Mantles contain alpha emitting isotopes, but are a bad example for testing tubes for alpha sensitivity. Here you can see a comparison of tubes https://sites.google.com/site/diygeigercounter/technical/gm-tubes-supported
The last chart shows almost identical counts for the mantle on the SMB-20 (gamma tube) and the SBT-11A (alpha tube) i think that's the one Paul uses. Paul Andrews schrieb am Mittwoch, 2. Dezember 2020 um 18:01:47 UTC+1: > I have an old gas lamp mantle. Very active, but apparently not alpha - > interposing a piece of paper (as has been suggested) has no effect at all. > > On Dec 2, 2020, at 11:11 AM, alb.001 alb.001 <[email protected]> wrote: > > > > I have a few as well in the original packaging. I find them at flea > markets and antique shows. All of the sellers are unaware of their > radioactivity. I paid $2 for each. I have also found some old > pharmaceutical products such as corrosive sublimate pills ( contain > mercuric salts ) which were used to make disinfectant solutions. Also > dangerous and never packaged in anything resembling child-resistant and > very poisonous. I buy them to protect the public who might buy them as a > curiosity and not be aware of the danger they pose. > > Pharma Phil > > ---------- Original Message ---------- > From: GastonP <[email protected]> > Date: December 1, 2020 at 10:00 PM > > An old gas lamp mantle is good enough for the purpose, as its main > emission is alpha particles. It must be an old one because those ones use > thorium oxide to get its distinctive bright, while new ones don't use > thorium. I keep 3 of them, which I got from a local auction site, in a > small ziploc bag that saves me from touching the mantles themselves. > > > On Friday, November 27, 2020 at 8:10:19 AM UTC-3 Sgitheach wrote: > > Would just a chunk of granite (or a granite kitchen worktop if you have > one) be good as a cheap starting point? > On 27/11/2020 10:56, SWISSNIXIE - Jonathan F. wrote: > > I advise against using smoke detectors. To detect heir alpha radiation, > you would have to disassemble the source until you get to the radioactive > isotope plated strip - or button - element. This is sort of not allowed, > and also can be very dangerous if you scratch off radioactive material. > From outside the detector you can only detect the Gammas from the Am-241 > Also Quantities are sort of really high in these devices, depending on make > and model (1-100 uCi Am-241). If you really want to have alpha radiation, i > would purchase a Po-210 source from here: > > https://www.spectrumtechniques.com/products/sources/disk-sources-and-source-sets/ > > > They are like 60$, safe and legal to handle. Only disadvantage is short > half life of 138 days. > You also can find high power Po-210 sources here: > https://www.imagesco.com/geiger/radioactive-sources.html > > Paul Andrews schrieb am Donnerstag, 26. November 2020 um 17:00:06 UTC+1: > > And by 'alpha', I meant 'beta'. I actually did mean alpha, but I was > wrong. Still my old Geiger/Muller tube couldn't detect anything from these > nixies, so at least I can now detect beta particles. Now I need to find an > alpha source! Smoke detectors apparently. > > On Thursday, November 26, 2020 at 10:27:17 AM UTC-5 Pramanicin wrote: > > Still a bit of juice left! > > Sent from my iPhone > > On Nov 26, 2020, at 07:25, Paul Andrews < [email protected]> wrote: > > Finally got an alpha detector for my GK-Mini geiger counter. First > picture is a regular nixie tube. Second is one doped with Kr85 > <IMG_5681.JPG> > > > <IMG_5683.JPG> > > > On Friday, November 6, 2020 at 9:20:54 AM UTC-5 SWISSNIXIE - Jonathan F. > wrote: > > Could also be Ra-226 on the 6140 > > gregebert schrieb am Mittwoch, 4. November 2020 um 16:32:02 UTC+1: > > Maybe it's Thorium, used in the filaments. > > On Wednesday, November 4, 2020 at 4:13:16 AM UTC-8 Paolo Cravero wrote: > > Hi. > Let me add two pictures and a story. > > Lately I picked up locally a bunch of small CRTs (2BP1, that also fit in > the vintage tuner currently on eBay, plus a Marantz) and the guy had a few > NIB tubes too. I was looking for gas-filled ones and that resulted in a > W.E. 6167 dekatron, some 0B2WA and some W.E. 6140/423A. Of particular > interest was the 6140 shown in the picture whose box mentions Kr85, but no > symbol on the glass. > When I came home I checked with a Geiger counter and SBM-20 probe (hard > beta and gamma particles) these tubes and the 6140 from 11/61 shows no > action. Same goes for other 6140 except for one, much older from 12/52 > marked 423A. Neither the box nor the glass carry any warning sign, but this > tube hits >600 CPM vs 40 CPM background when put close to the SBM-20 probe > (it's not the right way to measure radiation, but it's cool :) ). There is > definitely something else than Kr-85 in there! I have blurred pics of it > and it has been stored away from home. > > As already mentioned, Nixies did contain Kr-85 and I knew I had one > clearly marked. It's a Burroughs Self-Scan display that probably needed > some "doping" to handle the almost 1 MHz scan rate. BTW, it contains gas > and I might never use it, so if someone wants to experiment with self-scan > contact me off the list. > > One question for the knowledgeable people in here. I have some Mullard > Nixies marked "Kr-0A": has it got something to do with Kr-85? I can't check > with the Geiger since my probe does not detect Kr-85 leftovers. > > So, if you are on the hunt for active tubes, better look for unmarked > pre-1960 editions and carry a Geiger counter with you ;) > > Paolo > > -- > > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/3f26a1e5-5836-4ff5-b1ea-f95fab53151cn%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/3f26a1e5-5836-4ff5-b1ea-f95fab53151cn%40googlegroups.com?utm_medium=email&utm_source=footer>. > > > <IMG_5683.JPG> > <IMG_5681.JPG> > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/d65b18e5-dbaf-4d6c-8d86-fc88fbf2f7bdn%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/d65b18e5-dbaf-4d6c-8d86-fc88fbf2f7bdn%40googlegroups.com?utm_medium=email&utm_source=footer>. > > > > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/6945048a-53f8-4b96-9006-7d712986adc7n%40googlegroups.com > > <https://groups.google.com/d/msgid/neonixie-l/6945048a-53f8-4b96-9006-7d712986adc7n%40googlegroups.com?utm_medium=email&utm_source=footer>. > > > > > > > -- > > You received this message because you are subscribed to a topic in the > Google Groups "neonixie-l" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/neonixie-l/BL83MEnFSbA/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/377314040.1518586.1606925507144.JavaMail.open-xchange%40mtlgui07 > > <https://groups.google.com/d/msgid/neonixie-l/377314040.1518586.1606925507144.JavaMail.open-xchange%40mtlgui07?utm_medium=email&utm_source=footer> > . > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. 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