Interestingly just within the past few years, a few small scale gem cutters and dealers have realized that the companies making this material have failed boules and offcuts that they will sell very cheaply which can be turned into highly unique jewelry with stupendous qualities of ultra bright fluorescence, extreme color play due to high index of refraction, and incredibly long lived (many hours) phosphorescence. Specifically House of sylas and Angry Turtle Jewelry in the US are essentially creating a whole new market around synthetic crystal jewelry usually involving things like BGO, lutetium-yttrium oxyorthosilicate, and lutetium aluminum garnet. If you search for these terms or their names on social media you can see examples of some really fantastic material they're making.
My wife has a set of earrings made of less-than-perfect ruled diffraction gratings, which have drawn many compliments over the years. Not commercially available, sadly.... 😎✌️
@@liesdamnlies3372 Yes, think of that item as an oven thermometer to tell you when your goose has already been cooked. The photomultipliers they're typically attached to have an amplification factor of something huge like 100,000 and they are looking for single photons so don't expect your eyes to have similar sensitivity. Side note: if you power up a photomultiplier tube in room-light, you'll cook it.
It's worth mentioning that a pair of photons emitted during during a positron/electron annihilation travel away from the point of the annihilation at exactly 180 degrees. The system detects each pair of photons as a 'coincidence', allowing the system to reconstruct a straight line between the two scintillations that were detected. More advanced systems also process 'time of flight', whereby a tiny delay between the detected scintillations indicates the position along the straight line that the annihilation took place. Sorry if I'm boring you, but I found this relevant since other nuclear medicine tracers such as TC99m or I131 don't exhibit this unique property.
aktschualllllly it's not exactly 180° since the position is usually moving during annihilation, lorentz transforming back gives you slightly less than 180° and introduces an error source
A couple minor details to note. When one of those 511 keV gamma rays undergoes photoelectric absorption in the crystal, the gamma ray disappears and all of its energy gets put into the photo-electron. On the other hand, you have another phenomenon that can occur called Compton scatter, where the gamma ray does bounce off with lower energy, but having given some of its energy to an electron. Both of these processes occur in scintillators, with Compton scatter becoming more important for lighter elements and higher energy gamma rays. Second, the valence band of a scintillator is all full up of electrons. When an electron is excited out of the valence band, it leaves behind a missing electron (called a "hole") in the valence band. The hole acts like a particle, in that it can move around and carry charge (although as you might expect from something that is a missing electron, it carries positive, not negative, charge). In order to generate scintillation light, the conduction electron can't just fall back to the valence band anywhere, because as mentioned the valence band is all filled up and there's nowhere for the electron to go. Instead, the conduction electron needs to find a valence hole, so there is a place for it to fall down in to. When it does encounter a hole, it can emit a scintillation photon as the conduction electron and valence hole recombine.
also: you often get multiple excitations per photons, that's why some systems even add additional WLS crystals to convert the blue LYSO light to green for better detection (eg that insane CERN ToF PET project using axial instead of radial scintilators)
what is the band gap for these crystals? Recombination need not be slow but the shape of the fermi band is going to be critical. What are the crystal structures of these compounds?
Also I think there is one more condition a scintillation crystal has to fulfill and that is high light transmission. It needs to be as transparent as possible basically so the light can get to the PMT or Si detector without much attenuation or scattering.
same theory on why scintillation detectors work...Are you a Health Physics Tech or specialist by any chance? You sound like a bored HP tech explaining detector theory to a junior....;-)
@@TheRadconranger I'm a physicist that has worked for more than a decade now in the field of radiation detection and material science (usually material science as applies to the electronic excitations from radiation detection). My thesis work was looking at the electronic excitations in condensed matter which you get from x-ray absorption. I work at a U.S. national lab (PNNL) where we worry about things like detecting smuggled nuclear material, scanning spent nuclear fuel, building new x-ray machines for emergency response or airline security, and other stuff where detecting high energy radiation is rather useful. Obligatory disclaimer - in this reply, I am speaking as a private citizen and not in any official capacity on behalf of PNNL.
