Summations Only

Hi Mindspawn.
I just had to get involved here as this thread has moved firmly into my area of expertise.
In case you are unfamiliar with my background, and you may well be as I don't post here very often, I am an analytical radio-chemist working in a research reactor.
The nuclear reactor that I work at was specifically built to test and answer questions such as the ones that you have been posting. It has a very tightly monitored and controllable neutron flux into which we deliberately place samples before actively measuring their decay rates.
One of the processes that we specialize in is called NAA (Neutron Activation Analysis) in which we irradiate a sample then measure the wavelengths of the prompt and delayed gamma rays that are always associated with radioactive decay.
So let's address a few of your points. So you are suggesting that neutron flux can have an affect on the rate of decay correct?
It doesn't.
Samples decay at precisely the same rate whether they are left in the reactor core, left on a lab bench or completely surrounded by shielding. This has been tested quite extensively for more than 30 years here.
I do find myself wondering if you might be confusing something a little though.
It would make logical sense for neutron flux to slow down the decay process if the neutron capture path were identical but reversed to the decay path. Such a situation would indeed result in an equilibrium between neutron capture and decay.
However this is not the case.
The decay path is always different than the neutron capture path. To put it another way, the daughter isotope is always different than the original target isotope (the one that captured the neutron)Let's take iron as an example as it has been mentioned a lot in this thread.
56Fe is the most common isotope at 91% of the total iron. It is also stable so it does not decay.
If 56Fe (thermal cross section 2.59) captures a neutron it becomes 57Fe which is also a stable isotope but which has a much lower natural abundance 2%
If 57Fe (thermal cross section 2.48) captures a neutron (it is slightly less likely to do so than 56Fe as it has a more tightly packed nucleus and therefore a slightly reduced Thermal cross section) it becomes 58Fe which is also stable.
if 58Fe (thermal cross section 1.28) it becomes 59Fe which is unstable and decays to 59Co with a half life of 44.5 daysIncidentally the reason that Boron shielding works to stop neutrons is because 10B has a thermal cross section of 3837 so a reasonably thick layer (couple of inches or so) is enough to capture any neutrons coming its way.
The Boron shields need to be replaced periodically though as capturing those neutrons results in an alpha particle and a 7Li atom That is actually a very well thought out experiment.
Scientists here thought that as well and tests such as this have been performed repeatedly at this and other reactors throughout the several decades of their existence.
The effects that you predicted were not discovered. the decay rates and hence the ratios, were found to be the same for all situations. OK two points here.
First of all as I have pointed out above, the effects of neutron flux on decay rates has been tested rather thoroughly and categorically ruled out as a possible way to change decay rates.
Secondly and much more seriously, the kind of thermal or fast neutron flux needed for any isotope to capture a neutron would be many orders of magnitude higher than any form of organic life could survive. Such a flux on the surface of the planet would inevitably result in a sterile radioactive wasteland.

Thanks for that.
I could probably dig up all kinds of references if pushed but they would all be pretty old now. This question was considered to be fully resolved many many decades ago. It might be kind of hard to find papers online now.I was aware of some data from Purdue and Stanford, as well as several others, that show a very tiny (fractions of a percent) cyclic fluctuations but until now I hadn't really read about it in detail.
It's actually extremely interesting reading and surprisingly well accepted in the scientific community. I half expected to find papers that challenge the initial findings but on the whole, every team of researchers that have repeated the same experiments, with and without modifications, have come up with pretty much the same results.
The decay rates of whatever isotope is being studied appears to slow down very slightly in response to increased activity in the sun. It has even been successfully used to measure the effect 2 days before a solar flare.However there is still a question of what the actual cause of the effect really is. It was initially thought to be neutrino flux but it is still quite possible that some unknown particle is responsible.Some experiments have been carried out in order to determine if neutrino flux is indeed the culprit
http://arxiv.org/pdf/1006.5071v1.pdf
their conclusion was not entirely conclusive though
They experimentally took two radioactive samples and made them into two different shapes (flat sheet and sphere). In the sphere, the neutrino flux produced by the decay of the sample itself was many times greater than the solar Neutrino flux while in the flat sheet it was negligable. They did indeed note a small change between the two but it was so small that more experiments are needed to confirm the hypothesis.

