Its actually a photo multiplier tube which first detects a photon and then produces more photons so that they can be counted and then they are counted.
Nice video! Correct me if I'm wrong, but it looks like the electron multiplier works like an image intensifier tube, except for the fact that there isn't a phosphor screen for the electrons to hit, but a gas filled chamber containing an anode and a cathode (like a Geiger-Muller tube). When the electrons hit the gas, it is ionized causing sparks to jump across, equalling gamma rays striking the crystal.
So bionerd aparently another nuclear reactor is in trouble and this time its in the United Stated. The Fort Calhoun Nuclear Plant aparently is in a level 4 meltdown and Obama has orderd a no fly zone im not sure how many miles away from the plant. Aparently the plant has sufferd a electrical fire and it affected the cooling pool for the spent fuel rods.. On top of that flood waters are now entering the turbine building from the near by river...
@1ownjoo2 There is no black out - I can get news updates from the UK. There is meltdown or equivilent level 4 incident either. No fly zones are standard at all NPP regardless of their operating condition. Seeing as the cooling issue was resolved in 90 minutes and resulted in a 2 degree temperature rise, anyone making "fukushima style accident" claims is hyping up a very minor incident. The reactor is designed to cope with floods. I see no cause to be concerned.
@1ownjoo2 Yes, but no level 4 incident is occuring or has been declared. And as I can find that out in ten minutes from the UK, along with updates from the last day or even a few hours ago, it's hardly a media black-out, is it? A level 4 incident, by the way, does not necessarily mean a meltdown has occured.
Hey bionerd what kind of degree's do you hold if i may ask.. You work as a radioloigical assistant or technition or something, and you are extremely smart. So you must have some kinda fancy degree right ?
What is the least amount of radiation to which these crystals can glow? I guess not at the level of natural background radiations of 0.01 uSv/hr dose rates?
nope, definitely not. not even at 1000 times the normal background radiation, flashes will be visible for the human eye. dose rate for this experiment was 30,000,000 uSv/h, or 30 Sv/h.
Photomultipliers are very sensitive to light; for each photon of light that passes, you can (in theory) get 10^(large-2-digit-number) times the input, or the maximum possible for the multiplier (whichever is lower) - so these are good for this kind of detector due to the sheer sensitivity.
Wow that's amazing, such a beautiful shade of blue too! (Though I'm sure the camera and my monitor ends up rendering it a false blue anyway, but I still like it!). Any flashes visible in the good crystal next to your glorious collection?
Soooooo COOOOL!!!! I always wanted to see this directly! Such a beautiful sky blue color! I've taken vials of scintillation fluid used in a liquid scintillation counter with large amounts of tritium added into it in a dark room for a long period of time, but I've never been able to actually SEE it scintillating at all. Now the only things left on my list to see are lyoluminescence and galvanoluminescence! :P
I have a question, can beta particles be detected in vacuum without the use of a dielectric such as a crystal, water or air to slow them down or to produce photons? If no, why? Seeing they are excited electrons more energetic than accelerated electrons. Do you know their speed in vacuum?
i wouldnt know how that would be possible, as "detection" of something is always a transfer of energy to a detector. in quantum mechanics, we even found that particles behave differently when they're "looked at" as opposed to when they're not looked at. look for the "double slit experiment".
@bionerd23 "in quantum mechanics, we even found that particles behave differently when they're "looked at" as opposed to when they're not looked at. look for the "double slit experiment"."
Yeah I am trying to understand the "double slit experiment" or how the wave function collapses. From what I understand it collapse when an EM wave front changes the speed and so its momentum and kinetic energy, reducing the wave properties of the particle, is the wave function reduced completely?
if i remember right, beta particles move near the speed of light in a vacuum; i dont remember exactly, i think at about 80% the speed of light. in a dielectric, such as water, high-energy beta particles can move faster than the speed of light for that given medium (water), and thus, lead to cerenkov-radiation. however, of course, the speed they travel at in water is still below the speed of light in a VACUUM; light only travels at "light-speed" in a perfect vacuum, too.
