New helium retention work suggests young earth and accelerated decay

[QUOTE]Originally posted by Tranquility Base:
[B]In all the kafuffle and misunderstandings between our Joe Meert and ICR's Russell Humphreys et al we have not been able to celebrate an important creationist result!Acts and Facts Magazine | The Institute for Creation ResearchOn the face of it, it appears that the radioactively generated helium present in zircons suggests that the helium was generated only in the last 4,000 to 14,000 years rather than gradually over the last 1.5 billion years. There is simply too much of it (up to 58% compared to the long-age expected 0.0002%) still in the rocks. The diffusion rates are experimentally measured and, on the face of it, rule out the ancient ages. [/quote][/b]
Dos the RATE book contain these "experimentally measured" diffusion rates?

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Here we can discuss how this finding fits into the creation model.

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OK. Sounds like fun. I've been doing some research on the subject (obviously I need it after starting the whole -196C closure confusion).If you have the numbers from those diffusion experiments, we can use them to mathematically evaluate the Creation model WRT helium diffusion in zircons, etc. We can also compare them to the diffusion parameters measured by Reiners (the ones that Humphreys claims support his results)...
http://www.geology.yale.edu/~reiners/zirconpaper040401.pdfIf you would, please, consider the Arrhenius plots in Figure 2 and the data in Table 1 of Reiners. From them we can infer diffusion rates relevant to the Jimez zircons, and plug them into the equilibrium age equation (incorrectly labeled closure interval in eq 22 from Preprint of section 10) that Humphreys uses.I would like to see if you come up with the same results I did.I find it very interesting that Humphreys calculates a temperature of -196C (77K) for his "retention temperature". How can he do this? If you look at how the Arrhenius plots work, this requires extrapolating experimental data along the X-axis measured in the 12 to 18 range (the units are 10000/temp) up to 130 (10000/77 = 130). Does this seem reasonable?Did you notice that Humphreys calulates a closure temp for the Jimez zircons using standard geological assumptions? I wonder what the closure temp would be if we assumed a 4-14K age for the Earth and the extremely fast cooling rates implied by that. And what about the unspoken assumption in conventional science of unchanging radiodecay constants? If we use the decay acceleration required by the YEC timeframe, and plug that into Humphrey's definition of closure temp...
"... a temperature at which the rates of loss and production are equal. That point is essentially what Dodson meant by the closure temperature."
... then we need to adjust our calculated closure temp upwards until we find a diffusion rate that is proportionally higher. Are you willing to give it a try, TB?

Thanks for looking that up for us, TB.Now... sorry to be a bother, but we really must be quite careful with terms and numbers here. What you gave us is not enough. As edge pointed out, a diffusivity value is relevant only at a specified temperature. A range of 130-280C is sufficient to make diffusivity vary by a factor of about a MILLION. So when you quote 10^-15 to 10^-17 cm^2/s, is that for 130degC or 280degC ???Please clarify what you mean by "extrapolated helium diffusion constant from the argon experimental one." Are you saying the helium diffusion number is extrapolated from [i][b]argon[/i][/b] diffusion values??? That makes no sense. You must have meant something else. Please help us poor confused skeptics.And when you said this...

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If He diffused at the Ar rate things would be all hunky-dory for you.

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Did you realize that you are comparing apples to oranges? Argon diffusion is usually measured in K-feldspar or biotite - never zircon. Zircon contans no potassium, therefore no argon to diffuse out.When you get the values and temps straight, would you be willing to go through the calculations with me, TB?But just as an amusing side-note in the mean time......if we take your numbers at face value... i.e. the diffusivity at 280degC = 10^-15 cm^2/s, and diffusivity at 130degC = 10^-17 cm^2/s......then use those numbers to calculate the Ea (activation energy) and Do......then use that to calculate closure temperature, then we arrive at the value Tc = 77K, which, in Celsius is......you guessed it... exactly minus 196 degrees C !!!Of course I am not claiming that Humphreys actually did this. Its just an amusing coincidence, right?Right???

