Talk:Electron capture

message: Surely 26 should become 25 not stay as 26.
no, the only mass change in ε is the loss of an electron.
--metta, The Sunborn 19:54, 6 April 2006 (UTC)
thread_title: 26 v 25

message: It might be worth mentioning inner bremsstrahlung, a gamma photon being emitted at the expense of the neutrino, especially since this is mentioned in the double electron capture and double beta decay articles (although admittedly the prospect of neutrinoless double capture is more exciting than bremsstrahlung in normal beta decay, given the consequences for the standard model).
However, I have no idea how to fit this into the article. (P.S., why does using even a single German word seem to invariably lead to writing ridiculously-long sentences?) --69.107.75.113 08:55, 16 March 2007 (UTC)
thread_title:  Inner bremsstrahlung 

message: It might be illuminating to mention that, because of the shape of the binding energy curve, electron capture is mostly seen at the middle of the periodic table (above the Fe hump), and mostly with the lighter isotopes. While the examples fit this pattern, it isn't exactly obvious.
Also, Co-57 might be a better example, just because cobalt is so much more familiar to people that krypton or rubidium--and because it's probably the most-studied example (thanks to the Mossbauer effect, and the fact that it's just over the Fe hump in the curve). --69.107.75.113 09:13, 16 March 2007 (UTC)
thread_title:  Binding energy curve 

message: The first referential link is broken. Needs to be fixed.  —Preceding unsigned comment added by Sean keevey (talk • contribs) 13:18, 24 March 2008 (UTC)
thread_title:  Link Broken 

message: Is there any reason why the three reactions which are written out towards the top of the article aren't listed as common examples lower down?  It's not important, it just seems odd...  Djr32 (talk) 20:58, 16 November 2008 (UTC)
thread_title: Examples query

message: Is this the same thing? ie.: When a high energy-proton collides with an atom, it causes the ejections of an electron from the outer layer of the atom.? --CyclePat (talk) 16:09, 6 August 2009 (UTC)
thread_title:  Proton bombardement? 

message: In the Common Examples section, the electron capture half lives of some elements are given, but there is no explanation of the units.  For instance,  "55Fe - 2.6 a".  What is "a"?  This may be a standard unit for those with the specific domain knowledge, but lots of people reading this won't know it. 24.79.82.67 (talk) 15:10, 15 May 2012 (UTC)
replies: text: d = day, a = an = year (in French). Évidemment! I don't know why French is used here, but for some reason this seems to be the standard abbreviation in nuclear physics. But I agree that this is confusing in an English encyclopedia for general readers, so I'll change the "a" in the table to "yr" which should be clearer. Dirac66 (talk) 16:25, 15 May 2012 (UTC)
thread_title:  units of half life for common examples? 

