Observatory Version of Misc Musings, Ravings, and Random Thoughts

[Dmytry]

I found exactly the anekdote in Surely You're Joking, Mr. Feynman, you can find a PDF online (which is apparently completely cool in the age of AI).

Notable parts of the story: it happened at Oak Ridge, and Emil Segrè was the one who originally went there for another reason (not Feynman as I misremembered) and he noticed all the scary shit they were doing with tanks of solution. They had no criticality safety whatsoever because the Army figured there was never to be more than a critical mass on the plant at one time. They had hazards with solutions, but also hazards with dry powders in boxes, presumably wood etc would act as a moderator. They resolved this by adding cadmium to things.

You can find the right chapter by searching for "Emil".

edit: and it was indeed uranyl nitrate (uranium nitrate in old terminology).

edit: and other thing to note about all that business is how a lot of it, like uranyl nitrate, was also extremely toxic.

As I understand in the short term and acutely, for uranium it was genuine chemical toxicity. Unlike for say radium for which even the longest living isotope is nowhere near as chemically toxic as its radioactivity. (Although I am not 100% sure for uranium 235 which is shorter living and all that)

The question of chemical vs radiation toxicity is one of those things that sound like "hmm, pilosophical", but (in most cases) is easily resolved by comparing different isotopes. I spend way too much time gazing into the abyss of radiation biocrackpots, and they often do a "prove me wrong" thing about chemical toxicity of radium, expecting it to go as if the question is unknowable, and not as if it had been settled in the most straightforward way forever ago.

 

[Dmytry]

Uranium is chemically toxic and there are regulatory limits related to that toxicity. I think it causes kidney damage.

What I mean is that for natural uranium the chemical toxicity would have been the primary concern, but I'm not sure that's true for enriched uranium. U235 is more radioactive than U238, plus there's U234 (also an alpha emitter) being concentrated too (from initially same activity as U238). So enriched uranium would be equally toxic chemically, but much more toxic radiologically, than natural.

edit: Little Boy had 80% enriched uranium on the average, and if U234 was enriched with U235 , I figure it would make it output >100x more alphas than natural uranium? I don't know if that would eclipse the chemical toxicity, but seems plausible that it would.

 

[Dmytry]

At the Christmas party, in-laws did a white elephant gift-stealing thing with an Amazon returns box. It was great fun, and oddly enough, I got something radioactive:



I didn't even have to "steal" that from anyone, it was in the bag I opened. How random. I was also the only one at the party who knew it for what it was, because of being entirely too online.

About 300 CPM with beta-gamma SI-22G Geiger counter. Checked it with a small homemade scintillation counter (using one of those Hamamatsu r7400u tiny photomultiplier tubes and 5cc or so CsI), looks like thorium. (On the x axis is not energy but bin number, still needs to be converted to energy. The device is a bit temperature dependent).

On a broader note, what a perfect specimen of the opposites day, counter science push of 2020s.

Back in the day "anti radiation" just did nothing, maybe had a foil backing so its technically true. But since its opposites day in pseudoscience, "anti radiation" has to be radioactive.

edit: Also what timing, too! Before Christmas I started building a bigger gamma spectrometer using a much larger NaI:Tl crystal, eventually with temperature compensation, adjustable supply voltage and all that jazz.

 

[Dmytry]

Wow, that's a pretty "hot" random gift ;-)

I think I remember an Arsicle or Civis thread about most of these Amazon anti‑5G necklaces, bands or stickers containing thorium, so that might validate your spectrum once you get it.

At the very least, you might have gotten yourself a free calibration sample ;-)

One bit of advice – you might try to reach out to your local or federal radiation control agency to get it measured on their expensive fully calibrated spectrometers. They might even do it for free if it's a new item for them, like ours (EU) did for my old thorium glass 1970s photographic lens – they were just really interested in getting a spectra and an estimated total Bq amount in something that was new for them, being the same geeks that we are...

In the end, if it's safe enough, you might repurpose it into an ionised anti‑static brush I guess?

I think NRC went after them last year. Don't sure if they have the staff to do that any more.

I saw some videos on Youtube of far more radioactive quack nonsense, disks that you are supposed to wear as pendants or put on your head while you sleep, eyemasks and pillows with radioactive dust, "male power rings", the whole shebang like its 1925.

NRC said:

However, wearing pendants continuously can result in an elevated skin dose due to beta radiation, so you should limit the time you are exposing yourself to radiation. The Dutch National Institute for Public Health and the Environment conducted similar assessments and concluded the estimated skin exposure exceeded the Dutch and International Atomic Energy Agency limit for local skin equivalent dose (50 mSv per year). Analyses conducted in Malaysia showed similar results for several bracelets and necklaces.

