Thread by @AngelicaOung

OK Guys...you know I’m taking this MOOC for Nuclear Energy. I’m speedrunnning module 1.1 this afternoon. I’ve done the work throughout the week but took no notes because I was too busy with reporting etc. Doing this so I don’t forget everything.
learning.edx.org/course/course-…

1.1.1: ”Ionizing” is just anything that can knock an electron from an atom. Can be electron, proton, neutron, larger fragments. Light? Yes, but must carry at least 3-4electron volts. UV, X-rays, Gamma rays are ionizing. Don’t be afraid of your microwaves and cellphones.

Geiger counter: A thing that picks up ionizing radiation
Background spectrum: naturally existing radiation. Could be cosmic radiation. Could be coming from the walls, from the ground, from yoself.

1.1.2: History time. 1985, some random dude named Wilheim Roentgen thought it would be fun to pass some currents thru vacuum tubes, as you do. But then he noticed this solution of Barium which he likes to keep handy nearby, y’know, in case, started glowing!!!

Wilheim was like “WUT?” What’s getting to the barium? He put some paper between the vacuum tube and the barium. Kept glowing. Wood. Kept glowing. Metal. Finally stopped. “I’ll just call this thing X-ray for now and think of something cooler later” Oops. Still called x-rays now.

"hey honey, come over here for a moment. It'll be fun, I promise."

1899: Ernest Rutherford and Paul Villard found 3 types of radiation.
Alpha: stopped by paper
Beta: stopped by wood
Gamma: stopped shitton of metal

What were they? *Shrug* but wait! We just invented spectroscopy!

"Alpha particle, eh? Or should we call you *dramatically rips off hood* A HELIUM NUCLEUS"

But so far all this activity had to be induced. Then Henri Becquerel and his magnificent mustache entered the chat. Uranium salts, he found, naturally gave off rays. r a d i o l u m i n e s c e n c e

Followed of course by the Power Couple of nuclear, Marie and Pierre Curie. They found radium, polonium, thorium and won 2 Nobel prizes. Unf. Marie died from all that radiation. Ah, well, lesson learned...

...not! In fact we remained kinda completely ignorant of the harms of radioactive exposure and kept inventing new kewl things to put radioactive elements in to make them atomic. Like these spark plugs in the 1940s!

Saddest cases were the radium girls, who primed paintbrushes with their lips to paint glow in the dark watchfaces. Radium is a "boneseeker" just below calcium on the periodic table. The radium settled in their bones and irradiated their marrows😢

So remember when Asimov said any sufficiently advanced technology is indistinguishable from magic? It's true! Rutherford literally figured out how to do an alchemy. Unfortunately, it was shitty alchemy that literally only turned lead into gold one atom at a time.

He was also afraid to call it alchemy even though it was literally what he did because you will get your ass cancelled by the scientific community back then if you claimed you could do alchemy. "They'll have our heads off as alchemist!"

Charged particles were pretty easy to detect but the wily neutron remain stealth until 1932. James Chadwick was bombarding some beryllium with polonium, as you do, resulting in a very penetrating stream of radiation! It cannot possibly be this energetic...unless it had mass!

Take that neutron and bombard a uranium with it...something totally unexpected happens. The Uranium atom split into two other atoms and released 2-3 more neutrons. It was called nuclear fission, and those new neutrons released made it a possible chain reaction.

Enrico Fermi: Sounds fun. Let's build the world's first nuclear reactor under a squash court at U of Chicago. YOLO!

1.1.3: OK we all went to high school so we know the nucleus contains +ive protons and neutrally charged neutrons, about the same weight. They are orbited by much lighter -ive electrons. Number of protons determine what this atom IS. 2 protons? It's a Helium.

If we ionize it, it's a Helium ion and now has a charge. If it has more or less neutrons than normal? Then it's an isotope. And we'll call it helium3 or helium 5 depending on the number of nucleons (protons+neutrons). Can an atom be an ion AND an isotope? Duh yes!

"Hey there, I'm Helium 5. Some say I'm a little negative with a couple extra electrons hanging around, but to me that just means we're a reaction waiting to happen, girl. Isotope/ion."

