Photomultiplier Tubes - Page 1
Forum section: electronics / general

author: dexters_lab
author_rank: Unknown
timestamp: February 20, 2015, 08:17:34 am
content: I have just been looking around for photomultiplier tubes as i'm going to experiment making my own scintillation radiation probe and came across these guys in Canada who need to clear out their stock of PM tubes.I think that the Philips branded ones are all $25ea, most are brand new in their original boxes so a good time to pick one up if your a mad wannabe scientist like meTheir website is a bitbut they are friendly, helpful and will ship worldwide.http://www.sphere.bc.ca/test/photo-tubes.html

author: GK
author_rank: Super Contributor
timestamp: February 20, 2015, 10:53:52 am
content: Can I assume that you already have your thallium-activated sodium iodide crystal then? The last I bought new was about $1500 for a little 1/2". A PMT only makes half the detector. Stay away from secondhand scintillation assemblies such as Bicron with the PMT and crystal encapsulated together. It's pot luck that you'd get one with a still decent crystal inside (shock/vibration kills them and they also seem to go cloudy just with age).

author: Psi
author_rank: Super Contributor
timestamp: February 20, 2015, 11:06:59 am
content: Maybe Mike has some laying around.

author: dexters_lab
author_rank: Unknown
timestamp: February 20, 2015, 02:54:31 pm
content: no scintillation crystal at the moment, there are some on ebay of various types from eastern europe/russia but i'm not so inclined to buy yet, i want to just look at the PM bit at the momentThough i did just buy some BC-408 scintillation plastic cheaply off ebay, it's not big enough and the wrong shape but should work enough to test it before i buy an organic crystal.

author: amyk
author_rank: Super Contributor
timestamp: February 20, 2015, 03:07:08 pm
content: "scintillation crystal" sounds so much like something out of sci-fi... or audiophoolery.

author: dexters_lab
author_rank: Unknown
timestamp: February 20, 2015, 03:38:06 pm
content: Quote from: amyk on February 20, 2015, 03:07:08 pmlol, yea something like"wearing a scintillation crystal helps to re-align your quantum entangled aura, improving your well-being"Funny, i read only this morning this passage from a reference book on geiger muller tubes, which could sound equally pseudo science to the uneducated;"To eliminate cosmic mesons it has been customary to surround the beta tube with a ring of cosmic ray tubes in anti-coincidence"

author: jwm_
author_rank: Frequent Contributor
timestamp: February 20, 2015, 04:03:36 pm
content: No need for a crazy expensive crystal, presumably you are not looking for neutrinos. what are you using as a power supply? I have a kiethley tube deal but am swiitching to a modern compact spelman. You know what part of the design I spent the most time agonizing about? Deciding on a connector for the HV line... I went back and forth between BNC, MHV, and SHV and which type of coax a dozen times. Dogshed in my head.Incidentally, it seems that shv connectors are often misidentified as RP-BNC by those that don't know better, you can use this to find deals on them.

author: dexters_lab
author_rank: Unknown
timestamp: February 20, 2015, 04:36:19 pm
content: power supply, well i'm kinda cheating... i picked up a Ludlum counter which can run GM or PM Scintillation probes upto 1.5kv

author: Mechanical Menace
author_rank: Super Contributor
timestamp: February 20, 2015, 05:16:01 pm
content: Quote from: dexters_lab on February 20, 2015, 03:38:06 pmWhich is one of the reasons Woo salesmen love throwing "quantum" into everything. And "Tesla" too...

author: GK
author_rank: Super Contributor
timestamp: February 20, 2015, 10:39:46 pm
content: Quote from: jwm_ on February 20, 2015, 04:03:36 pmA thallium doped sodium iodide crystal is the standard for sensitive gamma ray detection.

author: GK
author_rank: Super Contributor
timestamp: February 20, 2015, 10:42:08 pm
content: If you're going to buy a used crystal from ebay or the like, make sure to see a good photo of the crystal looking down into the window end under bright light. The crystal should be clear. If it looks white and milky the crystal is stuffed, which will most likely be why the crystal is no longer in service.

author: GK
author_rank: Super Contributor
timestamp: February 20, 2015, 10:54:14 pm
content: Quote from: dexters_lab on February 20, 2015, 03:38:06 pmWhen I started playing with these things professionally ~11 years ago I spent ages on a first system design trying to track down the source (presumed to be electrical interference) for the huge scintillation event certainly not originating from my source that the oscilloscope triggered on every so often - cosmic rays.

author: dexters_lab
author_rank: Unknown
timestamp: February 21, 2015, 08:48:15 am
content: thanks GK, yea dont worry i have been doing my research - will be a while before i start investing significant cash for NaI crystalsfound these on ebay too, which is what i will probably use to start with:http://www.ebay.co.uk/itm/251819562390if you look at the sellers other items he does kits of pretty much what i was thinking of doing, PMT, round plastic scintillator, heatshrink etc

author: Kaptein QK
author_rank: Regular Contributor
timestamp: February 21, 2015, 10:59:09 am
content: Quote from: dexters_lab on February 20, 2015, 08:17:34 amThat web design reminded me of this beauty:http://arngren.net/