message: :If all the protons of OO9F18 were paired with neutrons, (as they should be to minimize the atomic mass value), then the occurrence of "electron capture" would require that one of the 9 deuterons would have to be broken up to create 2 extra neutrons. And I don't know of any reduced mass value for 2 paired neutrons. So for this to happen, where would the OO9F18 get the (2Mev} activation energy required to break up the proton-neutron pair? And is there any evidence that this decay mode of the OO9F18 is valid for the atom at a temperature of 0 degrees Kelvin? And why isn't that EC occurrence mentioned in the article?WFPM (talk) 23:17, 17 June 2012 (UTC)
replies: text: According to the table at Isotopes of fluorine, F-18 decays not by electron capture but by β+ emission. So that is why this isotope is not mentioned in this article about EC. I will not try to analyze why it decays by β+ emission, but it clearly does since this isotope is the main source of positrons for medical PET. Dirac66 (talk) 01:03, 18 June 2012 (UTC)
replies: text:  This table only shows major decay routes. Of course, all isotopes that decay by positron emission also decay by EC (though sometimes at lesser probabilities). The reverse is not true if the isotope is proton rich but doesn't have enough excess energy for e+ decay, in which case only EC is possible. In the case of F-18, the branching ratio is 96.86 (19) % by beta plus (positron emission), and 3.14 (19) % by EC.  As for WFPM's question, as usual, he's assuming that which is not in evidence -- in this case a model of F-18 in which is composed of 9 deuterons. It's not composed of 9 deuterons. That's all that need be said. If you think it is, WFPM, answer your OWN question! SBHarris 01:45, 18 June 2012 (UTC)
replies: text: I'm trying to!! But OEH3 Tritium goes the other way, and the incremental mass value for excess neutrons is skewed in favor of multiples of 2, as well as EE6C14 and OO7N16. So we've got this quick change of tendency  between Nitrogen and Oxygen. And maybe you can visualize these atomic nuclei without seeing proton-neutron pairs but I can't. As you have explained it's a packing problem involving some magnetized particles and your images neglect the magnetic property and utilize spherical nuclei which don't indicate its physical orientation. A question? when you bombard a target with deuterons and get a merge, what do you use for the incremental deuteron mass value in the reaction calculation? I'll bet it's the deuteron mass value increment. And that implies that the merged composite atom didn't disassociate within the nucleus or at least you assumed it didn't.WFPM (talk) 02:48, 18 June 2012 (UTC)
replies: text:  Well, that's your problem. In light nuclei the N/P ratio tends to be about 1:1, so you can look at them as NP pairs, or you can look at them equally well has having been built out of helium/alphas, which of course they were. After Ca-40 there aren't any stable nuclei with N = P, so you need to have excess N. By the time you get to the heaviest nuclei the N/P ratio is about 3:2. I see no deuterons at 3:2.  There's no mystery why N and P tend to be even: it's just the same in molecules where the Pauli principle tends to make electrons come in pairs since they can sit in the same orbital in a pair with no extra energy cost (one spin up, the other spin down). Neutrons and protons are the same way. Even-P elements are more abundant and have more stable isotopes. Even N isotopes are common for the same reason-- neutron pairing has nothing to do with deuterons-- it's just neutron pairing. No more mysterious than electron pairing, and happens for the same reason. SBHarris 04:26, 18 June 2012 (UTC)

text:  So you're in favor of neutron pairing. And I see extra neutrons as a balancing factor in the nucleus, which involves their being separately located. And I agree with you that pairing involves 1 upspin with 1 downspin. So the question comes up as to whether identical particles can pair up and we know that PN's can and PP's cannot. That might explain the OE1H3 instability, with the P's staying as far apart as possible. But you ought to like EE6C14 and OO7N16 if you're willing to pair N's. I have nothing against the stability of EE8O18, but I don't see any paired N's in there and the question is as to what's wrong with OO9F18? If the PN's are paired then why should 1 of them break up and where did the breakup energy come from? And in trying to balance the nuclear structure of unbalanced (odd Z) atoms I have to add a number of neutrons I notice that the even number of neutron additions is superior for achieving and/or maintaining stability but I still don't see any neutron pairs, because the neutrons have to be added in a balancing manner to the nucleus, which wouldn't be in associated pairs.WFPM (talk) 15:32, 18 June 2012 (UTC)
replies: text:  C-14 and N-16 gain a lot of stability from neutron pairing-- C-14, with pair of N's AND pairs of P's, has a half-life of thousands of years even though it has too lopsided a P/N ratio for a nucleus of its size. Poor N-16 has paired neutrons but not paired protons. Neutron pairing, even with proton-pairing, won't save you from an infinite excess of N, you know-- and that excess is smaller with smaller nuclei. By the time you get up to oxygen at Z=8, you can take 2 extra N over your even P number, and stay stable. That's the first it can be done. That's not possible with lighter elements, is all. What's "wrong" with F-18 has been explained to you-- it isn't "composed" of 9 deuterons (P and Ns are NOT paired with each OTHER-- that's YOUR mad idea, not mine), and that's it. So it's not stable. There is some limited evidence that "alphas" exist in a sort of way in nuclei, particularly heavy ones, but deuterons-- no. Protons are not paired with neutrons in nuclei-- they don't even notice each other. They are in separate orbital-sets like electrons; one for all the protons, one other set for all the neutrons. Orbitals like to have NN and PP pairs, due to Pauli. F-18 is a perfect example of an odd-odd nucleus that could become even-even (with all P's and N's paired with other P's and N's, if it simply underwent positron emission or electron capture. This would allow pairing of both protons AND neutrons, even though they would not have equal numbers, but that wins out here, since, as noted, O-18 is the lightest stable element to have N-P = 2. It has one more neutron pair than proton pair, and gets away with it.  I don't know what you think a "balancing" addition of neutrons is, but I assume you that pairs of neutrons are like pairs of electrons in an atoms. The "pair" is everywhere, with wavefunction spread out over a large nuclear volume. Nucleons don't simply sit there like marbles. And you might think of U-238 as 92 deuterons and 54 extra neutrons, but nobody else does. A nuclear physicist would use the nuclear shell model and guess that U-238 is blessed with 82, 8, and 2 protons in closed proton shells, and 126 and 20 neutrons in closed neutron shells. And that's why U-238 is very nearly stable, and other configurations (+/- a neutron or +/-a proton) are NOT.SBHarris 22:02, 18 June 2012 (UTC)