"Ionizing radiation, like people falsely call radioactive radiation"
So this detector is an x-radiation (gamma x-rays) detector, since x-rays are ionizing rays and not actual radioactive particles such as beta and alpha ones, right? I suppose it can't detect radioactive particles?
The electron accelerator is a cathode ray tube like the ones used on crt tv's I bet.
beta and alpha radiation is not "radioactive". it's "ionizing". alpha radiation, for example, is a standard non-radioactive helium (4/2 He) nucleus. that isotope is NOT radioactive. however, it is ionizing, as it carries a lot of kinetic energy and a +2 positive charge. however, once it got rid of the kinetic energy and acquired two electrons to fill the shells, it will be a happy, non-radioactive noble-gas atom and never undergo radioactive decay.
@bionerd23 Very interesting, thank you. Since light travels at about 0.03% slower than c in air, if you had high-energy beta particles in the order of 20.4 mega electronvolts could they produce the Cerenkov radiation in air and move at something very close to c, like at more than 99.9% of c? So if you had high enough energy particles could they move at c in vaccum?
@bionerd23 I know there is the argument that mass can't travel at c or faster, but the particles wouldn't accelerate to c, I suppose they would start off at c and have a complex mass?
as far as i know, they could only move close to c in a vacuum, but never at c, no matter how high the energy. at least thats what scientists currently claim - i never investigated it myself. :P
I don't know much chemistry, but I know that Thallium is supposed to be fairly toxic. Does that make those scintillation crystals dangerous to handle?
Have you considered baking the "bad" crystal to remove the humidity? It may also help to change the colour back to normal, since this yellowing effect is often caused by colour centres induced by ionizing radiation- crystal structure dislocations.
Some older camera lenses contain lanthanum and other lanthanides since it produces an excellent high index glass, and this tends to turn the lens brown for this reason. They can sometimes be "fixed" by irradiating them with ultraviolet light.
Wonderful! I really need to make myself one of those. The parts shouldn't be too expensive. If you have any good advice or good sources for components, I would love to know. Thanks!
sorry, i'm getting those from private contacts or educational institutes, mostly. the latter is where you may try and ask for old equipment, as especially the "broken" crystal as seen in this video is absolutely useless other than for "toying around" with it. such crystals are usually discarded.
@bionerd23 Ich werde sehen, ob ich das bekommen kann. Es kann eine Weile dauern, aber es würde sich lohnen die Jagd sein. Dank! Und ich danke Ihnen, google translate!
@7alex That is also the reason why scientists never did studies on the effects of these radio waves on the human body, because it has always been considered "common sense" within the scientific community. But when the public want answers, and science is mostly funded by the public, it has to be done. Many are though reluctant to waste their time, but major studies have been done the last few years, revealing nothing new. Anything else? (PM?)
@7alex The potential harmfulness of light depends on the frequency, we all know that gamma rays and x-rays can damage cells and cause cancer. (but breaking the DNA chain in those cells). So by this scale, which scientists have been using all the time, the light from all around you is 10,000 to 100,000 times more dangerous to your body than the signals from your cellphone. I did one mistake in the earlier post, I said "frequency" instead of "wavelength", which the numbers refer to.
@7alex The signals sent and received from your mobile phone is light, or electromagnetic radiation. This radiation has different intensities based on the frequency of the light wave. You have very high intensity light, gamma radiation, which is dangerous. And you have radio waves, which are completely harmless. Gamma rays are 10^-13 to radio waves which are 10^3. Visible or optical light is pretty intense at 10^-6. (continue)
@dado1802 They are not only accelerated, but also multiplied. The signal from one photon is way too weak to detect with ordinary optical sensors because of all the noise associated with them. So the PMT accelerates electrons so that they land on special electrodes and knock off more electrons that in turn knock off more electrons, effectively multiplying the intensity of the signal by several orders of magnitude, to a level that the counter can register.
Assuming it can be properly isolated from environmental contamination, could this material be integrated into a piece of jewellery such as a ring or necklace pendant? Seeing this video instantly made me think back to LOTR and Frodo Baggins' magic sword ... what if someone invented a necklace that glowed when radiation was near?
