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From: Tom Roberts <tjoberts137@sbcglobal.net>
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On 11/23/24 1:12 AM, ProkaryoticCaspaseHomolog wrote:
> [...] Of all the schemes I could think of whereby a DIY amateur scientist
> can verify E=mc², the only feasible one that I can think of is to
> measure the energy of electron-positron annihilation. 

You'll need a budget of at least $10,000.00 (probably more), and I doubt 
you could obtain a useful resolution (say, 1%).

> I'd need
> the help of an expert former EE to put things together (hint, hint).

Or better, the assistance of an experimental particle physicist. But it 
would be quite difficult to interest someone with the requisite 
skills.... I have those skills, but am not interested.

> Sealed sodium-22 positron sources are readily available for sale
> online.

Yes. But I don't know if they will sell to an unaffiliated DIY 
experimenter. Sales of radioactive objects are often restricted, and 
they are usually prohibited in standard delivery channels (UPS, FedEx, 
USPS, ...).

> Calibrating the gamma-ray detectors will be the hard part. 

Yes. You'll need several different gamma sources with known emission 
energies.

> Once
> calibrated, I'd place two gamma-ray detectors 180 degrees apart
> equidistant from an appropriate target. Connected to the detectors
> will be a whole slew of equipment for coincidence counting, energy
> measurement, etc. that the expert former EE will be responsible for.
> 
> With luck, the DIY experimenter will be able to confirm the
> simultaneous emission of two 511 keV photons from each annililation.

This is certainly doable. Whether it is worthwhile is a quite different 
issue -- personally I doubt it.

Note: this is the sort of experiment that could be in the syllabus of 
the appropriate undergraduate lab class at a good college or university. 
(They would use the equipment for several different experiments and many 
students.)

Tom Roberts