Thanks TB,Diffusion in biotite is, of course, nearly irrelevant to this discussion, as Humphreys hinted in the Impact 352 article. I was hoping it had the zircon data in it, too.Anyway, with the correct temps and diffusivity, we can now calculate Tc for [b][i]biotite[/b][/i], just for practice. I get about 30 to 40 degC. How about you?Like edge, I am also worried about that word "extrapolated". Did you mean to say that? I thought RATE had experimental data?Finally, you said:
"Neither the experimental argon nor extrapolated helium change by 6 orders of magnitude over that temperature range."Correct. But now you have switched to biotite, not zircon as I was originally discussing, and you changed 130 to 160degC. According to the experimentally measured diffusivity for zircon from Reiners(2002), the difference between 280 and 160degC would be about 20,000 times - for zircon.From ICR Impact352:

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So the RATE project commissioned experiments to measure helium diffusion in zircon and biotite samples specifically from the Fenton Hill borehole...

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...Our experiments showed that we need to account for both diffusion from zircon and biotite, but zircon is more important.

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This certainly seems to imply that zircon data is already published in the RATE book.From the recent AIG spin piece:

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...as the new RATE experiments (confirmed by new published data from other laboratories) show, helium diffuses so rapidly out of zircon that it should have all but disappeared after about 100,000 years.

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So what are Humphreys' "experimentally" derived diffusivity constants for zircon? Do they really agree with Reiners(2002)? If they do, then we can just use what Reiners has already published on the web:
http://www.geology.yale.edu/~reiners/zirconpaper040401.pdfWhat do you think, TB, would you like to apply Humphreys' calculations to Reiners' data?*note to edge: Humphreys' Tci equation is not made-up. He copied it from Wolf(1998) or independently derived it in a similar fashion. Either way, he should have given credit for it to Wolf (who called it the equilibrium age), and he uses it wrong (no surprise there, heh?).*

edge,Read this:
http://www.agcrc.csiro.au/...cations/9900/melbourne/580.htmlIt looks like Humphreys' equations are correct, even if he doesnt use them right. If we plug in Reiners' diffusivity data, we get reasonable numbers for equilibrium age (millions to billions of years for the low temps, thousands to dozens for zircon above closure temp).
So we need to check Humphreys' diffusion constants against those reported by Reiners (which he claims as confirmation of the RATE experiments).All of Humphreys' paper boils down to a cumbersome restatement of the helium Partial Retention Zone concept, which is both age and temp dependent. Older means less helium (proportional to that produced), and hotter also means less helium is retained at an equilibrium of He production vs diffusion (assuming isothermal conditions). At a given temperature, the apparent age can never rise above the equilbrium age. It takes about 7.5 times the equilibrium age to arrive at that constant level. At that temp, older zirons appear to have retained less and less of the helium produced over their residence time at that temp.

edge,

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Is Humphreys ignoring the fact that more He is constantly produced as uranium decays? Elsewhere, he has shown that the He concentration reaches an equilibrium state and can go no higher. So if the concentrations are so high doesn't that argue against his equilibrium limitation? Or does it mean that his diffusion calculations are way off?

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Neither. Humphreys makes the case that these zircons are NOT at equilibrium. Given the diffusion rates he calculates and their current temps they must be currently losing more He than producing. Therefore we have a disequilibrium that can be dated.His diffusion calculations are correct, the question to ask is... where does he get his diffusion constants from (Ea and Do)?

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If not then why are we even using this element as a clock?

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Humphreys is trying to argue that the helium clock is good for only a few thousand years at these temps, therefore any zircons still containing He must be younger than that.

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But above, we learned that the He could diffuse away from such small zircons in a matter of decades (Magomedov). Why is it now 6000 years?

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Shhhh.... don't give away the ending.

