you are walking down the hallway while weaving left and right, and I am walking down the hallway while weaving left and right, then if our weaving motions are synchronized we can ensure the chances of our colliding with each other.
 
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  • #26
sanman said:
How can you control a laser beam of photons to etch pits on a DVD? The laser beam has the wave properties.
How can you do laser interferometry? Lasers have those wave properties.

In the case of an atom laser, the wavelength is far smaller than the wavelength of light, because of the higher mass of the atoms. Likewise, those atoms have kinetic energy.

YES - MUCH SMALLER - which is the answer to the question of WHY you can't control
them!

Let's calculate the wavelength of a 1 keV proton.

[tex]\lambda = {h \over p}[/tex]

[tex]\lambda^2 = { h^2 \over p^2 } = { h^2 c^2 \over 2 mc^2 E }[/tex]

[tex]\lambda^2[/tex] = ( 4.135e-15 eV-s )^2 ( 3e+08 m/s )^2 / [ 2 (9.38e+08 eV) ( 1000 eV) ]

The mc^2 is the rest energy of a proton = 938 MeV = 9.38e+08 eV

[tex]\lambda^2[/tex] = 8.203e-25 m^2

[tex]\lambda[/tex] = 9.067e-13 m = 907 fermis.

The wavelength is about 500 times the diameter of a proton.

This wavelength is about 1/1000-th of a nanometer.

The smallest wavelengths that we can control via optics - the ultraviolet region - have
wavelengths greater than about 200 nanometers.

So your 1 keV proton has a wavelength 200,000 times SMALLER than the SMALLEST
light wavelengths we can control.

The wavelength of that DVD laser is about 700 nanometers. So your proton wavelength
is 700,000 times smaller than what the DVD laser has for a wavelength.

So it's UTTER NONSENSE to say if we can control a DVD laser we can control
something that is 700,000 times smaller.

We don't even have a mirror that works at those wavelengths; let alone prisms and
other optical components.

For Heavens sake - do your homework - do the math before you talk NONSENSE!

Dr. Gregory Greenman
Physicist
 
  • #27
Why does it have to come down to using lightwaves to control the matterwaves?

If we can use coherent matter and its ultra-small wavelengths to make very fine measurements, we can use the same to make ultra-find adjustments for precision targetting.

This will enable us to target 2 opposing atom laser beams so that their opposing trajectories overlap very precisely -- enough to ensure many more nuclear collisions than would otherwise be possible.

The coherence and phase-sychronization of the opposing beams means that the quantum jiggles of oncoming atoms can be matched precisely, so that their nuclei are more likely to be lined up for collision.

Again, I'm not claiming that each atom will collide with the first oncoming atom it approaches in the opposing beam. But as each atom traverses down the full length of the beam path, it's going to be encountering a whole lot of oncoming atoms which are in phase with it, JIGGLES AND ALL. That's going to mean more collisions.

Let's worry about Dr Phillips' statement on the low particle velocity later. Let's first focus on obtaining the highest fraction of collisions we can, and then later we can worry about accelerating these collision velocities to the speeds necessary to overcome Coulomb's repulsion. Remember, a dead-on collision is directing more of that velocity/KE towards breaking the Coulomb barrier than a glancing blow is. Furthermore, a superatom has the masses of multiple atoms stacked together, yielding a particle with more KE for a given velocity. So the required KE of particles in our opposing beams setup is lower than what's required in a tokamak or some other stochastic setup.

We should try to think out of the box, and not always feel that we're trapped in stochastics. Superpositioning can help to overcome quantum fuzziness -- it can boost the signal-to-noise ratio.
 
  • #28
Let's worry about Dr Phillips' statement on the low particle velocity later. Let's first focus on obtaining the highest fraction of collisions we can, and then later we can worry about accelerating these collision velocities to the speeds necessary to overcome Coulomb's repulsion. Remember, a dead-on collision is directing more of that velocity/KE towards breaking the Coulomb barrier than a glancing blow is. Furthermore, a superatom has the masses of multiple atoms stacked together, yielding a particle with more KE for a given velocity. So the required KE of particles in our opposing beams setup is lower than what's required in a tokamak or some other stochastic setup.
Look at Rutherford scattering! One is not able to control atoms to the degree that a 'dead on' collision is possible.

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/rutsca2.html

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/ruthcross.html

That is inherent in atomic collisions, and there is no way around it.

With respect to superatoms - which are clusters of atoms which seem to exhibit some of the properties of elemental atoms. The BEC are formed by supercooling or condensing atoms into a solid mass. What would happen to this 'superatom' when another atom collides with it? What would happen to the superatom if the colliding atom induces a single fusion reaction?

Then consider - Have BEC superatoms been formed from molecular hydrogen? What are the conditions for metallic hydrogen? What happens when fusion takes place in this mass? Then ultimately, how does one transform the energy from the fusion reaction to more useful energy, e.g. electricity or thermal energy?

It is not practical to target individual atoms with respect to a given nuclear reaction in order to generate power. One puts more power into achieving that reaction than one obtains from the reaction.