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Our results in Table 1 indicate a ~2.3 sigma deviation of the foil/sphere ratio in experiment 1 from unity.
From Table 2, based on the initial 30 spectra, the foil/sphere ratio for experiment 2 deviates from unity by ~2.6 sigma.
These results thus leave open the possibility that the half-life of a radioactive nu-clide could in fact depend on its shape (due to the internal flux of neutrinos, photons, or electrons)

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So yes there does seem to be a measurable change in the decay rates due to something going on in the sun.
But what effect does slowing the decay rate by a fraction of 1 percent for short periods of time during increased solar activity have on radiometric dating?First, initial decay rates were probably (I'm not sure about this) measured over a relatively long period, say a few months, due to the inacuracies of the timers that were available back in the day. If this is true then those rates would have been an average. No?Second. If there had been much greater activity in the sun in times past then the dates as we measure them today would be incorrect (by 0.1%) in the direction of the measurements being too short.Third. A difference of 0.1% in the measurements would be lost in the experimental noise of most dating methods. In any analytical process it is typical to have a standard deviation of up to 0.5% around the mean value. ) 0.2% is considered to be almost perfect.
I will grant you though, isotope ration measurements need to be a bit better than that, typically in the order of 0.05% or better but that is just in the actual ratio measurement and not in the resulting calculations related to sample age. The potential error bars there are well in excess of 0.1% so as i said this error would be lost in the noise. It's possible that I misspoke just a little bit. It's a difficult subject to research apparently.
Here is some stuff that I've been able to find on the subject.We should be able to work out the actual neutron flux at sea level easily enoughfirst of all here is the measured average dose for the USA measured in mili-rems
http://web.mit.edu/newsoffice/1994/safe-0105.html

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The average exposure in the United States, from natural sources of radiation (mostly cosmic radiation and radon), is 300 millirems per year at sea level. Radiation exposure is slightly higher at higher elevations-thus the exposure in Denver averages 400 millirems per year.

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Here is a table showing the relative conversion factor from neutron flux to mili-rems http://miscpartsmanuals3.tpub.com/...5-315/TM-55-3150014.htm
I can't get the stupid table to display properly in this post because it seems to be in pdf form so here is a summary of the information.
The lowest energy neutron (thermal) flux when measured in neutrons per square centimeter per second is compared to mili-rems per hour in the following proportions268.0 neutrons/square centimeter/second == 1 mili-rem per hour (note this is measured as a whole body dose)
if the average whole body dose from background radiation in the USA is 300 mili-rem then we need to divide that 268.0 by the number of hours in a year (8760 assuming exactly 365 days)therefore the average neutron flux (assuming only thermal neutrons exist)
268 / 8760 = 0.0306 neutrons/square centimeter/second or about 1 neutron every 30 seconds or so.
In actual fact there are quite a large proportion of neutrons that are higher energy so the total flux would be significantly less than that.The whole body dose that is considered to be borderline 'safe' is about 50,000 mili-rems per year. That is 166 times greater than the basic flux at sea level so that means that a flux of 5.1 neutrons/square cm/second would be approaching the upper limits of survivability. Any more than that and we would require shielding to survive.I'm not going to take the math any further than that for now.
The only point that I would like to make here is that such a low neutron flux is not likely to activate very many atomic nuclei in a given sample. Sure over a large area it is eventually going to be lethal to most life forms but to a chunk of iron, one cm cubed, there will not be very many activations if you get my meaning. most neutrons will pass straight through solid matter.

Can you tell me where you got this figure from.
My research leads me to a conclusion that the true value at sea level is closer to 0.05 neutrons/square cm/second or even less.
http://www.lanl.gov/science/NSS/issue1_2012/story4full.shtml

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These neutrons, like ghosts, can pass through materials without being noticed. At aircraft cruising altitudes, about 2,000 of them per second penetrate each square yard of the aircraft's surface, passing through the passengers, seats, and onboard electronics and exiting on the other side.