Thanks for helping out TC,Is that an online or CD-based version or did you type all that in by hand?And what's the date on that edition? It mentions planned diffusion experiments that the ICR Impact 352 imply are already completed.I'd like to see that figure 6 that gives the 32 year old diffusion data from Magomedov. That is the only zircon diffusivity data mentioned anywhere in the several articles we have been discussing.Since TB seems uninterested, maybe you'd like to go over the calculations with us, TC? All we need is the most up-to-date zircon diffusivity data that Humphreys is using. Or we can use the Reiners data that Humphreys claims to confirm his experiments.Are you willing, TC?

Thanks TC,It looks like those data are not the ones used in the recent Impact article 352. If we plug them into Humphreys equations from Humphreys refutes Meert, we don't get the same results. An activation energy of 15 kcal/mol is WAY too low for zircon, even for Humphreys.I've put out a call on several fora to try to get the latest diffusivity constants that Humphreys is using.But if you want to check Humphreys' results against Reiners data, look here:
http://www.geology.yale.edu/~reiners/zirconpaper040401.pdfTake the diffusivity measured by Reiners and plug them into Humphreys' equations.For more background, check out the rather technical discussion on T.O.
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In the thread titled:
helium in zircons means young earth?
The message number 43 (currently) by Chris Ho-Stuart 11/09/02 has a lot of good references.

Fair enough TB,But since I am still learning all this myself, I don't have a comprehensive treatment prepared. And as you said, without Humphreys' raw data, we are kinda stuck.But we can evaluate Humphreys' claim that Reiners' data support his findings, can we not?What values do you get for equilibrium age (Humphreys calls it closure interval) using Reiners' data?

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Originally posted by Tranquility Base:
wehappy

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It's not that I'm uninterested I just have my doubts whether we'll be able to sort this out from the data we have. So, until its presented somewhere by Humphreys I was perpared to trust. If you can work out what's going on in between then that's great. If you really did present a carefully laid out summary of the ENTIRE story (and calcs you have done) I would be prepared to comment/check. I don't have time to do it completely independently however.

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OK, time for an update. I suppose this will not be a "summary of the ENTIRE story", but we might consider it the first installment. As such, I hope you and TC will be kind enough to review it from the YEC perspective. I'm sure Joe and the rest of the evos will not be too shy to point out any errors I will surely make...The Story of Gentry and his ZirconsIn the beginning, a man named Gentry got ahold of some zircons from a geothermal energy test well in New Mexico. He measured the helium and lead contents, found no evidence of significant lead diffusion, and found helium concentrations like this (thanks to TC for the table):

Depth (km)	Temperature (oC)	Helium (cc/kg)	Retention (%)
0.95 ​ 1.17 ​ 2.90 ​ 3.50 ​ 3.93 ​ 4.31	105 ​ 151 ​ 197 ​ 239 ​ 277 ​ 313	86 ​ 36 ​ 28 ​ 0.72 ​ ~0.2 ​ ~0.2	58 ​ 27 ​ 17 ​ 1.2 ​ ~0.1 ​ ~0.1

