Talk:Radioactive decay

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Perhaps this page can be folded into the Radioactivity page? It seems a bit redundant having both...

Both are usefull, this one on the mechanisms and pyhsics, the other one for the seconadry effects of decay, on environment, bioloy etc.

Btw. does anyone know if there exists a formula by which, given the number of protons and neutrons, the half-life of a nucleus can be derived?

The best that I know is Table of Nuclides, which I added to the article. I believe that these are all measured values, I don't think science can calculate these things accurately at present. pstudier 22:55, 7 Oct 2004 (UTC)

If only nuclear physics were that advanced! Each of the decay mechanisms are very different processes with separate theoretical treatments. I think it's fair to say that most decay rates can be reproduced by theory to within an order of magnitude or thereabouts. All but the lightest nuclei represent extremely complex many-body problems that cannot be solved exactly (not at the moment anyway). You can make general comments, like for a particular isotope (i.e. constant proton number) the beta decay half-life gradually shortens as you move away from the line of stability (increasing or decreasing the number of neutrons).

There is a formula that given A (total nuber of proton and neutron) and Z (number of proton) give you the approximate mass of the neuclide. But (in my opinion) is an empirical law (it has some parameter that are choose to make it better appriximate the empirical data). From this given a nuclide (A,Z) and a new neuclide (A*,Z*) you cnan know if the transform would be energetically favorible. But you have to take in account also the mass of the particle emitted. Unfourtunatelly it is not so easy, and this is not all of physics.AnyFile 11:38, 22 Nov 2004 (UTC)

Would someone be able to elaborate on the following: what makes a nuclide unstable? what accounts for differences in radionuclide decay constants? how does radioactive decay relate to the second law of thermodynamics?

[edit] Merge

The above argument for maintaining separate articles here and at Radioactivity is no longer valid. We need to decide which article will be kept, and which will be made into a redirect. The case as I see it is thus:

In favor of Radioactive decay: More precise term. Radioactivity would then be turned into something between a stub and a disambig page, linking perhaps to Radiation, Radioactive decay, and Radioactive contamination.
In favor of Radioactive decay: Leave redirect at Radioactivity. pstudier 23:00, 2004 Nov 14 (UTC)

In favor of Radioactivity: More common term, more likely to be searched, easier to link to.
In favour. At the moment both page are not very scientific. Maybe also a rewriting or an extension are neededAnyFile 11:40, 22 Nov 2004 (UTC)
- Contesting your logic. I've been planning for weeks to rewrite this page, and I plan to proceed as soon as the merge takes place. It just seems foolish to start rewriting an article when I don't yet know what it will be entitled.
  - May be I have express myself in a bad way. What I wanted to say is that there a lot of argument not covered and what is already written will need to be changed if I want to enlarge it.AnyFile 15:30, 24 Nov 2004 (UTC)

--Smack 06:26, 23 Nov 2004 (UTC)

Please add any new arguments to this list. --Smack 22:09, 14 Nov 2004 (UTC)

I can see no problem with keeping both. Wikipedia is not written on paper and data can be held several times over in different places with minimal extra cost. The principal search term will probably be Radioactivity but a more detailed look at Radioactive decay, perhaps detailing the rate of decay of specific elements and isotopes would be very interesting and would be too much detail to hold on the Radioactivity article. Lumos3 09:43, 23 Nov 2004 (UTC)

While it is often useful to have some minor subtopics discussed in more than one article, it is generally accepted that it is impractical to keep multiple articles on essentially the same topic. Consolidating these two articles in one location will facilitate all manner of maintenance tasks and help prevent inconsistencies from arising. If you wish to continue this discussion further, please do so at Wikipedia talk:Duplicate articles, where it may garner input from Wikipedists more competent to address the issue. --Smack 18:18, 24 Nov 2004 (UTC)

[edit] Question of naming

Let's have another vote. Should this article live here, or at Nuclear decay? The present title is favored by a Google test, seven to one. --Smack (talk) 23:56, 24 Mar 2005 (UTC)

Those in favor of 'Radioactive decay':

Those in favor of 'Nuclear decay':
- Smack (talk) 23:55, 24 Mar 2005 (UTC)

[edit] Types of radioactive decay

What determines which type of radioactive decay will happen? Thanks. --Eleassar777 12:09, 30 May 2005 (UTC)

It depends on many things like atomic weight, number of neutrons, number of protons, the relation of the previous values to each other and how much energy is "left over". --metta, The Sunborn 02:20, 31 May 2005 (UTC)

Are there any (simple) equations that roughly describe this? How do these factors interact? Thanks. --Eleassar777 08:38, 31 May 2005 (UTC)

The decay mode that occurs is the one that releases the greatest amount of energy. As I understand it, if nucleus A can lose energy by emitting particle x, it will. (I'm not sure that this is true, but I don't see any reason why it wouldn't be.) If it can also lose energy by emitting particle y, it can go either way. I thought I'd made this clear in the article. Please tell me what's not clear, so that I can go and fix it.