Also, just how much radiation DO you need to make these crystals glow?
I don't really know. But if they would visibly glow before you get to dangerous radiation levels, don't you think they would already be used as simple batteryless ionizing radiation detectors?
@superdau -- The glow makes me wonder if someone hasn't already done that. If they respond to low level X-rays, there's got to be a way to put one of these in a plastic capsule and use it to determine if one is being irradiated, basically this would be the opposite of a tritium light. From what I hear, though, cost might be a barrier as others have said these crystals are rare and expensive. There's also the lack of a measurement readout to consider.
Although I still have to wonder: would something like a radioactivity-detecting necklace not be useful in a high risk disaster area, like the Japanese nuclear exclusion zones?
@crimsonhalo13 The X-ray tube here was probably delivering a dose rate of HUNDREDS OF REMs per hour. You wouldn't get anywhere near that dose rate level in the case of the Fukushima disaster for instance, until you were inside the containment buildings standing next to the molten cores. And at that point, well, you're pretty much effed anyway. You wouldn't be able to see the glow from one of these things by eye outdoors until the dose rate was phenomenally high.
yes, absolutely correct. the dose rate for this experiment was very high, as the x-ray tube was very close to the scintillation crystals. in face, if it was a full body dose, this amount of radiation would make you sick with deadly radiation poisoning within about 10 minutes.
the dose rate was about 30 Sv/h, which is enough to kill you in just minutes (if it were a full body dose). usually, these scintillation crystals are attached to so-called photomultiplier tubes that will GREATLY intensify the emitted light, as it would otherwise not be possible to detect. with save / low x-ray doses, you cannot see any "glow" in the crystal at all with your eyes or a normal camera.
Very cool. I love the way you have access to expensive tools to display the underlying principles of operation of common tools.
Trodan101 2 months ago
Its actually a photo multiplier tube which first detects a photon and then produces more photons so that they can be counted and then they are counted.
Sangeet1903 4 months ago
Illy, Great video...
Steven Sesselmann
beeresearch 5 months ago
Nice video! Correct me if I'm wrong, but it looks like the electron multiplier works like an image intensifier tube, except for the fact that there isn't a phosphor screen for the electrons to hit, but a gas filled chamber containing an anode and a cathode (like a Geiger-Muller tube). When the electrons hit the gas, it is ionized causing sparks to jump across, equalling gamma rays striking the crystal.
TheLegoboy1997 6 months ago
can you make a video explaining all units used to measure radiation and some tips on what geiger counter to buy and there precision...
megamarko94 7 months ago
Kann ich die Szintillatoren zwischen 10. und 14. August in Finowfurt ansehen ... und vielleicht sogar eine Ausleseelektronik dran halten?
Tatzelbrumm 7 months ago
Heh, I like how the camera gets additional noise and the framerate gets choppy when the x-rays are on.
Do photomultiplier tubes in scint counters use a multichannel plate? Or is it just straight-up linear acceleration?
lollazers 7 months ago
did you modify your counter? if so how?
johnyz656 8 months ago
So bionerd aparently another nuclear reactor is in trouble and this time its in the United Stated. The Fort Calhoun Nuclear Plant aparently is in a level 4 meltdown and Obama has orderd a no fly zone im not sure how many miles away from the plant. Aparently the plant has sufferd a electrical fire and it affected the cooling pool for the spent fuel rods.. On top of that flood waters are now entering the turbine building from the near by river...
There is also a media black out now..
1ownjoo2 8 months ago
@1ownjoo2 There is no black out - I can get news updates from the UK. There is meltdown or equivilent level 4 incident either. No fly zones are standard at all NPP regardless of their operating condition. Seeing as the cooling issue was resolved in 90 minutes and resulted in a 2 degree temperature rise, anyone making "fukushima style accident" claims is hyping up a very minor incident. The reactor is designed to cope with floods. I see no cause to be concerned.
XtalQRP 8 months ago
@XtalQRP
There is a media black out...