text: The emission of alphas is common because the neutrons and protons interpenetrate so they aren't in any separate "domains." Their wavefunctions are in orbitals and shells like electrons in atoms. The helium nucleus is a thing of beauty and joy forever, simply because it is the only bound structure of nucleons in which no nucleon has any orbital angular momentum. It's like the helium atom with two electrons in the 1s orbital, except in the nucleus there are 2 protons in their 1s and 2 neutrons in the same space in THEIR 1s. Add a fifth particle of any kind and it must go into a 1p and have orbital momentum and a lot more energy, so that is why no 5 nucleon nucleus is stable. Atoms spit out an alpha whenever they can, since the energy of binding of those 4 particles is so high, and that energy is available to drive the process. Be-8 cannot resist breaking into two alphas. The extra neutron inhibits this only because when the two alphas leave, they need to leave the free neutron with all the mass-energy a free neutron has and needs (this can't go with either alpha, for reasons explained) and leaving the free neutron with alimony and child support costs a ton of energy. So the alphas stay together for the sake of the little thing. Excuse the metaphor.SBHarris 01:51, 19 June 2012 (UTC)

text: Once again, the charge density of an alpha has been measured. It is not planar. It is maximal at the dead center, and it falls off exponentially and symmetrically from there. It look exactly like the electron charge structure of the helium atom, and for the same reason (the protons are in 1s orbitals in the nucleus, just as the electrons are in 1s orbitals outside the nucleus). That is all. You can't argue with experiment. You keep asking "Why is nature like THIS, when my pet model demands THAT?" How many times do I have to say that it's because your pet model is wrong? No other explanation is needed.  Oxygen-16 has no spin; the reason for that is obvious. Now, tell me why O-17, which is 0-16 plus one more neutron, has a spin of 5/2? And why F-17 has the same spin? Looks like either an extra P or N go into a new orbital with total spin of 5/2. But F-18 has a spin of 1. If you put in both a P and an N, the orbital spins cancel, and all you have left is the particle spins of 1/2, pointing in the same direction. Oxygen-18 has no spin at all, just like O-16. Why? The two extra neutrons go into the same neutron-orbital, cancelling orbital momentum, but now one can go in spin-up, the other spin-down, and the net is zero. SBHarris 19:42, 20 June 2012 (UTC)
thread_title: Fluorine-18

message: This evening I added a "by whom" to the first paragraph under "Reaction Details"
After more browsing, I found a couple of references that might be relevant to the basic physics, but so far no references to the cosmological assertion.
H. Irnich et al., Phys. Rev. Lett. 75, 4182 (1995).
Yu.A. Litvinov et al., Phys. Lett. B 573, 80 (2003).
Update, same poster: I found a reference that might be suitable. Here's a raw URL:
http://articles.adsabs.harvard.edu//full/1964ApJ...139..318B/0000335.000.html
I plan to inquire in the physics forums whether this will serve.  — Preceding unsigned comment added by 76.115.88.202 (talk) 04:22, 9 September 2012 (UTC)
thread_title:  By Whom comment 

