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KhashayarShatti
2012-Apr-15, 02:47 PM
Usually we hear experiments regarding proton-proton collision at close to speed of light are carried out but it seems to me due to the electrostatic force of protons, retardation occurs that slows down protons before collision.
Is it not so important to make a neutron-neutron collision at this speed? If it is:
Is it possible to neutralize protons by electrons just before collision? What would be the consequences of a head on impact between two neutrons at this speed? Sorry if this subject has already been discussed.

swampyankee
2012-Apr-15, 03:01 PM
I suspect because none of the accelerator labs are set up to produce neutron-neutron collisions. Since neutrons can't be accelerated, they have to be created at high velocities, by slamming charged particles into a target and removing everything but the neutrons that get sprayed out of the back side. OK; we've got a spray of fast-moving neutrons. We can get a second spray on the reverse course, so the two sprays are directed at each other, but they're sprays, and neutrons can't be accelerated, so they can't be focused. The beam luminosity is going to be low, so the probability of collision is going to be poor.

I think some physicists are interested in performing extremely high energy neutron-neutron collisions, but it's currently impractical. They can, of course, model them. Anybody a particle physicist out there in BAUTland?

trinitree88
2012-Apr-15, 03:25 PM
I suspect because none of the accelerator labs are set up to produce neutron-neutron collisions. Since neutrons can't be accelerated, they have to be created at high velocities, by slamming charged particles into a target and removing everything but the neutrons that get sprayed out of the back side. OK; we've got a spray of fast-moving neutrons. We can get a second spray on the reverse course, so the two sprays are directed at each other, but they're sprays, and neutrons can't be accelerated, so they can't be focused. The beam luminosity is going to be low, so the probability of collision is going to be poor.

I think some physicists are interested in performing extremely high energy neutron-neutron collisions, but it's currently impractical. They can, of course, model them. Anybody a particle physicist out there in BAUTland?

swampy. yep with regards to neutron accelerations. The idea of neutralizing high speed protons just before colliding with an electron in the OP is incorrect. The charge would be neutralized, making a hydrogen atom, not a neutron. To convert a proton to a neutron, the quarks must change....an up in the proton must be converted to a down. That's a weak interaction and involves the W+ boson being emitted. Lots of energy is required to do the conversion since essentially it's the reverse process of neutron decay which is exothermic. In fusion the release of binding energy from the formation of heavier nuclides supplies the energy needed to do this, but time, temperature and density of a plasma are limited to a narrow range of variables.....which is why we wait yet to power our houses with the deuterium in sea water. pete

ShinAce
2012-Apr-15, 06:10 PM
I don't see a problem with proton-proton collisions. All that speed lost to coulomb repulsion is stored as energy in a field. When the particles collide, that energy is potential energy. Why wouldn't it be available to create new particles?

korjik
2012-Apr-15, 06:29 PM
Even if it werent available from the field, the fact that protons can be accelerated to something like 6 orders of magnitude more energy would make the proton collisions more energetic.

KhashayarShatti
2012-Apr-16, 03:10 PM
..... In fusion the release of binding energy from the formation of heavier nuclides supplies the energy needed to do this, but time, temperature and density of a plasma are limited to a narrow range of variables.....which is why we wait yet to power our houses with the deuterium in sea water. pete
Lawson criteria concerns temperature and density, but what is ,in fact, temperature and density in particle collision from an engineering point of view? We have the largest possible temp. and density from head on collision of neutrons. Just imagine the yield stress of these dense particles whereas by proton-proton collision these conditions may not be achievable and such a high density may never be achieved.
Secondly if by 20Kev, a hydrogen atom ionizes , would it be possible to generate hydrogen atom so easily when proton's (energy)speed may exceed 4Tev? What would be generated from P+e collision above 1Mev? I can't find any article that gives a mainstream result and there seem to be so many non mainstream explanations.

KhashayarShatti
2012-Apr-16, 04:58 PM
The idea of neutralizing high speed protons just before colliding with an electron in the OP is incorrect. The charge would be neutralized, making a hydrogen atom, not a neutron.
One more point to add: At half energy, collision between neutron and proton will overcome the above ambiguity where a free neutron could be used. Is there any reason that a half neutral impact may have not been under attention?

John Mendenhall
2012-Apr-16, 05:56 PM
Here's a cheerful piece of information, from Wiki:

"High-energy neutrons

These neutrons have more energy than fission energy neutrons and are generated as secondary particles by particle accelerators or in the atmosphere from cosmic rays. They can have energies as high as tens of joules per neutron. These neutrons are extremely efficient at ionization and far more likely to cause cell death than X-rays or protons."