Level 4 metdown is how its called, doesnt mean a meltdown is happeneing but thats what its called on the scale go look it up.
1ownjoo2 8 months ago
@1ownjoo2 Yes, but no level 4 incident is occuring or has been declared. And as I can find that out in ten minutes from the UK, along with updates from the last day or even a few hours ago, it's hardly a media black-out, is it? A level 4 incident, by the way, does not necessarily mean a meltdown has occured.
XtalQRP 8 months ago
@1ownjoo2 A level 4? Quick, call Jack Bauer.
lollazers 7 months ago
That was interesting! Thanks )
mdofxds 8 months ago
Hey bionerd what kind of degree's do you hold if i may ask.. You work as a radioloigical assistant or technition or something, and you are extremely smart. So you must have some kinda fancy degree right ?
1ownjoo2 8 months ago
What is the least amount of radiation to which these crystals can glow? I guess not at the level of natural background radiations of 0.01 uSv/hr dose rates?
svrkprabhakar 8 months ago
@svrkprabhakar
nope, definitely not. not even at 1000 times the normal background radiation, flashes will be visible for the human eye. dose rate for this experiment was 30,000,000 uSv/h, or 30 Sv/h.
bionerd23 6 months ago
Photomultipliers are very sensitive to light; for each photon of light that passes, you can (in theory) get 10^(large-2-digit-number) times the input, or the maximum possible for the multiplier (whichever is lower) - so these are good for this kind of detector due to the sheer sensitivity.
AgentCROCODILE 8 months ago
beautiful experiment, thanks
mcjhn 8 months ago
Nice video, where did you get this type of GM-counter? Thanks
XerxesArtifex 8 months ago
Wow that's amazing, such a beautiful shade of blue too! (Though I'm sure the camera and my monitor ends up rendering it a false blue anyway, but I still like it!). Any flashes visible in the good crystal next to your glorious collection?
AScannerClearly 8 months ago
@AScannerClearly
nope, nothing visible with the bare eye. it needs one hell of a dose. dose from x-ray machine was approx. 30 Sv/h.
bionerd23 6 months ago
Finally back :* I've been waiting far too long :D
Phacias 8 months ago
Soooooo COOOOL!!!! I always wanted to see this directly! Such a beautiful sky blue color! I've taken vials of scintillation fluid used in a liquid scintillation counter with large amounts of tritium added into it in a dark room for a long period of time, but I've never been able to actually SEE it scintillating at all. Now the only things left on my list to see are lyoluminescence and galvanoluminescence! :P
10mintwo 8 months ago
@bionerd23 wo kannst du deine gegenstände Röntgen?? Ist das nicht teuer??
Tririnityfirst 8 months ago
I have a question, can beta particles be detected in vacuum without the use of a dielectric such as a crystal, water or air to slow them down or to produce photons? If no, why? Seeing they are excited electrons more energetic than accelerated electrons. Do you know their speed in vacuum?
SuperFinGuy 8 months ago
@SuperFinGuy
i wouldnt know how that would be possible, as "detection" of something is always a transfer of energy to a detector. in quantum mechanics, we even found that particles behave differently when they're "looked at" as opposed to when they're not looked at. look for the "double slit experiment".
bionerd23 6 months ago
@bionerd23 "in quantum mechanics, we even found that particles behave differently when they're "looked at" as opposed to when they're not looked at. look for the "double slit experiment"."
Yeah I am trying to understand the "double slit experiment" or how the wave function collapses. From what I understand it collapse when an EM wave front changes the speed and so its momentum and kinetic energy, reducing the wave properties of the particle, is the wave function reduced completely?
SuperFinGuy 6 months ago
@SuperFinGuy
if i remember right, beta particles move near the speed of light in a vacuum; i dont remember exactly, i think at about 80% the speed of light. in a dielectric, such as water, high-energy beta particles can move faster than the speed of light for that given medium (water), and thus, lead to cerenkov-radiation. however, of course, the speed they travel at in water is still below the speed of light in a VACUUM; light only travels at "light-speed" in a perfect vacuum, too.
bionerd23 6 months ago
"Ionizing radiation, like people falsely call radioactive radiation"
So this detector is an x-radiation (gamma x-rays) detector, since x-rays are ionizing rays and not actual radioactive particles such as beta and alpha ones, right? I suppose it can't detect radioactive particles?
