rcain wrote:not that i am really qualified to join in here, but an interesting looking treatment of Oppenheimer-Phillips in the raw by Ragheb & Miley (1990) - here: http://www.springerlink.com/content/u87311484300658g/
Cross-section?
Conditions?
i thought that's what you were after. i don't have those figures i'm afraid.
PS. from my little understanding would not the question be more precisely composed as: 'Oppenheimer-Phillips processes and the probabilities of traversing the Coulomb barrier?'
rcain wrote:i don't have those figures i'm afraid.
I know. Not only you but nobody has those data.
Including my not so smart opponent.
But he said:
chrismb wrote:If you pick 1MeV as the collision energy, sure some may fuse, but another reaction begins to dominate for deuterium called Oppenheimer-Phillips, which simply knocks off neutrons like a marble game.
Like a marble game!
Lord Byron
For note: binding energy for deuterium more than 2MeV
And I have never proposed center-of-mass collision energy more than 100keV.
Joseph Chikva wrote: And you are right, may be "overcome" has many meanings.
But what means "overcome of Coulomb barrier" in Rostoker's text and not mine?
Since I don't know which of "your" text is being refered to, I cannot be sure.
But it is quite clear that to totally exceed the ability of coulomb repulsion to keep an ion away requires much more energy (~1.4MeV for D-T) than to bring it close enough for tunneling to allow fusion (~30-100keV frequently cited). Some folks are insistant that "overcome" is the first case. Others allow as how the second is sufficient. It is a matter of mutual understanding. The folks who use the word in the second case either understand that that it is shorthand for "overcome enough for tunneling to happen" and those who don't understand that. I am fully convinced that Rostaker used the term in its second case (shorthand) while knowing the real situation. Rostaker knowingly communicated in a convenient and, for his purposes, suffiently accurate way.
Looking at a limited sample of your ... discussions... with ChrisMB it seems that he may have thought that you did not understand the shorthand nature of the second usage and that you thought it meant the first.
Since I have not followed your discussions with him, and have no real interest to go back and do so now, I don't know how he may have come up with that understanding (or indeed THAT he had that understanding) but it seems consistant with the ... discussions... to date.
In the last paragraph of his original post in this thread, in particular in his explanation of the significance of Gamow's quantum tunneling to the experiments for which Cockcroft and Walton won the Nobel Prize in Physics.
As far as the relevance of the Oppenheimer-Phillips process to the reaction rate peaks of nuclear reactions involving deuterium is concerned, I will leave that for others to debate.
Temperature, density, confinement time: pick any two.
By these 'questions' I am put in a position where I feel obligated to clairfy, though I will say that I expect self-learners will go hunt for the information themselves.
It is not like I have walked into a lab and run experiments myself to determine O-P reactions. I think that is pretty much understood. What I know is a representation of what is written as CONVENTIONALLY ACCEPTED physics, and there can be no further expectation on me.
As far as I presume these things to be (given that I am not actually standing over an accelerator generating this data myself) that if you go to nndc and look up, for example, D(d,p)n then you'll find a number. Some of that number will be 'fusion', some will be nuclear smashing. In this regards the clown is correct that all that really counts is that cross-section number.
{But the whole discussion on 'O-P' that he generated was not to do with what happens in fusion and O-P (nor to do with the point I made), because he already rejected that as relevant to the discussion, and rejected 'quantum tunnelling' as being needed for explaining fusion. In this regard, there was no question over what he meant, he restated this several times in different forms and he has made it clear that his understanding was that the Coulomb barrier is "90keV" high. }
It is essential for anyone considering how to improve fusion processes to recognise that tunnelling energies are much lower than Coulomb repulsion energies, and that fusion is more likely at those lower tunnelling energies, because otherwise they might think it is viable just to wind up the energy to the "11's" until fusion starts, but it just isn't so.
