Talk:Spallation

"A high energy pulsed laser (typically Nd:YAG) is used to create a compressive stress pulse in the substrate wherein it propagates and reflects of as a tensile wave at the free boundary." Should this be "A high energy pulsed laser (typically Nd:YAG) is used to create a compressive stress pulse in the substrate wherein it propagates and reflects off as a tensile wave at the free boundary." instead? (missing an "f" in "off", as in we should change "of" to "off"?) —Preceding unsigned comment added by 68.53.24.121 (talk) 23:44, 11 May 2010 (UTC)

Why pulse a neutron beam
What is the advantage of a neutron beam can be pulsed with relative ease?--Anthony Duff 01:18, 8 February 2006 (UTC)

I'm not a nuclear or accelerator physicist, but it is my impression that the advantage is "high time resolution" in regards to the products of the downstream nuclear reaction for which the beam is intended. At low to moderate energies, many of the products of a nuclear reaction (e.g. ones initiated by neutrons in the beam) will move at nonrelativistic speeds, i.e. speeds not close to that of light. Therefore, by clocking the time between a burst (pulse) of neutrons is known to have hit the target, and the time at which a counter records a reaction product, the speed of that product particle can be calculated and thus its energy. In fact, the very identification (determining what kind of particle it is) of detected reaction product may depend on its speed. For highly relativistic energies this will not work because all the products will travel at nearly the speed of light. At slower speeds, the energy :$$E = {m c^2 \over {\sqrt{1 - v^2/c^2}}} \,\!$$ can be found from the velocity v, but as v-> c the necessary accuracy that would be required in measuring v, to get a reliable value for E is impractical. Yet, there is a lot of nuclear physics that can be done at lower energies, where v reliably determines E. I am having trouble finding a simply described experiment using this method, but on you can see they sell detectors for use in it. (Item D).

According to this paper:, time-of-flight techniques can also reduce background. This application is simpler than the one I just gave. One uses the time of flight of the neutron bursts themselves to determine when they hit the target. The observations are then made in a narrow time-window based on that "hit" time, so extraneous counts (e.g. from cosmic rays or local natural radioactivity can be reduced.

This paper: deals with using the time of flight of the neutrons themselves to determine their energy. Carrionluggage 03:30, 8 February 2006 (UTC)

Overhaul needed
Spallation is a much more general term than nuclear spallation alone. I have updated the introductory paragraph to reflect this; but additional sections are needed to describe impact spallation and other processes. Some nice figures (e.g. of spalled impact sites such as meteor craters and spacecraft surfaces) would be helpful too. No time just now but I'll make an effort over the coming days/weeks to add at least something. zowie 17:05, 14 March 2006 (UTC)

Weird symbol/unit
What does the letter ų (Polish letter ogomek) mean in ųA? Was it perhaps meant to be μA (Greek letter mu), meaning one millionth? --Jaapkroe (talk) 14:36, 16 June 2008 (UTC)

Material/Oxidation Spallation
A category for the spallation of material is needed due to the affects of oxidation. —Preceding unsigned comment added by 129.22.154.234 (talk) 19:59, 3 October 2008 (UTC)

Should the Spall & Spallation Articles Be Merged?
Is there a good reason why these two articles should remain separate? This is not my area of expertise so with my current bandwidth I can do no more than raise the question. Thanks! Geekdiva (talk) 22:18, 9 August 2009 (UTC)


 * Hello Geekdiva -- You are absolutely right. It's a distinction without a difference.  It even says so in the Spall article. In that article is a section on mechanical spall. To that should be merged laser and neutron sections. It's an unnecessary FORK arising from spalling (gerund) and the noun spallation deriving from to spall. Rhadow (talk) 15:17, 30 November 2017 (UTC)

Topics & DABing vs. terms & merging
From Wikipedia:Content forking § Related articles (WP:RELART):

"...it is perfectly proper to have separate articles for each different definition of a term; unlike dictionaries, a single encyclopedia article covers a topic, not a term."

