Regarding measurement, lasers are useful vs. standard light because lasers can have a specific wavelength or very tight wavelength range. You can then build a reciever that is only looking for THAT specific wavelength/s (either direct or from a reflection).

Also the light from lasers is directional, meaning the light is all directed in the same orientation, hence why lasers are a beam and not diffuse like a flashlight

Lasers can also be used in safety systems (and standard systems) as a "plane" that when broken (meaning something has passed into the beam of the laser, disrupting its unaltered flow to the reciever), it triggers something (like a shutdown, an arm to pick up the object, etc.

I would take source to be the largest point of entry, and point from where the radon gas diffuses out into say the basement. However, I see your point in that it's not like a heat source or lead atom generator that constantly acts like a "lead source"

From what I can see, the gas gets in via cracks/voids in the foundation so in theory you could take those points of entry as "sources"

Chemical engineer by education, Process engineer in a steel mill by trade (we manufacture electrical steel).

There are no metallurgical differences nor chemical differences to my knowledge. I work in decarburization (carbon removal) and finishing(we anneal then coat the steel in a non conductive coating), but talk to the metallurgists who control the heat chemistry and what they DO care about are

-Carbon

-Manganese

-Phosphorous

-Silicon

-Chromium

-Nickel

-molybdenum

-Titanium

-Copper

-Tin

-Aluminum

-Nitrogen

-Oxygen

-Lead

-Boron

Some of these are only present up to ~3% while others are on the orders of PPM (parts per million) or PPB (parts per billion).

To the original question, any one of these elements being out of wack can ruin the heat and make it a different grade of steel or completely ruin its properties. I have never heard of Iron 54 or 56 ever even mentioned regarding melt chemistries. So I would say this supports a lack of difference both chemically and metalurgically between the isotopes

This genuinely never came up in school even once, and I'm a chemical engineer! Very interesting concept, thank you! I'll edit my reply

It appears it would be useful for refrigeration or leak finding when combined with thermal imaging. Microleaks are extremely hard to detect even with leak detectors

For all things not including (Hydrogen, Neon, and helium) they usually will not cool down when compressed. That's not how pressure and temperature are related for most substances.

A perfect example is the ideal gas law PV=nRT

Where:

P= pressure of the observed system

T= temperature of observed system

As you can see, Pressure becomes divided by Temperature or vice versa (depending on what you're solving for), which means they are directly proportional (instead of inversely proportional, where if pressure went up, the temperature would drop)

Now, I can go more into detail as to WHY this physically happens (hint, temperature is a measure of energy in a system, as you compress a system things, they bump more, create more friction, etc.) but I did not want to just unload a ton of info if you didn't need it to answer what you are actually asking

Edit: accounted for the Joule Thompson effect as described below in comments

So this question has a few levels I would like to touch on so you fully understand what is happening.

1. Acids are generally described and referred to in the way in which they react when dissolved in water. This means when they are in solution with water. Ex. Hydrochloric acid is hydrogen chloride gas (a colorless gas at room temp) dissolved in water

2. The solubility of solids in water trends downward with temperature while the solubility of gas actually trends opposite. Meaning the amount of the compound that is the acid that can be dissolved in water (the concentration of the acid) changes with temperature, especially if we are talking talking a room temp acid then freezing the water

3. Once water freezes you're no longer liquid and you begin forming a solid crystal structure (ice). At this point lots of gas would escape as it freezes and solids will fall out of solution (while some would be trapped in the solid ice).

So for your question, say you froze a cylinder of sulfuric acid and placed it on a steel table. It would begin melting at the interface between the ice and the table (table is very large and warmer than the ice, it also transfers heat between the atmosphere and the ice much faster than the air). This interface will be cold but liquid and will begin acting as an acid (and produce heat, melting more water) which would lead to corroding the table.

Now assuming we place the cylinder in a cold, atmosphere controlled box on an actively cooled table to prevent the ice from melting. it likely wouldn't be corrosive at all to the table but you'd have to see how the materials of the solid may interact with the base acid material when not dissolved in water