I was disappointed to learn that if I undergo a PET scan or radiation for cancer treatment, I don't get a t-shirt saying "I've been irradiated. Where's my superpower?"
One driver for fast and bright scintillators is time-of-flight PET with coincidence time resolutions below 500ps. This was what LSO/LYSO scintillator made possible, as they produce enough photons in the beginning of the light pulse to enable this time resolution (LaBr would be another candidate, albeit with higher scatter fraction). It would be a topic on its own, but it may be interesting to mention the recent transition from photomultiplier tubes to silicon photomultipliers, and the "10ps PET challenge".
since 500 ns at light speed (time of flight) is 150 meters, I'm guessing you meant to write "500 ps", which means 0.15 meters. 10 ps give 3 millimeters.
@@crackwitz yes, I meant 500ps not ns 🙂 CRT of 10ps would potentially eliminate the need for reconstruction as the voxel size is in the order of 3mm, though that depends on system setting and application.
You should do CT scanners and MRIs next! I was born with Osteogenesis Imperfecta or brittle bones and I can’t tell you how many countless MRIs and CTs I’ve had in my day. Super interesting 10/10 as always buddy ❤
You can also find scintillation crystals in xray equipment. Some facilities that are older or in poorer areas use computed radiography, which was developed due to its ability to easily obtain a digital image with minimal changes to a older traditional film systems making it a cheap upgrade. You fire the x ray beam through a target and when the beam reaches a phosphor layer to store some of the energy. They the shine a laser on it one row at a time which releases the stored energy as visible light. They then have a photodetector to read the signal and construct the image. You also see it in some fully digital xray radiography systems and CT scanners. Where the xrays are converted into visible light and the signal is captured with photodiode on an amorphous selenium or silicon layer. There is also direct detection as well there they measure liberated charge inside a substance but could require higher radiation dose because of the weaker signal from this method.
That's the method they used when they diagnosed me with Gastroparesis and imaged my digestion after I ate a meal of radioactive scrambled eggs and slice of bread.
Other neat applications: detectors in astronomy and particle physics and for tissue equivalent dosimeters. PMMA is a scinitlator (though a bad one) and happens to interact with xrays very similarly to water. So you can readings for radiation doses that require a little less guesswork/conversion to convert them to the dose which tissue would receive.
Great video! Small correction, your images of yttrium lutetium and cerium say they have a melting point of 2,400c while you say they have a melting point of 24,000c. This might be confusing for people who are only listening to the video.
@@41chemist19 I was gonna mention it if you didn't. People get stuff like this wrong all the time in presentations and generally you want to hear about it sooner rather than later. I corrected a professional chemist who kept mistakenly saying "glyphosphate" instead of "glyphosate" and that kind of correction is just a matter of professional courtesy. Letting it go without commenting on it would be disrespectful. Letting it go is basically saying "you're not smart enough to ever get this right so why bother correcting you?"
FYI: if you want to see scintillation (and check the UV absorption of your windows), get a gatorade bottle safely plastic seal: in sunlight it will emit bright violet light out of the sides: that is UV converted to visible via scintillation. Works best on a low-cloud day. You can also put tonic water in a black light, it will glow blue...same color as Froto's sword.
That is fluorescence, not scintillation. If you want to see scintillation, look at the luminous hands of an old radioactive watch with a strong lens, you will see the individual scintillations of the alpha particles striking the phosphor.
@@karhukivi where I’m from scintillation is fluorescence, and phosphorescence is delayed fluorescence, unless it is microwaves, then scintillation is speckle noise
@@DrDeuteron Most scintillators will also fluoresce . But if for example you have a ZnS screen and bombard it with alpha particles, there will be a succession of flashes which translate into pulses in a PMT. I would not consider that as fluorescence. A bit like the distinctions between killing, murder and dying, it depends on the circumstances!
11:41 perks of playing Geoguessr: seeing that black/yellow spiral warning pattern on a utility pole and immediately thinking that's Taiwan! (If the lines were straight vertical, it would be Japan. If spiral but positioned over the ground, South Korea. If no warning pattern but pictures of the Dear Leader everywhere, North Korea.)
