Another brilliant video! I have a number of PMTs including the side window ones - I also have two of those geiger counters that you are using in the video - I find them absolutely excellent and they must have cost a bit back in the day. I have never had a solid state detector to try them with only GM ionisation chamber tubes. I also use a Fluke 73!
Thanks, yeah, PMT are quite fascinating devices. These old Geiger counters are quite easy to work on. I've repaired a few but never found a circuit diagram for one. Only recently acquired a solid-state alpha detector (on another video), which is interestingly sensitive to visible light but other than that only alpha particles. Although semiconductor detectors are becoming more common I remember an early solid-state detector back in the 1980s at work that needed to be constantly maintained at a low temperature with liquid nitrogen or it would quickly degrade.
brilliant vidéo!! i'm making my own too ; by the way whats the model of the geiger counter you're using ? i'm look for its reference to get its high voltage schematic ;) thanks
Thanks, I was using a Nuclear Enterprises contamination meter 95/0339. These come up in eBay quite a lot but I haven't found a circuit diagram for them. They are not too complicated and used discrete components so can be worked on easily. I did have one with a transformer fault which was a bit more difficult to repair. The PMT was a Mullard 150AVP
What sort of plastic is that scintillatorplastic? Can you use normal plastic or does it have to be a special and probably costly scintillator? Great idea you tried that other piece too!
Plastic scintillators for PMTs are manufactured and are quite expensive but cheaper and more workable that others such as Sodium Iodide crystals. Not too sure of the types I have here, most seem to be made with benzine compounds. I just wondered, but wasn’t too hopeful, if something fluoresced under UV it might scintillate under higher levels radiation. Most scintillators used with PMT seem to fluoresce under UV.
Hello! What is the difference between square vs hexagonal vs round photo multiplier tubes? In gamma cameras still using round shape which is covers lower area compare to square or hexagonal. Thanks in advance.
Good point, not sure I know exactly either, but as you say hexagonal and square can be closer packed to cover an area efficiently with effectively more sensitivity. Don’t think I have seen many square ones though. Interesting the gamma camera you mention uses round tubes. I have seen light pipes used to couple scintillators to the PMT that way avoiding missed areas but at the cost of possible light attenuation so the scintillator shape may be more important that the PMT.
Really good ideas and good work
Nice to see you are keeping busy! Keep the experiments coming 🤓
Another brilliant video! I have a number of PMTs including the side window ones - I also have two of those geiger counters that you are using in the video - I find them absolutely excellent and they must have cost a bit back in the day. I have never had a solid state detector to try them with only GM ionisation chamber tubes. I also use a Fluke 73!
Thanks, yeah, PMT are quite fascinating devices. These old Geiger counters are quite easy to work on. I've repaired a few but never found a circuit diagram for one. Only recently acquired a solid-state alpha detector (on another video), which is interestingly sensitive to visible light but other than that only alpha particles. Although semiconductor detectors are becoming more common I remember an early solid-state detector back in the 1980s at work that needed to be constantly maintained at a low temperature with liquid nitrogen or it would quickly degrade.
@@tuopeeks Excellent - I will have to look at the video of yours on the solid state detector.
Nice
PMT's are awesome. Is that a Hamamatsu?
These are all quite old, the largest is, I think a Thorn-EMI tube the next is Mullard and the smallest is RCA
Thanks! I appreciate the info, I enjoy your videos too!@@tuopeeks
brilliant vidéo!! i'm making my own too ; by the way whats the model of the geiger counter you're using ? i'm look for its reference to get its high voltage schematic ;) thanks
Thanks, I was using a Nuclear Enterprises contamination meter 95/0339. These come up in eBay quite a lot but I haven't found a circuit diagram for them. They are not too complicated and used discrete components so can be worked on easily. I did have one with a transformer fault which was a bit more difficult to repair. The PMT was a Mullard 150AVP
@@tuopeeks thank you very much^^
Yay
What sort of plastic is that scintillatorplastic? Can you use normal plastic or does it have to be a special and probably costly scintillator? Great idea you tried that other piece too!
Plastic scintillators for PMTs are manufactured and are quite expensive but cheaper and more workable that others such as Sodium Iodide crystals. Not too sure of the types I have here, most seem to be made with benzine compounds. I just wondered, but wasn’t too hopeful, if something fluoresced under UV it might scintillate under higher levels radiation. Most scintillators used with PMT seem to fluoresce under UV.
Hello! What is the difference between square vs hexagonal vs round photo multiplier tubes? In gamma cameras still using round shape which is covers lower area compare to square or hexagonal. Thanks in advance.
Good point, not sure I know exactly either, but as you say hexagonal and square can be closer packed to cover an area efficiently with effectively more sensitivity. Don’t think I have seen many square ones though. Interesting the gamma camera you mention uses round tubes. I have seen light pipes used to couple scintillators to the PMT that way avoiding missed areas but at the cost of possible light attenuation so the scintillator shape may be more important that the PMT.