Talk:Nuclear isomer/Archive 1

Archive 1

Nuclear isomer

This article is missing a discussion of what a nuclear isomer is (it hints at spin, but how do spins turn into nucleuses in such a way that there are two ways to do it?) What kind of excited state are we talking about (more potential energy in terms of the strong force? You can tell I don't know enough to write the article...)? Also, if there are two nuclear isomers of, say, Element-99, how does one decide which one is designated "99" and which one is designated "99m" (I assume the former is the ground state, but without some quantum mechanical context it isn't clear that we are talking about "ground state" and "excited state" instead of two states which are somehow equal)? --Kingdon 21 Feb 2006

I am not entirely sure of what the above author is diuscussing. There are a lot of points which are misguided. I agree that the article is missing a definition of nuclear isomerism. However, nuclear physicists are also lacking in a defininition. I define (simply personally) an isomer to be an excited state which has a half-life of greater than or equal to 1 ns. I am not sure what the above comment is talking about strong force potential energy. This is not clear. It is clear that the above does not know what they are talking about (which they admit). To answer the question regarding the m nomenclature, even in the case of an element with no stable isotope one still has ground states and excited states. Any excited state which fulfills the criterion for calssification as isomeric is then assigned the letter m. If there is more than one then a number 2,3,4,...,n follows. The classification as ground state does not simply apply to the most stable state but is strictly applied to the state of lowest energy. I hope that the above questions have been answered. I will try to modify this page such that it reads better. However, all of the correct info is there. —Preceding unsigned comment added by 80.47.185.55 (talk) 03:48, 17 May 2009 (UTC)

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Metastable isomers of a particular atom are usually designated with an "m" (or, in the case of atoms with more than one isomer, 2m, 3m, and so on).

Is it possible that the article should say "in the case of atoms with more than one excited nucleon" instead? --Yath 00:19, 26 Apr 2005 (UTC)

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I think the latest consensus is that the stimulated emission of Ta-180m's potential energy is possible, but the mechanism is different from that hypothesized for Hf-178m's, and that for Hafnium it may not be possible.

--24.80.110.173 04:45, 5 August 2005 (UTC)

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I do not claim to be an expert on this, and my understandinng of nuclear isomerism is spotty, but here is my attempt. Having said that, I think the Pauli Exclusion Principle is relevant here. Two Nucleons cannot be in the nucleus and be in the same energy state. If they have the same energy and the same spin, that is not a stable situation. So eventually one of them has to change - it decays. Maybe some experts better than I can confirm or deny this. Jokem (talk) 05:09, 25 August 2021 (UTC)

Housecleaning

Obsolete estimates of cost and availability of rare materials removed as is encouraged by Wiki guidelines discouraging introduction of quantities dependent upon market forces. Also, removed erroneous interpretation of Washington Post article, replacing interpretation with reference to the actual article. Drac2000 (talk) 15:13, 15 August 2008 (UTC)

notation confusion

The article states that successive metastable states are indicated with a number prefix to the "m" (m, 2m, etc). In the "Nearly-stable isotopes" section, however, there are some that are as a suffix (Hf-178-m2). Which way is right? DMacks 07:17, 25 August 2006 (UTC)

Probably m2 is better.

--Drac2000 14:38, 25 August 2006 (UTC)

It certainly would be less ambiguous...does ^178mHf mean the isotope with mass=178, or the 178^th "m" isotope? If the former, there really isn't a way of inserting a prefixed "2" on the "m". Where is this notation officially documented? DMacks 15:11, 25 August 2006 (UTC)

The "new" [[1]] templates document "m2", not "2m".

Please see if the link Examples helps. Taking a link to any of the isomers on the left of that page (ie one with an "m") gives some interesting insight.

