Summations Only

Yes the neutron flux is around us all the time. That is my point. The flux would have been weaker in the past when the magnetic field was stronger. What did I originally post that has changed?1) We are living in a neutron flux, possibly a better term is neutron background. Obviously its not at dangerous levels.
Just a moment...
http://www.mpi-hd.mpg.de/.../lngs07_slides/071107_zhukov.pdf
We took into account, that neutrons occurred both due to natural radioactivity of surrounding rocks and induced by cosmic muons.2) I am saying that what we already observe in iron occurs within an already existing neutron background.3) I not referring to higher elements, I'm referring to heavier isotopes. Isotopes do get heavier under neutron bombardment (neutron activation). With a slight neutron background this slows down the decay effect, the decay still continues, but the production of the daughter isotope is currently slow. At the rates we observe, even though there is an existing neutron background, heavy isotopes still do decay albeit slowly. Obviously if we remove the neutron background they will decay faster into daughter isotopes.

Not possible for the flux to be slight. According to you, the neutron flux intervenes by converting atoms to higher isotopes. Thus the flux must affect enough atoms to explain the entire difference between the high decay rates you say used to exist and the current rates.Also radioactive decay is a random process. The neutron flux must hit affect each atom before it would have decayed to be effective. Every time it strikes the wrong atom we get increased decay rates because the original atom decays anyway. So the neutron flux must greatly exceed the high rate of decay way back when.So the required neutron flux is not "slight". It must be great. And what happens when the flux is blocked? According to you, any time U235, or any other radioactive material is put behind borated poly shielding it should decay away at extremely high rates. But this does not happen.And do the non radioactive isotopes in an iron bar get continously heavier over time. Not observed.Further, isotopes are not uniformly abundant. In fact when we measure the rate of decay of U235 or U238, we take a sample in which the other isotopes have been removed. What explains the slow decay rate in a pure sample containing a single isotope? Your neutron flux would simply remove the single isotope at an increased rate.Edited by NoNukes, : No reason given.

Hum. Makes sense. Yet I'm sure that elements above iron are only created in supernovae. Maybe neutron capture is not important in making new elements?

Yes, in fact there is. A lawyer's rule is to never ask questions that you cannot anticipate the answer for. Here are several reasons not to expect a proportionate effect.Because the decrease in decay rates depends on a radioactive isotope being replaced by neutron absorption of lighter elements; yet the relative abundance of the lighter elements varies with the element in question. In some cases there are no lighter isotopes elements around at all. Thus your effect cannot be proportionate. Do you understand that the relative abundance of isotopes is something that we can and do measure?Also some nuclei don't simply become heavier when they absorb a neutron. Instead some other reaction, liked fission or alpha particle emission occurs. U-235 simply cannot behave in the way you require it to, and its slow rate of decay cannot be caused in the way you claim.Because nuclei vary in their neutron absorption cross section (think of this as the target size the neutron sees) they will be absorb neutrons at different rates. Different isotopes of even the same element have widely different cross sections. So we cannot expect that neutron absorption is proportionate to and in fact nearly matches the decay rate for every single radioactive element used for dating.Also U-Th dating depends on an equilibrium amount of daughter products, but the daughter products are produced by the decay of the parent atoms. Thus the relationship between the ratio of the amounts of the daughter products and the passage of time is non-linearly related to the decay rates. Multiplying all rates by a constant factor would remove agreement between C-14 dating and say U-Th dating.And then you still have to explain the agreement between C-14 dating and non-radiometric dating.Show us the math for how this complex chain of events might work out. Or admit that you really haven't thought this through.ABE:Thought of one more argument. The rate of neutron absorption depends on the geometry of a sample. For a large sample, the inner portions of the sample are shielded by the absorption of neutrons by the outer part of the sample. A sample spread out so that it has greater exposed surface area would have a greater rate of neutron absorption even when the external neutron flux is the same as for the large compact sample.So this neutron flux non-sense cannot explain the independence of decay rates from the geometry of the sample. In fact, it predicts something entirely different. Also neutron absorption rates are strongly affected by temperature while decay rates are essentially independent of temperature.In short, this is a non-starter proposition. Edited by NoNukes, : No reason given.

Elements above iron and possibly cobalt are all created during supernova. Neutron capture makes heavier isotopes of the same element. As mindspawn pointed out, I was a bit sloppy about that. But then he used that error as an excuse not to explain why a pure sample of U-235 could not possibly follow his scheme.