Muons have a lifespan of over 2 microseconds:
Yes. Thank you for the correction. Evenso, the muon has to slowdown from its birth to essentially rest in order to induce 2 d's to fuse. How long does it take to slow down?

Also, what does it take to create muons?
 
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  • #29
Astronuc said:
... Yes. Thank you for the correction. Evenso, the muon has to slowdown from its birth to essentially rest in order to induce 2 d's to fuse. How long does it take to slow down?
10ps secs to form a Muonic D or T atom. 5 ns to make a DD+ or DT+ Mu molecule. 1ps for fusion. Total cycle time is ~ 5ns, so a couple 100 fusions per Muon; BUT
Also, what does it take to create muons?
This is the problem. Presently the energy required to produce a Mu-: must be made from Pi- =139MeV, make stuff other than Pi- = 10x, Lab vs CM frame 2x, accelerator efficiency = 2x. Total Mu- production E (just one) = ~ 5GeV >> than the 1GeV fusion E produced.

Therefore either reduced cycle time or more efficient mu production methods are required.

Summarized in T. Rider, "http://www.fusor.net/board/getfile.php?bn=fusor_future&att_id=3718" [Broken]" April '05 seminar, see slide 10 for Muon catalyzed fusion, which references:

Brunelli & Leotta (eds.), Muon-Catalyzed Fusion and Fusion with Polarized Nuclei (Plenum Press, 1987)
M. C. Fujiwara et al., Phys. Rev. Lett. 85, 1642 (2000) "only decreases the time for the first cycle, not later ones"
 
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  • #30
sanman said:
The coherence and phase-sychronization of the opposing beams means that the quantum jiggles of oncoming atoms can be matched precisely, so that their nuclei are more likely to be lined up for collision.

Quit thinking about this a classical hard-sphere collision.

This is a "collision" in the quantum mechanical realm - and all this precisely lined-up
beams means precisely ZIP!

Again, I'm not claiming that each atom will collide with the first oncoming atom it approaches in the opposing beam. But as each atom traverses down the full length of the beam path, it's going to be encountering a whole lot of oncoming atoms which are in phase with it, JIGGLES AND ALL. That's going to mean more collisions.

WRONG! This is UTTERLY COMPLETE GARBAGE!

Your concept of how fusion occurs is TOTALLY WRONG - you don't have to
line-up the collisions and worry about the "jiggles" - you just have to get the particles
in range of the strong nuclear force - and then you don't have to worry.

So the required KE of particles in our opposing beams setup is lower than what's required in a tokamak or some other stochastic setup.

More handwaving NONSENSE!

We should try to think out of the box,

The problem is you want to think OUTSIDE the LAWS of PHYSICS.

Dr. Gregory Greenman
Physicist
 
  • #31
sanman said:
Atom lasers have been shown to have interference patterns -- these occur when they are interfering with themselves.

An atom laser beam can be split, and then re-collided with itself.
sanman,

NOT at the temperatures in which you get fusion!

You are taking the physics of degenerate matter and applying them to circumstances
where the matter is not degernerate.

Dr. Gregory Greenman
Physicist
 
  • #32
sanman said:
10ps secs to form a Muonic D or T atom. 5 ns to make a DD+ or DT+ Mu molecule. 1ps for fusion.
I strongly disbelieve these numbers. Please show the calculations!

One has to look at the initial energy of the muon. How are the mouns created - e.g. electron-positron annihilation or pion decay? What about the precursor nuclear or subatomic reactions.

Let's say a muon has KE ~ 1 MeV, how long will it take to slow down to ~1 eV to be captured by a d? Then what is the density of d's, or conversely, what is the mean free path between d's?

Even starting with a mass of D2, as soon a one fusion takes place (and produces a few MeV) - the solid is vaporised, AND one will SCATTER muons, much more than they will be combining with d's.

The physics is what it is!
 
  • #33
Astronuc said:
One has to look at the initial energy of the muon. How are the mouns created - e.g. electron-positron annihilation or pion decay?
Pion decay as I stated above

What about the precursor nuclear or subatomic reactions.
Yes there are several such and are energy expensive as I stated above

Let's say a muon has KE ~ 1 MeV, how long will it take to slow down to ~1 eV to be captured by a d?
Thats an engineering problem of placing the D in the same frame as the muon. It requires energy (as I stated above) but its not an impediment to whether or not one can do cyclic muon fusion. <- This is the subject of my post; I make no claim about net power in fact implied the opposite.

Even starting with a mass of D2, as soon a one fusion takes place (and produces a few MeV) - the solid is vaporised, AND one will SCATTER muons, much more than they will be combining with d's.
Solid? Where did that come from? Plasma. I assume you are again thinking of some thermal Tokamak like containment. Try a beam for instance.
 