--Drac2000 16:05, 25 August 2006 (UTC)

Your recent edit finally motivated me to follow up on this. Thanks for the reference. DMacks 22:28, 26 October 2006 (UTC)

Thanks to you for the nice examples in this new edit. --Drac2000 23:39, 26 October 2006 (UTC)

It is evidenrtly the consesus of opinion that all equal numbered isotopes of the same element have the same nuclear structure. And accordingly can only differ in some physical property like spin. This is why an observed occurrence of atomic decay in an element (in the ground state) is assumed to be a common property of all members of the particular element. And the idea that 2 different isomers of the same element could have a different structure and a resultant difference in ground state stability has yet to be developed. Thus when a few atoms of OE93Bi209 were determined to decay to OE91Tl205 it is assumed that all atoms atoms of OE93Bi209 have the same instability characteristic. —Preceding unsigned comment added by WFPM (talk • contribs) 02:39, 14 November 2008 (UTC)

Nearly Stable Isomers

In the paragraph discussing Thorium-229, is it really correct to talk about "ultraviolet gamma rays?" I thought whether or not a photon was a "gamma ray" was simply a question of its energy. Is it really accepted in the field to call any photon emitted by a nucleus a "gamma ray" regardless of its energy? I don't work in this field so I honestly don't know, but it seems wrong to me. Cs30109 (talk) 00:15, 13 June 2009 (UTC)

From the article on Gamma ray:

"Hard X-rays can have higher energy than low energy gamma rays. In the past, distinction between the X- and gamma rays was arbitrarily based on wavelengths. Now the two types of radiation are usually defined by their origin: X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus."

The point is that the type of transition (nuclear or electronic) is of more fundamental interest than the exact wavelength, so it makes sense to classify all nuclear transitions together. Of course the UV example is very unusual and may not even be genuine. Dirac66 (talk) 01:29, 13 June 2009 (UTC)

IUPAC

Shouldn't the notation really be Hafnium-178m, not Hf-178m?

IUPAC notation allows Element-n or ⁿEl, but not El-n.

Is that true? Writing "C-14" or "U-235" is really non-IUPAC? How dumb of IUPAC, if so! Got a cite? SBHarris 05:36, 14 June 2009 (UTC)

One source is this IUPAC report (2004). Section 3.3.1 says that "For example, the atom of atomic number 8 and mass number 18 is named oxygen-18 and has the symbol ¹⁸O". However IUPAC does not actually forbid or discourage the use of abbreviations such as O-18, which are very common and perfectly clear. So I agree with Sbharris' implicit opinion that there is no reason to change such abbreviations in this article. Maybe in the section describing the notation, we could write only the first example in all three ways as "Cobalt-58m (or Co-58m or ^58m
₂₇Co
)". Dirac66 (talk) 16:28, 14 June 2009 (UTC)

External Links

I note that three of the external links are described as being to a department of the University of Dallas at Texas however only one of these links to that institution, the others link to the domain hafniumisomer.org. On checking I find this domain is not registered to that University but to a private citizen, Doina Collins. Accordingly I propose that those links be attributed to hafniumisomer.org rather than to an academic institution.Daffodillman (talk) 07:37, 25 August 2009 (UTC)

No need for that. The second link that you discuss leads to a open letter from a Professor at The University of Texas at Dallas. The second reference to which you do not object is a JASON report described as something to do with the Washington Post mounted on a website belonging to the Federation of American Scientists (FAS). Who cares in either case, and if so why? The third link to which you object points to the URL where material from the Center for Quantum Electronics was moved to repair broken links. Taking the links leads to material for which the origin is perfectly clear. One does not suspect the FAS of anything except kindness in hosting an interesting document that was not available from the originators at JASONS. Leave it all alone. --Drac2000 (talk) 16:34, 25 August 2009 (UTC)

Tantalum

The introduction used to say that one nuclear isomer had a quintillion year half life. This appears to refer to the long-lived tantalum isomer with a half-life at least 10^15 years (a quadrillion, not a quintillion). I changed the introduction to say at least 10^15 instead of quintillion.CharlesHBennett (talk) 21:04, 16 June 2010 (UTC)

Ground state of F18

How is it known that the particular instability characteristic of a reported unstable isotope is associated with it's ground state? For example the isotope 9F18 is reported to be unstable and to decay to the stable isotope 8O18. However, if the protons in 9F18 were all paired with neutrons, it would take more energy to unpair the deuteron than there is in the mass difference between the 2 isotopes. So couldn't there possibly be a ground state of 9F18 that is stable?WFPM (talk) 11:09, 22 July 2009 (UTC)

Note: I have moved this question from the article to the talk page. Dirac66 (talk) 13:40, 22 July 2009 (UTC)

Answer: it is known from the experimental facts that (1) stable F-18 has never been observed. The only F-18 known is radioactive and beta-decays to O-18 with a half-life of 110 min. (2) O-18 is stable with a measured mass less than that of F-18.