ShinAce
2012-Apr-16, 08:07 PM
Neutrons aren't stable as free particles. You'll have to make them within a few minutes of using them.

Why not just capture anti-protons? They're stable and charges. You collide them with protons and everybody is happy. No residual quantum conservations to worry about.

Half neutral impact? Isn't that called bombardment? Like when you direct a beam of particles at a target.

Nereid
2012-Apr-16, 08:29 PM
Usually we hear experiments regarding proton-proton collision at close to speed of light are carried out but it seems to me due to the electrostatic force of protons, retardation occurs that slows down protons before collision.
Is it not so important to make a neutron-neutron collision at this speed? If it is:
Is it possible to neutralize protons by electrons just before collision? What would be the consequences of a head on impact between two neutrons at this speed? Sorry if this subject has already been discussed.
Neutron-neutron collisions, at close to the speed of light, have indeed been studied.

Extensively.

In fact that's one of the things RHIC (http://www.bnl.gov/rhic/physics.asp) (Relativistic Heavy Ion Collider) is about! :)

Of course, they also collide protons with protons, and neutrons with protons ... all in the one and the same package; amazing stuff! :D

Ara Pacis
2012-Apr-16, 09:32 PM
Neutron-neutron collisions, at close to the speed of light, have indeed been studied.

Extensively.

In fact that's one of the things RHIC (http://www.bnl.gov/rhic/physics.asp) (Relativistic Heavy Ion Collider) is about! :)

Of course, they also collide protons with protons, and neutrons with protons ... all in the one and the same package; amazing stuff! :D

If you just want neutrons and nothing else, then you'd have to find some way of extracting them from a stream of heavy ions, right? Is there a way to make a proton sabot? or shoot neutrons through a zone of neutron flux between fissile masses near or at critical mass?

Jens
2012-Apr-17, 12:09 AM
If you just want neutrons and nothing else, then you'd have to find some way of extracting them from a stream of heavy ions, right? Is there a way to make a proton sabot? or shoot neutrons through a zone of neutron flux between fissile masses near or at critical mass?

I think you can do that by deflecting the other (charged) particles. The ones that keep going straight are the neutrons.

ShinAce
2012-Apr-18, 02:08 PM
Deflecting those charged lead or gold nuclei is how you make them go around the accelerator. The protons and neutrons are bound by the strong nuclear force. They're basically one big particle.

KhashayarShatti
2012-Apr-18, 04:54 PM
Neutrons aren't stable as free particles. You'll have to make them within a few minutes of using them.

Why not just capture anti-protons? They're stable and charges. You collide them with protons and everybody is happy. No residual quantum conservations to worry about.

Half neutral impact? Isn't that called bombardment? Like when you direct a beam of particles at a target.

Perhaps there are two objectives to achieve. I think many scientists think of explosion of matter and many others think of implosion of matter similar to laser fusion. However I think in this context implosion may have implications when neutron-neutron collision takes place. But perhaps if this collision could occur in 3 directions(120 degrees) or many more directions(if possible to focus) then implosion and the highest possible density might be achieved. Could this process lead to a kind of shrink process due to increase of gravity or density? In this case perhaps space could be occupied more and more.....

ShinAce
2012-Apr-18, 05:31 PM
Perhaps there are two objectives to achieve. I think many scientists think of explosion of matter and many others think of implosion of matter similar to laser fusion. However I think in this context implosion may have implications when neutron-neutron collision takes place. But perhaps if this collision could occur in 3 directions(120 degrees) or many more directions(if possible to focus) then implosion and the highest possible density might be achieved. Could this process lead to a kind of shrink process due to increase of gravity or density? In this case perhaps space could be occupied more and more.....

I just don't understand your obsession with neutron-neutron collisions. What is it about neutrons that makes you think they have an advantage over other particles in colliders?

Density and temperature are a function of the energies involved. People already complained that the LHC was going to create mini black holes and such. We're still here! If you want particles to collide from every angle, I think you'll need many accelerators that cross over at a specific point. Even then the odds of two collisions happening at the same place and the same time will be rare.

They were smashing electrons and positrons at energies of 209 GeV in the year 2000. Compare that with the rest mass of the pair, 1.022 MeV, and you find that 99.9995% of the energy from the collisions was from speed. 0.0005% came from the existence of the particles themselves. That's 99.9995% of the density, temperature, and energy, coming from speed alone.