[Ignorable: 1. Wow, check out how I used to capitalize section titles on talk pages back then, before I was influenced by the Manual of Style guidelines for article titles! ... I amuse me. 2. Heh. DABing, not any of these dabbings.]

Hello! Thanks for your reply! I noticed that same statement in the lead ("Spalling and spallation both describe the process of surface failure in which spall is shed."), but I wasn't sure if there was some nuance I was overlooking, such as one field emphasizing one term and another field emphasizing the other. In that case, the articles would be on different topics that use the same term; changing the article titles to the same form of "Spall" with the topics in parentheses, followed by disambiguating with hatnotes would be the better overall solution. Otherwise, following the structure you propose would be excellent.

Also, just to understand your points as well, is there any other reason (besides that statement and your comparison of the articles) that you think they should be merged? You're probably perfectly correct, especially since you agree with the me from 2009 [grin], but just in case I think I should post for review (by other editors as well) my reasons for leaning towards concluding the articles cover two topics using via analogy the same set of terms:


 * 1) The statement itself links to the other article, indicating that the person who wrote it might have been aware that there was a related article. (Although there is a possibility that I linked it myself to alert others that there's another article that needs to be considered.)
 * 2) Overall, the articles are written with greater emphasis on either physical- or nuclear-level spallation as paired with their categories.
 * 3) The different focus of the two sets of categories:
 * Spallation:, ,
 * Spall:, , , ,.

BTW, "physical" might not be the best term to contrast with "nuclear," so until we finalize the contrasting term, we shouldn't change the titles even if we choose disambiguation alone as the way to go. Plus, it's easier to change a hatnote than a title.

No one's gotten around to applying Template:Merge or related templates to either article since your reply. I'll try to finish adding both them (with a link to this discussion) and Template:For to cover all bases under consideration, but my real life limitations often get in the way of my following through, which is why I did such an extensive data dump here all at once. Thanks again! —Geekdiva (talk) 11:49, 26 February 2018 (UTC)

I find the term "spallation" used in many physics textbooks explicitly to describe the phenomenon of neutron production in spallation sources. I never came across the term "spall" in this context. Therefore I think, keeping two separate articles is appropriate here, probably with a disambiguation such as "spallation(neutrons)" vs. "spallation(technical)". I started editing the neutron spallation part of this article to be more informative, although it definitely needs more specific information to be an article by itself. Probably, this parts could also be merged into the "neutron" article as a section for neutron production, comparable to nuclear fission and linked to in this article. -- Dschoni (talk) 12:48, 25 July 2018 (UTC)

Wrong statement
"Whilst protons can be focused since they have charge, chargeless neutrons cannot be, so in this arrangement the instruments are arranged around the moderators." Since neutrons have a magnetic moment they can be focused using a magnetic field. The reason for the experiments to be arranged around the moderators should be the finite lifetime of neutrons (about 10.6 minutes) whereafter they decay to protons. Long distances between source and experiment would therefore significantly reduce the amount of neutrons available for the latter. (Ajc04 (talk) 12:03, 11 March 2015 (UTC))

Split out spallation neutron source - suggestion
or move it to a section in neutron source ? - Rod57 (talk) 03:25, 13 December 2015 (UTC)


 * Agreed. Arianewiki1 (talk) 23:24, 21 February 2017 (UTC)

Spallation
Does 'Nuxlear Spallation' explicitly mean that on the irradiation of heavy metal nuclei with high energy particles, only buttons s be produced, or copying it include the ejection of protons due to such collisions? Viv73 (talk) 09:56, 25 December 2018 (UTC)

My original question: Does 'Nuclear Spallation' explicitly mean that on the irradiation of heavy metal nuclei with high energy particles, only nuetrons should be produced, or does it include the ejection of protons due to such collisions? Viv73 (talk) 10:07, 25 December 2018 (UTC)

Spallation products
Evidently spallation will not only produce neutrons, but also one or several residual nuclei. What isotopes do typically form in the more common spallation targets? 150.227.15.253 (talk) 14:49, 19 August 2021 (UTC)