|WikiProject Physics||(Rated Start-class, Mid-importance)|
|WikiProject Astronomy||(Rated Start-class, High-importance)|
Is one to assume that "p-isotope" means an isotope created through the P process? It's not very clear, and google mostly turns up references to phosphorous isotopes. --Belg4mit 06:02, 17 July 2007 (UTC)
- This will depend upon the context. Usually an upper-case "P" stands for phosphorous, and a lower-case "p" stands for a proton. So, a "P isotope" is likely to be an isotope of Phosphorous, where as a nuclei made through the p-process may be called a "p-process nuclei." So, I would say that calling something a "p-isotope" to mean an isotope created through the p-process is sloppy language. Particularly because there are many names for nuclei, such as isotope (same number of protons (Z), different number of neutrons (N)), isotone (same number of neutrons (N), different number of protons (Z)), and isobar (same number of total protons + neutrons (A)). So, discussing a p-process nuclei as a "p-process isotope" is not at all clear, because the p-process creates many different nuclei with different number of protons, and so using isotope here is not the correct choice. Conversely, saying a "P isotope" meaning an isotope of phosphorous is correct language, because stipulating that it is phosphorous fixes the number of protons as Z=15. I will review this article and attempt to make this point more clear if I can. DAID 01:59, 20 July 2007 (UTC)
Large scale editing
I did a lot of editing to the article tonight, as part of my project to expand, update, and correct wiki articles relating to nucleosynthesis. Below I am posting this article prior to my re-write, incase anyone wishes to compare the two versions, or revert the wiki back to its former state. I have neglected to include the unchanged things like references header and categories. I removed detailed discussion of the rp-process and X-ray bursters because I have recently updated those wikis, and the only references to those here should be when they specifically relate to the p-process. DAID 06:44, 20 July 2007 (UTC)
The p process is a proton process for creating proton rich elements beyond the rp-process. It is believed that photodisintegration reactions are responsible for the production of the proton-rich isotopes with masses A > 100. The relevant reactions are (γ,n) and (γ,α) reactions. The temperature during a supernova explosion reaches up to 2×109 to 3×109 K. The black body radiation produces a photon bath that can disintegrate the seed nuclei created by the s-process and r-process. This is the reason why the p-process is sometimes called the gamma-process, because when it was named in 1957 in a famous paper by Burbidge, Burbidge, Fowler and Hoyle, the specific process was not known, and it was only known that it must be different from the s-process and r-process
The p-process contribution to isotopic abundances of elements that can also be produced in the s-process or r-process is usually very small. However there are p-only isotopes that cannot be produced in the s- or r-process (e.g. Pt or Yb). These isotopes have very small abundances compared to neighbour nuclei.
Sometimes the term p-process includes also the rp-process (rapid proton capture process). The astrophysical scenario for this process is still not firmly established but it is believed that a neutron star in a binary system which is accreting mass from a main sequence star could be one possible scenario. During X-ray bursts the temperature and the proton density are high enough to start proton capture reactions and proton rich elements up to mass A=100 can be produced.
Now there is a page describing p-nuclei, giving a list of the p-nuclei and also summarizing the possible nucleosynthesis processes. I have extensively rewritten this p-process page to properly reflect the current status of research and the historical context, and to make it fit to the p-nuclei page. (The previous version was talking about the gamma-process which is now separately covered on the p-nuclei page.) Confusingly, also the scientific literature also mixes different uses of the term "p-process". I tried to explain this in the introduction. --TRauscher (talk) 14:07, 2 February 2011 (UTC)
having trouble copying. R. L Macklin Copies sent previously to Clayton and Truran. FIVE BILLION YEARS AGO A NEARBY STAR IN OUR GALAXY EXPLODED AS A CORE COLLAPSE SUPERNOVA. The high density zone ahead of the shock wave intercepted neutrinos from the collapsing core, thus producing electrons and a flood of gamma rays. The gamma rays stripped neutrons from p process precursor nuclei to successively form the p process isotopes. The gamma rays also stripped neutrons from the much more abundant light elements including beryllium and lithium thus fueling the r process. Only three of the r process isotopes, one from thorium and two from uranium decayed slowly enough to leave some to be found with their progeny in the minerals and ores of the earth. The stable p process isotopes could be studied and measured in laboratories. Their abundances showed a strong positive correlation with their neutron binding energies. I published* a graph showing this correlation forty years ago, expecting scientists studying explosions behind a wall of secrecy to find further information. My own work was at the start of a twenty year campaign to measure neutron capture and it’s resonance structure in all the stable isotopes up to lead and bismuth. We were able to include a few of the long lived radioactive isotopes also. While priorities were often set by an official request list, we were able to give an average neutron capture cross section at star center temperatures for use in many studies of s process production. The p process correlation and a few extinct radioactive nuclear decay products are our best evidence of nucleosynthesis in a supernova explosion. Wikipedia readers should have the information.
- Astrophysical Journal Notes, 162,353-355(1970)
- Burbidge, E. Mr., Burbidge, G.R., Fowler, W.A. & Hoyle, F. (1957), Synthesis of elements in stars . Rev. MOD. Phys., 29 , 547-650.