The electron accelerator is a cathode ray tube like the ones used on crt tv's I bet.
SuperFinGuy 8 months ago
@SuperFinGuy
beta and alpha radiation is not "radioactive". it's "ionizing". alpha radiation, for example, is a standard non-radioactive helium (4/2 He) nucleus. that isotope is NOT radioactive. however, it is ionizing, as it carries a lot of kinetic energy and a +2 positive charge. however, once it got rid of the kinetic energy and acquired two electrons to fill the shells, it will be a happy, non-radioactive noble-gas atom and never undergo radioactive decay.
bionerd23 6 months ago
@bionerd23 Very interesting, thank you. Since light travels at about 0.03% slower than c in air, if you had high-energy beta particles in the order of 20.4 mega electronvolts could they produce the Cerenkov radiation in air and move at something very close to c, like at more than 99.9% of c? So if you had high enough energy particles could they move at c in vaccum?
SuperFinGuy 6 months ago
@bionerd23 I know there is the argument that mass can't travel at c or faster, but the particles wouldn't accelerate to c, I suppose they would start off at c and have a complex mass?
SuperFinGuy 6 months ago
@SuperFinGuy
as far as i know, they could only move close to c in a vacuum, but never at c, no matter how high the energy. at least thats what scientists currently claim - i never investigated it myself. :P
bionerd23 6 months ago
@bionerd23 It would be pure awesomeness if you made a video about it with your knowledge and stuff. It would be very very interesting.
SuperFinGuy 6 months ago
"I think you should be able to somewhat see inside if you focus on that." YouTube in 3D!!!!! Just kidding. Thanks for showing us the inside story.
tharlowXY 8 months ago
I don't know much chemistry, but I know that Thallium is supposed to be fairly toxic. Does that make those scintillation crystals dangerous to handle?
AsymptoteInverse 8 months ago
@AsymptoteInverse
not really, as they're sealed up. however, they require special disposal, you cannot just throw them into the trashbin.
bionerd23 6 months ago
Have you considered baking the "bad" crystal to remove the humidity? It may also help to change the colour back to normal, since this yellowing effect is often caused by colour centres induced by ionizing radiation- crystal structure dislocations.
Some older camera lenses contain lanthanum and other lanthanides since it produces an excellent high index glass, and this tends to turn the lens brown for this reason. They can sometimes be "fixed" by irradiating them with ultraviolet light.
skonkfactory 8 months ago
Wonderful! I really need to make myself one of those. The parts shouldn't be too expensive. If you have any good advice or good sources for components, I would love to know. Thanks!
antiprotons 8 months ago
@antiprotons
sorry, i'm getting those from private contacts or educational institutes, mostly. the latter is where you may try and ask for old equipment, as especially the "broken" crystal as seen in this video is absolutely useless other than for "toying around" with it. such crystals are usually discarded.
bionerd23 6 months ago
@bionerd23 Ich werde sehen, ob ich das bekommen kann. Es kann eine Weile dauern, aber es würde sich lohnen die Jagd sein. Dank! Und ich danke Ihnen, google translate!
antiprotons 6 months ago
@7alex That is also the reason why scientists never did studies on the effects of these radio waves on the human body, because it has always been considered "common sense" within the scientific community. But when the public want answers, and science is mostly funded by the public, it has to be done. Many are though reluctant to waste their time, but major studies have been done the last few years, revealing nothing new. Anything else? (PM?)
Poleschs 8 months ago
@7alex The potential harmfulness of light depends on the frequency, we all know that gamma rays and x-rays can damage cells and cause cancer. (but breaking the DNA chain in those cells). So by this scale, which scientists have been using all the time, the light from all around you is 10,000 to 100,000 times more dangerous to your body than the signals from your cellphone. I did one mistake in the earlier post, I said "frequency" instead of "wavelength", which the numbers refer to.
