So, in the fine tradition of using bananas for scale…
Bananas are slightly more radioactive than the background, due to potassium-40 content. So an informal unit of radiation measure in educational settings is the ‘banana-equivalent-dose’, which is about 0.1 microsieverts.
My particle spectrometer saw first light today, and I figure that I could use a banana to calibrate it. Then I noticed that K-40 undergoes a rare (0.001%) decay to 40Ar, emitting a positron. So not only is a banana a decent around-the-house radioisotope source, it’s also an antimatter source.
Nice – you wouldn’t happen to have any ideas on how to differentiate positron annihilation, from the continuous distribution of β− energies caused by the more common decay mode, using only a PIN photodiode? I’m a bit stumped on this point and suspect it’s not possible. I probably need to do gamma spectroscopy but would really rather not.
Bananas are not typically very high on the danger scale except in exotic (and universally embarrassing) circumstances.
In fact, that’s another thing we could use bananas for scale with. Probably driving to work is equivalent to several kilobananas worth of danger daily :)
Anyway, I think the positron should be about 44keV if that helps you calibrate your magnets. The typical banana should produce something on the order of a positron every 10 seconds (although I used much rounding for the sake of brevity). Most commercial positron sources e.g. used in hospital PET scanners, are many times stronger than that!
So, in the fine tradition of using bananas for scale…
Bananas are slightly more radioactive than the background, due to potassium-40 content. So an informal unit of radiation measure in educational settings is the ‘banana-equivalent-dose’, which is about 0.1 microsieverts.
My particle spectrometer saw first light today, and I figure that I could use a banana to calibrate it. Then I noticed that K-40 undergoes a rare (0.001%) decay to 40Ar, emitting a positron. So not only is a banana a decent around-the-house radioisotope source, it’s also an antimatter source.
Truly a remarkable and versatile fruit.
Sorry, I understood that.
Nice – you wouldn’t happen to have any ideas on how to differentiate positron annihilation, from the continuous distribution of β− energies caused by the more common decay mode, using only a PIN photodiode? I’m a bit stumped on this point and suspect it’s not possible. I probably need to do gamma spectroscopy but would really rather not.
the trickery is to detect two gammas emitted simultaneously in exactly opposite directions
This is some seriously dangerous information to be feeding me bro.
Now… to find magnets able to contain the antimatter…
Bananas are not typically very high on the danger scale except in exotic (and universally embarrassing) circumstances.
In fact, that’s another thing we could use bananas for scale with. Probably driving to work is equivalent to several kilobananas worth of danger daily :)
Anyway, I think the positron should be about 44keV if that helps you calibrate your magnets. The typical banana should produce something on the order of a positron every 10 seconds (although I used much rounding for the sake of brevity). Most commercial positron sources e.g. used in hospital PET scanners, are many times stronger than that!