I don't think there is an equation that predicts nuclear decays. Everything depends on the strong force, and physicists don't have a good model of that yet. AFAIK, the only analytical tool they have is nuclear binding energies. --Smack (talk) 19:12, 31 May 2005 (UTC)

Unfortunately things are not as simple as that. It depends on what the nucleus has too much of, protons or neutrons (this tells between beta and alpha decay), then how energetic the atom is (how much gamma emission). Random chance seems to have a large hand in things too. --metta, The Sunborn 22:20, 31 May 2005 (UTC)

No, no, things really are that simple. All of the considerations you mentioned are covered by the question of what transformation releases the greatest amount of energy. If a nucleus is tremendously proton-rich, it can lose a lot of energy by emitting a proton (and the same for neutrons). If it's in an excited state, it can lose energy by emitting a photon. --Smack (talk) 04:57, 2 Jun 2005 (UTC)

[edit] Emission of a Carbon 14 nucleus

One rare decay process that is not mentioned anywhere is the emission of a carbon-14 nucleus. I think it's like spontaneous fission, but acts like alpha decay in that the nucleus that is emitted always has the same mass number (14).

Some isotopes of radium can decay by this method, such as Ra-221, Ra-222, Ra-223, Ra-224 and Ra-226.

Reference: Isotopes of Radium -- B.d.mills (Talk) 03:13, 15 Jun 2005 (UTC)

The reason they are not mentioned is that they occur so freaking rarely. But you are correct as far as I know. There are other rare decays not mentioned either. They include a Neon nucleus emission, a "double-beta" decay, and a triton decay. For instance the Ra-222, Ra-223, Ra-224 do a C-14 emission decay less than 0.001% of the time, the other two are much less than that. This is wikipedia, add the information if you can. I have much more important things to do, like make sure the actual articles on the elements have the correct data. You would be shocked by the wrong numbers. --metta, The Sunborn 03:39, 15 Jun 2005 (UTC)

Neon emission, that's one I've not heard of before. Double-beta decay and double-electron capture are relatively common decay modes. They only happen rarely because they are only encountered as decay modes for long-lived isotopes like Calcium-48. I note them here for completeness. I don't plan to edit the articles because my current project is getting the articles for the constellations up to scratch. Good luck with your efforts to make the articles complete and accurate. -- B.d.mills (T, C) 05:44, 22 Jun 2005 (UTC)

Double electron capture is so rare most sources don't even say that it exists. My chart of the nuclides doesn't list it as a decay method, neither does environmentalchemistry.com. I have not heard of it other than here and will ask my professors when I get back to university. However, your quoted source does but it also lists the following types of emissions too:

Emission of an oxygen-20 nucleus (Th-228)
Emission of a neon nucleus (U-232)
Emission of a carbon-14 nucleus (Ac-225)
Emission of a magnesium-30 nucleus (U-236)
Emission of a silicon-34 nucleus (Cm-242)

--metta, The Sunborn 15:05, 22 Jun 2005 (UTC)

Also, as per your request I started an article on all these particle decay emissions under the name, Cluster decay. I figure this is one of the terms used for this class decays. --metta, The Sunborn 19:20, 22 Jun 2005 (UTC)

I made a minor error, I listed Calcium-48 as an isotope that decays by double elctron capture. It actually decays by double beta emission. For an isotope that decays by double electron capture, see Cadmium-106. Isotopes of Cadmium I get the impression that research into the decay of long-lived isotopes is relatively recent, because older texts still list these isotopes as stable. One test of these references is to inspect their entry for Bismuth. If they state that Bismuth-209 is stable then they may be unreliable sources for decay modes of long-lived isotopes. -- B.d.mills (T, C) 02:15, 23 Jun 2005 (UTC)

The linked-to article above gives a decay for cadmium 116, while the Wikipedia article lists cadmium 116 as stable. I assume the link is right and Wikipedia is obsolete, is that right? Ken Arromdee 02:04, 18 September 2005 (UTC)

No, it doesn't. --Smack (talk) 04:44, 18 September 2005 (UTC)