As per Ivy M.'s post, an assumption often made by those who think they have a clever idea but have never studied fusion is that there is some level of energy at which they will be able to make 'the majority of particles fuse', as if there is some guarantee that they can make fusion happen in every collision, if only they can make the energy high enough and focus the collision accurately enough. This was THE, and THE ONLY point I made originally to the clown and the comment about O-P was merely to explain why that is the case once into the MeV level. That was the only reason I commented on it, so that if anyone wants to comprehend why the probability of fusion doesn't just go up with increasing energies that they had something to look up. What is the actual percentage of 'tunelling' versus 'O-P' reactions? How the cr@p should I know?! If we could really know I expect we would find it is all bundled up together in that collision cross-section data.
I know of one person who is currently considering how to exploit an 'O-P' type of collision (a neutron first, to screen the proton), so as to better enable a fusion. Maybe there is merit in that, but if possible then you can see that this could be descibed as either a fusion or O-P. Take your pick. It is not a distinction I was attempting to draw, it was merely to counter the claim that fusion reactions would ever occur as a majority outcome.
But if anyone wants to believe that they can make the probabilities of fusion so high that particles ALWAYS fuse in their device, then they are sadly mistaken. O-P is one of the first such 'mechanisms' [for deuterium] that begins at the top end of 'fusion' energies and begins degrading the fusion cross-section. There are many more at higher energies I expect.
I am no expert on O-P. I commented on it as a single, lone, comment to help the clown understand why fusion reaction cross-sections don't keep going up indefintely (thus, you cannot get to a point where 'the majority of particles fuse'). But the whole thing has been perpetuated and used as a 'false argument' by the clown so he can push a non-sequitur argument against everything I have said.
I really REALLY don't want to read any more questions that the poster could go look up for themselves on this. I am neither an expert on O-P, nor the experimenter on an accelerator, nor have I ever been small enough to shrink down to the size of a nucleus to watch what actually happens in real-time with my own eyes!! So don't expect me to claim to have answers that require such experiences, and try go figuring things out for yourselves if you are not happy with the things I have said here.
- even some cross section graphs for anyone still yearning for them. (i cant make mine big enough to make out the numbers properly and i should probably misinterpret them if i tried. so i wont.).
Ivy Matt wrote:As far as the relevance of the Oppenheimer-Phillips process to the reaction rate peaks of nuclear reactions involving deuterium is concerned, I will leave that for others to debate.
chrismb wrote:It is not like I have walked into a lab and run experiments myself to determine O-P reactions. I think that is pretty much understood. What I know is a representation of what is written as CONVENTIONALLY ACCEPTED physics, and there can be no further expectation on me.
Nobody should walk into lab and run experiments for getting each number.
But if you said that Oppenheimer-Phillips will be the main process in my invention, so instead of writing the long and tiresome text better if you would explain.
One number: Deuterium&Tritium Cross-section for example for center-of-mass collision energy 100keV (or 1MeV if you wish).
If no number: many words with lack of sense.
PS: for D-He3 it is well known as O-P is a target reaction.
Joseph Chikva wrote: 100keV (or 1MeV if you wish).
If no number: many words with lack of sense.
Check your numbers than, they make no sense.
What numbers?
What sense?
My numbers are the following (all in center-of-mass frame): 10keV, 20, 30, 50, 64, 90, 150, 500, 1000.
At what collision energy Oppenheimer-Phillips will have any significant cross-section?
I think sense to answer at last or shut up and not to wag an ass.
Man wrote the text with about 3000 characters. Let he answer now.
Hydrogen-4 (quadrium)4H is known as quadrium and contains one proton and three neutrons in its nucleus. It is a highly unstable isotope of hydrogen. It has been synthesised in the laboratory by bombarding tritium with fast-moving deuterium nuclei.[4] In this experiment, the tritium nuclei captured neutrons from the fast-moving deuterium nucleus. The presence of the hydrogen-4 was deduced by detecting the emitted protons. Its atomic mass is 4.02781 ± 0.00011.[5] It decays through neutron emission with a half-life of (1.39 ± 0.10) × 10−22 seconds.[6]
A state of 4H with Eres=3.22±0.15 MeV and obs=3.33±0.25 MeV was obtained in t+d reaction from the spectra of protons leaving the target at lab=18°–32° and detected in coincidence with tritons.
