Talk:Linear energy transfer

message: The definition of linear energy transfer should be changed to correspond to that defined by the International Commission on Radiation Units and Measurements: the difference between LET and stopping power is not due to emission of secondary radiation, but rather to the emission of high energy secondary electrons.  —Preceding unsigned comment added by HPaul (talk • contribs) 17:40, 23 March 2009 (UTC)
replies: text: Something doesn't work in the current definition. I don't have ICRU reports 37 and 60 on hand, so I can't verify those at the moment, but I am dubious that they define LET significantly differently from modern ICRP or ICRU reports. In ICRP report 92, almost all references to LET are for unrestricted LET, either explicitly or implied. The "L" quantity used in pre-1991 dosimetry is definitely unrestricted, with delta = infinity. ICRU report 51 defines linear energy transfer as synonymous to linear collision stopping power, both of them unrestricted. It notes that "a more general concept of linear energy transfer involves an energy cutoff. For the present report, however, the simpler definition of the 'unrestricted' energy transfer, as given above, is adequate." I could not figure out in what context the restricted LET is used, or why LET is considered separate from stopping power.--Yannick (talk) 00:00, 25 November 2012 (UTC)
thread_title: Definition

message: I wonder if LET is really used to describe the effects of space radiation on electronics, since on earth, it is neutrons/cm2/hour.HPaul (talk) 11:22, 2 April 2009 (UTC)
replies: text: Yes it is. The LET of incident cosmic rays in space varies widely (from low LET particles such as electrons, mid LET particles such as protons, and very high LET heavy ions), and the LET an effect on the probability of a bit flip, and (very strongly) on that of a destructive Single event Latch up.AE1978 (talk) 22:16, 5 June 2011 (UTC)
thread_title: Electronic effects

message: Since the gamma LET discussion is getting messy, let me start this new section by clarifying my position. I agree that LET is not defined for uncharged indirectly ionizing radiation such as gamma. However, it is common for experts to talk about the LET of electrons set in motion by gamma or even neutron radiation, and it is common for experts to shorten their phrases or graph labels by simply talking about the LET of gamma, x-ray or even neutron radiation. Here are some examples of what I'm talking about:
*"Typical LET values for commonly used radiations are: 250 kVp X rays: 2 keV/µm; Cobalt-60 γ rays: 0.3 keV/µm; 3 MeV X rays: 0.3 keV/µm; ... X rays and γ rays are considered low LET (sparsely ionizing) radiations, ..."
*"Les photons, les électrons et les muons sont des rayonnements à faible TEL avec des valeurs de TEL inférieures à 10 keV/µm." (Photons, electrons and muons are low-LET radiations with LET values below 10 keV/µm.)
*"For alpha particles, the LET is much greater than for gamma radiation ..."
*I can list dozens more if you need...
This was baffling to me when I was first learning about LET, until I found a reasonably direct explanation in an FAQ from the Health Physics Society: "When the term 'stopping power' is used in reference to photons, as seems to be the case for the example you give, it is not really being used for the photons themselves, but for the electrons set free by the photon interactions." That FAQ indicates that this usage is common, and I am not alone in getting confused by it. Wikipedia aims to write technical articles for the widest possible audience including those who are unfamiliar with the topic before reading. I think it would be helpful to those readers if we gave an explanation of gamma LET similar to the one the Health Physics Society has given. That is what I tried to do in the Application to Radiation Types section. I welcome help in making this explanation clearer or more accurate.--Yannick (talk) 06:10, 14 December 2012 (UTC)
replies: text: Thank you, Yannick, for this clear exposition. I am shocked, and I have to think. I'll probably ask Steve Seltzer what he thinks about this apparent contradiction between ICRP and ICRU concerning LET for photons.HPaul (talk) 09:28, 16 December 2012 (UTC)
replies: text:  Yay, mutual understanding! I would be interesting in hearing Seltzer's view when you find out. Are there other parts of the current LET article that might need corrections?--Yannick (talk) 22:38, 17 December 2012 (UTC)
thread_title:  Gamma LET 

message: * The above discussion on nuclear stopping made me realize there is no wikipedia article on "Non-ionizing energy loss" NIEL, which is similar to nuclear stopping roughly as LET is similar to electronic stopping. Although again they are used confusingly in different communities and are not exactly the same. Should we make a wikipedia article on NIEL? I added a mention here and will at least add a short mention to the stopping power page. Knordlun (talk) 20:18, 26 December 2012 (UTC)
thread_title:  Article on NIEL? 

message: I think it has become clear in the meantime that the two articles should not be merged but should be connected by appropriate cross referencesHPaul (talk) 10:30, 16 January 2013 (UTC)
thread_title:  No advantage in merger