From this data, he concluded that zircons would make a good place to store nuclear waste, since plutonium diffuses even slower than lead in zircon (which already diffuses incredibly slowly), and the lead hasn't had time to leak out even after 1.5Gya, as evidenced by the zircon data and calculated rates of lead diffusion.But the helium was another matter. The only diffusion data Gentry knew about was Magomedov(1970) whic gave an Activation Energy of 15 kcal/mol. Given a value this low, the helium should have quickly diffused out of these zircons at these temperatures. Apparently Gentry, working pretty far outside of his area of expertise, was unaware of even older research by Hurley(1952), Hurley (1954), Damon and Kulp(1957), and Damon and Green(1963) suggesting that zircon was pretty good at retaining helium at moderate temperatures except when heavily damaged by radiation.Regardless, Gentry, presented with the opportunity to re-evaluate his assumptions about zircon diffusivity, and thereby found a whole new branch of geology we now call thermochronology... instead chose to interpret this data as proof of his religious belief in a young Earth. Only five years later, Zeitler(1987) DID lay the foundations of thermochronology by studying apatite - another mineral that retains helium (although not quite as well as zircon).Fast forward a few years...
Gentry is still touting the "amazingly high" helium retention in his zircons...
and creationists like the Drs. Walt Brown and Russ Humphreys are citing Gentry's work as Young Earth evidence...
yet all the while, scientists like Zeitler, Wolf, Reiners, Farley, et al are applying the concepts of thermochronology to a wider array of new minerals and geologic settings and applications.Now here's where the story gets a little murky...Humphreys and his cohorts decide to study Gentry's zircons in more depth. They promise to commission new diffusivity experiments, construct elaborate mathematical models, make bold predictions based on those models, and gather it all up in a book called RATE. But the results of those promised experiments are yet to be published, the models are quite puzzling in their peculiar logic and obtuse language, and the predictions seem to bear little resemblance to real-world conditions.At this point it is difficult to discern what data Humphreys has gathered, what new data he has, what comes from very old sources like Magomedov(1970), and how he has combined it into a (presumably) coherent explanation of helium behavior in zircon.In the next installment, I will examine the few bits and pieces revealed so far by Humphreys in an effort to shed some light on what is going on behind the curtain at ICR.Stay tuned....
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Damon, P.E., and Green, W.D., 1963, Investigations of the helium age dating method by stable isotope dilution technique, Radioactive Dating: Vienna, IAEA, p. 55-69.Damon, P.E., and Kulp, J.L., 1957, Determination of Radiogenic Helium In Zircon by Stable Isotope Dilution Technique: Transactions of the Royal Society of Edinburgh, v. 38, p. 945-953.Gentry, Robert V., Gush, Gary L., and McBay, Eddy R., Geophysical Research Letters, Vol. 9, no. 10, p. 11291130, Oct 1982Hurley, P., 1952, Alpha ionization damage as a cause of low He ratios: Transactions of the American Geophysical Union, v. 33, p. 174-183.Hurley, P.M., 1954, The helium age method and the distribution and migration of helium in rocks, in Faul, H., ed., Nuclear Geology: New York, John Wiley and Sons, p. 301-329.Magomedov, S. A., Migration of radiogenic products in zircon, Geokhimiya, 2, 263267, 1970Zeitler, P.K., Herczig, A.L., McDougall, I., and Honda, M., 1987, U-Th-He dating of apatite: a potential thermochronometer: Geochimica et Cosmochimica Acta, v. 51, p. 2865-2868.

Actually, moose, diffusivity experiments are done under vacuum. That's the way the experimental apparatus must operate. Presumably, what really matters is the partial pressure of helium. Even at great depths, this is still pretty low (but not zero).Mathematically, I think it's possible to work out the diffusivity at ambient helium partial pressures other than zero, based on the experiments. There's some differential calculus involved, so don't ask me to do it. Here's a few equations to chew on:
Page not found - Canadian Society of Exploration GeophysicistsA change in helium partial pressure (from inside the zircon to the surrounding medium) results in a change in diffusivity that is more linear, while changing temp has an exponential effect on the diffusivity curve.

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Originally posted by Coragyps:
I'm not positive exactly how this factors in, but it's well established in the oilfield industry that pressure can have a very dramatic influence on "permeability" (approximately rate of diffusion) of gases in whole rocks. Measured perms in "tight gas sands" are frequently lower by a factor of 1000 at realistic native confining pressures than at atmospheric pressure. I would think that there should be some sort of analogy between this inter-grain permeability and the diffusivity along crystal defects that would control helium flow out of zircons. I'm not too sure I have the perseverance to look for documentation, though.