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  • #34
Astronuc said:
I strongly disbelieve these numbers. Please show the calculations!
...
Let's say a muon has KE ~ 1 MeV, how long will it take to slow down to ~1 eV to be captured by a d?
The 5ns D-T-muon is the rate limiting factor and the most complicated. However you seem to be challenging the initial picosecond muon atomic capture. D. Wightman first calculated that in 1950.
"[URL [Broken]
A.S. Wightman
Moderation of Negative Mesons in Hydrogen I: Moderation from High Energies to Capture by an H2 Molecule [/URL] Phys. Rev. 77, 521 - 528 (1950)

The moderation of negative μ- and π-mesons, as well as of hypothetical negative particles of mass 1000 m and 1837 m is described for a hydrogen moderator and a meson energy range: 10 Mev→0 ev (capture by an H2 molecule). In this energy range, there are three principal modes of energy loss by the mesons: 1. High energy ionization loss, describable by the ordinary stopping power theory. 2. Energy loss due to nuclear collisions. 3. Low energy ionization loss caused by non-adiabatic processes special to hydrogen. From estimates of the probability of these three processes, the moderation times of a meson in liquid hydrogen from 10 Mev to capture by an H2 molecule are calculated:

I simplified the table here -
μ-
From 10 Mev to v / c=5×10-2 : 8.6×10-10 sec.
From v / c=5×10-2 to v / c=6×10-3: 7.4×10-13
From v / c=6×10-3 to v / c=5×10-5{in 1H2}{in 2H2}{in 3H2}:
7.9×10-13
9.0×10-13
9.4×10-13

Something before diving in is that the muon base ionization energy is on 1-2 eV, not ~13 as per the usual atomic hydrogen.
 
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  • #35
mheslep said:
Solid? Where did that come from? Plasma. I assume you are again thinking of some thermal Tokamak like containment. Try a beam for instance.
I used the phrase "Even starting with . . . .", because that represents the minimum distance between deuterons in a material. I am responding to the ~103 fusion reactions/muon, and in a plasma that means something on the order of 103 mean free paths if everything else was ideal.


From estimates of the probability of these three processes, the moderation times of a meson in liquid hydrogen
This is fine for a small number of reactions, but very impractical for a power source.

If one wants to produce a few fusion reactions, there are easier and more practical ways than using muons.
 
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<h2>1. What is atom interferometry for nuclear reactions?</h2><p>Atom interferometry for nuclear reactions is a technique used to study the properties and dynamics of nuclear reactions by using atoms as probes. It involves manipulating the quantum states of atoms and measuring their interference patterns to gather information about the nuclear reaction.</p><h2>2. How does atom interferometry work?</h2><p>Atom interferometry works by using lasers to split a beam of atoms into two paths, which then recombine to create an interference pattern. This pattern is sensitive to any changes in the atoms' quantum states, which can be influenced by the nuclear reaction being studied.</p><h2>3. What are the advantages of using atom interferometry for nuclear reactions?</h2><p>One major advantage of using atom interferometry for nuclear reactions is its high sensitivity. It can detect even small changes in the quantum states of atoms, allowing for precise measurements of nuclear reaction dynamics. Additionally, it does not require the use of radioactive materials, making it a safer option for studying nuclear reactions.</p><h2>4. What types of nuclear reactions can be studied using atom interferometry?</h2><p>Atom interferometry can be used to study a wide range of nuclear reactions, including fusion, fission, and other types of nuclear decay. It can also be applied to studying the properties of exotic nuclei, such as those found in high energy collisions.</p><h2>5. What are some potential applications of atom interferometry for nuclear reactions?</h2><p>Atom interferometry for nuclear reactions has many potential applications, including improving our understanding of nuclear fusion and fission processes, aiding in the development of new nuclear technologies, and providing insights into the fundamental properties of matter and energy. It may also have practical applications in fields such as energy production, nuclear medicine, and national security.</p>

1. What is atom interferometry for nuclear reactions?

Atom interferometry for nuclear reactions is a technique used to study the properties and dynamics of nuclear reactions by using atoms as probes. It involves manipulating the quantum states of atoms and measuring their interference patterns to gather information about the nuclear reaction.

2. How does atom interferometry work?

Atom interferometry works by using lasers to split a beam of atoms into two paths, which then recombine to create an interference pattern. This pattern is sensitive to any changes in the atoms' quantum states, which can be influenced by the nuclear reaction being studied.

3. What are the advantages of using atom interferometry for nuclear reactions?

One major advantage of using atom interferometry for nuclear reactions is its high sensitivity. It can detect even small changes in the quantum states of atoms, allowing for precise measurements of nuclear reaction dynamics. Additionally, it does not require the use of radioactive materials, making it a safer option for studying nuclear reactions.

4. What types of nuclear reactions can be studied using atom interferometry?

Atom interferometry can be used to study a wide range of nuclear reactions, including fusion, fission, and other types of nuclear decay. It can also be applied to studying the properties of exotic nuclei, such as those found in high energy collisions.

5. What are some potential applications of atom interferometry for nuclear reactions?

Atom interferometry for nuclear reactions has many potential applications, including improving our understanding of nuclear fusion and fission processes, aiding in the development of new nuclear technologies, and providing insights into the fundamental properties of matter and energy. It may also have practical applications in fields such as energy production, nuclear medicine, and national security.

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