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Request for help on reviewing new web page

  1. Sep 30, 2007 #1
    Hi Folks

    I made a mistake on a web page I created a while back and because I had nobody to help check my work the error stayed there until today. I hve corrected the error and made a new page with a different decay process. I originally used Uranium fissioning into two other nucleons and three neutrons. But somehow an error got through and I accidently had a reaction that would have produced a negative value of Q. I have corrected this but would like someone else to make sure I didn't make an entirely new mistake. :rofl:

    The web page is here - http://www.geocities.com/physics_world/sr/nuclear_fission.htm

    Please take a look to see if there are any errors in the page. Thanks.

    I'd rather use an example where a uranium nuclei decays into two nuclei each of which have large atomic number. Maybe the following would be a good example. It comes from the process used in an atomic bomb.

    n + 235U ----> 88Kr + 143U + 3n

    This is an exoergic process isn't it? Thanks.

    Pete
     
  2. jcsd
  3. Sep 30, 2007 #2
    Equation 1. as written is junk.
     
  4. Sep 30, 2007 #3

    malawi_glenn

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    Why not say what it should be instead/also ? ;)
     
  5. Sep 30, 2007 #4
    As malawi_glenn pointed out, in the futuure it would be nice if you had explained why you believe it is junk. I also prefer the term "incorrect" as compared tp "junk" since the later gives the impression that the entire expression is wrong.

    I see that I made a mistake in that expression since there is a "238" by Th where there it should be a "144". The error has been fixed. It has also been fixed in the isotope tables since they had the same mistake.

    I take it that was the only problem that you and malawi_glenn found?

    Thanks to both of you for your help!

    Pete
     
    Last edited: Sep 30, 2007
  6. Sep 30, 2007 #5
    To be honest the more I read it the more confused I am? The equation isn't even balanced? There is an alpha decay to to Th-234 but this isn't spontanenous fission?
    U-238 -> Th-234 + alpha would be the balanced equation...
     
  7. Sep 30, 2007 #6

    malawi_glenn

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    pmb_phy

    The reaction is as Steleo pointed out, the reaction you have shown is alpha decay.
     
  8. Sep 30, 2007 #7
    Yes. That this is alpha decay is obvious since the Helium nucleus shown in the picture and appears in the equation is an alpha particle per definition.

    It appears that when I 'corrected' it I made another mistake in doing so. But it seems okay now. If Steleo had explained why it was wrong, as you mentioned, I wouldn't have made this mistake. But thanks anyway Steleo. Your helo is greatly appreciated.

    Also the fission process in that page does happen spontaneously, or at least that's what it says in the text where I got the picture. I was merely seeking a process that occured spontaneously and that book stated one nicely. I may find another reaction which spontaneously splits into nuclei of nearly equal atomic numbers. Know of any?

    Note: The picture is temporary. It serves to illustrate the process until I can create a picture of my own from scratch ... which won't be so pretty. :)

    Pete
     
  9. Sep 30, 2007 #8

    malawi_glenn

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    Is still dont understand why you want to make a web page about Nuclear Fission.. we usally dont call alpha decays for fission in nuclear physics.

    And how much have you studied Nuclear physics? It seems to me that you are just writing of a book :S
     
  10. Sep 30, 2007 #9
    Sorry pmb_phy I might be completely confused (given the high standard of the other work on the site it's likely). Alpha decay is a very distinct process from nuclear fission. The alpha particle is formed inside the nucleus and quantum tunnels through the coulomb barrier. There IS a spontaneous fission mode with U-238 to isotopes of Krypton and Xenon (not sure on exact abundances).
     
    Last edited: Sep 30, 2007
  11. Sep 30, 2007 #10

    malawi_glenn

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    well hehe, now that is just a model of alpha decay, that it is formed inside nucleus and then tunneling through. The same model can be used for spontanous fission, but of course the probablity to have a daugher nuclei inside the mother nuclei is much smaller and the probability for tunneling is also way much smaller.
     
  12. Sep 30, 2007 #11
    I've studied the amount a chemist would in chemistry, enough a physics major would in Physics 103 and in modern physics. I'm also presently reading a nuclear physics text. Its one of my favorite subjects. The purpose of the page is not to teach nuclear fission, per se. The purpose of the page is given in the very first line of the page, i.e.
    People often get into discussions/battles when they get into whether nature coverts mass into energy or not. This page may not help because such a debate is usually about semantics but I'm hoping that this page will give the clear physical description about what is going on.