message: Hi, as an interested layman I would like to know how the capture of an electron can turn a proton into a neutron. Both particles consist only of three quarks. I suppose electron capture turns one up quark into a down quark, thereby quanging the hadron's nature. But where does the electron stay? In the quark? Probably not, quarks are not thought to be compound. In the neutron, between the quarks? That would mean neutrons consist of more than just their three quarks. Well, if neutrons contain an electron, that would explain both their neutral charge and their slightly bigger mass.
If the article is slightly confusing to me, it might very well be my fault. On the other hand, there are more people who want to find out more about these topics, so it might be worth while explaining them. Steinbach (talk) 23:17, 17 June 2014 (UTC)
replies: text: in fact it is not correct to think with "classical" arguments. In fact electron and quark are not balls. The idea is just that, as shown in the diagram on the right, a W+ boson is created via the interaction of the electron with the up quark. The boson disintegrates almost immediately into one neutrino and a down quark. It is well described by the electroweak interaction. Pamputt (talk) 20:04, 19 February 2015 (UTC)
thread_title:  How is this possible 

message: I've rewritten the first paragraph to include the X-ray, Auger electron and gamma ray emissions. The distinguishing text at the top of the article was also made more specific, and the caption to the diagram was greatly expanded. The caption makes the diagram box large; this could be turned into a show more tab or removed. Why does the atom in the diagram have one electron each in three shells? Roches (talk) 03:35, 24 April 2015 (UTC)
thread_title:  Some changes 

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thread_title:  External links modified 

message: This topic is incomplete without quark-boson representation, the full equations of how the reaction proceeds.
Asgrrr (talk) 22:02, 15 August 2017 (UTC)
thread_title:  Quark, W-boson representation needed 

message: "In the Auger effect, the energy absorbed when the outer electron replaces the inner electron is transferred to an outer electron. "
Should this not be  "the energy released?" 165.255.60.165 (talk) 06:34, 15 October 2022 (UTC)
replies: text: Maybe. But if you think of the energy as being absorbed by the atom and then getting transferred to an outer electron, it might be okay as it is. P.E of the first electron is converted to K.E. as it falls, I guess, which is not clearly absorption, nor release. Somehow that K.E, if that's the right thing to call it, ends up as K.E. of the outer electron, and eventually P.E. of the outer electron, to put it in classical terms. Not sure what this would be in QM terms. Polar Apposite (talk) 18:24, 13 July 2023 (UTC)
thread_title:  Auger effect 

message: This page could use an "Electron capture in astrophysics" section.
Sadly, I'm unqualified to write it.
Web search for `"electron capture" astrophysics"' brings up a number of promising surveys which might help. 50.0.193.12 (talk) 06:25, 6 April 2023 (UTC)
thread_title:  Electron capture in astrophysics 

message: In the above as it stands, charge conservation is violated, either write Mg– in the right side, or do not write e– in the left side. 93.150.81.118 (talk) 16:36, 22 June 2023 (UTC)
thread_title:  EC representation 

message: In the article it says:
If the energy difference between the parent atom and the daughter atom is less than 1.022 MeV, positron emission is forbidden as not enough decay energy is available to allow it.
But the rest mass of a positron is 0.511 MeV. 1.022 MeV is the minimum energy needed to create an electron-positron pair.  — Preceding unsigned comment added by 213.80.51.126 (talk) 13:47, 27 June 2023 (UTC)
replies: text: In comparison with an electron capture process, the positron emission one doesn't gain one electron mass and has to produce one electron mass, so the difference is exactly two electron masses. 93.150.81.118 (talk) 18:12, 30 June 2023 (UTC)
thread_title:  Energy Difference 

message: "If the energy difference between the parent atom and the daughter atom is less than 0.511 MeV, positron emission is forbidden as not enough decay energy is available to allow it, and thus electron capture is the sole decay mode. For example, rubidium-83 (37 protons, 46 neutrons) will decay to krypton-83 (36 protons, 47 neutrons) solely by electron capture (the energy difference, or decay energy, is about 0.9 MeV)." This seems to make no sense because 0.9 MeV is *more* than 0.511 MeV. Polar Apposite (talk) 18:13, 13 July 2023 (UTC)
thread_title:  Decay energy 