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that works out at about 0.2 neutrons/cm squared/second at 30,000 feet above sea level.Or is your claimed flux not expressed per second?
I notice that there is no time component listed in your post.
The figure above (0.2/sec) when calculated out to neutrons/square cm/year is indeed around 6 million. 6,307,200 to be exact

All true.
however there has not been a positive correlation between solar wind and the observed decrease in decay rate. In fact the decrease is always noticed a considerable time before a solar flare, while the solar wind is, as yet, unchanged.

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Fischbach and Jere Jenkins, a nuclear engineer and director of radiation laboratories in the School of Nuclear Engineering, are leading research to study the phenomenon and possibly develop a new warning system. Jenkins, monitoring a detector in his lab in 2006, discovered that the decay rate of a radioactive sample changed slightly beginning 39 hours before a large solar flare.

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source http://www.purdue.edu/...r-flares,-give-advance-warning.html
From what I am reading, this decreased rate continued until after the solar flare was finished, a period of more than 48 hours. 2 days and 2 nights at least. There may have been overlaid diurnal fluctuations in this rate but it isn't mentioned either way.
Solar wind doesn't seem to me to be a strong contender for the cause of this effect. I have no idea what does cause it and neither does anyone else as far as I know. All we really know is that something inside the sun is giving us a couple of days warning prior to a solar event using some unknown mechanism. I agree completely. We cannot make any such assumption.
in fact I would assume only that whatever affect we are seeing will be proportional to whatever the sun is doing. I would expect a really big solar event to slow radioactive decay more than a small event. I have no idea if the correlation is linear or not.Assuming that the effect would be large just means that for solar events in the past, the decay rate could potentially (assuming the maximum possible effect) have almost stopped for short periods.Again I ask; What effect do you think that would have on radiometric dating?
Just as a thought exercise.

Hi Jonfjust a quick point I don't really agree with your point.let's say that in the past we might have had a few massive solar storms that came about once per century and lasted about a week each.
Let's also say that the decay rate during each of these massive storms was almost zero
Furthermore, let's assume that the storms didn't strip away the Earth's atmosphere or irradiate it to the point of causing mass extinctions.7 days of suppressed (zero) rates for every 36443 days of normal rates.
That's less than 0.02%
I contend that the graph would look precisely the same.What if we had a major event every 10 years and it lasted 2 week?
That would be a 0.38% deviation.The effects would be SOOO minor. That graph isn't gonna look any different at all. ^_^Edited by PurpleYouko, : missed a decimal place

Yes I am aware of that. I might not post often here but I keep up with the threads that interest me. Thanks for the reminder anyway.All I was saying was that even giving these effects a considerable amount of "benefit of the doubt" they aren't big enough to make any noticeable difference to the existing dating schemata.
Apart from that, they slow down decay rather than speeding it up so the effect is in the wrong direction to help with a proof for a young Earth.
The larger these slow downs get, the more it means that conventional dating is underestimating the true ages.The only valid argument that could possibly support a young Earth while taking these observations into account is if the present flux of whatever the heck is causing the slow down were much much smaller in the past, hence making decay rates faster back then.
I don't see that as a very strong hypothesis but at least it's a "what if" that could actually be explored logically.