I am afraid environmental chemistry is out of date. The BNL, or the source that we use as the most comprehensive and up-to-date has Cd-116 as a double beta decay with a half-life of 3.1E19 years. [1] --metta, The Sunborn 13:44, 18 September 2005 (UTC)

So does anyone want to fix the cadmium article? Ken Arromdee 21:20, 23 September 2005 (UTC)

I tried fixing it myself. However, the two sources above contradict. One says >1.2E21 years and the other says 3.1E19 years. Which is correct? Ken Arromdee 18:20, 19 October 2005 (UTC)

The source saying about >1.2E21 years means the neutrinoless double beta decay of Cd-116 whereas 3.1E19 years is the half-life for two-neutrino mode of double beta decay of Cd-116. The first one was never observed (only lower limits on T1/2 are known); the second one is observed by three groups of authors (an the measured values are in agreement). So, the article has to refer to the second value. V1adis1av 18:49, 28 November 2005 (UTC)

what type of radioactivity produces only energy waves

[edit] Measurement of radioactive decay

Is this the right page for clarifying the bewildering variety of measurements associated with radioactivity, or has this been done elsewhere? Joffan 01:13, 31 October 2005 (UTC)

This is probably the right place; if this discussion has been done elsewhere, it probably belongs here. If you want to go looking, start with the disambig on Radiation. --Smack (talk) 22:47, 11 November 2005 (UTC)

[edit] Unanswered questions

How common is radioactive decay? Which materials exhibit radioactive decay and why? Where am I likely to encounter them? Rtdrury 05:12, 2 January 2006 (UTC)

In order: 1) Depends what you mean by "how common" 2)Any materials containing radioactive isotopes as listed on Isotope table (divided) article 3)and depends on your indivudual circumstances. Tompw 12:55, 2 January 2006 (UTC)

There should be an obvious link to the Isotope table (divided) on this page, something along the lines of 'For a list of elements that Radioactively Decay, click here' or something. Its what I wanted to know when I first came to this page.

BlueEVIL42066.20.103.36 16:36, 24 February 2007 (UTC)

[edit] Request for Mediation

(template removed - request rejected. Vsmith 04:40, 24 March 2006 (UTC)

[edit] I don't agree with the "Random" statements in the article

I am sure all of do not agree on the existence of true randomness.....I for one, do not belive it exists.....evrything is caused by something and also reacts in some way. An atom will not start behaving in a manner that is not triggered by something else. In case of radioactive decay, I am sure you all agree that we do not yet completley understand all the sub-atomic forces working, and their consequences.....so just because we do not know why, it is wrong to assume that something is truly random. In this article, there are several uses of the word random used in a sense implying that true randomness does exist. 'On the premise that radioactive decay is truly random...' etc... I simply wish to change the languge used throughout the article to eliminate this sense, but thought I should bring it out on the discussion board first. Again, my intention is only to slightly modify the language in those parts on the article, not to change or challenege any other factual information provided.

According to the article on randomness on wikipedia.... "The word random is used to express APPARENT lack of purpose, cause, or order." Hence true randomness seems to me as an oxy-moron.

Abhishekbh 04:23, 24 March 2006 (UTC)

Refusal to believe in randomness, i.e., the believe that everything happens due to a cause or reason, even if we haven't found it, is a philosophical position. It is akin to belief in God, and in fact one favorite argument for God is the percieved need for an uncaused prime cause, or prime mover-- but I fail to see why this solves any problems, and for me, it only creates new ones. In this case, the idea of causality for everything insists that even in cases where things seem to happen for no reason or cause that has been identified, that the unseen cause nevertheless must be presumed to exist anyhow. WHY?

I happen to think this simply introduces an unnecessary assumption, without reason, and should be rejected following Occum's razor. But in any case, I see no reason a priori to reject the very idea of causeless events. If you can't see the cause, you have no good reason to demand that something you can't find or point to, still exists.

And besides, if you reject causeless events, you are left with strict determinism, by excluded middle argument. Are you happy with determinism? I guess you must be <grin>. You have to be <grin>. S B H arris 23:02, 24 February 2007 (UTC)

[edit] trefoil

I keep seeing the trefoil upside down in certain publications... is that wrong, or are both directions acceptable?

[edit] Measurement of Activity

The measurements of activity I've seen are Bq/gram. I don't know how simple Bq would mean anything significant. In any case, I think its an important relation to have: the relation between half-life and decays/gram/second. Fresheneesz 18:58, 31 May 2006 (UTC)

IMHO it was the wrong source or you dropped part of the definition. Notice that the dimensional equation corresponding to the definition of A does NOT contain units of MASS. Also, IMHO, when you are close to a radioactive source what fries you is the activity, not the activity (bluntly, the NUMBER OF COUNTS) divided by the mass of the source.