Wrong question. The burden of proof is yours. I see no reason why it should be proportionate. It's your job to provide evidence that it would be proportionate. That's required as one of the many questions you must answer to establish your fantasy as a viable hypothesis. Ar-Ar dating is calibrated against existing methods. Other methods are not. (well, occasionaly they are,but it's rare; see below). You need to explain all the consilience. It's not all that difficult to find. Begemann et al have a good summary in the introduction of Call for an improved set of decay constants for geochronological use. It's not open access, but I have a copy:

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Accurate radioisotopic age determinations require accurate decay constants of the respective parent nuclides. Ideally, the uncertainty on the decay constants should be negligible compared to, or at least be commensurate with, the analytical uncertainties of the mass spectrometric measurements entering the calculations. Clearly, this is not the case at present. The stunning improvements in the performance of mass spectrometers during the past three decades, starting with the seminal paper by Wasserburg et al. (1969), have not been accompanied by any comparable improvement in the accuracy of the decay constants.The uncertainties associated with direct half-life determinations are, in most cases, still at the percent level at best. The recognition of an urgent need to improve the situation is not new (cf., e.g., Renne et al., 1998; Min et al., 2000a); it has presumably been mentioned, at one time or another, by every group active in geo- or cosmochronology. The present contribution is intended to be a critical guide to the existing experimental approaches. Except in a few cases, we do not evaluate the individual reports on decay constants, and we also do not make any recommendations as to which values should be considered “correct” and be used by the dating community at large. This must, in our opinion, be left for existing commissions to decide, following the precedent of Steiger and Jager (1977). Three approaches have so far been followed to determine the decay constants of long-lived radioactive nuclides.

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1. Direct counting. In this technique, alpha, beta or gamma activity is counted, and divided by the total number of radioactive atoms. Among the difficulties of this approach are the self-shielding of finite-thickness solid samples, the low specific activities, imprecise knowledge of the isotopic composition of the parent element, the detection of verylow- energy decays, and problems with detector efficiencies and geometry factors. Judged from the fact that many of the counting experiments have yielded results that are not compatible with one another within the stated uncertainties, it would appear that not all the difficulties are always fully realized so that many of the given uncertainties are unrealistically small, and that many experiments are plagued by unrecognized systematic errors. As the nature of these errors is obscure, it is not straightforward to decide which of the, often mutually exclusive, results of such counting experiments is closest to the true value. Furthermore, the presence of systematic biases makes any averaging dangerous. Weighted averaging using weight factors based on listed uncertainties is doubly dubious. It is well possible that reliable results of careful workers, listing realistic uncertainties, will not be given the weights they deserve-this aside from the question whether it makes sense to average numbers that by far do not agree within the stated uncertainties.

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2. Ingrowth. This technique relies on measuring the decay products of a well-known amount of a radioactive nuclide accumulated over a well-defined period of time. Where feasible, this is the most straightforward technique. Ingrowth overcomes the problems encountered with measuring large fractions of low-energy b-particles, as in the case of 87Rb and 187Re. It also comprises the products of radiation- less decays (which otherwise cannot be measured at all) like the bound-beta decay branch of 187Re and the possible contribution to the decay of 40K by electron capture directly into the ground state of 40Ar. Among the drawbacks of this approach is that the method is not instantaneous.The experiment must be started long before the first results can be obtained because long periods of time (typically decades) are required for sufficiently large amounts of the decay products to accumulate. “Ingrowth”-experiments further require an accurate determination of the ratio of two chemical elements (parent/daughter) as well as an accurate determination of the isotopic composition of parent and daughter element at the start of the accumulation (see below). Moreover, because of the hold-up in the chain of intermediaries, for uranium and thorium measuring the ingrowth of the stable decay products in the laboratory does not work at all.

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3. Geological comparison. This approach entails multichronometric dating of a rock and cross-calibration of different radioisotopic age systems by adjusting the decay constant of one system so as to force agreement with the age obtained via another dating system. In essence, because the half-life of 238U is the most accurately known of all relevant radionuclides, this amounts to expressing ages in units of the half-life of 238U.