As for comparing the pairing energy vs. proton-neutron mass difference, the nuclear shell model indicates that eight nucleons of the same type is a closed shell. A possible explanation then is that O-18 has a closed shell of protons which would stabilize it relative to F-18 which has no closed shells. Dirac66 (talk) 15:54, 22 July 2009 (UTC)

Among the 288 primal nuclides double odd ones (odd number of protons and odd number of neutrons) such as deuterium or are extremely rare. There are only nine and five of those are known or thought to be slightly radioactive. There are 168 doubly even primal nuclides such as He-4 or O-18. The pairing effect is for pairs of neutrons or protons not one of each. — Preceding unsigned comment added by 24.23.67.46 (talk) 06:17, 15 June 2011 (UTC)

See discussion under Isotope here in Wikipedia. — Preceding unsigned comment added by 24.23.67.46 (talk) 08:27, 15 June 2011 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Nuclear isomer/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

== Rank of A == This article is well-written with an appropriate series of sections identified by headings. It does have external references to scholarly articles in peer-reviewed journals. It also has a history of years of contribution and refinement so I believe it represents a consensus. Myself, I already knew the material, but I do believe this article would be very useful to non-expert readers. Personally I would recommend it to colleagues in other fields of interest. --GoodElfNo3 16:57, 4 December 2006 (UTC) == Importance of High == This article contributes a depth of knowledge about a topic of broad concern, the physics underlying the existence of a loophole in the nuclear non-proliferation treaty. That makes the importance "High" in my opinion. --GoodElfNo3 17:07, 4 December 2006 (UTC)

Last edited at 17:07, 4 December 2006 (UTC). Substituted at 01:35, 30 April 2016 (UTC)

Derivation of the supression factor

The text suggests a suppression factor of about five orders of magnitude for each unit of angular momentum. A theoretical derivation, even approximate, of this factor would be nice. I think it has something to do with the overlap of the Legendre polynomials in the nucleus, but seeing the details would be nice. 67.198.37.17 (talk) 21:15, 4 July 2017 (UTC)

Nucleus

The "Nucleus" section currently says:

. . . "Excited atomic states decay by fluorescence which usually involves emission of light near the visible range." . . .

Would it be correct to use "ionic" rather than "atomic" as the 2nd word of that sentence?

Or much better still to slide in the word "electron" near the beginning of it so as to clarify that the excitation being discussed is not the excitation which the entire remainder of the article is about?

Note that if the answer to _either_ of those questions is "no" then it seems to me that the paragraph is even less clear than I am guessing it to be. — Preceding unsigned comment added by 134.134.139.74 (talk) 05:34, 14 April 2014 (UTC)

The answer is "no". The paragraph is slightly misleading/confusing, as it starts out talking about atomic states, and ends up talking about nuclear states. It is trying to say that nuclei are just like atoms, but different, with the assumption that the student already knows all about atoms. 67.198.37.17 (talk) 21:29, 4 July 2017 (UTC)

Decay processes

As of the moment I write this item, the "Decay processes" includes the following text:

"An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer."

What about the other way (i.e. energy going _into_ the nucleus)?

Would it improve the article (and maintain _accuracy_) to insert a new 3rd word into that sentence, yielding "An isomeric decay transition is a radioactive decay process . . ."?

There is very little in the article about how, how often, when higher energy isomers are formed so while I would expect that creation _and_ decay would both be validly labeled as "isomeric transitions", as is the article says that only one is. — Preceding unsigned comment added by 134.134.137.75 (talk) 05:11, 14 April 2014 (UTC)

That is correct, except that the excited states are pretty much never formed as the inverse process. Yes, in some certain mathematical sense, the processes are inverses of one-another. In practice, however, the isomeric states are usually created in some other way, e.g. fission, fusion, followed by alpha or beta decay. The analogous idea in atomic physics would be to say that you don't make pink neon lights by shining pink light on neon atoms: instead, you drive an electric current through a gas, which emits ultraviolet, which then hits other fluorescing atoms, etc. and only after a bunch of effects does it glow pink. 67.198.37.17 (talk) 21:37, 4 July 2017 (UTC)

Ratings

In response to the request for ratings for this article, I have rated it A. But it might be even better and qualify as FA. See the Comments section for discussion.