message: Previously someone else wrote: 'Electron capture in astrophysics. This page could use an "Electron capture in astrophysics" section.'
I concur. I'm not a physics graduate, so I'm also not volunteering to write it. MathewMunro (talk) 03:04, 7 January 2024 (UTC)
thread_title:  Electron capture is broader than suggested in the opening paragraph - it also happens in neutron star formation 

message: This table does not include those nuclides with theoretical beta plus energy greater than 1.022 MeV but with no positron emission observed according to NUBASE2020: 85Sr to 85Rb (decay energy 1.0647 MeV), 134Cs to 134Xe (decay energy 1.2333 MeV), 146Pm to 146Nd (decay energy 1.4712 MeV), 146Gd to 146Eu (decay energy 1.0291 MeV), 170Hf to 170Lu (decay energy 1.0563 MeV), 174mLu to 174Yb (decay energy 1.5449 MeV), 192Ir to 192Os (decay energy 1.0473 MeV), 227Pa to 227Th (decay energy 1.02558 MeV) and 252Es to 252Cf (decay energy 1.26 MeV).
Nuclide	A  	Z  	N  	Decay energy (keV)	Branching ratio (%)	Proton excess to the isobar with the lowest energy
5Li    	5  	3  	2  	292.65            	0                  	1
7Be    	7  	4  	3  	861.893           	100                	1
37Ar   	37 	18 	19 	813.873           	100                	1
41Ca   	41 	20 	21 	421.315           	100                	1
44Ti   	44 	22 	22 	267.63            	100                	2
49V    	49 	23 	26 	601.856           	100                	1
51Cr   	51 	24 	27 	752.576           	100                	1
53Mn   	53 	25 	28 	596.837           	100                	1
55Fe   	55 	26 	29 	231.212           	100                	1
57Co   	57 	27 	30 	835.927           	100                	1
67Ga   	67 	31 	36 	1000.76           	100                	1
70Ga   	70 	31 	39 	654.56            	0.41               	-1
68Ge   	68 	32 	36 	106.34            	100                	2
71Ge   	71 	32 	39 	232.506           	100                	1
73As   	73 	33 	40 	340.83            	100                	1
76As   	76 	33 	43 	923.543           	0.02               	-1
72Se   	72 	34 	38 	335.4             	100                	2
75Se   	75 	34 	41 	863.392           	100                	1
81Kr   	81 	36 	45 	280.801           	100                	1
83Rb   	83 	37 	46 	906.91            	100                	1
86Rb   	86 	37 	49 	518.554           	0.0052             	-1
82Sr   	82 	38 	44 	179.82            	100                	2
90mY   	90 	39 	51 	135.81            	0                  	-1
88Zr   	88 	40 	48 	676               	100                	2
93Mo   	93 	42 	51 	404.78            	100                	1
97Tc   	97 	43 	54 	320.33            	100                	1
100Tc  	100	43 	57 	168.08            	0.0018             	-1
101Rh  	101	45 	56 	541.7             	100                	1
100Pd  	100	46 	54 	358               	100                	2
103Pd  	103	46 	57 	543.075           	100                	1
110Ag  	110	47 	63 	888.6             	0.3                	-1
109Cd  	109	48 	61 	214.24            	100                	1
111In  	111	49 	62 	861.79            	100                	1
116In  	116	49 	67 	469.37            	0.23               	-1
110Sn  	110	50 	60 	631.1             	100                	2
119Sb  	119	51 	68 	590.92            	100                	1
124Sb  	124	51 	73 	616.46            	0                  	-1
124mSb 	124	51 	73 	616.46            	0                  	-1
118Te  	118	52 	66 	278.4             	100                	2
123Te  	123	52 	71 	52.22             	N/A                	1
125I   	125	53 	72 	185.77            	100                	1
130I   	130	53 	77 	419.03            	0                  	-1
122Xe  	122	54 	68 	725               	100                	2
127Xe  	127	54 	73 	662.33            	100                	1
131Cs  	131	55 	76 	355.42            	100                	1
136Cs  	136	55 	81 	86.43             	0                  	-1
128Ba  	128	56 	72 	529.9             	100                	2
133Ba  	133	56 	77 	517.499           	100                	1
133mBa 	133	56 	77 	805.746           	0.0096             	1
137La  	137	57 	80 	620.6             	100                	1
134Ce  	134	58 	76 	382.7             	100                	2
139Ce  	139	58 	81 	278.88            	100                	1
142Pr  	142	59 	83 	745.75            	0.0164             	-1
140Nd  	140	60 	80 	443.5             	100                	2
145Pm  	145	61 	84 	163.37            	99.99999972        	1
148Pm  	148	61 	87 	541.51            	0                  	-1
150Pm  	150	61 	89 	86.32             	0                  	-1
145Sm  	145	62 	83 	616.03            	100                	2
149Eu  	149	63 	86 	695.36            	100                	1
154Eu  	154	63 	91 	717.22            	0.02               	-1