    And I'm aware that a lot of people don't call this fission but I'm not interested in that interested. Its just more semantics to me. Some texts do define it that way I gave it, in fact the text I took that picture from is one such place. I had to change if from a previous page which was clearly fission. The problem was that the reaction was not spontaneous.


    I'm not really copying the text to a web page and calling it my work. I used the text to tell me of an example of spontaneous fission. That is I took Eq. (1) from the book and the fact that this is spotaneous decay. That's all I needed for it. The next page in the book has some calculations which I'm not sure what their about. A quick preview shows me that its about the energetics and the calculation of Q.

    My purpose was to elaborate how the change in potential energy associated with the change in configuration of the system meant that (1) that potential energy has the same value as Q and also has the same value of the kinetic energy of all the fission products. This also demonstrates why mass is conserved in such a process according to the definition of mass that I used. This definition and debate is also found in a ver old article. It dates back to soon after WWII when the first atomic bombs were used. There was debate of whether mass was conserved in the process. The author explaned what it meant for mass to be conserved in such reactions. Perhaps I should have inserted that debate in the beginning. Hmmmm! Nice idea!

    Pete
     
    Last edited: Sep 30, 2007
  13. Sep 30, 2007 #12

    malawi_glenn

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    Okay, then I see.
     
  14. Sep 30, 2007 #13
    Not in this case it seems. I don't consider a page done until I've found all errors in it and that usually comes from asking knowledgeable others to take a look. You've been of great help finding the error in Eq. (1) which I corrected and then corrected the tables

    That's a very kind think of you to say Steleo! I'm very happy to hear that you found my web site to be of high standard! It tells me that (1) I'm doing a good job and (2) its usefull to others, which is part of the intent of the site. The other intent is to help me get an idea of what I'd put in a book if I ever chose to do so.

    At present a friend of mine (Rielly Atkinson! A very smart particle physicist) has been helping proof read my web site. I called him last night about an error I found as I was going through my web pages and making them have a uniform look to them. As I started reviewing this web page (which was Uranium decaying in Kr and Cs isotopes - a fission process beyond doubt!) I originally got a positive value for the value of Q. However I figured that since I was reviewing this page I might as well redo the calculations myself. Plus I got a brand new CRC Handbook since then and I could duble check values of the isotopes I was studying. I went back to the book where I got the fission process from and there was a serious error in their calculaions which gave them a positive value for Q. This was a learning experience that I shouldn't copy values from a text. In anycase I prefered to be given a process that occured spontaneously and do the calculations myself. I chose this process because last night I couldn't find a spontaneous fission process to use as an example. This web page is just something temporary until I can find such a process. Know of any?

    In the mean time Rielly said that my web site was "very good," very high praise comming from Rielly (Rielly and I used to work at the same company in the early 1990's_). Rielly tod me that he believes I have the beginnings of a book here. Very cool! I was hoping to write my own book someday. Perhaps I'll accelerate the timeline I had thought out.

    I see from your profile that you're studying nuclear physics too, is that correct? If so that's great! I may need some help on my stuidies in nuclear physics in the future. May we exchange PMs so that I can learn from you? As a matter of fact here's something you may be able to help me with today! Can you recommend a good text book in Nuclear Physics. The one I'm using now is called

    Atomic and Nuclear Physics, by Derek L. Livesy, Blaisdell Pub. Co. (1966).

    Its pretty old so I'm trying to find one I can afford that is a very good text book.

    Note - Last night I had a pretty serious vision problem. My primary care doctor sent me to the ER yesterday morning because I was seeing streaks of light. I wanted to be careful in case this was a warning of a stroke. It turned out to be an opthalmic migrane which I've had in the past. I had a strong feeling it was that but wanted to make absolutely sure it was since I didn't want to end up a vegitable because I was too proud to go to the ER. While I was there they placed pupil dialating drops in my eyes. I haven't been able to read that well since then. Its still making my vision blurry. Hence my problem reading, especially super/sub scripts.
    The definition of fission varies text to text. But I'm not here to discuss semantis. This is a temporary page anyway. An acquantance of mine, Hans C. Ohanian, whom, upon my request, sent me a copy his new book

    Physics - For Engineers and Scientists - 3rd Ed., Hans C. Ohanian, John Markert, W.W. Norton & Company, (2007)

    This is where I found his use of the term fission and according to his definition, alpha decay is an example of fission . Since he's great at a really great physicist/relativist, I take him at his word in things like this.
    Yes. Thank you. I'm aware of that. Its something studied in quantum theory, which I continued in grad school.

    Thanks

    Pete
     
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