Based on the count rates I seen on youtube I'll believe that some items are way over 50 mSv / year to the skin (although not the one I got).

What blew my mind the most, something that someone else found, is that the reason this shit is so radioactive is that there are Geiger counters re-branded as "negative ion counters" that are used by the vendors, so they wouldn't be "scammed" by their suppliers. Here's a premium one. This is very fascinating. Where do they get the Geiger tube, looks like a nice pancake alpha beta gamma tube? Do they just rebrand some radiation detector, or is it a whole actual product branded like this from the start?

That is apparently why most of that stuff really is radioactive and not just fake. The whole site is fascinating. They sell 3 micron Tourmaline dust (a very hazardous particle size), and various sleep items made with that dust (like mattresses / blankets). I don't know how radioactive their dust is but it is a prime silicosis hazard. They said that it works better than typical 50..60 micron dust!

You'd think they'd have foil backing in the stickers and technically wouldn't even be lying about blocking EMF or whatever, but no.

I think there's mens rea of a crime somewhere behind it all. Maybe an old crime (but not radithor era), a cold war psyop campaign to get ahead of opposition to fallout from atmospheric testing. Maybe an ongoing thing.

 

[Dmytry]

Ouch. And I fully hope the respectable agencies fully went after them.

Just for comparison, the thorium glass photographic lens I had measured at the agency was in the end legally considered as a "minor source", meaning unless I use it for a pillow or a camera eyepiece for a decade or so, it's quite safe. Unlike most of those unregulated gadgets.

I think it really depends. The thing I got really isn't dangerous, however you slice it "5x background" and most of it beta, isn't much. Only about 2.5x background count rate to my tiny CsI scintillator (which is not beta sensitive).

But I seen things on Youtube go up to 3000cpm on a counter that only gets 40cpm background.

Of course, the whole body equivalent won't be much, but locally to the skin it is a lot, and there had been incidents of contaminated gold jewellery. It is an interesting case of how even when the whole body dose is low enough that one could naively expect cancer risk not to be statistically significant, and thus to be able to tout threshold model or even hormesis (if for some reason those rings were correlated with wealth and thus longer lifespan), the background incidence of cancer on precisely this location on the exposed fingers is extremely low, and thus even minor increases in lifetime cancer rate are detectable. It also has a potential relation to e.g. radioactive insoluble dust exposure, although in the latter case the mass of exposed tissue is a scatter of small dots.

edit: some rather hot disk on Youtube:
View: https://youtu.be/UgPMtmtHGhs?t=173

Also there's metal pens which sometimes contain nothing and sometimes contain fine thorium dioxide powder. Which is presumably hazardous to inhale.

Doses are hard to estimate since a lot of it is hard beta. Note that red fiestaware can be that hot, but it is very non powdery, and is not worn against the skin continuously. And radium dial wristwatches have small activities, on the order of 0.1 uCi (3700 Bq), and your arm is shielded from beta radiation by the watch.

 

[Dmytry]

Not sure how old hardware compares to new hardware. New stuff tends to have higher and higher dopant concentrations which could instead make it less prone to permanent damage from the sheer radiation dose. And as far as transient effects, space hardware is designed not to have latch-ups that can damage it.

At the end of the day, there's always galactic cosmic rays whose energy range extends well past solar cosmic ray energies.

I'm thinking that for satellites the biggest problem would be getting hit with very high flux of relatively low energy solar protons, not with exceptionally high energy solar protons. Not to mention that Earth's uppermost atmosphere would heat up a great deal, increasing drag.

 

[Dmytry]

So the new nuke tech fusion thread reminded me of something I wanted to do, that I have all the parts for.

Allegedly, sparks in atmospheric air can produce some x-rays:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2008JD010315

Now granted they had fast rise time, and I have a Van de Graaff generator that charges slowly, but I am specifically curious if 1: xrays are still produced without fast risetime (there's gotta be fast rise time somewhere in the air), and 2: I can probably get fast rise time on a second gap, with some additional spheres and rods (just having VDG discharge into a nearby isolated terminal that then discharges into grounded terminal, may work)

First I need to finish and box up my bigger scintillation counter, though.

 

[Dmytry]

I was thinking about putting this in the SpaceX thread here, but no.

spaceweather.com has a rant about Starlink streaking astronomical photos - this is what it looks like today. I don't observe or do any astro-photography any longer but if I did ...

View attachment 129237

the commentary Dr. Phillips writes is good.

Probably a self solving problem, eventually... if we don't get Kessler syndrome, this will be literally the first time our species had avoided a new technological disaster or mishap without having to learn it the hard way.