That's everybody, right? Wrong. There's one last particle. Elusive, almost massless, traveling almost at the speed of light and can ionize. It's the neutrino, and its anti-matter cousin the anti-neutrino. Try to pick up these guys in a Geiger Counter? **Laughs in neutrino**

1.1.4: Ya kinda need to know your isotopes. Boron 10 vs Boron 11 is just one neutron apart, right? But that changes their affinities where one absorbs neutrons more than the other by a factor of 1,000! Good to know for controlling neutron population in light water reactors.

1.1.5: Alpha decay, as previously discussed, is but a plus-2 charged helium nucleus. Beta decay? Just an electron, but one that CAME FROM THE NUCLEUS (v important). Gammas? Just a very high-energy proton.

Here's a classic banger of an alpha decay that never gets old...the classic Americium-241 into Neptunium-237, plus an alpha particle, or, y'know 4-2 helium:

The Q value of this alpha reaction, or amount of matter turned into energy, is 5.638 MEV

Here's an example of a beta decay, Strontium-90 to yttrium-90. Notice: number of protons went UP because a neutron up and transformed into a proton, an electron and an anti-neutrino!

Sorry green marker should be neutron+proton ie total number of nucleons.

And here comes Gamma decay! Note no stable nucleus just throw off a high energy proton for no reason. Here we have a molybdenum-99 beta decaying into a technetium-99 metastable. This is an excited isotope that hangs around for about 6 hrs before giving off a gamma ray.

Finally there's spontaneous fission but I'm outta markers. Let's say californium-252 fizz into two products plus a few neutrons. Likelihood? Maybe 3% only. But that's actually considered high, making californium-252 a good source to jump-start nuclear reactors.

1.1.6:
Alpha decay: 2-5 MeV
Beta decay: almost any energy from a few KeVs to 2MeVs
Gamma ray: typically a few thousand KeV to 1 MeV

Reminder:Kev is "thousands of EVs" but MeV is "millions of EVs." BIG DIFFERENCE!

Neutrons:1-14 MeV they can cause fission events and do damage

Lone protons don't occur in nature but can be induced from nuclear reactions.

Those bad boys are heavy like a neutron and reactive like an electron! Sound dangerous? Yes but also perfect for nuclear medicine where you want to blast a tumor to smithereens perfectly targeted.

Every particle has a corresponding anti-particle but for whatever reason the one we usually see is the positron, or bizarro-electron. You find it in bananas or road salt. You know...stuff with potassium-40.

Then there are the fission products...super heavy, don't go far.

Finally we have the family of high energy protons that can eject electrons out if an atom. This is the photoelectric effect, where photons with just 4-5 eVs can cause electrons to be ejected. This is what won Einstein his Nobel prize btw, not E = MC squared!

1.1.7 is literally just a reminder for the fourth or fifth time in this course that only electrons that come from the nucleus are betas and only photons that come from the nucleus are gammas. We got this, dude!

1.1.8 heavy submodule incoming. Chew on this for now, those of you following at home:

To do your nuclear reaction equations, balance is everything. Mass (number of nucleons) is conserved. Energy is conserved. Charge is conserved.

To me, this is where this course got mean. Here's an equation for the beta decay of tritium. No more nice reminders of how many protons hydrogen has (1) or Helium (2).

E=mc squared is a formula easier memorized than internalized. But let us hold on to Q...he is matter, he is energy. Whatever change went on from the left side of the equation to the right side IS Q! At least, I think this is helping me thru some mind-breaking concepts.

Nuclear reactions can also take place in a series of steps like a waterfall going through a series of pools. Each drop of water will stay but not remain in each pool, and there are multiple ways down to the ground state. You can look up the possible paths in charts.

In the most likely set of decays for Cobalt-60, something like 99 percent, it's gonna go one beta emission, one electron emission (like a gamma ray kicked an electron on the way out) followed by two more gammas to get down to the ground state.

So far we talked about how heavy isotopes decay. But how do those heavy isotopes get created from a ground state isotope? Short answer: bombard with neutrons. That's how Cobalt-60 is created from Cobalt-59.

I think it's time to call it a 🧵 only 3 submodules left but they're all equation heavy. I've done all the homework but hard to tweet them so that it's not one tiresome equation after another! Or I might not tweet them and focus on actually learning the next module!