It is super cool to hear someone else talking about these things! Really nice coverage too--I only get to make ultra short videos but there is so much more to tell about these things. I feel like the story of having to develop an entire market and processing pipeline for lutetium so they could make enough LSO could make its own miniseries.
Wow this is insane. I'm a researcher for PET and at 7.53 seconds, this PET scanner is the JPET. It is design as plastic scintillators rather than crystal (reduce cost and easier to work with) and because of that the dominant interaction is Compton scatter, at the density for plastic, and so they needed multiple layers of the plastic scintillators for it to increase the sensitivity (fraction of gamma photon detected to gamma photon emitted). The image shown at 7.53 s is of the first generation prototype where it is using the photomultiplier tubes with lots of gaps between scintillators while the second generation has less and smaller gaps and uses SiPM modules. The most insane part is that I was there for a conference meeting in Krakow at the end of April and they showed everyone around the labs and of these prototype scanners. Now I see it on a video of someone I subscribed to on YT.
Just one quick comment, the term "aromatic" when talking about organic scintillator crystals doesn't mean they're smelly. It's a chemical property involving the electrons in certain ring structures (pi electrons in resonance). Admittedly, many of the first studied aromatic compounds (benzene for example) did have distinct odors, but as a general term its not a requirement.
Remember finding a PET scanner at s junk yard that had the 4 section square PMT tubes and the BGO scintillating crystals. You can change the resistors on the end and make a position sensitive radiation detector with one.
you overlooked a major problem in PET scanners: higher resolution sensors don't create higher resolution images. the resolution is already now limited by the random time the positron takes to recombine with an electron!
LYSO/LSO are definitely on the soft side, but fortunately other scintillators like Ce:YAG, GAGG and LuAG are all pretty durable and can even work as ring stones.
I have a gigantic version of those crystals sitting on my desk right now. Found the whole detector in the trash a few years ago. The PM tube is also still somewhere downstairs in my workshop
@@gus473 Yes! They make the best PMs, Scintillators and Scintillator based detectors. I think they have silicon detectors too. They used gallium a lot I think.
Very happy the topic ended up working out for a video! After your polite email response and no content on it for so long I assumed it was deemed not a good fit :D 6:59 3D PET is probably supposed to refer to ToF PET here? PET is pretty much always reconstructed in 3D, that's why you typically limit yourself to coincidence measurements where both 511keV photons are detected.
didn't you see what happened in 2020 just because 5% of the population had to go to the hospital at the same time ? imagine if it was higher than that, under funded is selling it short, its way more underfunded than that
To get a higher spatial resolution, SiPMs are the way to go. They're very cheap compared to regular PMTs, but the measurement equipment to get a signal out of a large array is very expensive. My lab wanted a 12" diameter array of SiPMs but the cost would be at least in the tens of thousands of dollars.
Well, literally scintillation means sparkling, because in Latin and then Italian "scintilla" means spark. It seems that it has a common etymology with shine.
I have the second sight i know excatly what next weeks topic will be: 'The failure of the terranian lightsabre-industry and why corrosant is dominating the market'
BTW, using E=MC^2 works well to calculate the energies of those two anti-parallel gamma photos. It's a good exercise. There are TWO photos created because the net momentum must also be brought to zero by two photos moving in opposite directions.
I am endlessly fascinated with MRI machines. I’ve had a dozen or more MRI scans due to my arthritis. I had NO idea that a PET scanner was that different! That was a fascinating episode, thanks so much. It is wild to me that chemical scientists can create so many different compounds of materials.
A bit nit-picking I know, but 511 KeV radiation is not "high-energy" gamma radiation, rather it is on the low end of the gamma radiation range of 300 to 3000 KeV.
I have worked in medical image (DICOM) processing software for years but i did not know about PET, only the calssical modalites like CT or MRT. So this machine is basically an Antimatter-Gun firing anti-electrons?