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I agree. But I suspect that the effect is small enough at the shallow depths we are dealing with to safely ignored - at least for the relatively non-rigorous evaluation I am capable of. Any such effect would result in an overestimation of diffusivity from step-heating experiments conducted under vacuum. So this works in favor of Humphreys - my analysis will err in his favor.

Time for the next installment:Let's look at Humphreys' equation for "closure interval" which is identical to Wolf's(1998) "equilibrium age."Tci ~= a^2/(15*D)As Humphreys defines it, this "closure interval" means the time at which "the loss rate approaches the production rate, an event we call the reopening of the zircon."This is not strictly correct, and Humphreys admits this is an "estimate" using some simplistic assumptions as a "first approximation." But the equation itself is valid, and Humphreys use of it in this way is off by a factor of only 7.5, so this is not too bad for a Creationist.If we use this equation to evaluate Humphreys' results, we find some serious discrepancies between reality and Humphreys' ideas.From Missing Link | Answers in Genesis ...we have this quote:"After re-opening, [the zircons] would again be an open system, again losing helium as fast as nuclear decay generated it for most of the alleged 1.5 billion years. Today the zircons would have retained less than 0.0002% of the helium, instead of the (up to) 58% observed."This means the zircons would be unable to accumulate more helium because the "closure interval" was exceeded, diffusion equalling production, after only .0002% of the 1.5 billions year's worth of helium was produced. Thus the "closure interval" in this case is .0002% times 1.5Gya = 3000 years. Remember, this is the way Humphreys uses this equation, so it is not quite right, but even when applying it correctly, the results are the same (in this case).Thus we have 3000 years ~= a^2/(15*D)Solving for D/a^2, we get a value for diffusivity of about (7*10^-13)/sec at 378K. (378K = 105degC)Drawing again from Missing Link | Answers in Genesis ...Humphreys says:
But the —196C I mentioned in the Impact article is what I will call here the retention temperature. That is the temperature at which the Jemez zircons would have small enough diffusion rates to retain the observed large amounts of helium for 1.5 billion years. That’s essentially what I said in the article:

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‘For most of that alleged time [1.5 billion years], the zircons would have to have been as cold as liquid nitrogen (196C below zero) to retain the observed amount of helium.’That's a very straightforward way of saying the closure interval is long enough to allow the observed level of helium only at the very low temperature of 77K.If we once more apply Humphreys' "closure interval" equation to approximate the "closure interval" at 77K,Tci = 1.5Gya = 1/(15*(D/a^2))...we get a value for diffusivity of (1.4*10^-18)/sec at 77K.Again, even if we correct Humphreys' usage of this equation, the results are essentially the same (in this case, a little worse for Humphreys).With 2 values of diffusivity vs temperature, we can now calculate the activation energy and infinite temperature intercept on an Arrhenius plot. I get 2.521 kcal/mol for the activation energy, and (2.0*10^-11)/sec for the infinite temperature intercept.While Joe and the other geochronologists are cleaning the spittle off their keyboards and monitors, we can use these numbers to illustrate for the rest of us how ridiculous Humphreys' fairy tale has become. If we use the diffusivity constants from above to calculate the closure temperature, we get the astonishing number of 120K !!!That's minus 153 deg C!!! Yet Humphreys states that he has calcualted a closure temp of +120 to +140 degC for these zircons. So we are right back to where we started. It looks like Humphreys has made some serious mistakes. What they are, we can't tell for sure without seeing all the data that went into his work. But from the results published so far, we can easily see that Humphreys' articles are not even internally consistent.In the next installment, we will see what realistic values for diffusivity can tell us about these zircons..
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Wolf R.A., Farley K.A. and Kass D.M., 1998. Modeling of the temperature sensitivity of the apatite (U-Th)/He thermochronometer. Chem. Geol., 148: 105-114.<< edited to correct some minor rounding errors in the math, and a misread digit in one of the ln(D/a^2) results. 2.555 kcal/mol was changed to 2.521 kcal/mol, 2.5*10^-11 was changed to 2.0*10^-11, and (8*10^-13)/sec was changed to (7*10^-13)/sec. The net result was to change the final Tc number from 119K (rounded) to 119.8K (rounded to 120K). In Celsius, it remains at -153C. >>[This message has been edited by wehappyfew, 11-18-2002]