Maybe I wasn't reading his post correctly then
I know he was talking about solar wind just before and I did address the fact that I do not believe there is an established correlation between that and the observed effects.When I said I agreed with him I mean about the fact that a slight increase (in the flux of whatever particles are causing the effect) would likely result in a slight change in the effect itself. I also agree that we cannot make an assumption that the effect was slight in the past during periods of strong activity in the sun. It might not have been.I have to say though that I'm not quite following the last bit of his post The thought crosses my mind that he might be alluding to the question of what would happen if the sun should stop it's activity altogether? Would decay rates speed up? maybe. If so then by how much?That hypothesis should be testable to some degree though.
If we were able to get our hands on a piece of a comet or something else that has spent most of its lifespan in an area of space that is vastly more distant from the sun than we are, we should be able to date it and if the hypothesis is correct then it should show up as being much older (less sun flux should result in faster decay rates. no?) than moon rock or terrestrial rock even though they were probably formed around the same time.If, however, the Earth's magnetic field is affecting the flux from the sun (i.e. if it is from the solar wind) that too is testable since the hypothesis would predict that the moon should be subject to vastly more flux than we get here on the surface of the earth so radioactive decay would be much slower there.
Therefore moon rocks should appear much younger than terrestrial rock of the same age.did they use atomic clocks on moon missions?
or on any space missions for that matter?
how about GPS satelites. They need some pretty accurate timing.
Atomic clocks in space should run slower than those on the ground if the earth's magnetic field and/or solar wind is involved in any way.[ABE]
Just answered my own question. lol

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The satellite orbits are distributed so that at least 4 satellites are always visible from any point on the Earth at any given instant (with up to 12 visible at one time). Each satellite carries with it an atomic clock that "ticks" with an accuracy of 1 nanosecond (1 billionth of a second).

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source http://www.astronomy.ohio-state.edu/...Ast162/Unit5/gps.htmlGuess that kind of debunks the hypothesis that the solar wind has anything to do with it. Ah well.Edited by PurpleYouko, : added more data

I certainly wasn't agreeing to that kind of time scale. lol
a couple of tenths of 1% error in the dates is a long way from a few tens of thousands of percent error which is what that would take.As I pointed out earlier in my post about dose rates the maximum "safe" (i.e. not immediately lethal) dose rate is normally considered to be about 50,000 mili-rems per year. that is 166 times larger than the average measured dose at sea level.
That means that if the decay rate was faster by a factor of 166 times in the past then we could have just about survived.
For his proposed time scale it would need to have been a few million times higher.

Maybe you missed the link that mindspawn posted earlier.
here it is again
http://www.purdue.edu/...2010/100830FischbachJenkinsDec.html

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The Purdue team previously reported observing a drop in the rate of decay that began a day and half before and peaked during the December 2006 solar flare and an annual fluctuation that appeared to be based on the Earth's orbit of, and changing distance from, the sun

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The Purdue team observed a drop in the decay rate a day and a half before a solar flare.
This has since been reproduced by dozens of labs around the world and it is pretty well accepted that it does indeed happen.
Nobody knows the cause yet though.
It doesn't appear to be neutrinos or neutrons or any of the other obvious choices. OK I'll conceded that one.
I got a little ahead of myself and didn't do the research.
I thought I remembered reading somewhere about an atomic clock that actually relied on radioactive emission but perhaps I'm remembering that wrong.
I'm not suggesting that the resonance frequency of atoms would in any way be affected by changing the rate of decay.

I'm not sure what exactly you are arguing here.The drop in decay rates has been observed repeatedly and it correlates with various factors related to the sun.
They also hypothesize that it also fluctuates in time with the rotation of the sun's core although it was found not to correlate with the apparent rotation of the sun at its surface. There is a difference of some 5 days in the cycleThe only thing uncertain is how the sun causes decay rates to decrease.
It is apparent that something from the sun is causing the effect. the only thing we have no evidence for is what that something actually is.Note that the effect has also been reproduced in the laboratory by using radioactive materials in thin sheets, flat as opposed to rolled into a sphere.
I linked to this experiment in message 957.
here is the link again http://arxiv.org/pdf/1006.5071v1.pdf
Their experiment was somewhat successful but not entirely conclusive.Edited by PurpleYouko, : No reason given.

well if the effect was as small as the Purdue team found then I doubt they would even see a difference with a small nuclear battery unless super sensitive equipment were specifically looking for the effect.It would still be interesting to actually reproduce their experiment in outer space to see if the effect is any different outside the atmosphere.