I've never heard vrom something like this. Thank you for giving me a look inside a, otherwise undetectable, world of technology. Thank you! (not native speaker, sorry)
😅 I know just enough to now have a new fear of/reason to avoid this procedure 😆 no desire to inject myself with anything, let alone something radioactive 😂
I saw this very interesting and informative video (thanks!) and ordered some raw materials from turtle hoard (angry turtle). But I must say they are now far away from cheap, especially for the european customers. (the cheap samples are out of stock) Nevertheless the have very rare materials and I hardly can't await my order 😊
@@pierrefaucon2875 Ohh yes god bless you for saying so because without saying so what would you be saying so god bless saying things and being able to speak and god bless god for making vocal chords and god bless propagation mediums and god bless ear drums because without them all we would perceive is whatever rattles around in our sinuses so god bless sinuses and epithelial tissue
I see that You successfully use Artificial Inteligence in Your scripts. Its opinion of us disgusting organics scintilates through... Organics smell, right? 😂 Great Matrix reference, threw me for a loop for a second... 😅
I kinda assumed the smell comment was about how the crystals are mostly comprised of aromatic hydrocarbons (aromatic here referring to a chemical feature, not smelliness)
You said 24 thousand degrees celcius but the video shows 2,400 degrees :) It's not that much higher than platinum or titanium. Not sure why the surface of venus is a good thing to compare it to. Tungsten's melting point is 3400celcius
Jon is amazing. but we can see/realise, he's itching to do new ground. I reckon, Jon, just to stretch your brain legs.. do an ANTI series... "this fake chip maker claims this but in truth it's more like ...." use your research skills for investigating DARK purposes. "Asianometry DARK" channel .. i'd subscribe in a blink.:) Thanks. As always.
small correction: you said 24000 °C instead of 2400 °C. that would be an impressive melting point. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-XpYYGiUX0x0.html
At 4:30, "visible" is irrelevant since photomultiplier tubes (and NOT our eyes) detect the flashes. However, the photon given off by electron-hole recombination has enough energy to excite another valence electron into the conduction band. Thus, the scintillator crystal is opaque to these photons and that is why we dope the crystal with thallium. Eventually, a conduction band electron will excite a thallium atom. Since thallium emits at a slightly lower energy, these photons can no longer excite the crystal and the crystal is transparent to them allowing these photons to reach the photomultiplier tube.
I went to a factory in the US that grew them. Two independent power companies supplied the site, and they had this ginormous UPS. Why? Because an interruption to the power would interrupt the crystal growth and would ruin a whole batch. The guy handed me a crystal - it looked like glass but weighed like steel. "Careful! That's worth like a BMW." You should also see the wiring inside a PET scanner. Truly amazing technology.
I work in scintillator manufacturing. Not sure if that was our facility, though, our power flickers far too often 🙄 we do have a gigantic UPS and a massive natural gas generator though to keep the furnaces running for that reason. I heard once of a research facility that was growing extremely sensitive crystals that would be ruined by even the brief interruption before the generator kicked in, and it had a giant flywheel that would keep everything running just long enough to bridge the gap until the generator kicked in.
So at 11:57 you said 24000°C but the screen says 2400°C. That's obvious. But then you say it's five times the temperature on Venus. If you measure it in Celsius, it seems correct. But absolute Celsius cannot meaningfully be multiplied because its zero point is arbitrary. So better to use Kelvin then in which case is about 3.5 times, not 5. To be clear, when using Fahrenheit you get a different multiplier than Celsius because its zero point is just as arbitrary as Celsius. Five times as hot only has meaning when measured from zero heat. It's like saying a 6 foot table is twice as long as a 5 foot one, but you don't measure the first 4 feet. A table that's twice as long as another is that in any measurement, feet, thumbs, arms-lengths, miles, etc. In Celsius you don't measure the first 273°C (which is °K, when used relatively, since one °C is as big as one °K).
↑ This (One does not simply divide or multiply degrees °C. ) However.... if it happens we're talking about the temperature for nuclear fusion, some millions of *degrees* the units don't matter very much, since 273.15 is rounding error here, while Celsius and Fahrenheit differ by 9/5 which is less than an order of magnitude. 😛
