[Swlug] DIY solid-state photoluminescent ionising radiation detector

Fri Mar 14 15:48:33 UTC 2025

At Z+0000=2025-03-12Wed21:33:13, peredur.net via Swlug sent:
> Reply from my contact in the radiation world.PeterSent from my Galaxy
> -------- Original message --------From: Gareth Thomas <jgbcthomas at talktalk.net> Date: 12/03/2025  21:25  (GMT+00:00) To: "'peredur.net'" <peredur.net at gmail.com> Subject: RE: [Swlug] DIY Geiger counter
>> Hi Peter Rhys seems like a keen electronics guy. What he describes is making a solid state photo luminescent ionising radiation detector rather than a much more basic ‘regular’ Geiger counter.

    :-D  That's a really cool name!  It's the sort of thing Sheldon Cooper would say! X-D

    A deeper insight is that it's also really useful to know that this project will detect any kind of ionising radiation, not just gamma, beta, & alpha (as long as it does not get blocked by the crystal housing -- that might be a problem to solve later, though).  So given that EMI over a particular frequency or photon energy becomes ionising, all the way up through X-rays and up to gamma, and that ionising radiation is dangerous to biological health, can cause tissue damage, cell damage, and increase the risk of cancer, an ionising radiation detector is a really useful tool for detecting most types of radiation that can harm human health.  Maybe not alpha, depending on design, and almost definitely not neutron radiation, but in the case of nuclear fallout, there would probably be multiple types of radiation present, and your detector will detect at least one of them.

    It'll be interesting to know whether Rhys's detector can also detect ionising radiation from a poorly-designed circuit with high emission of EMI.  Can it detect EMI from a faulty switch-mode power supply, arcing switch, spark plug, or welder?  Can it detect x-rays as it passes through a border baggage-surveillance machine?  Can it detect any concerning amount of ionising radiation in radiation sources that are supposed to be "safe" (nonionising), such as microwaves, 5G, or the hot bottom of a laptop? :-]

    Does it sometimes detect ionising radiation with no apparent cause or explanation?  Does the timing of these coincide with any astronomical events reported by observatories, or any human activities reported globally, such as nuclear detonation tests or plant meltdown or leakage accidents?  Or will we be expected to believe some supernatural Fear-Uncertainty-Doubt poltergeist bullcrap? :-P

    Also, does anything ever inhibit the detector from detecting the background radiation?  Can it ever be inhibited strongly enough to block a strong signal from a direct source of ionising radiation?  What are the failure modes of the device?  Does it fail safe or fail secure?

>> It is a long time since I studied the electronics of radiation detectors so not sure I have the answers he is seeking, but I am pretty sure most Geiger counters don’t ‘store’ the electrical pulses, they just amplify them to a sufficient level to be able to register them on a needle or electronic display. Gareth

    Technically, the capacitors involved in the circuit are storing a value of charge representing the pulses.  But in terms of usages, it is effectively an instantaneous reading, at least the ones with needle dials or real-time digital displays would be (then again, the digital hold function is a limited kind of storage as well).  But in the age of microcontrollers, there's no reason why we can't datalog a stream of analogue values of the envelope of the pulses, just like recording sound from an AM radio receiver.  A lot of possibilities open up for how we can process that datastream if it is recorded digitally.

Kind regards,
James.
-- 
Wealth doesn't bring happiness, but poverty brings sadness.
Sent from Debian with Claws Mail, using email subaddressing as an alternative to error-prone heuristical spam filtering.
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