GoodElfNo3 16:39, 4 December 2006 (UTC)

Oofdah. Ten years later, its at best a C. 67.198.37.17 (talk) 21:46, 4 July 2017 (UTC)

Shell structure and Pascal Triangle math

The nuclear magic numbers, under a pure harmonic oscillator scheme with no spin-orbit coupling term in the Hamiltonian, are 2,8,20,40,70,112,168... which are exactly twice the tetrahedral numbers 1,4,10,20,35,56,84... which occupy their own diagonal in the classical Pascal triangle.

For spheres, intervals between the harmonic oscillator (HO) magics therefore must be twice the triangular numbers from the next previous diagonal of the Pascal Triangle, thus 2,6,12,20,30,42,56,72,90....

When the spin-orbit term is included in the Hamiltonian, the resulting spin-orbit (SO) magic numbers 2,*6,14,28,50,82,126,184... all have intervals, for spheres, of 2Tri+2, that is 4,8,14,22,32,44,58,74,92.... (6 is not considered to be a magic number by most nuclear physicists, though there have been sporadic claims made for magicity. Mathematically it does fit right into this scheme, and its cosmic abundance would be evidence in favor of this status).

The interval upshift is due to the fact that intruder levels are included, and each intruder is 2 particles larger for each new shell.

Interestingly, the DEPTHS of intrusion appear to belong to the same family of Pascal Triangle relations, mathematically.

That is, they are all, for neutrons at least, in spheres, themselves double triangular numbers.

So g9/2 has depth of intrusion 2. It starts after 38 (HO 40-2) and ends at 48 (SO 50-2). h11/2 has depth of 6, starting after 64 (HO 70-6) and ending at 76 (SO 82-6). Next comes i13/2 with depth 12, starting after 100 (HO 112-12) and ending at 114 (SO 126-12). Finally j15/2 has depth 20, starting after 148 (HO 168-20) and ending at 164 (SO 184-20).

The same general scheme holds for protons in spheres, though some published Nilsson diagrams have depth 20 where we should be expecting 12.

One of the reasons for the adherence to Pascal Triangle mathematical motivations comes from the structure of period analogues in the nucleus. Because of parity sorting, each such period analogue contains orbitals of only odd or even parity (except for intruders themselves). The LENGTHS of such period analogues, disregarding intruders, are ALWAYS doubled triangular numbers in terms of nucleon numbers.

s=2, p=6, ds=12, fp=20, gds=30, hfp=42, igds=56, jhfp=72 and so on.

When we include an intruder from the next shell, surprisingly its contribution raises the size of the period analogue to the very next double triangular number- thus fp=20+ g9/2 (10) gives 30, gds=30+ h11/2 (12) gives 42, and so forth.

Subtraction of the intruder from its 'home' period analogue leaves the remainder the next LOWER double triangular number in size, so gds=30, minus 1g9/2 (10) gives 20, hfp=42, minus 1h11/2 (12) gives 30, etc.

When both addition and subtraction of intruders occurs, the NET change is a double triangular number PLUS 2, which explains the SO magic number intervals.

Where the possibility exists of multiple isomers for a shell, then the Pascal Math still holds- the positions available all depend upon the size of the orbital partials, which sum to double triangular numbers. However, the USUAL position of insertion of intruder levels is after the THIRD orbital partial.

108.35.168.107 (talk) 19:41, 12 December 2015 (UTC)

The nuclear shell model reviews much of the Pascal triangle stuff, but your concluding remarks are a bit unclear and opaque. So I'm not quite sure what you are getting at, other than that the Pascal triangle rules for filling shells also more-or-less still work for isomers (!?) 67.198.37.17 (talk) 22:21, 4 July 2017 (UTC)