148Gd  	148	64 	84 	26.67             	0                  	2
151Gd  	151	64 	87 	464.18            	99.9999989         	1
153Gd  	153	64 	89 	483.64            	100                	1
155Tb  	155	65 	90 	822.7             	100                	1
157Tb  	157	65 	92 	60.052            	100                	1
160Tb  	160	65 	95 	105.69            	0                  	-1
152Dy  	152	66 	86 	599.8             	99.9               	4
159Dy  	159	66 	93 	365.57            	100                	1
161Ho  	161	67 	94 	858.29            	100                	1
163Ho  	163	67 	96 	2.555             	100                	1
164Ho  	164	67 	97 	986.22            	60                 	1
158Er  	158	68 	90 	887.2             	100                	2
160Er  	160	68 	92 	329.6             	100                	2
165Er  	165	68 	97 	376.26            	100                	1
167Tm  	167	69 	98 	748.42            	100                	1
167mTm 	167	69 	98 	927.90            	0                  	1
170Tm  	170	69 	101	313.99            	0.131              	-1
164Yb  	164	70 	94 	865.7             	100                	4
166Yb  	166	70 	96 	305.4             	100                	2
169Yb  	169	70 	99 	909.65            	100                	1
176Lu  	176	71 	105	106.77            	0.45               	-1
176mLu 	176	71 	105	229.62            	0.095              	-1
172Hf  	172	72 	100	337.8             	100                	2
175Hf  	175	72 	103	686.85            	100                	1
179Ta  	179	73 	106	105.622           	100                	1
180Ta  	180	73 	107	852.2             	86                 	1
180mTa 	180	73 	107	929.3             	0                  	1
182m2Ta	182	73 	109	144.88            	0                  	-1
176W   	176	74 	102	723.8             	100                	2
178W   	178	74 	104	91.2              	100                	2
181W   	181	74 	107	187.68            	100                	1
183Re  	183	75 	108	556               	100                	1
186Re  	186	75 	111	579.35            	7.47               	-1
186mRe 	186	75 	111	727.55            	0                  	-1
182Os  	182	76 	106	838               	100                	2
185Os  	185	76 	109	1012.797          	100                	1
189Ir  	189	77 	112	532.3             	100                	1
188Pt  	188	78 	110	505.12            	99.999974          	2
191Pt  	191	78 	113	1008.45           	100                	1
193Pt  	193	78 	115	56.794            	100                	1
195Au  	195	79 	116	226.82            	100                	1
198Au  	198	79 	119	325.57            	0                  	-1
192Hg  	192	80 	112	765.1             	100                	2
194Hg  	194	80 	114	69.1              	100                	2
197Hg  	197	80 	117	600.11            	100                	1
201Tl  	201	81 	120	481.2             	100                	1
204Tl  	204	81 	123	344.27            	2.9                	-1
200Pb  	200	82 	118	804.8             	100                	2
202Pb  	202	82 	120	49.7              	100                	2
203Pb  	203	82 	121	974.62            	100                	1
205Pb  	205	82 	123	50.5              	100                	1
210mBi 	210	83 	127	207.82            	0                  	-1
212mPo 	212	84 	128	659               	0                  	0
211At  	211	85 	126	785.36            	58.2               	1
213At  	213	85 	128	73.93             	0                  	1
216At  	216	85 	131	473.199           	0                  	-1
216mAt 	216	85 	131	634.199           	0                  	-1
213Rn  	213	86 	127	881.21            	0                  	2
215Rn  	215	86 	129	86.55             	0                  	1
217Fr  	217	87 	130	656.03            	0                  	1
220Fr  	220	87 	133	869.48            	0                  	-1
216Ra  	216	88 	128	312.1             	<0.00000001        	2
219Ra  	219	88 	131	775.87            	0                  	1
223Ac  	223	89 	134	591.78            	1                  	1
226Ac  	226	89 	137	641.11            	17                 	-1
220Th  	220	90 	130	917.3             	0                  	2
222Th  	222	90 	132	581.5             	0                  	2
225Th  	225	90 	135	672.01            	10                 	1
229Pa  	229	91 	138	311.46            	99.52              	1
232Pa  	232	91 	141	499.53            	0.003              	-1
228U   	228	92 	136	300.5             	2.5                	2
231U   	231	92 	139	381.65            	99.996             	1
235Np  	235	93 	142	124.214           	99.9974            	1
236Np  	236	93 	143	933               	86.3               	1
238Np  	238	93 	145	147.32            	0                  	-1
234Pu  	234	94 	140	393.1             	94                 	2
237Pu  	237	94 	143	220.03            	99.9958            	1
239Am  	239	95 	144	802.11            	99.99              	1