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This procedure is less than ideal, however.The different radioisotopic dating systems were developed, and as a rule are being utilized, because different parent/daughter element pairs are affected in different ways by different geological processes. Thus, employing a variety of element pairs often allows to distinguish chemical, thermal, mechanical, or other processes capable of fractionating or homogenizing the chemical signature of its minerals during a rock’s history. It is the sequence of such events that one wants to learn about.This, in turn, implies that there is the practical problem of selecting a sample where the initial event starting the radioisotopic clock was so short and simple as to be truly “point-like” in time, and whose subsequent perturbations were totally nonexistent. As illustrated by the case of early comparisons between Rb-Sr and K-Ar ages, or K-Ar and U-Pb ages, on non-retentive materials like micas, feldspars, and uraninites in plutonic rocks, simple concepts about “ideal” samples that were considered valid a quarter of a century ago have not withstood the test of time. Our present perception of isotopic closure has been changed as a result of improved understanding of mineralogy and isotope systematics; consequently, now the definition of a “point-like event” is more restrictive than that implicitly assumed by the studies that influenced Steiger and Jager (1977). The obvious requirements are that the two isotopic systems being compared are exactly coherent due to simple thermal, chemical, and mechanical histories. In addition to selecting a sample which was rapidly quenched from a magmatic stage, it is of vital importance to ascertain that the sample escaped any retrogressive change of mineralogy and especially any exchange with fluids, and was spared any later disturbance, chemical and/or thermal. This can be investigated by detailed microchemistry of major and trace elements. Vagaries and problems potentially encountered with the “standard” Pb-Pb and U-Pb ages used for this kind of calibration have most recently been discussed by Tera and Carlson (1999).

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{ABE: Mindie, see Message 933 before responding to the following section}Wrong again, as usual. The relationship between raw unadjusted carbon dates and varve counts is within 10% or less of perfect linearity. From RADIOCARBON DATING: The line at 45 degrees is perfect linear relationship. The X-coordinate of the purple crosses is the varve count age, the Y coordinate of the purple crosses is the raw 14C age of the varve (that's why they specified "(14C)" in the axis label, that mens "radiocarbon unadjusted"). If those cross's 14C ages were adjusted by the standard calibration method they would lie directly on the 45 degree line. But once Suigetsu varve counts have been used to construct the calibration curve, you can't adjust their 14C ages by using the calibration curve; that would be circular reasoning. Real scientists aren't that stupid.{ABE}And note the near-perfect consilience between tree rings and varve counts and unadjusted 14C ages.{ABE again}Note the total lack of consilience between the raw 14C ages and the magnetic field history I posted earlier.Edited by JonF, : No reason given.Edited by JonF, : Clarify Y-axis labelEdited by JonF, : No reason given.Edited by JonF, : Add note to Mindie.

What you originally said was that it is well known that a neutron flux would stop or impede radioactive decay. Now you are postulating a phenomenon that is not "well known" at all, and that actually does not occur at all.

It's unclear whether mindie's speaking of isotopic or elemental transmutation, but I think he means transmuting daughter elements back to parent elements. Another excerpt from Begemann et al seems appropriate:

quote:

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The decay of 238U and 235U to 206Pb and 207Pb, respectively, forms the basis for one of the oldest methods of geochronology. While the earliest studies focused on uraninite (an uncommon mineral in igneous rocks), there has been intensive and continuous effort over the past three decades in U-Pb dating of more-commonly occurring trace minerals. Zircon in particular has been the focus of thousands of geochronological studies, because of its ubiquity in felsic igneous rocks and its extreme resistance to isotopic resetting.

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No decay constant of any radionuclide used for geochronology has been (or, arguably, can be) more-precisely measured than those of 238U and 235U”a consequence of the mode of decay (alpha), favorably short half-lives, and the availability of large quantities of isotopically pure parent nuclides {bombs and reactors, ya know - JonF}. The most recent measurements by Jaffey et al. (1971) (Figs. 1, 2) quote precisions (recalculated to 95%-confidence limits) of 0.11% for 238U and 0.14% for 235U, with the somewhat cryptic statement that “systematic errors, if present, will no more than double the quoted errors.”

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{emphasis added}

Perhaps overly pedantic, but U-Th dating depends on the lack of an equilibrium amount of daughter products. E.g. corals. Uranium is pretty soluble in seawater, Thorium is not. When U decays to Th the Th settles out and is incorporated into coral. But it's not in secular equilibrium with its daughter products and won't be for may thousands of years. We take advantage of that fact.

Thanks. I should have referred to the ratio of elements and the distance of that ratio from the equilibrium value.No need to apologize for being pedantic when discussing science.Edited by NoNukes, : No reason given.

