azzaman333
meh
Car battery dead, can't afford to replace it.
I mean, it could have been, but I find it pretty unlikely. If so, it would have formed iridium-192 which has a half-life of something like 73 days. If it becomes measurably less radioactive over a couple of weeks, that would explain it. But it's probably thorium or uranium instead.
I had no idea that iridium was likely to come contaminated with radioactive stuff. I would have figured this for a rare-earth element (thorium and uranium are chemically similar and show up in the same ores) but iridium is one of the platinum group metals, which are hard to separate from each other but none of which are radioactive. Maybe some of it is obtained as a byproduct of uranium mining or something instead.
Those are some pretty awful photos on the news, of all that flooding.Rain.. rain everywhere.. until sunday. Then snow? Okay..
Very few neutrons come out of ore. The only way that happens is by spontaneous fission of uranium, which is a very uncommon process - a little under 1 atom per gram of uranium per minute, so maybe 2 neutrons/minute/gram U. There's no way that it could have gotten activated to an easily measurable degree in ore - the steady-state concentration of Ir-192 even in 50% U3O8 would be quite small. Neutron activation plateaus out at a level proportional to the neutron flux times the half-life of the activation product, so even a billion years wouldn't help because Ir-192's half-life is ~73 days.If it was recently separated from uranium ore then that in itself means that it was recently exposed to neutron flux. I'm thinking that your sample is already activated. You may have to set it aside for a year.
Very few neutrons come out of ore. The only way that happens is by spontaneous fission of uranium, which is a very uncommon process - a little under 1 atom per gram of uranium per minute, so maybe 2 neutrons/minute/gram U.
A few of the neutrons eventually will go on and induce other fissions, either in U-238 on the first couple of collisions with other nuclei or in U-235 on any collision, which would slightly raise the neutron flux (a small amount above an already low amount). But we know this isn't very high because it takes a lot of work to get anywhere near a nuclear reaction with modern isotopic concentrations, so that even pure natural-abundance uranium cannot sustain a nuclear reaction by itself unless heavy water is used as the moderator under carefully controlled conditions. (unlike in the good old days)
This means that in a real ore, the effective neutron multiplication factor, the number of neutrons produced per initial neutron, is going to be much less than 1. Criticality occurs when k=1. If, say, k=0.1 (which is probably very generous), then the steady state neutron flux is 1/(1-k) = 1.11 times the initial spontaneous fission flux. Even halfway to criticality you're only at double the initial flux, which is already low.
Bitcoins up to $1600 and I could've bought a bunch last summer when they were $600 but was waiting for them to drop to $500.
Those are some pretty awful photos on the news, of all that flooding.
But as for snow... After the Blizzard of '86 that dumped a humongous pile of snow on us here on May 29, I never consider spring to have arrived until after June 1.
This is Canada. Snow is possible in any month of the year (and I have seen it in every month of the year - not all in the same year, mind you).Snow in may here is very uncommon. I think? Maybe I just can't remember.