Talk:James Chadwick

message: After comparing articles from Encarta Encyclopedia, and this one, Wikipedia, I noticed that the date of James Chadwick's death differed from one to the other. In Encarta, it said tha tChadwick died December 10th, whereas here it said July 24th. — Preceding unsigned comment added by 216.16.55.2 (talk) 23:32, 22 November 2004 (UTC)
replies: text: I don't have encarta premium...so I can't check it myself, but if that's what it says on encarta, then I would say that encarta's wrong:: ODNB states 24 July 1974Cj1340 (talk) 14:16, 21 October 2014 (UTC)
thread_title: Encarta Encyclopedia

message: In the header (1891) and in the box on the right of the bio (1872). --125.60.241.188 (talk) 21:58, 30 September 2008 (UTC)
thread_title:  Conflicting birth years 

message: The Cambridge Section is word for word from its link. Is that okay? —Preceding unsigned comment added by 206.82.20.126 (talk) 17:10, 15 September 2009 (UTC)
replies: text: No, word-for-word copying from sources is not OK, unless part of a direct quote or acknowledged copying from free-use (free under copyright rules, not just no-charge) sources. I rewrote the paragraph to avoid this problem. Thanks for pointing it out. --RL0919 (talk) 18:20, 15 September 2009 (UTC)
thread_title:  Cambridge 

message: The text formerly stated that Dr. Chadwick discovered nuclear fission and that he received the Nobel Prize for this. He did not, and I have corrected this.
Dr. Chadwick discovered the neutron in 1932, and he won the Nobel Prize in Physics for this achievement in 1935. In any case, this was an eartshaking discovery, and it was one of the top discoveries in Physics between 1930 and 1941. There is no need to exaggerate about Dr. Chadwick.
Nuclear fission was not observed until about 1940 by Otto Hahn and his associates in Germany. Interestingly, based on the limited amount that he published. Hahn won the Nobel Prize in Chemistry in 1944, despite the fact that several Nobel Prize awards were cancelled during World War II. Meanwhile, during the Manhattan Project in America, a HUGE amound of progress was made in deep secrecy on nuclear fission, including the world's first nuclear reactor, which "went critical" in a chain reaction in December 1942. By the end of 1944, a HUGE amount of progress has been made towards producing atomic bombs in the United States, including large reactors in Washington State that were producing plutonium-239 by the kilogram.
The nuclear reactor project in Chicago was carried out by a team lead by Enrico Fermi who has won the Nobel Prize in Physics in 1938, but the plutonium production, separation, and purification project was a completely American one lead by Glenn T. Seaborg, who later won the Nobel Prize in Chemistry in 1951 and General Leslie Groves. The separation of the minority of U-235 atoms by electromagnetic means in Tennessee relied on word that had been done by Ernest O. Lawrence, an American who had won the Nobel Prize in Physics in 1939.
A big step in nuclear physics from the British Isles came beginning in about 1946 (post-war), when John Cockroft (England) and Ernest Walton (Ireland), working together, made many discoveries in the transmutation of elements. They won the Nobel Prize in Physics in 1951. (The doubtless duplicated a lot of work that had been carried out in great secrecy by Seaborg, Lawrence, and others during the Manhattan project. For example, Seaborg was a member of the teams that discovered neptunium, plutonium, curium, americium, and several other transuranium elements. On the other hand, Cockroft and Walton might have made discoveries with some of the lighter elements.)98.67.171.176 (talk) 03:17, 15 August 2012 (UTC)
thread_title:  Incorrect text 

message: *J. Chadwick (1914). Intensitätsverteilung im magnetischen Spektrum von β-Strahlen von Radium B+C. Verh. d. Deutsch. Phys. Ges. 15, 383.
*J. Chadwick, C. D. Ellis (1922). A Preliminary Investigation of the Intensity Distribution in the β-Ray Spectra of Radium B and C. Proceedings of the Cambridge Philosophical Society 21: 274-80.
*"magnetic beta ray" = Beta ray spectroscopy in a mag field?
Headbomb {talk / contribs / physics / books} 14:43, 14 August 2014 (UTC)
thread_title:  Possible resources 

