A lead apron, when exposed to a strong enough source of gamma rays, will be unable to sufficiently attenuate the radioactive flux. It will absorb gamma photons, and then emit a bunch of of them right into you. Radiation shielding has to take into account the total flux, and then it has to be built in layers to a given thickness and overall density. It doesn’t do you any good if the incident radiation is all absorbed, only for 99.9% of the original flux to be re-emitted by the shield!
You can think of it as roughly analogous to the excitation of atoms leading to emission of a photon in the visible range. It doesn’t help to wear a pair of goggles that will absorb all of the light you’re hoping to block, only to have your goggles glow brightly as a result. You’d rightly conclude that you need much thicker goggles, and the same is true here.
No holes needed, and a lot of the original gamma radiation is being absorbed and subsequently emitted, which defeats the point. There are also complications of a substance being exposed to some forms of radiation (primarily neutron) becoming radioactive themselves. It wouldn’t be visible, but it wouldn’t be good either.
A note that shielding, in addition to considering total flux, has to consider the type of radiation. Gamma (very high energy photon) is very penetrating, beta (high energy electron) is less so, and alpha (a helium nucleus) hardly penetrates at all. You also have to consider, in the case of a molten core, other contaminants and radionuclides actually getting on you or in you. Alpha emitters are pretty harmless outside of you, where your skin stops them cold. If you eat or breath them in however, they’re deveststing. So your concern with alpha emitters tends to be covering yourself and wearing a respirator, while that won’t even help a little with gamma.
It would not have holes in it. The main reason why the gamma radiation makes it through is because it never interacted with any of the lead. And even if a (unlucky) gamma photon interacts inside the lead sheet it would not do much damage there. The only thing that really do damage to the material is neutron radiation and even there the damage is on the microscopic level (atoms getting knocked out of place) than anything macroscopic.
From the point of view of the radiation, there's a lot of empty space between lead atoms and a lot of it will just slip through and not interact with the lead at all. A fraction will slam into lead atoms, a fraction will slam into your atoms, a fraction will keep going.
More like a sheet of paper held up to the light. Some light gets through, and if you have thicker paper it will allow less light through, but it doesn't noticeably damage the paper.
Depends how long you leave the paper exposed to light. if you have a sheet of paper half exposed and half shielded for a year of sunlight the effect is marked.
The equivalent in lead would probably manifest in some way, perhaps a visible patina on the surface? or, as a differential in decay products. you could call that 'damage' if you wanted to.
Glad to help. But I noticed the analogy is a bit flawed; testing for membership does not add anything to the set, but the analogy might imply asking yaSeenThisFaceBefore(x) will make the savant remember x. I should change the story and the 2 functions to "remember this terrorist" and "is this a terrorist?" or something like that.
Oh cool! so from the server you stop the image that's running on the server, then restart the CCL image, and then load in the source (like starting a repl on the server and doing a "load ./start-file.lisp")? (ps sorry for the rookie questions am quite new to this and very interested).
Yes, exactly. (And no worries about rookie questions. That's how people become non-rookies.)
In my case, I run the REPL using screen so I can go back to it for debugging if I need to. But you can also run "headless", without a REPL at all if you want.
Yep, pretty much. I've only ever dealt with low-load applications so there was no load balancer. You just put the Lisp server in a state where it refuses new connections (serves up a "temporarily down for mx" page, or reconfigure the ngingx front end to do that), wait for existing connections to finish, and then restart. It's no different from any other server.