 

[Dmytry]

The other thing is that for higher bandwidth you need higher signal-to-noise ratio, and you need all the right high bandwidth electronics for processing the signal on the receiving end. So let's say you have a radio telescope pointed there, and you have your signal, but you have to have it converted to a digital form and, instead of being simply stored to be analyzed later, do all the DSP on it to get the binary stream from what ever ADC you're using, that you can then process as usual.

Or you need to somehow cobble together the electronics to feed the analog signal from the radio telescope to some commercial off the shelf receiver, which is also not so straightforward.

Either way it'll require a bunch of work just to enable that 4k live stream. Because none of the equipment you actually have is built for that use case, and because high quality video is close enough to the edge of what's doable with specialized electronics, that it is hard (albeit not impossible) to deal with using any general purpose electronics and computing.

edit: to put some numbers on this, with an IPhone at 4k 60fps thanks to wonders of modern video compression, you get something like half a gigabyte per minute, or around 67 megabit per second, so that should be somewhere within range of what's doable by a modern digital receiver on a radio telescope, but still high enough to where it isn't super easy to do all the DSP stuff on it. Additionally, well compressed video is pretty fragile and ends up either with nasty looking block artifacts or needs a fair bit of error correcting data.

All in all I wouldn't necessarily expect a perfect 4K 60fps live stream from there. It's possible, and it is doable, but it isn't straightforward. I worked on projects where live aspect of them was deemed non essential and then horribly mismanaged and the resulting system just couldn't work live, even though it was technically very doable and accomplished by other smaller teams. And NASA doesn't have an unlimited budget.

I think a slightly glitchy 1080p is fine.

 

[Dmytry]

I would like to introduce you to O2O. Optical to Orion. We can do 4k live streaming.

https://www.nasa.gov/goddard/esc/o2o/

https://www.ll.mit.edu/news/lincoln...nal-launches-historic-artemis-ii-moon-mission

260 megabits/sec downlink.

Ok that’s actually pretty cool. I didn’t expect they would go for optical because it requires very exact alignment, and you have diminishing returns on usefulness of things like live 4k 60fps video (as opposes to eg saving weight or improving robustness or the like).

After all, the original Apollo did not send a live stream at a comparable or higher quality than what then-typical TV would display.

 

[Dmytry]

The live stream isn't exactly 4k 60fps ... this is a radio link, presumably? Does it need to be landed on the moon to be able to stream 4k?

 

[Dmytry]

I generally try to memorize the map before I go anywhere, along with whatever could be useful for navigation.

In completely unrelated to the above: I built a prism spectroscope, and was looking at my LED bulbs and most of them have what you expect, a broad blue and a broad green to red.

Some bulbs, however, have 5 well defined emission lines on the red side of the spectrum:



A pair in orange, a pair in red, and another one deeper red. edit: also funnily enough my computer screen's backlight has the same spectrum, so I can look at this spectrum with the spectroscope and see this spectrum.

(Taken a picture with an IPhone held to the eyepiece, hence the atrocious quality. Looks much better with my eye. I need to 3D print a camera adapter so I can take a decent picture).

I wonder what that is. Europium or other rare earth doping in phosphor, is my guess.

 

[Dmytry]

Keep in mind a lot of modern LEDs for mass production now have QD phosphors too. It's not necessarily reducible to elemental absorption/emission spectra anymore.

I kind of doubt they'd have QDs so perfect they make a narrow line (edit: when its probably not even desirable).

 

[Dmytry]

Picture of said spectroscope:



I bought a 32mm Eisco labs dense flint prism on Ebay, and took apart some very crappy 12x20 binoculars for all the lenses.

I used reflection from a sewing needle instead of a slit (which is a known trick in astronomy circles, apparently). On the right, the 90 deg coupling looking thing is the housing for the needle. With a extra mirror, I can make it into a direct viewing spectroscope.

I'm thinking of designing a whole optics learning kit, inspired by "Konstruktor-Optik" kit I had (which I used in a spectroscope build many many years ago, using an aquarium-like prism I glued from glass and filled with water).

With 3D printing I would be able to adapterize random lenses, old webcams, etc etc.

Interestingly, a lot of spectroscopes have optics pivoting around the middle of the prism, which is both mechanically and optically awkward. The collimating lens and the scope should revolve around the centers of respective prism faces.

 

[Dmytry]

Looked more into the red lines in modern LED spectrum, it may be this:

https://luminusdevices.zendesk.com/...duction-to-KSF-Phosphor-LEDs-Luminus-LUX-COBs

Quite interesting. I was thinking it would be lantanides or something, inner shell transitions shielded from all the interactions that normally broaden spectral lines of non gases. I wonder how K2SiF6: Mn4+ would get such narrow spectral lines.