The activity DIVIDED BY THE MASS is the SPECIFIC ACTIVITY. Please, review your sources before affirming something and always give a reference. I might have been wrong, but I cited the NIST for you and everone else to verify.

Please clarify the meaning of:

"I think its an important relation to have: the relation between half-life and decays/gram/second."

Jclerman 19:21, 31 May 2006 (UTC)

this source implies that the "radioactivity" is measured in counts per minute per gram. this source indicates 3 different types of "Activity" ratings with units of decays per time per mass. It also says that the total decays per second is called Total decays. this source says that the the "Activity used in calculation" is measured in units of Bq per area OR Bq per mass (other activity ratings are Bq "in ocean" (a volume), Bq "found in the volume of soil"). It also has the title "Total Activity" for flat Bq ratings other than for the ocean and "volume of soil".

This source, this one, and this one agree with you about specific activity.

So I think these discrepencies should be noted, I think I'll change the section a bit to reflect that. Fresheneesz 22:01, 31 May 2006 (UTC)

I thought the meaning of the quote you want me to clarify was pretty clear. Wikipedia didn't have anything about the specific activity, and I think its an important thing to note here. Also, what you do mean by "don't innovate out of context" ? How does one innovate out of context?

I have given many sources on the ambiguous use of "activity", yet you remove my note about it. Also your change of bolding is misplaced, bolding shouldn't appear in some side note. I'll wait for your comments "tomorrow", but I'm still going to fix the bolding and the defintions that I've given sources for. Fresheneesz 23:50, 31 May 2006 (UTC)

Also, please if you're going to revert my work, discuss your reversions here before or immediately after. Fresheneesz 00:01, 1 June 2006 (UTC)

[edit] stimulus info

Stimulus not a term usually found in context of radioactivity descriptions and is not found in the reference given. What are its meaning and its relevance for the article?

...predictions using these constants may be less accurate if the substances are in situtations that provide extra stimulus. [2]

Jclerman 13:06, 20 June 2006 (UTC)

Note that the stimulus reference concludes, in its last statement:

The radiometric decay rates used in dating are totally reliable. They are one of the safest bets in all of science.

The article has been edited to reflect the correct statement. Jclerman 00:37, 24 June 2006 (UTC)

[edit] nucleus et al

Nuclides are not nuclei. They have been edited. Jclerman 02:08, 24 June 2006 (UTC)

[edit] Merger

Modes of Decay has been merged into this page SuperTycoon 16:42, 15 July 2006 (UTC)

[edit] Multiple decay chains

A recent edit

The summary for this edit to the "Decay chains and multiple modes" section asks "Is this really true? A given uranium isotope always ends in the same lead isotope, no?". I can't find a reference for uranium having multiple decay modes, but some isotopes of some elements do have multiple decay modes. The section also mentions ²¹²Bi, which is a valid example according to the Decay chain article, so I edited the text to remove mention of uranium. The second part of the summary contains the hidden assumtion that a different decay mode early in a decay chain (or a "branch" to continue the chain analogy) will result in a different stable endpoint. This is not true; according to the Decay chain article, the two decay chains for ²¹²Bi reconverge at ²⁰⁷Pb. DMacks 20:26, 31 July 2006 (UTC)

Not all the same nuclide will end in the same point. There are branches. At every decays (or at some or most of them) there are a probability that the chain goes in one branch or in an another one). Note that we can not know the path followed by each starting nuclide. We start (as an example) with 1e6 nuclides of U-235 and after some time we look at what we have. We not know which original nuclide became the final one, but we statistically know that a certain fraction would be that nuclide, a certain other fraction that nuclide, etc. This sort of thing is used in analysis in the opposite direction. You can look at what you have now and ask what was before. Only if the proportion among the various nuclide you now have are what are expected by the chains of a particular nuclide you can conclude that in origin there was just that nuclide. On the other hand if the proportions are not the expected one, there have been some contamination or in the original sample there was not just one sort of nuclide. (for such method to be applied you should be sure the sample is completely sealed). -- AnyFile 19:29, 4 October 2007 (UTC)

[edit] Decay process- Why?