Let us be clear, transmuting the daughter product to a different isotope does not "slow down decay", it simply hides the evidence - or to be more accurate the most easily measured evidence.Even if there were zero effect before the present day, then you would need the actual decay rate to be 50,000 times the measured decay rate to place the beginning of the Triassic 4500 years ago.Unfortunately there can't be zero effect. Not only would there have been a neutron flux in the past, but the neutron flux in the present will still be affecting samples brought in for dating. In fact it should have a very large effect, if your hypothesis is correct.And because you assume that the actual decay rate is fast, any method which counts decays rather than measuring daughter products after the fact should show the real rate. A factor of 50,000 should easily be enough.Come to that where are the products of neutron capture. Shouldn't they show up in the mass spectrometer measurements, too ? Since the vast majority of the daughter product must be converted, it would seem that it would show up quite readily. Why has nobody noticed it ?And a final question for you. Why are you so confident in wild speculations that you clearly haven't thought about ?

The neutron flux nonsense requires that the decay rate of an isotopically pure parent be low due to conversion of a U235 to U236 and higher isotopes. Mindspawn has explicitly stated that the conversion is to new isotopes not new elements.In the case of a pure sample of U235, there are no U234 atoms present, so the sample would simple produce U236. Yet we know that U236 is produced only about 20% of the time a neutron is absorbed. More importantly though, U236 has a very low neutron cross section. We know that U236 is not very much affected by neutrons because it is found in the nuclear reactor waste. U236 does not fission readily. So U236 would be relatively unaffected by the muon produced neutron flux.So over time, if we ignore the 82 percent of U235 atoms which undergo fission when absorbing neutrons, and we must do that to give mindspawn's nonsense any kind of chance, under a flux we should see a buildup of U236 atoms over time and a depletion of U235 atoms. The rate of conversion must account for all of the radioactive decay of U235 that has been prevented by muon produced neutrons. According to mindspawn, the neutron free decay rate is very high.It also turns out that U236 has a fairly long decay half life > 120 million years. As the bar gets converted from U235 to U236 at a fairly rapid rate, we should see it's activity increase by a couple orders of magnitude (i.e. by the ratio of U235 to U236 decay constants) over a rapid period.How rapid? I mean time frames sped up by exactly the same ratio that mindspawn claims that the decay rate was more rapid in the past.Now how in the world the slow decay rate of U236 could be explained is anyone's guess. Given it's low affinity for neutrons, the process cannot be as suggested by mindspawn. And certainly any reduction in rate cannot be proportionate to that of U238.Edited by NoNukes, : No reason given.Edited by NoNukes, : No reason given.Edited by NoNukes, : No reason given.Edited by NoNukes, : No reason given.

Did good ole Buz actually make that argument?

Cross-posted since Mindie seems to have been scared away from the genetic thread: Well, you've got links and calculations. Which you obviously don't respect and are incapable of addressing. We ride into the sunset, leaving the charnel house that mindspawn's scenario would make of Earth as the fantasy that it is. Message 157 and Heat and radiation destroy claims of accelerated nuclear decay.And, mindspawn, your problem is much worse than I calculated in the linked message. Most proponents of accelerated nuclear decay have it happening during the fludde so Noah et. al. are somewhat shielded by water. That's not your scenario. In your scenario life is exposed to all the background radiation from the Earth itself and other living things and construction materials an whatnot. This "terrestrial background" exposure varies widely, from 2 nGy/hr (Ireland) to 1,300 nGy/hr (China) (from United Nations Scientific Committee on the Effects of Atomic Radiation, UNSCEAR 2008 Report to the General Assembly, with scientific annexes Annex B, table 6 on the 109th page.) That translates to 17.5 to 11,388 μGy/year. The conversion to Sieverts requires a weighting factor that depends on the type of radiation and ranges from 1 to 20 (see Wikipedia). So let's be as kind as possible and use 1 as the weighting factor. Therefore, 17.5 to 11,388 μSv/year.In the linked message I calculated that mindie's scenario resulted in self-irradiation doses of about 10 Sv/year when radioactive decay is sped up by a factor of 100,000 relative to today. To that we must add the terrestrial contribution above; sped up by a factor of 100,000 that's 1.75 to 1,139 Sv/year. Those poor Chinese don't stand a chance, accumulating a 90% lethal dose every 6/(100 + 1139) = 0.0048 year = 1.8 days.Mindspawn, this refutes your fantasy. Obviously you have no refutation. Your scenario would kill all life on Earth (except perhaps for cockroaches and some exteremophile bacteria) many, many times over. Game, set, match.

He thinks that the present-day neutron flux is much lower than in the past.