242Am  	242	95 	147	751.295           	17.3               	1
244Am  	244	95 	149	75.4              	0                  	-1
238Cm  	238	96 	142	972.8             	90                 	2
240Cm  	240	96 	144	213.6             	0.5                	2
241Cm  	241	96 	145	767.42            	99                 	1
243Cm  	243	96 	147	7.48              	0.29               	1
245Bk  	245	97 	148	810.74            	99.88              	1
248Bk  	248	97 	151	687               	0                  	-1
248mBk 	248	97 	151	667±50            	30                 	-1
244Cf  	244	98 	146	763.7             	25                 	2
246Cf  	246	98 	148	123.3             	0.004              	2
247Cf  	247	98 	149	646               	99.965             	1
251Es  	251	99 	152	377.58            	99.5               	1
254Es  	254	99 	155	651.2             	0                  	-1
254mEs 	254	99 	155	731.5             	0.076              	-1
256Es  	256	99 	157	150#              	0                  	-1
250Fm  	250	100	150	847               	10                 	2
253Fm  	253	100	153	335.84            	88                 	1
257Md  	257	101	156	406.73            	85                 	1
260Md  	260	101	159	<5                	-1                 	
256No  	256	102	154	208.3             	0                  	2
259No  	259	102	157	486               	25                 	1
262Rf  	262	104	158	270#              	0                  	2
267Db  	267	105	162	630#              	?                  	1 or 2?
No such nuclide exist for Z = 2, 5~17, 19, 21, 28, 29, 30, 35, 39, 41, 44, and for Bi and Po there are only isomers (210mBi and 212mAt). Pb and Cm are the only known elements with four isotopes (200,202,203,205Pb and 238,240,241,243Cm) with beta plus energy not exceeding 1.022 MeV; the other elements have at most three. Gd is a near miss, as the beta plus decay energy of 146Gd is barely higher than 1.022 MeV, so there would be no hope to observe its actual positron emissions.
In this table, proton excess means (atomic number of the given nuclide) - (atomic number of its isobar with the lowest energy). Characterizations of proton excesses:
Proton excess 1: Neutron-deficient odd-mass nuclides with the EC products being beta-stable. The only known exceptions are 164Ho, 180Ta, 236Np, and 242Am which are odd-odd.
Proton excess -1: Neutron-rich odd-odd nuclides sandwiched by two beta-stable even-even isobars. The only known exceptions are 90mY, 182mTa and 210mBi whose EC products are not beta-stable, because the energies have 90mY>90Sr>90Y, 182m2Ta>182Hf>182Ta, and similarly 210mBi>210Pb>210Bi.
Proton excess 2 or 4: Neutron-deficient even-even nuclides. The only known exceptions are 145Sm and 213Rn, as witnessed by the low energy difference between 145Sm and 145Nd (779.40 keV) and between 213Rn and 213Po (955.14 keV). Neither 213At → 213Po nor 213Rn → 213At has been observed due to the high alpha-instability of 213At and 213Rn; see here and here. Curiously, both of the neutron numbers (83 and 127) are one plus magic numbers. It is likely that 267Db would be the third such nuclide (see below).
Proton excess 0: Isomers of beta-stable nuclides. The only known example is 212mPo, and the energies have 212mPo>212Bi>212Po.
The only known listed nuclides with proton excess 4 are 152Dy and 164Yb. 266Sg, 270Hs and 272Hs could also be examples (see below). It is very likely that 266Sg, 270Hs and 272Hs are also in the list above, but more precise measurements of atomic masses are required to confirm. For none of these nuclides the process of electron capture has been observed. Their proton excesses:
Nuclide	Zagrebaev et al. prediction                                                                                                                                                                                                                                                                                                                                                                                                                                       	Zagrebaev et al. prediction	KTUY prediction              	KTUY prediction
Nuclide	Isobar with the lowest energy                                                                                                                                                                                                                                                                                                                                                                                                                                     	Proton excess              	Isobar with the lowest energy	Proton excess