Time for another update:I must say that I am slightly disappointed at the lack of interest or even a response from the YECs on this board and other fora where I have tried to start a discussion of Humphreys' work. Is there something I am not explaining clearly enough, or maybe skipping some crucial concepts needed to understand this material? Or do they just close their eyes to the evidence that one of the most prominent YEC "scientists" has made some serious errors?Welcome to Chris Ho-Stuart, BTW, we're glad to have you.I was going to discuss the use of realistic diffusivity constants as measured by Reiners and apply them to Humphreys' zircons. But there's not really much to say. If we use Reiners' experimentally measured values for activation energy and D₀ intercept we get the expected closure temp of 190degC; we find that diffusion drops off rapidly at lower temps; and the equilibrium age at 105degC is in the range of hundreds of millions of years or more. No surprises there.But what I find more interesting is how badly Humphreys' statements and numbers conflict with the physical reality of how diffusion works.If we examine more closely this paragraph from Humphreys' response to Joe's letter..."Closure temperature is irrelevant. You misunderstood my statement because you misunderstood closure temperature. You thought that zircons below that temperature would remain a closed system. Wrong! See the preprinted section below to understand why. Even if the Jemez zircons had gone below their closure temperature, according to the uniformitarian scenario they would have re-opened within a few dozen years to a few thousand years after closure. After re-opening, they would again be an open system, again losing helium as fast as nuclear decay generated it for most of the alleged 1.5 billion years. Today the zircons would have retained less than 0.0002% of the helium, instead of the (up to) 58% observed."In the previous installment (post 72) we've already covered the problems with the 0.0002% number. It requires a diffusion rate that is completely unrealistic given the known diffusivity constants. This time I'd like to point out the sentence in bold above..."Even if the Jemez zircons had gone below their closure temperature, according to the uniformitarian scenario they would have re-opened within a few dozen years to a few thousand years after closure."This is not correct. Due to the mathematics of the way closure temperature is calculated, at a temperature just below the closure temp (about 97.5%), the diffusivity (D/a^2) is approximately (1.7*10^-16)/sec. That translates into an equilibrium age of about 1.2 million years, requiring 7.5 times that interval to actually reach the equilibrium. This relationship holds true no matter what the medium, diffusivity constants or closure temp.For example, if we take the closure temperature calculated by Humphreys (120 to 140 degC), multiply by 97.5% (after converting to Kelvin), we get 110 to 130 degC. At that temp, we calculate the diffusivity (using any combination of diffusivity constants that give the stated closure temp), and find it to be about (1.7*10^-16)/sec. The equilibrium age at that diffusivity is about 1.2 million years. Humphreys cannot have the zircons "re-opening" after a few dozen to a few thousands years when the equilibrium age (he calls it closure interval) is 1.2 million years.Humphreys' claim in the paragraph cited above is mathematically impossible. All his claims seem to be based on a combination of incorrect data (which we knew right away from the numbers he gave), and now we can add mathematical error to his problems.

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Originally posted by Tranquility Base:
wehappy

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It's not that I'm uninterested I just have my doubts whether we'll be able to sort this out from the data we have. So, until its presented somewhere by Humphreys I was perpared to trust. If you can work out what's going on in between then that's great. If you really did present a carefully laid out summary of the ENTIRE story (and calcs you have done) I would be prepared to comment/check. I don't have time to do it completely independently however.

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I've laid out several specific problems with Humphreys' paper and response to Meert, including the summary and calculations you asked for.
Are you prepared to comment/check yet?