message: I've been contemplating the brief history of the neutron as a composite of the proton and electron from the time of its discovery until it was recognized as a thing on its own.  I think this article has it about right with the emphasis on the mass of the neutron compared to proton.  I write because the article states that both Bohr and Heisenberg saw the neutron as elementary, whereas I don't think Heisenberg did.  There is a careful review at this reference,  Brown and Rechenberg (1996) cited in the neutron article.  This article cites Heisenberg's famous trio of papers - but those were rather tortured insofar as the electron was concerned.  He still explicitly saw the neutron as a composite, I believe; or at least didn't quite know what to think.  (Bohr I know nothing of.)   I would suggest a different approach, which I am considering for the neutron article - the 7th Solvay conference had this issue front and center.  So one may discuss the issue generally, without claims as to who believed what (which is likely to be incorrect - these guys were nothing if not cautious and flexible).  The second factor, which I think must be mentioned, was the Fermi paper where he described how beta decay can occur by the creation of an electron, thus finally explaining where those pesky electrons came from.  The Chadwick and Goldhaber paper on the mass of the neutron seems to embrace this (correct) theory wholesale.  Between the mass results and the Fermi paper, the neutron as a composite was finished. I know of no big paper in which this was explicitly concluded, though (other than Chadwick and Goldhaber), that the community embraced as the definitive statement.
On the Fermi paper, this article presently has "The continuous spectrum of beta radiation, which Chadwick had reported in 1914, was explained by Wolfgang Pauli in 1930 by recourse to another hypothetical neutral particle, which Fermi named the neutrino in 1934."  That seems not quite right to me - Pauli suggested, with great tentativeness, the neutrino idea.  Fermi put the neutrino on rigorous theoretical foundation. I think Pauli would object to the suggestion that he "explained", as too strong a word, but I can't really speak for Pauli, of course.  Bdushaw (talk) 03:09, 9 February 2015 (UTC)
replies: text: Falsch! Hawkeye7 (talk) 21:16, 10 February 2015 (UTC)

text: I found a good article on the subject,  I have reworked the text. Let me know what you think. I'm afraid the two of us may be sounding like Bohr and Heisenberg. Hawkeye7 (talk) 21:16, 10 February 2015 (UTC)
replies: text: That's a nice article.  It is looking good to me.  I made two small changes, the neutrino changes to fix what seemed to me to be a run on sentence; I've very hesitant to edit articles like this, since I know they have a fabric that only the regular editors know.  The gamma ray in question, 2.6 MeV from Th-232, is actually unique - it has about the strongest energy of any naturally occurring gamma ray and just enough energy to disintegrate a deuteron.  The next highest energy gamma ray doesn't have enough energy.  Chadwick and Goldhaber were lucky...  At that time, of course, one could only use the radiation that nature provided.  Now to blatantly plagiarize the new material over to the neutron article...  Bdushaw (talk) 00:17, 11 February 2015 (UTC)
replies: text: Thanks. I had trouble with this section of the article, trying to explain this part to laymen while not over-simplifying. I'm still confused myself about how a neutron can have a magnetic moment when it has no electric charge. Hawkeye7 (talk) 02:09, 11 February 2015 (UTC)
replies: text: Does the last section of neutron magnetic moment not answer the question?  It is supposed to...  Took me a moment to get the Falsch reference.  Bdushaw (talk) 03:54, 11 February 2015 (UTC)
replies: text: The last section of neutron magnetic moment doesn't explain it at all. I guess I'll have to look up the papers. Hawkeye7 (talk) 09:50, 13 February 2015 (UTC)

text: One more correction...so sorry...  It appears that the measurements of the mass of the neutron were rather confused in the 1933-4 time frame - Chadwick, Curie, Lawrence.  The 1935 Chadwick/Goldhaber result was AFTER these and rather resolved the issue - this was the first accurate measurement.  I need to double check that, here is a LINK maybe.  Even the 1935 paper concludes with some ambiguity - they needed to know the masses of the deuteron and proton better.  But that 1935 paper got the right answer - 1.0084u or 1.0090u, depending on the value for the mass of the deuteron used (1.00866u is the correct answer). One element to the confusion is that Chadwick/Goldhaber published a preliminary paper in 1934 in Nature.  I suspect this 1935 paper is the more accurate measurement that confirmed the Curie value.  Need to check the sources.  Bdushaw (talk) 04:56, 11 February 2015 (UTC)

text: I've revised the narrative concerning the early measurements of the neutron mass over on the neutron page - that is a tricky one.  I hope I got it right!  The reference to the biography of Lise Meitner was most helpful.  Also this LINK to an article by Goldhaber.  Bdushaw (talk) 05:59, 11 February 2015 (UTC)

text: Pais, "Inward Bound" p. 412 confirms that the Chadwick/Goldhaber estimates (1934/5) were the best early values.  Bdushaw (talk) 06:52, 11 February 2015 (UTC)

text: It's really good. But Goldhaber's 1934 paper is no longer referenced. Hawkeye7 (talk) 09:41, 13 February 2015 (UTC)
replies: text: I saw that - I don't know that reference, but it seemed to be misplaced; I don't think it has to do with the mass of the neutron, does it?  Seems unrelated to deuteron/gamma ray work.  Bdushaw (talk) 10:51, 13 February 2015 (UTC)
thread_title:  neutron as proton-electron composite 

message: Hans Falkenhagen discovered neutron in the same time as Chadwick.--79.119.208.152 (talk) 15:37, 25 February 2015 (UTC)
replies: text: There is a high probability that this is an urban legend. This text (in German) describes that in spite of intensive investigations there is (till now) no reliable source to confirm this story. --Jkbw (talk) 21:33, 20 October 2016 (UTC)
thread_title:  Parallel discovery