Total Activity (A) is the number of decays per unit time in the sample
Number of Particles (N) is the total number of particles in the saample
Specific Activity (Sa) is the number of decays per unit of time per unit of sample (mass, volume, moles, etc.)
Then the original Specific Activity (Sa0) = dN/dt|t=0| = lamda(N0), where
lamda = Sa0/N0 is the decay constant.
Then, half life (t1/2) = ln(2)/lamda
Thus for the same mass, the radioisotope with the shortest half-life will radiate the most energy.
That’s jives with my novice level of physics knowledge. You would need to change the fundamental nuclear forces to change the decay rates, and in doing so you would also change what the isotopes decay into and the energy released by each decay. In other words, you would not expect the same ratios of radii in the radiohalo if half lives were different in the past.
It’s the energy of each fission reactions that matters. The more energy a single fission produces the further the alpha particle gets before it is stopped by the rock and forms a ring. Therefore, the radius of the ring is not determined by the amount of energy released per unit of time but by the energy of a single decay.
I think we are looking at two aspects of the same thing. The total energy radiated from a sample is related to the specific activity times the particle energy per fission.
As you pointed out, the distance of the halo from the source is related to the E(Mev) of the particles from the source. The optical density of the halo is due to the number of particles causing dislocations in the crystal lattice over time.
This suggests that if somehow the decay rate went up by a factor of many (millions), the energy of an alpha particle would not change and the radius of a halo also would not change. Of course the rock would melt, but that’s a separate matter.
If I recall, Gentry didn’t suggest an accelerated decay rate, only a mass of polonium created in situ when the rock was also created, 6000 years ago.
Snelling makes a pretty good argument for accelerated decay under his heading “Accelerated Radioactive Decay” but then fails to believe his own conclusions about the passage of “100 million years”. And this is where I must part with YECs. I believe both in 1) the passage of mere days as well as 2) millions of years. In this way God could have brought about the deep (and beautiful) age of the entire cosmic system in short order.
By the way, the existence of radiohalos does seem to be a problem for the long-age view. I would like to hear their attempts to explain it. At least Snelling takes a risk and delves into specifics when he tries to offer an explanation (but no, I do not believe the halos are a result of the Flood as he does).
The relationship also shows that half-lives are exponentially dependent on decay energy, so that very large changes in half-life make comparatively small differences in decay energy, and thus alpha particle energy. In practice, this means that alpha particles from all alpha-emitting isotopes across many orders of magnitude of difference in half-life, all nevertheless have about the same decay energy.
However, because we are observing different size rings, I suppose that this trend should be visible in halo data.
Can someone explain this to me? I do not understand why this would be the case. Why does a ring form where the alpha particle stops, rather than also darkening the path the particle took to arrive there?
Again, I’m an armchair physicist, so large grains of salt required.
An alpha particle is a fast moving helium nucleus. The terms alpha, beta, and gamma radiation come from their ability to penetrate air. Alpha radiation quickly drops off as you move away from a source, beta is intermediate, and gamma radiation penetrates quite a ways since it is essentially high energy light. You could think of alpha radiation as a derailed locomotive where most of the damage occurs where the train hits something that finally stops it.
I don’t know much about these things but I simply assumed that each alpha particle travels until it hits just ONE obstacle and then stops there. For the “cleared path” to get extended further, a new alpha particle must come along in that same route.
I assumed that it is like the old space invader video, where each projectile fired by an invader makes a little “hole” in the defenses at the bottom—and it takes many such projectiles to pick away at the ground-defenses, pixel by pixel (or small pixel-group by small pixel-group.)
In contrast, I don’t think it is like ballistic gel where a bullet clears a path of some length before stopping. (Yes, goopy ballistic gel will mostly flow back in behind the bullet but I think you get the idea. It is not a great analogy.) Isn’t alpha particle decay in a crystal matrix more like “one alpha particle clears one spot in the crystal and disappears in the process” because it’s energy is gone? So it takes many alpha particles to gradually “hollow out” a shell of sorts—although “hollow out” is certainly going too far and fails as an exact description.
IN ANY CASE: This is an example of a very educational Peaceful Science thread. For a non-specialist, this sort of review of a lot of radioisotopic decay basics is very worthwhile—and quite fun. And I hope that the errors in my description will get corrected by those with a much better grasp of the science. Thanks.
But like so much of “creation science”, the radiohalos argument is not so much about doing actual science as convincing non-scientists that “creation science” is nice and “sciency.” It is also an excellent example of cherry-picking (and obfuscating) one relatively obscure phenomenon in nature and pretending that it outweighs piles and piles and piles of evidence for a very old earth.
Sadly, it is almost always about “creation science” apologetics, not actual science. And I think that the Young Earth Creationists who truly understand the basic science can admit that to themselves even if it is not usually mentioned alloud. (Of course, I’m venturing into assessing someone’s inner thoughts and perhaps even bordering on claiming to know their motivations—and that is always risky.)
This is what I would expect. Scattering, like the classic Rutherford experiment, meaning that alpha particles would deflect in all directions including 180 degree reversed. So it is not clear to me why this is not so.
I think the discoloration cannot be so much about where the particle has done damage in its path, but must be related to where it lands in the end as, at the end of its journey, a helium nucleus or merged with another nucleus. That must be what is causing the discoloration somehow.