Is there a theory about what causes the randomness of decay? I mean why should some atoms go off immediately, and others wait, perhaps, millions of years?--Light current 22:43, 25 September 2006 (UTC)

Well, think about it. Randomness is just a way of saying the cards or dice behave as if they have no memory. It would be even screwier if there WERE some non-randomness. Think about a really simple random system-- a ball bouncing around inside a large hollow sphere (with some roughness on the inside to change the bounce direction a bit each time) which has a hole in it, just large enough to let the ball out if it hits EXACTLY on target. Over time, such a system will behave as if it has no memory. The ball might take 5 bounces to get out, or a million. But consider a system that DOES seem to have a memory for decay-- like a watch or a car or a human body. Such systems must contain internal parts which store records of the passage of time (like wear-and-tear) as a sort of memory. Which means they need to be MUCH more complicated. So if you see anything that decays by anything other than the standard random type, where no "memory" is involved, THEN is the time to get interested, because those cards DO have a memory. So the system is complicated, shows wear and tear, has internal gizmos that keep track of time and previous events, and so on. I can't even imagine how to do that on an atomic scale, so I'm glad no particle decays behave in any other way than the way they do. S B H arris 23:57, 25 September 2006 (UTC)

I can see the ball in sphere explanation. That is a mechanism:(but pseudo random because the inside of the sphere cannot have infinitely fine detail). What is the mechanism of radio active decay?--Light current 03:37, 26 September 2006 (UTC)

Ultimately, at some point, explanations must stop. I don't think the mechanism you seek is known, because it is closely bound up with the mechanism for why things do (or don't) happen in quantum mechanics. One explanation is that actually things really don't happen, yea or nay. Rather, everything happens. For every universe where an atom decays, there is another where it doesn't. That stops the issue of THIS and not THAT. Because then you get BOTH THIS and THAT. But you also get a lot of universes. Not my problem. S B H arris 02:47, 17 February 2007 (UTC)

[edit] Dangers with radioactivity

I think this article should have its own section describing the dangers of radioactivity. Now, it's included in the end of the "Discovery"-section as a historical note only. Kricke 01:27, 17 February 2007 (UTC)

Agreed, needs an appropriate link to Ionizing radiation where it is discussed at length. 64.148.241.133 (talk) 06:32, 4 February 2008 (UTC)

[edit] anons comments inserted in the article

.(Note from curious passerbyer, when it says "all but vanished," doesn't that mean it didnt vanish from the market? I mean it translates to me as anything happened but vanishing from the market. I might be wrong but didn't radioactive treatments vanish from the market? (Touche, my friend. I find your logic rather sensible.))

Perhaps this definition helps? Regardless, I fixed to use a more straightforward wording. DMacks 17:34, 21 May 2007 (UTC)

[edit] Question

Are all matter radioactive? They say that only unstable atoms are radioactive, and that through radioactivity it eventually becomes stable again. So is it then no longer radioactive? Will the world one day be completely stable when everything has become stable? Or...? ► Adriaan90 ( Talk ♥ Contribs ) ♪♫ 18:35, 29 June 2007 (UTC)

Uhmm .. I actually can not understand your question properly. Anyway I will try to answer. First of all, not all matter is radioactive. For instance ⁴He and ¹⁹⁷Au are stable. About the other point of your question like in thermodynamics, the whole system is loosing energy. Note however that are in nature event that create height weight nuclides that are radiactive. In stars such nuclides are product and during supernova explosions very weight nuclides are produced and expelled. -- AnyFile 19:41, 4 October 2007 (UTC)

It depends on the timescale. If you are thinking of the normal "chemical" timescale of up to a few billion years, there are many stable isotopes. But if you are thinking about really long timescales, such as 10¹⁰⁰ years, all ordinary matter can decay, according to our article on the heat death of the universe. :) --Itub (talk) 14:20, 25 February 2008 (UTC)

[edit] NOTE

I think a graph showing an exponential decline curve would be useful in this article. —Preceding unsigned comment added by 212.219.123.32 (talk) 12:03, 4 October 2007 (UTC)

[edit] Negatron Emission

I know of the existence of a type of decay called negatron emission, however I do not see it listed on this page. Perhaps someone should add it. Nschoem 01:03, 21 February 2008 (UTC)

It seems that negatron is just an electron, so it sounds like the Beta-Negative decay entry. DMacks (talk) 01:10, 21 February 2008 (UTC)

The beta-negative link just leads to the Beta decay page. And I am pretty certain it is a different type of decay. 68.142.137.202 (talk) 02:37, 22 February 2008 (UTC)

No, a negatron is just a negative electron (not a positive one = positron). If you have some other kind of claim for a different decay than ordinary beta decay, give us a cite. But nothing special shows up on google. S B H arris 02:42, 22 February 2008 (UTC)

I see that the electron page does mention the use of the term "negatron" to indicate the negative electron specifically (vs positron). DMacks (talk) 02:54, 22 February 2008 (UTC)