267Db  	267Rf                                                                                                                                                                                                                                                                                                                                                                                                                                                             	1                          	267Lr                        	2
266Sg? 	266Rf                                                                                                                                                                                                                                                                                                                                                                                                                                                             	2                          	266No                        	4
270Hs? 	270Rf or 270SgFor an odd Z nuclide sandwiched by two beta-stable isotopes, it is equally likely that its isobar with one less proton or with one more proton has lower energy. The former happens for 36Cl, 40K, 64Cu, 108Ag, 152Eu and 242Am, while the latter happens for 70Ga, 80Br, 122Sb, 192Ir and 204Hg. 269Db and 271Db could both be beta stable in the prediction of Zagrebaev et al., so it does not tell us which of 270Rf and 270Sg has lower energy.	4 or 2                     	270Rf                        	4
272Hs? 	272Sg                                                                                                                                                                                                                                                                                                                                                                                                                                                             	2                          	272Rf                        	4
Note that alpha decay is or is estimated to be not ignorable for some of these nuclides with N < 126, i.e., the following nuclides are not stable enough even fully ionized:
Nuclide	A  	Z 	N  	Alpha decay energy (MeV)	Alpha decay half-life (yr) or estimation using Geiger–Nuttall law                                                         	Alpha decay half-life (yr) or estimation using Geiger–Nuttall law
Nuclide	A  	Z 	N  	Alpha decay energy (MeV)	Estimation 1Using \lg T_\alpha(\mathrm{yr})=\dfrac{aZ+b}{\sqrt{Q_\alpha}}+cZ+d with a=0.831, b=53.983, c=0.248, d=-73.565.	Estimation 2Using \lg T_\alpha(\mathrm{yr})=\dfrac{aZ+b}{\sqrt{Q_\alpha}}+cZ+d with a=2.073, b=-39.813, c=-0.511, d=-15.842.
145Pm  	145	61	84 	2.32                    	6.3×109                                                                                                                   	6.3×109
149Eu  	149	63	86 	2.40                    	5.0×1010                                                                                                                  	3.8×1010
148Gd  	148	64	84 	3.27                    	86.9                                                                                                                      	86.9
151Gd  	151	64	87 	2.65                    	3.01×107                                                                                                                  	3.01×107
152Dy  	152	66	86 	3.73                    	0.2715                                                                                                                    	0.2715
158Er  	158	68	90 	2.67                    	8.4×1010                                                                                                                  	2.1×1011
176W   	176	74	102	3.34                    	9.5×107                                                                                                                   	3.2×108
178W   	176	74	104	3.01                    	2.2×1011                                                                                                                  	6.7×1011
182Os  	182	76	106	3.37                    	1.2×109                                                                                                                   	2.9×109
188Pt  	188	78	110	4.01                    	1.07×105                                                                                                                  	1.07×105
192Hg  	192	80	112	3.38                    	6.3×1011                                                                                                                  	6.9×1011
129.104.241.214 (talk) 23:54, 13 February 2024 (UTC)
thread_title:  List of nuclides whose theoretical beta plus energy does not exceed 1.022 MeV