KhashayarShatti
2012-Apr-18, 06:00 PM
I just don't understand your obsession with neutron-neutron collisions. What is it about neutrons that makes you think they have an advantage over other particles in colliders?

Density and temperature are a function of the energies involved. People already complained that the LHC was going to create mini black holes and such. We're still here! If you want particles to collide from every angle, I think you'll need many accelerators that cross over at a specific point. Even then the odds of two collisions happening at the same place and the same time will be rare.

They were smashing electrons and positrons at energies of 209 GeV in the year 2000. Compare that with the rest mass of the pair, 1.022 MeV, and you find that 99.9995% of the energy from the collisions was from speed. 0.0005% came from the existence of the particles themselves. That's 99.9995% of the density, temperature, and energy, coming from speed alone.

To answer your question, I have to discuss about non mainstream subjects which, as you know, it is forbidden. But as far as I can say in most processes we get a conversion of energy to energy or matter to energy or matter to matter. In the process of neutron-neutron collision, the main objective could be 1- conversion of energy to matter at a stable neutral condition 2- A kind of yield point which currently may seem to be non mainstream. I am trying to find similar scientific processes for the 2nd case.

The subject of black holes is different, no black hole could be supposed to be created by this conversion because as you correctly said, many different particle collisions may lead to it.

ShinAce
2012-Apr-18, 06:52 PM
To answer your question, I have to discuss about non mainstream subjects which, as you know, it is forbidden. But as far as I can say in most processes we get a conversion of energy to energy or matter to energy or matter to matter.

Ahhh, now I get it. I don't peruse ATM, so hence why I didn't see this coming.

Remember that matter and energy should not necessarily be differentiated. I always start with the assumption that we convert matter-energy to matter-energy. Proportions along the way don't matter, as long as you conserve the total equivalent energy over long periods. Just a simple annihilation is complex if you break it down too much. You start with a particle pair, give them some kinetic energy, then when they combine you get pure energy, which gobbles up any remaining potential energy sitting around, then creates a shower of particles from that energy, which carry away energy as speed..... and you get particles heavier than the original pair. That's a mouthful.

The ideal for me seems obvious. Take the energy of a particle you want to create, multiply by 2, and create that in a collision. You want electrons, make sure there's enough residual energy to make an electron and a positron. You want free protons, have enough energy to create a proton and anti-proton. And so forth. If that's not some type of "stable neutral condition", what is? And what does stable neutral condition even mean?

BigDon
2012-Apr-18, 10:54 PM
Umm, just out of curiousity...

What would be the catalog of debris from a high speed head-on neutron collision?

KhashayarShatti
2012-Apr-19, 08:59 AM
The ideal for me seems obvious. Take the energy of a particle you want to create, multiply by 2, and create that in a collision. You want electrons, make sure there's enough residual energy to make an electron and a positron. You want free protons, have enough energy to create a proton and anti-proton. And so forth. If that's not some type of "stable neutral condition", what is? And what does stable neutral condition even mean?

A neutron at a relativistic speed of 0.99c can have m=7m0 . In terms of energy, it has 7 times equivalent mass of its rest mass. Now my question is: Is it possible to convert this extra mass(energy) into extra matter consisting of may be more neutrons, protons, electrons or whatever you mentioned and perhaps unknown particles! without this energy going into K.E. of perhaps quarks or so..? By stable neutral condition I meant a stable condition of matter at rest and being neutral without extra energy to disperse it. Of course this is not the 2nd objective that I previously referred to.

tusenfem
2012-Apr-19, 10:34 AM
A neutron at a relativistic speed of 0.99c can have m=7m0 . In terms of energy, it has 7 times equivalent mass of its rest mass. Now my question is: Is it possible to convert this extra mass(energy) into extra matter consisting of may be more neutrons, protons, electrons or whatever you mentioned and perhaps unknown particles! without this energy going into K.E. of perhaps quarks or so..? By stable neutral condition I meant a stable condition of matter at rest and being neutral without extra energy to disperse it. Of course this is not the 2nd objective that I previously referred to.

Isn't this just what is been done e.g. in CERN albeit not with neutrons?
Why would the charge be important if not for creating an extra barrier against the collision?
Maybe you should explain yourself more clearly about what it is that you are envisioning, up to now, it is incomprehensible.

Nereid
2012-Apr-19, 12:00 PM
Umm, just out of curiousity...