Poleschs 8 months ago
@7alex The signals sent and received from your mobile phone is light, or electromagnetic radiation. This radiation has different intensities based on the frequency of the light wave. You have very high intensity light, gamma radiation, which is dangerous. And you have radio waves, which are completely harmless. Gamma rays are 10^-13 to radio waves which are 10^3. Visible or optical light is pretty intense at 10^-6. (continue)
Poleschs 8 months ago
@7alex Heat kill sperm, that's all. If you have any more questions, please ask. Mobile phones pose no harm to biology.
Poleschs 8 months ago
Hi, wo kann ich solch einen Kristall für einen angemessenen Preis bekommen. Sieht interssant aus.
httpkiller 8 months ago
isnt that kinda dangerous to touch? i dont know. but when it has an radio active sign on it i kinda think it would be bad to touch it?
37474748 8 months ago
How cool. Thanks for posting. I want one.
xdoctorEQx 8 months ago
PMT. PhotoMultiplier Tube. Well done! thanks for posting and keep up the good work!
glasstronic 8 months ago
Hello, I like the video :)
Why do the electrons need to be accelerated to be amplified?
dado1802 8 months ago
@dado1802 They are not only accelerated, but also multiplied. The signal from one photon is way too weak to detect with ordinary optical sensors because of all the noise associated with them. So the PMT accelerates electrons so that they land on special electrodes and knock off more electrons that in turn knock off more electrons, effectively multiplying the intensity of the signal by several orders of magnitude, to a level that the counter can register.
yellowmetalcyborg 8 months ago 3
Nice video, thanks for explaining. I read about Scintillators, fascinating.
But by the way, I almost forgot how you looked like , are you camera shy?
kivanctube 8 months ago
Assuming it can be properly isolated from environmental contamination, could this material be integrated into a piece of jewellery such as a ring or necklace pendant? Seeing this video instantly made me think back to LOTR and Frodo Baggins' magic sword ... what if someone invented a necklace that glowed when radiation was near?
Also, just how much radiation DO you need to make these crystals glow?
crimsonhalo13 8 months ago
@crimsonhalo13
I don't really know. But if they would visibly glow before you get to dangerous radiation levels, don't you think they would already be used as simple batteryless ionizing radiation detectors?
superdau 8 months ago
@superdau -- The glow makes me wonder if someone hasn't already done that. If they respond to low level X-rays, there's got to be a way to put one of these in a plastic capsule and use it to determine if one is being irradiated, basically this would be the opposite of a tritium light. From what I hear, though, cost might be a barrier as others have said these crystals are rare and expensive. There's also the lack of a measurement readout to consider.
crimsonhalo13 8 months ago
Although I still have to wonder: would something like a radioactivity-detecting necklace not be useful in a high risk disaster area, like the Japanese nuclear exclusion zones?
crimsonhalo13 8 months ago
@crimsonhalo13 The X-ray tube here was probably delivering a dose rate of HUNDREDS OF REMs per hour. You wouldn't get anywhere near that dose rate level in the case of the Fukushima disaster for instance, until you were inside the containment buildings standing next to the molten cores. And at that point, well, you're pretty much effed anyway. You wouldn't be able to see the glow from one of these things by eye outdoors until the dose rate was phenomenally high.
10mintwo 8 months ago
@10mintwo
yes, absolutely correct. the dose rate for this experiment was very high, as the x-ray tube was very close to the scintillation crystals. in face, if it was a full body dose, this amount of radiation would make you sick with deadly radiation poisoning within about 10 minutes.
bionerd23 6 months ago
@crimsonhalo13
the dose rate was about 30 Sv/h, which is enough to kill you in just minutes (if it were a full body dose). usually, these scintillation crystals are attached to so-called photomultiplier tubes that will GREATLY intensify the emitted light, as it would otherwise not be possible to detect. with save / low x-ray doses, you cannot see any "glow" in the crystal at all with your eyes or a normal camera.
bionerd23 6 months ago
TY BioGirl, your the best :)
caddotservices 8 months ago