It has been synthesised in the laboratory by bombarding tritium with fast-moving deuterium nuclei.
So, cross-section is unknown? And, consequently, how that cross-section compares with target reaction's cross-section also is unknown?
Will this process be the dominant as you state for center-of-mass collision energies to up to 1MeV? As antimatter or some exotic isotopes also has been synthesised in the laboratory.
A state of 4H with Eres=3.22±0.15 MeV and obs=3.33±0.25 MeV was obtained in t+d reaction from the spectra of protons leaving the target at lab=18°–32° and detected in coincidence with tritons.
And why you did not quoted the title?
Hydrogen-4 and Hydrogen-5 from t+t and t+d transfer reactions studied with a 57.5-MeV triton beam
To me now laziness to make simple but tiresome calculations.
But 57MeV tritons hitting fixed deuterium target should provide center-of-mass collision energy not less than 10-15MeV.
And what collision energy is proposed in my invention? More than 0.1MeV?
My original comment on O-P was to show just one example of WHY the fusion cross-section does not keep going up indefinitely to the point where 'the majority of particles fuse'. I don't care when or where O-P happens, as I have stated I am no expert and you can look it up for yourself, but it DOES HAPPEN.
This is not a matter of comprehension, this is either just trying to wind me up, or just you being absolutely and totally stupid.
What you have done is trash this forum with swearing at people's mothers, and you get away with it. It is disgusting. YOU are disgusting. It DISGUSTS me that I feel obliged to try to protect my words against a scum-bag like you who throws his swear words at people's mothers!!!! It beggars all belief that no moderator has yet ejected you.
Just be absolutely clear, then:
O-P deuterium reactions happen in the order of MeV. I imagine that there is some resonance at its binding energy, AS GIVEN ABOVE BY SOMEONE ELSE WHO COULD BE BOTHERED TO LOOK IT UP.
The Coulomb barrier for most light nucleii fusion is in the order of MeV AS GIVEN ABOVE BY SOMEONE ELSE WHO COULD BE BOTHERED TO LOOK IT UP.
The peak cross-section for DT fusions is 64 keV AS IS WELL-KNOWN IN TEXT BOOKS AND AS I HAVE GIVEN BEFORE.
If you have the slightest comprehension about the comment I made, you would understand that this is accurate enough to explain when O-P (as an example of a 'non-fusion' collision) happens, in the context of why fusion reactions cannot be made to occur as the majority reaction. IF YOU DO NOT UNDERSTAND THAT THE PRECISE VALUES ARE IMMATERIAL TO MY COMMENTS THEN YOU HAVE NOT UNDERSTOOD THE COMMENTS I MADE. GO BACK AND READ THEM AGAIN.
IF YOU GENUINELY WANT TO KNOW PRECISE ANSWERS FOR YOUR OWN PURPOSES, GO GET ANOTHER SLAVE TO DO YOUR DIRTY WORK.
The peak for nuclear fusion is well below both the Coulomb barrier height and O-P reactions. Therefore, there is no energy at which you can ever justify your claim that 'the majority of particles fuse' in any fanciful idea you have dreamed up yet have no intention of ever building or doing anything with.
Just like how you have been exploiting all the good work put into this forum over the years, you just want to suck on other people's work and ideas for your own pathetic glorification. You disgust me, and because the moderators appear to have permitted you to remain [perhaps by their inattentiveness, but whatever..] therefore I am exiting this forum. I will just emphasise one final time - if there is any question you still have to pose for me, then you have not understood what I have said because I have provided endless caveats and clarifications to every point already, so just go back and read it all again. All you are doing is beating on every word in each clarification, rather than the original point you were p!ssing on.
You are sure to want the last word and/or make some additional remark to rouse me. But just to be clear to any reader, present or future, please understand that it is not for a lack of reply to the clown that I am not going to address any more remarks here, but because I cannot bear to continue any dialogue with this disgusting clown who insults people's mothers, or remain on a board that permits such behaviour.