What would be the catalog of debris from a high speed head-on neutron collision?
Pretty much the same as from a high speed head-on collision involving protons (as long as charge is conserved; i.e. the net charge on the debris would be +2).

In other words, it depends on just how high the speed is! At the highest speeds tested so far in labs, that is CERN's LHC, you get a great mess of particles. Check out this site (http://cms.web.cern.ch/) (the CMS detector/experiment at the LHC) to see some examples.

KhashayarShatti
2012-Apr-19, 12:52 PM
Isn't this just what is been done e.g. in CERN albeit not with neutrons?

There is no information available about how to distinguish between creation of new matter and the dispersion of existing matter. Most probably if the rest mass of all particles after collision would be more than the rest mass of the two protons, then one could say that new matter is created, yes?


Why would the charge be important if not for creating an extra barrier against the collision?
I don't know if I understood your point. But do you mean that deceleration due to charge can compress protons or disintegrate it? There is 200N electrostatic repulsive force when two protons touch.

ShinAce
2012-Apr-19, 02:11 PM
The first objective for cern, as we are told, was to recreate all particles seen in all other experiments. I think that is complete.

At these high energies, collisions create equal amounts of matter and antimatter. That's the whole point. Every once in a while you get a reactor/accelerator that's setup to make medical isotopes but let's forget about the practical side and focus on experimental.

When you smash any two particles, you get at a minimum, your original particles. As the energy or speed increases, you get new particles, but also their antiparticles. Go even higher and you may lose the original particles. Their energy and quantum numbersbcan carry over to some of the newly created particles. If you did manage to create new particles without left over kinetic energy, they would annihilate and emit gamma rays. So you want these new particles to fly away.

Even better, get enough energy there and you might create some very heavy particles. These guys decay quickly into lighter particles. Which is to say if you start high enough on the energy ladder, you might get to see all the rungs on the way down.

They didn't put billions into the lhc ONLY to find the Higgs boson. They can create any particle, and they have done so.

Tensor
2012-Apr-19, 02:24 PM
There is no information available about how to distinguish between creation of new matter and the dispersion of existing matter.

I suggest you go to say, the LHC home page, Fermilab home page and look around. The detectors there distinguish between creation and dispersion all the time.


Most probably if the rest mass of all particles after collision would be more than the rest mass of the two protons, then one could say that new matter is created, yes?

That's what accelerator do, accelerate the particles, giving them kinetic energy. When the particles smash into each other(or other targets) they smash in with an energy many times that of their rest mass. Go look at some of the LHC collisions. They produce many more particles by mass, then the mass of the two colliding proton would create. One of the objectives of the LHC is to find the Higgs, who's mass is around 125 GeV. The mass of two protons is ~200 MeV.


I don't know if I understood your point. But do you mean that deceleration due to charge can compress protons or disintegrate it? There is 200N electrostatic repulsive force when two protons touch.

Which, at the energies running at the LHC (7 -14 TeV) is negligible. That's like saying tissue paper will have an effect on two cars colliding.

KhashayarShatti
2012-Apr-20, 10:12 AM
That's what accelerator do, accelerate the particles, giving them kinetic energy. When the particles smash into each other(or other targets) they smash in with an energy many times that of their rest mass. Go look at some of the LHC collisions. .

You see, the probability of a direct CG-CG collision is very low. Perhaps 1 in 1 million tests. Even if you get a direct head on collision, the moment due to non aligned CG of the two particles(3 quarks, where is the CG?) that sets the particles in rotation similar to collision of two cars when the position of CG changes a lot after collision ,let alone not being aligned before collision. At least I imagine, however small the electrostatic force to be, this collision to some extent is an unstable collision and the presence of charge reduces the probability of direct hit. So I think neutron-neutron collision , at least, increases this probability.

ShinAce
2012-Apr-20, 03:55 PM
If neutron-neutron increases the probability of collision, then proton anti-proton increases it still further. You can't accelerate neutrons. That's another way of saying your what-ifs will remain what-ifs until that changes. Right now, there is science to be done.

Proton anti-proton is an option, but anti-protons must first be produced and stored for later collisions. Since proton-proton collisions are easy to setup, and we have beams of protons that are quite 'dense', or luminous, why not just let the collider operate for a while and gather all the data you need. The LHC is giving more data than we can crunch real time. Increasing the luminosity still further is only going to mean you need more time to crunch the numbers.

Your last resort is to ask why don't we use nuclei that have neutrons in them, like lead nuclei. But we do! the LHC was designed to smash protons and lead.

Let's recap. Neutron-neutron collisions will decrease the probability of impact, because we can't accelerate neutrons. We can, and do, collide nuclei of lead, which carries neutrons along with the protons. We can, and do, collide protons into each other on a daily basis. It might seem that they will deflect each other and miss, but experience tells us that this is not so. They collide just fine. We don't accelerate one proton in each direction. We accelerate so many at a time that we get a ridiculous number of collisions each second. That is the selling point of the LHC, the never before seen luminosity. You can increase luminosity by changing bunches of protons for anti-protons, making the beam tighter at point of intersection, using more bunches in the accelerator, or adding particles to each bunch. The LHC runs at higher energy and luminosity than any predecessor.

At this point, all the information you need is there. If you want to continue asking "why don't we collide loose neutrons" when the answer is "we can't, and if we could, there would be no advantage", that is your choice. But it is a personal choice, not a scientific pursuit. Rhetoric is your right. The intention of rhetoric is in part to learn effective speaking and critical analysis. Without these goals, it's simply a question that needs no answer.

You can read all about luminosity on the LHC website:
http://www.lhc-closer.es/php/index.php?i=1&s=4&p=9&e=0

Be sure to read about cross-section as well, since that is your stated concern.

KhashayarShatti
2012-Apr-20, 05:13 PM
Be sure to read about cross-section as well, since that is your stated concern.
Perfect. I don't know how much effective an accelerator could be or how much power is required to focus a beam(bunch) of protons since there is side electrostatic force to overcome, but if the bunch is neutralized, then we could get a highly packed bunch of neutrons at minimal power when they are being converged. There is no doubt that the birth of accelerators with protons or electrons is essential and in a development routine, complexity may increase. Generally the question is not to outperform proton-proton collisions, but to see if neutron-neutron could also be a possibility. In previous posts we had posts saying that converting proton to neutron may not be so easy. So far from the above posts I am convinced that this possibility CAN exist.

Nereid
2012-Apr-20, 05:20 PM
Let's recap. Neutron-neutron collisions will decrease the probability of impact, because we can't accelerate neutrons.
Nor focus them, unlike protons.

So not only is the energy available, in any n-n collisions, limited, but the luminosity (intensity, number of collisions per second, etc) necessarily going to be much lower than for p-p collisions.


We can, and do, collide nuclei of lead, which carries neutrons along with the protons.
Indeed.

And because, in a lead nucleus, there are lots of neutrons very close together, the probability of an n-n collision is correspondingly high. And lead nuclei are just as easy to focus as protons.

ShinAce
2012-Apr-20, 06:17 PM
Perfect. I don't know how much effective an accelerator could be or how much power is required to focus a beam(bunch) of protons since there is side electrostatic force to overcome, but if the bunch is neutralized, then we could get a highly packed bunch of neutrons at minimal power when they are being converged. There is no doubt that the birth of accelerators with protons or electrons is essential and in a development routine, complexity may increase. Generally the question is not to outperform proton-proton collisions, but to see if neutron-neutron could also be a possibility. In previous posts we had posts saying that converting proton to neutron may not be so easy. So far from the above posts I am convinced that this possibility CAN exist.

Converting a proton to a neutron is called inverse beta decay. There's a good wiki page for that. You also have plus beta decay, which follows the same route. Some people saw "Is it possible to neutralize protons by electrons just before collision?" and focused on that. That's fine, and is basic physics. All CERN physicists know about this. It's nothing new. By the way, it's a lot harder than just colliding protons. So in that sense, they're right, it's not easy.

You've also been shown that neutron-neutron collisions happen all the time, as a side effect. Side effect doesn't mean weakness, it means it's not necessarily intended. The neutrons have just as much energy as the protons. They get just as much love as anything you're about to try and destroy.

You're trying to reinvent the wheel. The wheel is right there in front of you, if you choose to read about it.

Right above this post, you'll see that Nereid is confirming that neutrons can not be focused into a tight beam. Yet you insist they can.

Neutron-neutron collisions are possible, but it's like trying to split an arrow with an arrow. We have cannons, and can simply crush that arrow to smithereens, even if a cannonball has more drag than an arrow. You many timea are you going to split an arrow versus me blasting them with cannonballs. Maybe you can fire faster, but you're also going to miss a lot more.

HenrikOlsen
2012-Apr-21, 07:24 AM
Maybe you can fire faster, but you're also going to miss a lot more.
Actually, for the metaphor to hold it's actually:

You can't fire as often and you'll miss a lot more as well.